A Design Tool for the Evaluation of Atmosphere Independent Propulsion in Submarines

A DESIGN TOOL FOR THE EVALUATION OF ATMOSPHERE INDEPENDENT PROPULSION IN SUBMARINES by Grant B Thomton LCDR USN BS Marine Engineering United States Naval Academy 1979 SUBMITTED TO THE DEPARTMENTS OF OCEAN ENGINEERING AND MECHANICAL ENGINEERING IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREES OF MASTER OF SCIENCE IN NAVAL ARCHITECTURE AND MARINE ENGINEERING and MASTER OF SCIENCE IN MECHANICAL ENGINEERING at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY May 1994 Copyright 1994 Grant B Thomton The author hereby grants to MIT permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part Signature of Author uDepartments of Ocean and Mechanical Engineering May 6 1994 Certified by Professor David Gordon Wilson Thesis Reader Department of Mechanical Engineering Accepted by Prfess A Douglas Carmichael Thesis Advisor and Chairma0 Jepartment Committee on Graduate Students W1IT Department of Ocean Engineering i JUN 2 i 1994 JUN 2 0 1994 Lonn Blank Reverse A DESIGN TOOL FOR THE EVALUATION OF ATMOSPHERE INDEPENDENT PROPULSION IN SUBMARINES by Grant Blount Thornton Submitted to the Departments of Ocean Engineering and Mechanical Engineering on May 6 1994 in partial fulfilment of the requirements for the Degrees of Master of Science in Naval Architecture and Marine Engineering and Master of Science in Mechanical Engineering ABSTRACT For the United States Navy submarine propulsion has long since evolved from Diesel Electric to a complete reliance on Nuclear Power Nuclear propulsion is the ultimate atmosphere independent power source allowing the submarine to divorce itself from the surface limited only by the endurance of the crew embarked Submarine construction and operating costs have grown dramatically due largely to the cost of the high performance nuclear propulsion plant Other options exist to provide Atmosphere Independent Propulsion of similar capability for extended underwater periods at a potentially lower cost This thesis explores the aspects of nonnuclear atmosphere independent propulsion as an integral part of the submarine design process focusing on methods for power generation and various options for fuel and oxidant storage Fuel sources include pure hydrogen stored cryogenically or in metal hydrides or more common fuels such as diesel or methanol used either directly or in a reformed state Oxidants include pure oxygen stored cryogenically or in compressed form as well as hydrogen peroxide and sodium perchlorate Energy conversion methods examined include mechanical such as closed cycle diesels Brayton cycles and Stirling engines to electrochemical designs such as fuel cells and aluminum oxygen semi cells A computer code was written which integrates these propulsion options with mission and owners requirements to provide a balanced design in terms of matching the weights and volumes of the equipment installed This code will serve as a tool for the concept design of nonnuclear air independent submarines Thesis Supervisor A Douglas Carmichael Professor of Ocean Engineering Thesis Reader David Gordon Wilson Professor of Mechanical Engineering 3 Blank Reverse ACKNOWLEDGEMENTS I wish for reference to acknowledge the following persons who aided me in my search material Dave Bagley Mark Cervi Henry DeRonck LCDR Norbert Doerry Richard Martin Warren Reid Ed Robinson Steve Sinsabaugh LT Cliff Whitcomb I hope that I have correctly available to me NSWC Annapolis NSWC Annapolis International Fuel Cells NAVSEA Draper Laboratory NSWC Annapolis NAVSEA PEO SUBR LORAL Defense Industries NSWC Carderock interpreted the information that you made I am grateful for the counsel in ship and submarine design provided by Professors Alan Brown and Jeff Reed in the Naval Construction and Engineering Program at MIT I wish to thank my Thesis Advisor Professor A D Carmichael who inspired me to investigate the realm of Air Independent Propulsion as a student who stood by me as I worked to put my research together in an orderly fashion and who taught me to be aware of the salesman and the customer when evaluating data But most of all I am thankful for the love and understanding of my family Daryl David and Megan as I complete my studies at MIT 5 Blank Reverse TABLE OF CONTENTS ABSTRACT ACKNOWLEDGEMENTS TABLE OF CONTENTS LIST OF FIGURES LIST OF TABLES CHAPTER ONE 10 Introduction 11 History 12 Air Independence Concept 13 Propulsion Options 14 Thesis Objective CHAPTER TWO 20 The Design Process 21 Mission Requirements 22 Required Operational Capabilities 23 Submarine Hull Synthesis CHAPTER THREE 30 Submarine Systems 31 Propulsion Integration 311 Conventional DC 312 Permanent Magnet AC 313 Superconducting Homopolar DC 314 Propulsors 32 Ship Service Power Requirements 33 Auxiliary Systems 34 Atmosphere Control CHAPTER FOUR 40 Power Sources 41 ElectroChemical Concepts 411 Fuel Cells 4111 Proton Exch Membrane Fuel Cells 4112 Alkaline Fuel Cells 4113 Phosphoric Acid Fuel Cells 4114 Molten Carbonate Fuel Cell 4115 Solid Oxide Fuel Cell 4116 Direct Methanol Oxidation Fuel Cell 412 Aluminum Oxygen SemiCell 413 Batteries 4131 Lead Acid Batteries 41 32 NickelCadmium Batteries 7 3 5 7 13 17 19 19 20 21 21 25 27 29 33 37 38 38 40 42 44 44 46 46 51 52 52 54 57 57 58 60 60 62 64 65 68 Blank Reverse 4133 SilverZinc 70 4134 LithiumAliminum Iron Sulfide 72 42 Mechanical Power Sources 74 421 Closed Cycle Engines 74 4211 Closed Cycle Diesel 74 4212 Closed Brayton Cycle 77 422 Stirling Engine 79 423 Other Power Cycles 80 4231 Rankine Cycle 81 4232 Small Nuclear Power 83 4233 Walter Cycle 83 CHAPTER FIVE 50 Reactants 87 51 Fuels 88 511 Hydrogen 88 5111 Hydrogen Gaseous Storage 89 5112 Hydrogen Cryogenic Storage 89 5113 Hydrogen Metal Hydride 90 5114 Hydrogen By Reformation 92 512 Other Fuels 94 52 Oxidants 95 521 Oxygen 95 5211 Oxygen Gaseous Storage 95 5212 Oxygen Cryogenic Storage 96 5213 Oxygen Chemical Reformation 98 5214 Oxygen Generation Onboard 99 522 High Test Hydrogen Peroxide 99 53 Waste Products 101 CHAPTER SIX 60 The Submarine Model 105 61 Hull Envelope 106 62 Volume Estimates 107 621 Pressure Hull Volume 107 6211 Mobility Volume 107 6212 Weapons and C31 Volume 108 6213 Ship Support Volume 108 622 Other Volumes 109 63 Weight Estimates 110 631 Surfaced Displacement 111 6311 Structural Weight 111 6312 Mobility Weight 111 6313 Weapons and C31 Weight 112 6314 Ship Support Weight 112 6315 Fixed Ballast and Variable Load Wt 113 9 Blank Reverse 64 Powering and Edurance 641 Powering 6411 Hydrodynamics 6412 Propulsion Motor Turndown 642 Snort Power and Bunker Fuel Calculation 643 Hotel Loads 644 Battery Endurance 65 The AIP Plant CHAPTER SEVEN 70 Computer Code Development 71 Overview CHAPTER EIGHT 80 Results and Conclusions 81 Model Validation 82 General Results 821 Overall AIP Impact 822 Impact of Reactants 823 Impact of Other Technologies 83 Ship Tradeoffs CHAPTER NINE 90 Areas for Future Study REFERENCES APPENDIX A APPENDIX B APPENDIX C APPENDIX D APPENDIX E APPENDIX F APPENDIX G APPENDIX H POWER SOURCE DOCUMENTATION REACTANT DOCUMENTATION BASELINE MODEL HULL ENVELOPE VOLUME DATA BASE WEIGHT DATA BASE SNORKEL POWERING RESULT DATA TABLES APPENDIX I COMPUTER CODE 11 114 114 114 117 117 118 119 120 121 121 125 125 127 128 130 132 135 139 141 147 163 175 191 195 201 205 207 211 Blank Reverse LIST OF FIGURES 21 Acquisition Milestones and Phases 26 22 The Design Spiral 27 23 Balancing Weights and Volumes 35 31 Battery Stepping Operating Modes for a Double Armature DC Mtr 39 32 Permanent Magnet Axial Gap Propulsion Motor 40 33 Permanent Magnet High Speed Generator 41 34 Example of Chopped AC Output from Input DC 42 35 Superconducting Homopolar DC Motor 43 36 Typical Ship Service Distribution System 45 37 Hydraulic System with Typical Loads 47 38 High Pressure Air System 47 39 Ventilation Arrangement 49 41 Efficiency vs Load for AIP Options 53 42 Proton Exchange Membrane Fuel Cell 55 43 PEM Cell Voltage vs Cell Load 56 44 Molten Carbonate Fuel Cell 59 45 Westinghouse Solid Oxide Fuel Cell 61 46 Aluminum Oxygen SemiCell 63 47 Lead Acid Battery Schematic 67 48 Typical Lead Acid Discharge Characteristics 67 49 NickelCadmium Discharge Characteristics 70 410 Silver Zinc Discharge Characteristics 72 411 LAIS Battery Discharge Characteristics 74 412 Closed Cycle Diesel with Exhaust Management System 76 413 Closed Brayton Cycle Combustion Power System 78 414 Closed Brayton Cycle Schematic Flow Diagram 79 415 Stirling Operating Cycle 81 416 MESMA Operating Cycle 82 417 AMPS Power Cycle 84 418 Walter Power Cycle 85 51 Metal Hydride Storage in ExU1 German Type 205 91 52 Hydrogen Content of Various Fuels 94 53 Torroidal Gaseous Oxygen Storage Concept 96 54 44 Inch UUV Oxygen Supply Concept 98 55 Comparison of Oxidant Storage Methods 100 56 Liquid Gas Flow Mixer 102 57 Cosworth Exhaust Management System 103 61 The Submarine Envelope 106 71 SUBSIZE Flowchart 122 13 Blank Reverse 81 Comparison of Canadian Hybrid Submarine and SUBSIZE Results 126 82 Comparison of AIP Plants 129 83 AIP Plant Variation with Endurance 129 84 Comparison of Oxidant Storage Methods 131 85 Comparison of Hydrogen Storage Methods 131 86 Comparison of Battery Options with Fixed Creep Endur Reqmt 132 87 Comparison of Battery Options with Fixed Burst Endur Reqmt 133 88 Effect of Propulsive Coefficient on NSC 134 89 Effect of LD Ratio on NSC and SHP 135 810 Effect of AIP Speed on NSC 136 A 1 NiCd vs Discharge Rate 160 B 1 Liquid Oxygen Tank Arrangement 167 C1 Profile View of Baseline Submarine 176 C2 Chart of Propeller Efficiency 178 D1 The Body of Revolution Hull 192 D2 Effects of na and nfon Hull Geometry 193 E1 Mobility Density 197 E2 Torpedo Tube and Reload Density 197 G1 Wave Drag Coefficient 206 15 Blank Reverse LIST OF TABLES 11 AIP Power Source and Reactant Options 22 21 Comparison of AlPConventional Submarines 30 22 Statement of Requirements 32 23 Design Philosophy 33 31 Propulsion Options 38 41 ElectroChemical AIP Concepts 52 42 Summary of Battery Types 65 43 Mechanical AIP Concepts 75 51 AIP Reactant Options 87 81 Comparison of AIP Plant Densities 127 82 Effect of Propulsion Motor Type on NSC 134 83 Indiscretion Ratio and Speed of Advance 137 A 1 Summary of Energy Conversion Devices 148 B1 Reactant Packing Factors 164 C1 Baseline Submarine Summary 177 C2 Summary of Propeller Characteristics 177 C3 Propeller Selection Spreadsheet 179 D1 Selected Values for Cp and Csf 193 E 1 Summary of Volume Data 196 F 1 Summary of Weight Data 202 17 Blank Reverse CHAPTER ONE 10 INTRODUCTION 11 HISTORY The submarine a dramatic addition to any countrys naval arsenal is well documented throughout history With modest beginnings as early as the Turtle in the Revolutionary War 11 the importance of the submarine has grown as technology has enabled the ship to develop greater agility and endurance in its operations Submersible boats powered by diesel electric propulsion plants on the surface and lead acid storage batteries submerged were first used extensively in combat during World War I by the German Navy where they were very effective in sinking considerable military and civilian shipping in an attempt to isolate England and her allies from the United States World War II brought more advanced ships into combat with similar tactics as these ships were still not true submersibles With a hull design more akin to performance on the surface these were still ships that operated largely on the surface of the sea only to submerge for their torpedo attack Though the Germans worked feverishly on developing new technologies to enable the submarine to stay submerged longer such as the snorkel and an air independent power plant the Walter Cycle a carbon dioxidesteam Rankine cycle powered by high test hydrogen peroxide 46 they were eventually overcome by Allied tactics and superior strength The United States submarine force was also successful in their campaigns against the Japanese Empire Instrumental in holding the Japanese in check while the United States recovered from the attack on Pearl Harbor their heroic actions against military and merchant shipping were critical to defeating the Japanese Still the submarine 19 was a surface ship that dived to attack and was limited in its ability to obtain air from above to sustain propulsion beyond slow speeds on battery power The advent of nuclear power in the late 1950s brought a significant shift in submarine design and use With a power source that was truly divorced from the surface an emphasis was placed on underwater performance Submarine hull shapes similar to the now familiar tear drop Albacore Hull became commonplace and tactics sensors and weapons evolved that were designed to be employed with the ship underwater The price of nuclear power however is not cheap Not only was the cost of development expensive but the necessary infrastructure to build maintain and train such a force limited its acceptance to only a few nations with the necessary financial resources This meant that those countries that wished to continue to develop their own submarine fleets must work on improving the diesel boat design 12 AIR INDEPENDENCE CONCEPT While submarine improvements can take many forms this thesis will concentrate on those which enhance propulsion endurance The concept of Air Independent Propulsion AIP can be defined many ways but will be taken here to mean propulsive power that is generated without inducting an oxidant air from the atmosphere Modern diesel electric submarines seek to improve the amount of time that they can divorce from the surface which is accomplished by increasing the storage capacity of installed secondary batteries and by decreasing the required submerged electrical load through more power efficient equipment and reduced electric propulsion loads more efficient hull designs and propulsors Modern diesel electric submarines extend this time to many hours but usually at the expense of limiting the submarine to slow speed and impacting the habitability of the crew It is the AIP 20 concept that may enhance the performance of this capable diesel submarine platform by extending this submerged endurance to many weeks without severely hampering the ship or the crew 13 PROPULSION OPTIONS Imagine any way to store any form of energy and to convert that stored energy to electricity or mechanical work and you have a potential AIP source These ideas however must be tempered by common sense and the bounds of what could conceivably placed in the hull of a submarine Table 11 presents a list of possible AIP power systems that have been proposed or developed divided into two areas Power Sources and Reactants All power sources must consume some combination of reactants usually a fuel and an oxidant to provide power output While nuclear power is considered the ultimate AIP source due to its infinite relative to any mission requirement stored energy capacity only nonnuclear AIP sources will be considered in this thesis 14 THESIS OBJECTIVE Many nations desire the goal of unrestricted submarine operations but are unable or unwilling to make the step to nuclear power Even the United States a world leader in safe and reliable nuclear propulsion may have cause to consider returning to a mix of nuclear and nonnuclear submarines to perform its assigned missions worldwide The question becomes which one of the possible AIP systems to choose and what will its impact be This thesis attempts to answer that question by development of a computer model in C to integrate the submarine design process with the various propulsion plant options and reactant storage methods 21 Table 11 AIP Power Source and Reactant Options Power Sources ElectroChemical Remarks Proton Exchange Membrane Fuel Cell Most promising HO cell Alkaline Fuel Cell Proven design Phosphoric Acid Cell Proven design low interest Molten Carbonate Fuel Cell Mature commercial applications Solid Oxide Fuel Cell Immature highest projected efficiency Aluminum Oxygen SemiCell Competitive with PEM cell Lead Acid Battery Proven performance Nickel Cadmium Battery Higher power density than lead acid LithiumAluminumIron Sulfide Battery Potential successor to lead acid Power Sources Mechanical Closed Cycle Diesel Mature lowest cost system Stirling Engines Mature low power only Closed Brayton Cycles Excellent potential for development Rankine Cycles Proven technology Walter Cycles Safety of HO Reactants Fuel Hydrogen Pure source hard to store Hydrocarbon Based Fuels With reformerbest hydrogen source Reactants Oxidants Oxygen Cryogenics best method Hydrogen Peroxide Potentially unstable if concentrated Chemical Reformation Competitive in some applications 22 including consideration of owners requirements for ship performance The model will allow a user to input various performance criteria such as range maximum speed AIP endurance select a type of AIP power plant and form of reactant and develop a balanced estimate of the required submarine size in terms of its principal dimensions as well as other submarine attributes such as displacement reserve buoyancy and lead margins For the propulsion plant and reactant options the field was limited to those options which are currently in development or which have had development work attempted although other options are mentioned 23 Blank Reverse CHAPTER TWO 20 THE DESIGN PROCESS The ship procurement process is long and complex employing many different strategies and methods to achieve a final product that meets the needs of the customer in terms of performance and cost While there are as many different ways to approach this problem as there are countries that attempt it they all share a common approach in that they Identify requirements which result in a need for a ship Determine required capabilities Examine alternatives on paper Tradeoff these alternatives using self imposed priorities Select a concept on which to do detailed design Construct the ship and measure its performance Evaluate the ships success in terms of meeting stated requirements The United States Navy has adopted the format illustrated in Figure 21 for this acquisition process Each milestone represents a decision point where the work from the previous phase is evaluated and if appropriate a decision made to proceed with requirements established for the next phase Each phase represents a process where options are evaluated and tradeoff decisions made to achieve the required level of detail for that design This thesis supports Phase 0 the concept design phase of the design process Given the operational requirements set out by the owner concepts to meet these requirments are explored then for the most viable concepts estimates are made of the required volume and weight for a ship meeting these 25 Acquisition Milestones and Phases Figure 21 9 requirements and a ship is synthesized including the buoyancy and balance requirements unique to submarine design This balancing process is iterative and can be best visualized as a spiral Figure 22 Because a successful design is the result of the efforts of many individual expert teams each will focus on the current set of requirements evaluating their impact on each other once all have completed their calculations From these results revised requirements are established and each team refines their estimates each time obtaining a solution more in harmony with the others Section 21 describes the mission requirements for AlP submarines one of the key inputs to the development of a concept design Section 22 addresses the process of establishing priorities among the required capabilities established while Section 23 provides an overview of the process required for submarine hull synthesis 26 Preliminary Sizing Arrangements The Design Spiral 34 Figure 22 21 MISSION REQUIREMENTS What performance characteristics should an AIP submarine possess Clearly the evolution from diesel to nuclear power brought an increase in the ability of the submarine to transit from station to station quickly and covertly remaining submerged for weeks on end Aside from this step increase in performance other improvements in hull and propulsor design have stretched the envelope even further How many of these and other improvements can be applied to AIP submarine design and what can the expected performance results be It will be shown that while an AIP power plant can significantly 27 improve the performance of a conventional submarine when compared to a nuclear powered submarine the current state of AIP technology places limits on key parameters such as patrol speed burst speed and submerged endurance When the United States committed itself to an all nuclear submarine force it adopted the philosophy that these ships should be multimission capable The LOS ANGLES class submarine exemplifies this mind set Built for speed this class of submarine was enhanced to improve its ability to keep pace with and support a high speed carrier battle group while maintaining the tools necessary to perform other submarine missions The addition of vertical launch cruise missiles to the LOS ANGLES class has added yet another dimension to this formidable platform Estimated SEAWOLF capabilities echo this commitment to a multimission platform It can be argued that the United States possesses the only true blue water navy in the world and perhaps the only one requiring a sustained high speed capability Most nations with submarines are concerned with defense of their home waters and have designed their navies accordingly For example Swedens submarines operate in the Baltic Sea which is nominally 200 nautical miles nm wide with a maximum transit distance to patrol of 1000 nm As a result Sweden has incorporated a low power 275 kW Stirling Engines AIP power plant in their submarine NAECKEN 20 Canada has expressed interest in a long range AIP capability for its next generation diesel submarine to enable her to control the vast ocean basin underneath the Arctic ice cap while Australia requires a similar long range capability of 9000 nm to patrol and defend her expansive coastline 67 68 Missions compatible with the role of the submarine in the U S Navy include 28 Peacetime Engagement show the flag Surveillance Deterrence Regional Sea Denial Precision Strike Warfare Ground Warfare Support Unrestricted Submarine Warfare 62 All of these missions can be performed by an AIP capable submarine Table 21 summarizes the operational capabilities of several classes of conventional and AIP capable submarines Included in the table are designs already in service as well as several designs not yet proven at sea The operational characteristics of a LOS ANGELES class submarine are included for comparison to illustrate the impact of nuclear power on submarine design As can be seen many nations have settled on designs that are significantly smaller than the LOS ANGLES class submarine It is also interesting to note that the conventional designs all have similar albeit less capable operational characteristics indicating the current limits placed on submarine design by AIP andor diesel technology 22 REQUIRED OPERATIONAL CAPABILITIES In developing the actual concept design for a submarine the owner or sponsor for the ship must specify what requirements the ship must meet to be considered an acceptable design From the Milestone 0 approval for example specific capabilities would be matched to the required missions for the submarine Section 21 above such as 29 Table 21 Comparison of AlPConventional Submarines a Janes Fighting Ships 199091 Capt Richard Sharpe OBE RN ed London England b Stennard J K Comparative Naval Architecture of Modem Foreign Submannes Thesis Ocean Engineering Department Massachusetts Institute of Technology May 1988 c Anon The WALRUS LaunchedFirst of a New Class of Dutch SSK The NavalArchitect Royal Institute of Naval Architects London England January 1986 d Anon Maritime Defence Volume 8 Number 4 April 1983 e Anon The Kockums Group Advertising Supplement to Janes Defense Weekly March 1994 f Australian Collins Class Submarine Takes Shape The Naval Architect Royal Institute of Naval Architects London England February 1993 g The A19 and Type 471 Submarines from Kockums The Naval Architect Royal Institute of Naval Architects London England May 1991 30 Los Angeles Kilo Walrus Type 2400 Type 1700 Naecken Collins Country US USSR Netherlands UK FGR Sweden Australia Info Source a a b c b d a ef Year in 1976 1980 1985 1986 1984 1980 1994 Service Submerged 6927 Ron 3000 Iton 2800 Iton 2400 Iton 2350 Iton 1085 Iton 2450 Iton Displacement 3000AIP Length 360 f 2395 ft 2231 f 2306 ft 2165 ft 1821 ft 2493 ft Diameter 33 ft 312 It 276 ft 25 ft 239 ft 18 ft 262 ft Diving Depth 1475 ft 1000 ft 1000 ft 660 ft It 1000 1000 f 1000 ft Max Subm 30 knots 17 knots 20 knots 20 knots 25 knots 20 knots 20 knots Speed Shaft 35000 hp 6000 hp 6900 hp 5360 hp 6600 hp 1800 hp 6000 hp Horsepower AIP Power Y N N N N Y Planned Source Nuclear Stirling PEMStirling Mission 90 days 45 days 70 days 49 days 70 days days Length Complement 133 men 45 men 50 men 44 men 35 men 19 men 42 men Range Unlimited 9600 nm 10000 nm 7056 nm 10000 nm 9000 nm Torpedo 4 6 4 6 6 8 6 Tubes Torpedo 22 18 24 12 20 12 Reloads Cruise Missile Y Y Y Y Y Y Y Y N Y NY Y Y Mine Capable Mission Capability Surveillance Coastline and Open Ocean monitoring Drug Interdiction Ground Warfare Seal Team Insertion and Recovery Strike Warfare Launch Cruise Missiles against land targets In meeting these capabilities operational performance parameters will be specified to give the naval architect measurable attributes upon which to base the design This Statement of Requirements will also provide a range of acceptable values from a Goal or optimum value for that characteristic to a Threshold or minimum acceptable value A ship that does not at least meet all the threshold values established by the owner will generally not be accepted The range of values specified for each requirement provide the latitude necessary for trading off capabilities Table 22 illustrates a typical Statement of Requirements for an AIP submarine The final piece of logic to be communicated in this statement of owners requirements is the priority to be assigned to the attributes which are mutually exclusive of each other This design philosophy is usually stated in some form of hierarchy assigning relative weights to the attribute the owner considers most important This concept is illustrated in Table 23 With the required missions determined the required capabilities in several areas stated and the relative priority for meeting the desired capabilities established the design team can proceed with concept exploration As an example of the type of tradeoffs to be made consider submerged endurance on the battery For a given battery type increasing endurance for a given speed on battery power alone means increasing the battery size weight and cost If the battery is larger the ship size may have to be increased to 31 Table 22 Statement of Requirements support the increased battery weight Increasing both the battery and ship size will most likely increase the cost of the ship By Table 23 cost is a higher priority 10 than battery endurance 8 Therefore after the impact of increasing battery endurance on the overall ship cost is studied one might expect that battery endurance would be sacrificed to keep costs down 32 Requirement Goal Threshold Diving Depth 1000 feet 700 feet Range Snorkeling 10 kt SOA 15000 nm 10000 nm Submerged 8 knots AIP 30 days 20 days Submerged 4 knots battery 120 hours 90 hours Submerged maximum speed 5 hours 2 hours Endurance 90 days 60 days Speed Submerged maximum 24 knots 20 knots Snorkeling sustained 12 knots 10 knots Surfaced maximum 15 knots 12 knots Indiscretion Rate Transit 10 knot SOA 03 04 On station 8 knots 005 01 Weapons Number of Torpedo Tubes 6 4 Total Weapons Load 24 16 Weapons Type Threshold TorpedoesCruise eapons Type Tresold MissilesMines Manning 40 men 50 men Main Ballast Tank Volume of everbuoyant 15 12 volume Lead Ballast of normal surfaced condition 10 5 Lead Ship Cost 500 Million 600 Million Table 23 Design Philosophy 23 SUBMARINE HULL SYNTHESIS With the ships requirements stated the process of determining the size of the submarine can begin While the details of the submarine model will be discussed in Chapter 6 the basic concept of submarine hull generation will be presented here to give a better understanding of the impact of the AIP propulsion options power sources and reactants on submarine design when explained in Chapters 3 4 and 5 For this thesis the shape of the hull will be assumed to be a body of revolution modeled after the hull of the submarine ALBACORE This basic shape has the best underwater hydrodynamic performance which will be important to best utilize the power available from the AIP power plant Even though a modern submarine is designed to spend most of its operating time submerged Archimedes principle for flotation of hull weight is applicable in both regimes As seen in Figure 22 the first logical step from ship 33 Requirement Relative Weight Mission Payload Performance 10 Cost 10 Maximum Speed 9 AIP Endurance 9 Battery Endurance 8 Risk 7 requirements is weight estimation Extensive data bases have been developed which catalogue existing equipment and structural weights From these data bases parametric curves have been developed which can be used to estimate each of seven major weight categories which form the fixed weight of the ship To this fixed weight is added lead ballast part of which is used to balance longitudinal moments later in the design process and part to allow for weight growth in equipment over the life of the ship Also to be accounted for are the variable weights on the ship which include fluids such as fuel and fresh water stores such as food and spare parts and weapons This summation of weights represent the total weight which must be supported at all times when the ship is on the surface and is designated as the normal surfaced condition NSC The left hand column of Figure 23 summarizes this weight summation process Similar to the weight estimation database data exists for the pressure hull volume necessary to enclose the equipment crew and weapons carried by the ship From these volumes established parametric relationships are employed to estimate the pressure hull volume Add to this volume all the items such as ballast tank structure hull plating and equipment which exist outside the pressure hull and you have the portion of the ship which will never flood with water and is termed the everbuoyant volume VEB The everbuoyant volume is equivalent in concept to the NSC and is the point where estimated weights and volumes are reconciled For the ship to achieve neutral buoyancy the estimated weight of the ship must equal the weight of seawater displaced by the everbuoyant volume If NSC is greater than VEB the ship is said to be weight limited with the ship not displacing enough water to float the submarine on the surface If VEB is greater than NSC the ship is said to be volume limited with the ship requiring more weight to achieve neutral buoyancy To bring these two 34 Weight Estimation Volume Estimation Group I Hull a Mobility Group 2 Propulsion Machinery b Weapon Group 3 Electrical c Command and c Command and Control Group 4 Electronics d Auiliaries Group 5 Auxiliary Equipment e Habitability Group 6 Outfit Furnishings f Storerooms Group 7 Weapons EGroup 1 7 function af I Condition Ai Pressure Hull Volume Vph AI Lead Ballast factor Vph Condition A Outboard Volume Vob A Variable Load Vph Vob Balance Normal Surface Condition Everbuoyant Volume Veb ii iii Main Ballast Tank Volume Vmbt factor Veb 11 111 111111 111111 11 1 ii i Submerged Volume Vsub Veb Vmbt Freeflood Volume Vff factor Veb Vo Ene u E nv Envelope Volume Venv Balancing Weights and Volumes Figure 23 concepts together either volume is added to the weight limited ship or lead ballast added to the volume limited ship rather than immediately refining any estimates made of the weights and volumes When the best value for VEB has been established the margin required for main ballast tank volume is applied along with an estimate of the volume of the ship which is free flooding on submerging to obtain the volume of the hull envelope This envelope represents the hull form and weight that must be propelled by the ship when submerged and forms the starting point for the powering calculations The next several steps refine the estimates made above in determining weights and volumes To begin the chosen hull form from above corrected for 35 added appendages is used to estimate the effective horsepower EHP of the ship EHP is the power necessary to push the hull through the water at various speeds The choice of propulsor and efficiencies associated with water flow past the stern and propeller combine to estimate the propulsive coefficient PC a measure of how effective the propeller is in converting the available shaft horsepower SHP to EHP With SHP determined a check of the initial propulsion machinery estimate can be made Likewise a preliminary set of arrangement drawings is made to ensure compartment layouts are sensible to locate weights and calculate moments to check the longitudinal stability of the ship Additionally with the principal hull dimensions known the pressure hull and its required scantlings can be estimated to refine initial estimates for structural weight Finally the dynamic performance of the ship is evaluated through the use of computer simulation and model testing to verify that the hull form and the first estimate of sail and control surface size and location result in acceptable underwater performance Upon completion of this final check the first trip around the design spiral is complete Now the design team must come together to compare results perform trade offs guided by the design philosophy and make any necessary changes to the initial weight and volume estimates With these revised values the procedure just outlined is revisited with the end result being a more balanced ship This circular procedure is repeated until the best design is produced 36 CHAPTER THREE 30 SUBMARINE SYSTEMS The systems required to support a submarines operating profile contain many aspects of those found in standard shipboard applications These systems are however complicated by the special considerations unique to submarine operations such as buoyancy systems for diving and surfacing and atmosphere control Conventional system designs are comprised of a central plant electric hydraulic pneumatic etc and some form of distribution energy storage network Systems of this type are important for several reasons a primary one being the conservation of space and power since a hydraulic operator for a valve is many times smaller than an equivalent motor operator A general description of the more important systems will be presented to provide a background for the AIP plant size decisions The integration of a shipwide electrical system with propulsion and ship service requirements is most critical to the make up of a conventional submarine Relying on different power sources at different times in an operating profile these sources must be capable of providing continuous power in parallel whether in transition between sources or together to increase the available output power The types of power available and the load requirements go a long way in determining the architecture of the system Power sources discussed in detail in Chapter 4 include electrochemical which provide a direct current DC output and mechanical which can be fitted with either an alternating current AC or DC generator to provide electrical power Ship service electrical loads Section 32 depend on the type of equipment application but are generally some form of 60 or 400 cycle AC or DC 37 power Propulsion loads have been predominantly DC power based but emerging technology has pushed AC and low voltage high current DC power applications to the forefront and are discussed first in Section 31 31 PROPULSION INTEGRATION Table 31 presents a summary of possible propulsion options to be considered in this study TABLE 31 Propulsion Options Propulsion Type Attributes Technology Status Conventional DC 220 880 VDC Mature proven atsea service for many years Permanent Magnet AC 800 VAC Variable Near maturity foreign Frequency shipboard installations planned Superconducting 100 200 VDC Immature Homopolar DC 100 200 kAMPS 311 CONVENTIONAL DC Advantages Disadvantages Reliable Technology Large WeightNolume Compatibility with Battery Systems The most common arrangement in service is the conventional DC motor from a high voltage 220 880 VDC bus which until recently was the only viable technology available Double armature motors with creative battery switching 38 Basic Circuit Mode I L HA RlI M I HiK M1 i I I L I I Mode 2 Mode 3 Mode 4 Mode 5 Battery Stepping Operating Modes for a Double Armature DC Motor 27 Figure 31 schemes such as Figure 31 gives the operator flexibility in terms of speed control and system configuration Based on its vast historical operating experience this concept is well proven in terms of reliability While improvements have been made these machines are heavy and volumous when compared to AC machines of similar power output Their widespread use however is a result of their excellent low speed torque characteristics and their ready compatibility to the varying DC voltage characteristics of the traditional LeadAcid battery based electrical distribution system 39 ii 7 f i I l r Lc 312 PERMANENT MAGNET AC Permanent Magnet AC PM motor technology is being developed and may gain acceptance as the possible successor to the conventional DC system The PM motor illustrated in Figure 32 uses permanent magnets to Permanent Magnet Axial Gap Propulsion Motor 16 Figure 32 40 Advantages Disadvantages Reduced Weight Volume Requires DCAC Inverters Heat Losses in Rotor Eliminated Heat limits in PM materials Current collectors not mature 7 D replace the magnetic field source on the rotor eliminating significant amounts of electrical wiring In this design the rotor and stator are disc shaped vice a conventional can shaped stator encircling the rotor core With the disc geometry a larger number of poles can be included with smaller end turn volumes and reduced stator back iron size and weight giving the motor a higher degree of speed control Estimates of the weight and volume savings for PM motors over comparable DC motors are on the order of 50 and 40 percent respectively 28 This technology can also be applied to power generation applications with similar savings in weight and volume Figure 33 illustrates one concept design currently under evaluation at the Naval Surface Warfare Center Annapolis 18 The cup shaped rotor with the stator located inside is designed to counter centrifugal forces generated by spinning the rotor magnets at speeds up to 12000 revolutions per minute RPM I 222 Mane i3 ATi jiiiiii II Mzt R O T O R Permanent Magnet High Speed Generator Figure 33 PM motors however require a slowly varying AC frequency that will allow the motor to operate at very low speeds This frequency can be achieved 41 iiiiiiiiiiiiiiii ijj CiijI WATir 2 iiii a i X j llli through the use of power electronics to chop a DC input signal to provide an output AC voltage of the appropriate frequency Figure 34 Alternately this AC voltage can be created by using a DC motor AC generator set varying the speed by control of the DC motor field 0 0 Input DC Voltage Output AC Voltage Example of Chopped AC Output From Input DC Figure 34 313 SUPERCONDUCTING HOMOPOLAR DC While still an immature technology in its final form the Superconducting Homopolar SC motor is a next generation of propulsion technology taking advantage of zero resistance properties of electrical conductors when they have been cooled to near zero degree Kelvin conditions The SC motor illustrated in Figure 35 is currently under development at the Naval Surface 42 Advantages Disadvantages Reduced Weight Volume Requires Cryogenic Cooling Reduced Noise Direct Mounting to High electrical currents hull Current collectors not fully developed Warfare Center Annapolis 6 Employing basic Lorentz force principles the motor contains large super conducting coils in a stationary cryostat cooled to 40K generating a torroidal magnetic force which appears radially outward in the active region of the motor Because the resistance of the coils is very close to zero a large current can be applied creating a very strong magnetic force for the stator current to operate against This allows the motor to generate very large values for torque relative to the size of the machine To the detriment of the concept the cryostat which contains liquid helium requires a separate cryogenic plant to maintain the temperature which draws approximately 100 kW of power a significant penalty in an AIP application Also the current collectors which are SodiumPotassium liquid metal are sensitive to water absorption causing corrosion problems and disperse under high rotational speeds Armature Stator Bars V Current Collectors Superconducting Homopolar DC Motor Figure 35 43 314 PROPULSORS The standard submarine propulsor is of fixed pitch design specially designed to minimize the effects of cavitation while submerged Other styles of propulsors such as contrarotating CR or ducted propellers have been proposed and installed on submarines but problems of one type or another have kept them from gaining acceptance The CR propeller offers a 10 percent increase in the propulsive coefficient for a submarine application 12 Historically the problem with a contra rotating system has been the transmission of power through some form of reduction gear to the propulsion shaft The emergence of PM and SC technology with its compact design offers a good solution to this dilemma 19 32 SHIP SERVICE POWER REQUIREMENTS While the propulsion load will vary constantly the ship service or hotel load of the submarine will remain fairly constant for a given operating profile Included in this hotel load are the minimum power requirements for ship control and operation and atmosphere control These loads can be expected to vary for each operating profile of the ship such as a battle station condition when all crew members are on station and most systems are operating to an ultra quiet condition when most crew members are retired and only a minimum number of systems are operating Most equipment is operated by some form of electricity from a ship service bus Conventional submarines generally employ ship service busses that are DC power based because of their link to the storage battery thus any load that cannot operate off a DC voltage source that varies with the state of charge on the battery must be converted Motor generator sets or static power inverters are utilized to convert DC power to its required form such as 44 Typical Loads 120 VAC 60 cycle 450 VAC 60 cycle Bilge Pumps Lighting Atmosphere Monitoring Equipment Appliances Ventilation Fans Hydraulic Pumps Air Compressors Galley Equipment 120 VAC 400 cycle Precision Electronic Equipment Gyro compass weapons control etc High Voltage DC Trim Pumps Lube Oil Pumps Direct from Battery Bus Lighting Low Voltage DC Ship Control Sonar Equipment Power The loads above are typical of those developed for nuclear powered submarine applications which use an AC ship service bus and for some uses be adapted to a different more convenient source Figure 36 illustrates a typical ship service power architecture 400 Hz AC Direct Loads 60 Hz AC Dies Genei DC 4 AIP Power Source Typical Ship Service Distribution System Figure 36 45 Power Type 33 AUXILIARY SYSTEMS The electrical distribution network is but one small part of the vital submarine support network A fully integrated system of pneumatic and hydraulic controls and operators supplements the ship operations providing compact high powered operating mechanisms for large equipment such as diving planes masts and antennas and seawater valves Most systems are comprised of a central power plant where the energy of that system is created then distributed to various operating points or to storage locations For example a typical hydraulic system features a storage tank pump and high pressure accumulator all in one package which then feeds a hydraulic distribution system Figure 37 A typical pneumatic system features air compressors connected to a high pressure air header which feeds high pressure air storage bottles and a distributed network of lower pressure air systems Figure 38 Here the air storage bottles are spread throughout the ship typically in the vicinity of the main ballast tanks to provide an immediate emergency source of surfacing air These types of systems are important supplements to the electrical network because of their simplicity in operation their reliability in the face of a propulsion plant casualty and the energy density available in the high pressure fluids they contain 34 ATMOSPHERE CONTROL A vital distributed auxiliary system but one which seems far less defined is the ventilation atmosphere control system This system comprises the necessary fans and ductwork to bring air into the ship recirculate it when submerged and purify it so that the air continues to be breathable All submarines have similar arrangements however AIP variants must contend with the additional concern of air revitalization that is the removal of contaminants 46 Towed Array Winch Seawater Valves Diving Planes Hydraulic System with Typical Loads Figure 37 700 PSI 20 PSI 150 PSI 250 PSI 400 PSI Main Air Header Air Bottles Located in Ballast Tanks 000 4500 PSI Air Compressors r 0v 00 High Pressure Air System Figure 38 47 Reduce To Emergency Ballast Tank Blow System A Trim Valves Masts Antennas oh such as carbon dioxide CO2 carbon monoxide hydrogen and odors and replacing the oxygen consumed by the crew Conventional diesel submarines rely on the fact that they snorkel periodically and use that opportunity to exchange air with the atmosphere and are therefore concerned with how to bridge the gap between snorkel evolutions These ships typically employ Chlorate Candle canisters which are burned to produce oxygen and a chemical reactant such as Lithium Hydroxide to absorb CO2 An AIP submarine could employ similar methods for atmosphere control but storage requirements for these expendable canisters could limit the submarines endurance Since it will be shown that some AIP options include liquid oxygen storage this tankage can be increased by the necessary amount to include breathing oxygen for the crew for the entire patrol estimated to be 0030 ft3 of liquid oxygen per person per day of patrol 7 This parasitic use has an additional advantage in that it can be used as a load for the boil off that occurs during normal storage of oxygen as a liquid CO2 removal can be accomplished by the use of scrubbers which use a monoethanolamine MEA spray to absorb CO2 from the air releasing it to an overboard discharge system Such a system is regenerable however its penalty is an additional electrical hotel load on the order of 6 kW Also of concern is the potential build up of hydrocarbons and hydrogen gas which can be cleaned up through the use of burners again at an electrical cost of about 9 kW 71 By locating this atmosphere control equipment in one location the air can be recirculated throughout the submarine and passed through this room to be revitalized Oxygen can be bled into the submarine at various locations so help distribute it evenly throughout the ship Figure 39 represents a typical ventilation arrangement 48 Ventilation Arrangement Figure 39 49 Blank Reverse CHAPTER FOUR 40 POWER SOURCES Many AlP power plants have been proposed with development conducted by those countries that have a genuine interest in promoting air independence for their own submarines or for the commercial submarine market This chapter investigates current and proposed power source options An AIP power plant is composed of several parts combined into one functional system These parts are Energy conversion device Fuel source Oxidant source Waste product management Reactants which include fuels and oxidants and waste product management which can involve the storage of pure water or discharging high volumes of carbon dioxide overboard will be examined in Chapter 5 The energy conversion device can be categorized as either electro chemical or mechanical depending on how the energy conversion is performed Mechanical AIP concepts include compact heat engines modified to run in the absence of a normal atmosphere such as the closed cycle diesel to entire cycles such as a Rankine cycle whose heat source is a simple combustor burning hydrogen and oxygen A discussion of these plants can be found in Section 42 Electrochemical concepts include a range of fuel cell and high performance primary and secondary battery options and will be discussed first 51 41 ELECTROCHEMICAL CONCEPTS Table 41 summarizes the electrochemical power concepts to be investigated Table 41 ElectroChemical AIP Concepts 411 FUEL CELLS Fuel cells represent a major area of interest among AIP power source options presenting a potential for very high efficiencies since the energy conversion process is not limited by Carnot principles As seen in Figure 41 their projected efficiency is roughly double that seen with heat engine cycles which can translate into large savings in fuel and oxidant for a given submarine hull 29 A fuel cell can be thought of as a black box where chemical reactants 52 Power Sources ElectroChemical Remarks Proton Exchange Membrane Fuel Cell Most promising HO cell Alkaline Fuel Cell Proven design Phosphoric Acid Cell Proven design low interest Molten Carbonate Fuel Cell Several commercial ventures underway Solid Oxide Fuel Cell Immature highest projected efficiency Aluminum Oxygen SemiCell Competitive with PEM cell Lead Acid Battery Proven performance Nickel Cadmium Battery Higher power density than lead acid SilverZinc Battery Prone to short circuits LithiumAluminumlron Sulfide Battery Potential successor to lead acid i flicicncv i I V In In IFuel cal Aluminum Peroxide Stirlina inRmeC CC 1iecl IP Nuclear Jo40 6 90 1 00 ltoad Factor o Efficiency vs Load for AIP Options Figure 41 are introduced and combined utilizing an electrical load to complete the transfer of electrons between anode and cathode thereby creating a DC electrical power source There are many proven fuel cell designs over a wide range of power levels however the auxiliary equipment necessary to support these cells and the materials themselves may not be compatible with submarine applications As a result only those technologies which appear to be favorable will be considered 53 4111 PROTON EXCHANGE MEMBRANE FUEL CELL The Proton Exchange Membrane PEM cell is presently the most popular fuel cell in terms of interest and development for submarine applications This thought is underscored by German industry which after successfully demonstrating a small alkaline fuel cell plant in a Type 205 submarine in 1987 has abandoned that variety of cell in favor of the PEM cell 29 The PEM cell is also being studied as a part of AIP development programs in the United Kingdom Canada and Australia In addition the US Navy has developed PEM technology for replacement of alkaline cell technology in the oxygen generating equipment found onboard its nuclear submarines 55 The PEM cell is a standard hydrogenoxygen cell depicted in Figure 42 except that the electrolyte is actually a solid polymer material rather than a liquid ionic material such as potassium hydroxide or phosphoric acid Hydrogen is introduced at the anode where a catalyst forces the release of electrons Hydrogen ions then pass through the polymer material to the cathode where they combine with oxygen and free electrons to form water The electrical circuit is formed by insulating the anode and cathode electrically forcing the electrons released at the anode to transit via an electrical circuit to the cathode where they are required to complete the reaction 13 54 Advantages Disadvantages Proven technology Hydrogen storage Solid cell technology Requires pure reactants Quiet reduced heat rejection Reformer for nonhydrogen fuels Pure water product immature Low operating temperatures 1 80F Cell poisoning due to impurities reduces output Hydrogen Water Overall Cell Reaction H2 O2 H20 2 Proton Exchange Membrane Fuel Cell 39 Figure 42 The size of the fuel cell is flexible and can be tailored to the application While most specific information is proprietary a single fuel cell can be expected to generate an output voltage of slightly less than 10 VDC with a current density on the order of 1 amp per square centimeter Thus for a certain power requirement individual cells can be connected in series to achieve the required output voltage with enough active area to achieve the required amperage power rating Figure 43 shows a typical cell voltage versus load profile The PEM cell requires relatively few auxiliary systems to support its operation The electrolyte is solid requiring no makeup or monitoring system as 55 Oxygen 1 09 08 p 07 06 1 05 o 04 03 L 02 01 0 0 05 1 15 2 Current Density Ampscm2 PEM Cell Voltage versus Cell Load 74 Figure 43 in liquid electrolyte designs greatly improving its simplicity The cell is classified as low temperature in comparison to other systems With an operating temperature around 2000 F the time required for the cell to reach operating temperature is relatively short making it ideal for rapid startup an important operating characteristic The lower operating temperature is also more compatible with an enclosed submarine environment 44 The only product discharge from the cell is pure water which is potable and easily handled either by storage for crew consumption or transfer to a variable ballast system for discharge overboard A significant issue for the PEM cell is the fuel source The solid polymer electrolyte membrane is susceptible to contamination by impurities in the fuel gas specifically carbon monoxide a byproduct of the reformation process While carbon monoxide contamination does not permanently damage the cell concentrations as high as 10 PPM can 56 dramatically affect cell performance requiring regeneration of the cell with a clean gas source 3 Development of a clean reformer is a significant developmental issue and is discussed further in Section 5113 Specific details on the PEM cell can be found in Appendix A 4112 ALKALINE FUEL CELL This fuel cell is very similar in concept to the PEM cell with exception of the electrolyte and its added complexities and has been demonstrated to operate successfully at sea in a German Type 205 submarine This system used potassium hydroxide to conduct the hydrogen ions to the cathode for recombination 55 Figure 42 presented earlier for the PEM cell applies to the alkaline cell as well 4113 PHOSPHORIC ACID FUEL CELLS 57 Advantages Disadvantages Demonstrated performance atsea Hydrogen storage Quiet reduced heat rejection Liquid electrolyte more complex Pure water product than PEM Low operating temperatures 1 800F Requires pure reactants Reformer for nonhydrogen fuels immature Advantages Disadvantages Demonstrated commercial High operating temperatures 4000 F performance Liquid electrolyte more complex Quiet reduced heat rejection than PEM Pure water product Larger heavier than PEM same Can reform hydrogen fuels internally efficiency Another variant of the basic hydrogen oxygen fuel cell is the Phosphoric Acid Fuel Cell PAFC which is conceptually similar to the alkaline cell using phosphoric acid as an electrolyte While this cell is fueled by pure hydrogen variants operated at higher temperatures 4000F may be able to reform hydrogen based fuels internally as this cell is not susceptible to carbon monoxide poisoning 21 Commercial development of the PAFC as a portable remote power source fueled with natural gas is mature At issue for submarine applications are the significantly larger volumes and weights for similar efficiency when compared to PEM technology and lower efficiency when compared to other similar sized high temperature cells to be discussed 65 4114 MOLTEN CARBONATE FUEL CELL The Molten Carbonate Fuel Cell MCFC is similar to other fuel cells in its basic principle of operation however its method of achieving energy conversion 58 Advantages Disadvantages Internal conversion of fuel High operating temperatures Variety of fuels possible 12000F Higher system efficiencies Safety to personnel High system temperatures utilized in Long start up time fuel reformation Corrosion issues Active commercial interest Largeheavy compared to other fuel Can support bottoming cycles cell plants is quite different Illustrated in Figure 44 the MCFC utilizes a molten carbonate salt as the electrolyte and thus must be heated to around 1200F to function If properly insulated this high heat can be used to internally reform any number of hydrogen based fuels such as marine diesel or methanol making this option especially attractive Similar to the PEM cell pure water is produced as a result of the reaction however other products such as carbon dioxide are produced as well The relative volume of carbon dioxide gas produced depends on the type of fuel used in the cell Because of the high temperature of the cell the waste heat from the cell can be used to operate some form of bottoming cycle improving overall system efficiency 65 Appendix A contains more specific data on MCFC Hydrogen Fuel IN C02 OUT Water OUT 4 Oxygen IN CO2 IN Reaction on Cathode Surface ½02 C02 2e CO3 Reaction on Anode Surface H2 C03 C02 H20 2e Molten Carbonate Fuel Cell Figure 44 59 4115 SOLID OXIDE FUEL CELL The Solid Oxide Fuel Cell SOFC is a new advanced technology which is still very immature Similar to the MCFC it operates at high temperature 18000F and can therefore internally reform various types of fuel Its electrolyte however is a solid nonporous metal oxide eliminating the need for a liquid electrolyte management system The higher operating temperature of the SOFC promises that it should enjoy a higher efficiency than the MCFC and projections are that SOFC technology should be very weight and volume efficient 65 One design by Westinghouse for possible shipboard applications is shown in Figure 45 Here an oxidant is passed inside a cylindrical cell with the fuel gas passed on the outside Similar to other fuel cell applications the ceramic metal oxide passes oxygen ions through to the cathode where they combine with hydrogen and carbon monoxide to form carbon dioxide and water 4116 DIRECT METHANOL OXIDATION FUEL CELL This cell represents research in PEM technology aimed at eliminating the reformer requirement when using fuels other than pure hydrogen It is very immature and is not formally evaluated in this study 60 Advantages Disadvantages Internal conversion of fuel Immature technology Variety of fuels possible High operating temperatures Highest system efficiency projected 1 8000 F High system temperatures utilized in Safety to personnel fuel reformation Long start up time Can support bottoming cycles The cell operates at low temperature and contains the solid polymer electrolyte The difference is a special catalyst at the anode which transforms methanol fuel into hydrogen and carbon dioxide a gas with no effect on cell efficiency Present cell performance has an output voltage of 06 VDC slightly less than PEM at a current density of 01 Ampscm2 110th of the PEM cell 37 Electro Air Electrod Air Flow Reaction on Anode Surface Reactions on Cathode Surface 02 4e 20 2H2 20 2H20 4e 2CO 20 2C02 4e Westinghouse Solid Oxide Fuel Cell 5 Figure 45 61 I U 911L V V 412 ALUMINUM OXYGEN SEMICELL The Aluminum Oxygen SemiCell aluminum is categorized separately from other fuel cells because although it relies on a chemical reaction to free electrons for electrical power output its fuel source is actually the cathodic aluminum plate contained within the cell Figure 46 Conceptually there are three variants of the aluminum cell each utilizing a different form of oxidant First is the use of pure oxygen which is currently under development in Canada for submarine applications and in the United States and Canada for autonomous underwater vehicle AUV applications A second variant uses air as the oxidant and is really a modification to the first A third variant suggests the use of hydrogen peroxide H202 for the oxidant While unstable in high concentrations this idea has merit because H202 provides not only oxygen but also water a reactant that the cell needs in large quantity In the cell pictured in Figure 46 a complete system was included to show one of the detriments of the aluminum cell In this cell the aluminum anode is literally corroded away to form a product called hydrargillite AIOH3 This product must be constantly removed otherwise it will reduce the conductivity of the electrolyte to the point where the cell will no longer function This removal 62 Advantages Disadvantages No hydrogen required Expensive fuel No products dischargednet weight Frequent cell replacement unchanged with time Hydrargillite management Requires one half the oxygen of High cell weight other comparably sized fuel cells Caustic electrolyte High density fuel source Elecric Load Pure Water i I Overall Cell Reaction 4AI 6H20 302 4AIOH3 Aluminum Oxygen SemiCell 39 Figure 46 process is proposed to be accomplished by flushing the electrolyte from the cell and stripping the hydrargillite storing the precipitate in one of the reactant tanks To maintain the proper ionic concentrations makeup tanks of pure water and potassium hydroxide must be included in the system 13 The purification of the electrolyte is still a developmental issue although advances in the 44 inch unmanned underwater vehicle UUV program sponsored by the Defense Advanced Research Projects Agency DARPA indicates that the problem may be solved on a 15 kW power plant scale 24 This overall system is attractive from a submarine perspective because the potential exists for no overboard product discharge Also with no overboard product discharge the net weight 63 change of mobility for the plant is theoretically zero with only the weight distribution changing The electrolyte described here is the option currently under development in Canada but other alkaline sodium hydroxide or saline solutions seawater could be used The concept that envisioned the use of H202 as an oxidant was actually in combination with seawater AIP studies conducted in Canada have concluded that aside from the hazards of handling H202 the most efficient oxidant option for large submarines is oxygen in liquid form 39 413 BATTERIES Batteries fall into two categories Primary and Secondary Primary batteries are just that a primary power source for an application They are not rechargeable and would be appropriate for one time applications where it is important to keep costs down ie not for frequent replacement over the thirty year life of a ship Secondary batteries such as the common lead acid battery are rechargeable and have been used successfully in submarines for many years The battery is a temporary energy storage source intended to provide submerged power for diesel submarines and emergency power in nuclear submarines Only secondary batteries will be considered in this thesis Table 42 presents a summary of current and near term secondary batteries Those technologies which are mature or have immediate promise will be discussed here 64 Table 42 Summary of Battery Types 15 Classification LeadAcid Alkaline Alkaline High Temperature Battery Type Lead Acid NiCd AgZn LAIS Maturity Mature Mature Mature Near Maturity Energy Density 2035 2037 90 160225 Whkg Power Density 0020175 0106 0204 019036 kWkg Cycle Life 2002000 5002000 1002000 1000 no of cycles Service Life 310 510 3 years Battery Effluent H2 Gas None None None Ease of Operation Good Very good Poor Projected to requires strict be frequent operating maintenance monitoring requirement free 4131 LEAD ACID BATTERIES Advantages Disadvantages Proven technology Least energy dense Long cell life Evolves hydrogen while charging Recent improvements Requires frequent monitoring 65 By far the most common battery type in use is the lead acid battery shown in Figure 47 A single cell consists of a series of negative and positive plates made of lead and lead dioxide respectively immersed in a sulfuric acid electrolyte and sealed in a rubber jar Charging and discharging of the cells transfers electrons back and forth between the plates and the electrolyte The cell voltage is nominally 2 VDC and any number of cells can be connected in series or parallel to provide the required output voltage for the battery group Connected directly to a DC distribution bus the instantaneous voltage can be expected to decrease as much as 20 percent depending on the state of charge of the battery 63 While the basic cell hasnt changed with time the addition of certain metals to the active cell matrix have significantly improved battery performance 42 Because the chemical reaction can proceed in both directions the batterys ability to deliver and receive a total amount of energy depends on the rate of the reaction In general when power is drawn from the battery at a low rate battery voltage will remain high for a longer period of time and more energy can be extracted Figure 48 Battery cooling systems are fitted in some cell designs to dissipate the heat generated by exothermic charging and discharging reactions and internal cell resistance Cell air agitation systems are also critical to battery performance by keeping the electrolyte thoroughly mixed 66 PbO2 Overall Reaction Pb PbO2 2H2SO4 Discharge 2PbSO4 2H20 Charge Lead Acid Battery Schematic Figure 47 High Discharge Rale Low Discharge Battery Energy Typical Lead Acid Discharge Characteristic 41 Figure 48 67 Pb electrolyte 0a U 0 co 4 U Ad w Lead acid batteries require frequent monitoring and careful operation Hydrogen gas is evolved during all phases of battery operation and is especially high during periods of charge and heavy discharge As a result air flow through the battery is closely controlled Figure 39 While charging on the diesel engine the battery ventilation exhaust is directed directly to the diesel intake to burn any hydrogen produced Nuclear submarines and now AIP submarines can charge their batteries while submerged and must rely on COH2 burners to catalytically convert the hydrogen gas at an electrical penalty of about 9 kW Catalytic conversion units installed in the battery compartment have been developed to handle normal hydrogen gas evolution 42 Current AIP systems provide for continuous low power operation at speeds up to 810 knots Any high speed burst capability is provided by the storage battery and is a key parameter for battery sizing Typical AIP battery installations involve 400500 cells with each cell requiring frequent monitoring for safety and overall battery performance As a part of lead acid battery improvement sophisticated battery monitoring systems have been developed which can provide an instantaneous readout of individual cell parameters and the state of charge of the battery 14 Specific details of lead acid batteries are contained in Appendix A 4132 NICKELCADMIUM BATTERIES 68 Advantages Disadvantages High energy density compared to Unproven at sea lead acid Abrupt cutoff when fully discharged Longer cell life compared to lead Memory effects acid Expensive relative to lead acid Rapid charging Reduced maintenance NickelCadmium NiCd battery technology is well established for commercial use but in sizes much smaller than that required for submarine applications Virtually any portable rechargeable electric tool or appliance is powered by NiCd batteries No NiCd battery systems have been installed in a full sized submarine The NiCd battery is schematically similar to the lead acid battery in Figure 47 with positive nickel hydroxide plates and negative cadmium plates in a potassium hydroxide electrolyte transferring energy according to the following equation Discharge Cd 2H20 2NiOOH 2NiOH2 2Cd OH 2 Charge The cells can either be vented or not releasing gasses developed by electrolysis of the electrolyte 25 NiCd batteries are attractive from the perspective of their higher energy density Compared to an equivalent lead acid battery capable of 800 kW of delivered power NiCd batteries are lighter and smaller 4 Lead Acid 800 kW NiCd 800 kW Weight tons 488 267 Volume ft3 520 390 The voltage characteristic of the NiCd battery is different than that of the lead acid battery Illustrated in Figure 49 the NiCd battery will maintain a fairly 69 constant voltage output over its period of discharge but drops abruptly at the end of its capacity Included on the chart is a comparison to the lead acid whose operating characteristic might be considered more acceptable to operators because of the more gradual decline in performance near the end of the discharge period The relative output voltage of each cell can also be seen Despite its lower voltage which would require more cells for a given output voltage the higher energy density of the NiCd battery more than offsets this difference 31 2 0 15 W Lead Acid NiCd I I I 0 20 40 60 80 100 120 140 Battery Energy Discharged NickelCadmium Discharge Characteristic with Lead Acid Superimposed 25 63 Figure 49 4133 SILVERZINC BATTERIES 70 Advantages Disadvantages High energy density compared to Prone to internal short circuits lead acid and NiCd batteries High heat generation Rapid charging Reduced maintenance Silver Zinc AgZn batteries have proven service in submersibles but not in full size submarines AgZn batteries have a high energy density and are a primary power source in special purpose submarines such as Deep Submergence Rescue Vehicles DSRVs and as a backup power source in the nuclear research submarine NR1 Classified as an alkaline battery AgZn batteries utilize a potassium hydroxide electrolyte and a sandwich of negative and positive plates made from zinc oxide and sintered silver powder to produce and store electrical power according to the following reaction Discharge Zn AgO ZnO Ag Charge To their credit AgZn batteries have excellent energy densities approximately three times greater than lead acid or NiCd 15 The battery efficiency or ability to withdraw the total energy stored in the battery is between 95 and 100 percent compared to a maximum of 90 percent for other batteries Operating procedures to maintain this type of battery properly are more demanding than for the lead acid battery and there are additional concerns for excessive heat generation during charging Add to this reliability problems with zinc dendrite growth from the negative plates into the plate separators and the battery becomes limited in its applicability to the deep cycling routine of a diesel electric or AIP operating cycle Figure 410 illustrates the distinctive discharge characteristic of the AgZn battery 15 71 2 o ao 1 o 0 20 40 80 100 120 Battery Energy Discharged Silver Zinc Discharge Characteristics Figure 410 4134 LITHIUMALUMINUM IRON SULFIDE The LithiumAluminum Iron Sulfide LAIS battery is the most promising of several high temperature storage batteries currently under development The United Kingdom has a strong research program underway to develop a reliable replacement system for the standard lead acid batteries in their diesel electric 72 Advantages Disadvantages High energy density compared to Not mature technology lead acid and NiCd batteries High operating temperatures Rapid charging Battery must be heated before Reduced maintenance operating High energy efficiency I and nuclear powered submarines The goal of this project is to produce a battery that is a significant improvement in terms of energy density but which has a minimum impact on existing shipboard arrangements and logistics The arrangement of positive iron sulfide and negative lithiumaluminum is similar to other battery designs however the electrolyte is a molten salt which must be kept at temperatures on the order of 8500 F to prevent it from freezing Power is transferred to and from the battery according to the following chemical reaction Discharge 2LiAI FeS Li2S Fe Al Charge Because the battery operates at such a high temperature it must be heated initially to melt the electrolyte Once placed in operation frequent charging and discharging of the battery will generate enough heat to maintain the molten electrolyte as long as the battery is well insulated While the LAIS battery has a lower voltage per cell at 13 VDC its discharge characteristic is not unlike the lead acid battery Figure 411 Each cell is completely sealed so despite its high operating temperature the cell is projected to be safe for submarine operations With an advertised efficiency in extracting energy for use of almost 100 percent the fully mature LAIS battery should be a contender for replacement of the lead acid battery Details on the LAIS battery are contained in Appendix A 73 I 01 0 8 14 12 1 08 06 04 02 n 0 20 40 60 80 100 Battery Energy Discharged LAIS Battery Discharge Characteristics Figure 411 42 MECHANICAL POWER SOURCES Table 43 summarizes the mechanical power concepts to be investigated 421 CLOSED CYCLE ENGINES 4211 CLOSED CYCLE DIESEL 74 Advantages Disadvantages New application of proven technology Noise Uses off the shelf components Exhaust management Common fuel source Cycle gas contamination corrosion Low cost relative to emerging technology v Table 43 Mechanical AIP Concepts By far the most popular mechanical source among nations investigating AIP is the closed cycle diesel CCD engine Investigated as a possible method to improve underwater endurance as early as 1901 this technology is based on the adaptation of proven diesel engines to the underwater operating environment and is currently being pursued either singly or in partnerships by Italy the United Kingdom Germany the Netherlands and others 52 The former Soviet Union is believed to have the most experience with a combatant CCD submarine the BELUGA although few details are known 65 To date most systems demonstrated at sea are for commercial or research purposes at up to 600 kW The CCD system can operate either closed or open cycle with air from the atmosphere since it is based on standard diesel engine Figure 412 illustrates the CCD concept Focusing on the air intake and exhaust system in the closed cycle mode engine exhaust gasses are cooled and passed though an absorber unit where they are sprayed with low pressure seawater to absorb the CO2 in the mixture The resultant mixture is then replenished with oxygen 75 Power Sources Mechanical Remarks Closed Cycle Diesel Mature lowest cost system Stirling Engines Mature low power only Closed Brayton Cycles Excellent potential for development Rankine Cycles Proven technology Small Nuclear Power Under development Walter Cycles Safety of H909 COSWORTH SYSTEM I e Closed Cycle Operation MANAGEMENT SYSTEM Overboard Open Cycle Operation Closed Cycle Diesel with Exhaust Management System 54 Figure 412 and an inert gas such as argon and returned to the engine intake to repeat the cycle The Cosworth exhaust management system developed by Cosworth Engineering UK consists of a high and low pressure seawater loop and is discussed further in Section 53 At sea test results by a German CCD consortium headed by Thyssen Nordseewere showed that the CCD suffers a 5 percent increase in fuel consumption and a 15 percent loss in brake power to overcome the effects of discharging CO2 at pressures other than atmospheric 8 76 The introduction of makeup gasses such as oxygen and argon are important for several reasons Oxygen is obvious for without it the engine could not sustain combustion As for argon or other inert gas this makeup volume is important to replace the CO2 water and other gases stripped in the absorber unit CO2 is a triatomic gas with a low ratio of specific heats Studies have shown that by leaving CO2 alone as the makeup gas Y for the engine atmosphere would be too low reducing the pressure rise during compression needed to sustain combustion forcing physical changes in the engine increasing the compression ratio beyond acceptable limits 50 The long term effects of sulfuric acid and other contaminants in the atmosphere are also of significant concern Studies to determine the appropriate synthetic atmosphere composition continue Details of a typical CCD system are contained in Appendix A 4212 CLOSED BRAYTON CYCLE The Closed Brayton Cycle CBC is an AIP application of the basic gas turbine engine While the concept is plausible and interest has been expressed in developing such a system by several countries including the United States as a possible replacement for emergency diesel engines on nuclear submarines 77 Advantages Disadvantages Strong technical base Immature as a closed cycle Quiet signature high frequency Combustion product management Low power compact engine High temperature corrosion problems demonstrated in direct combustion applications High power density Variety of fuel sources other more mature technologies such as the closed cycle diesel and Stirling engines have so far limited development of the CBC engine 65 Several papers have been presented on the specifics of the CBC scaling parameters from proven low power designs from other applications One compact concept designed for UUV and submarine applications is shown in Figure 413 with the gas cycle in Figure 414 The system classified as indirect combustion consists of two cycles a working gas cycle at high pressure with a monatomic gas Helium Xenon etc operating between a turbine and compressor through a recuperator and a combustion cycle transferring the heat of combustion through a heat exchanger to the working fluid cycle Cycle efficiency for this system is claimed to potentially exceed 50 percent 26 Another possible design could be a direct combustion cycle utilizing a synthetic atmosphere similar to that described for the CCD however such a system would bring with it high temperature corrosion problems 58 Additional details on CBC are contained in Appendix A Closed Brayton Cycle Combustion Power System 58 Figure 413 78 RECUPERATOR Closed Brayton Cycle Schematic Flow Diagram 58 Figure 414 422 STIRLING ENGINE The Stirling engine is an established heat engine concept that has recently and successfully been applied to service in submarines The Swedish government has operated a 150 kW Stirling AIP power system at sea in 79 Advantages Disadvantages Proven by Sweden at sea Noise Common fuel source Exhaust management Adaptable as a bottoming cycle High temperature corrosion Low vibration compared to CCD Complicated Reliable operating profile Presently limited in size High Efficiency NACKEN since 1988 30 Developed by Kockums Marine AB of Sweden the Stirling plant is one of two plants being considered by the Royal Australian Navy for introduction to their new COLLINS class submarine The Stirling engine whose basic operating cycle is illustrated in Figure 415 is an external combustion engine and can utilize any heat source to power the engine the Swedish arrangement uses a form of diesel fuel with liquid oxygen The working gas is trapped between a hot and cold piston moving continuously between the hot and cold volume and is continuously heated or cooled The working gas passes through a regenerator which stores heat when the gas moves from the hot to cold side and gives the heat back when the gas moves the other way The two pistons are mechanically linked to keep the cylinder volumes properly timed 17 Although presently limited in power output Sweden reports the Stirling has performed well in NACKEN because of her low patrol hotel load The Stirling engine combustion chamber can be operated at high pressure so the issue of overcoming the back pressure of the sea is minimized This high pressure and temperature leads to corrosion problems and will be of concern as Kockums develops engines of higher power 20 Details on the Stirling engine can be found in Appendix A 423 OTHER POWER CYCLES This section provides an overview of several other thermal power cycles that are being considered for AIP applications In performing a concept design of an AIP power plant these cycles could very well encompass the entire propulsion plant as a mono source rather than the hybrid application evaluated in this thesis These cycles are not considered in this thesis and are included here for completeness only 80 HEATER HOT VOLU Compression Displacement Expansion cold gas cold to hot side hot gas 3 4 3 4 4 Displacement hot to cold side 2 4lq VOLUME Stirling Operating Cycle Figure 415 4231 RANKINE CYCLE A Rankine cycle is any vapor power cycle which utilizes a constant pressure heat addition to the working fluid such as the basic steam cycle in a nuclear powered submarine This principle can be applied as long as an appropriate heat source and working fluid is used One such application named MESMA Autonomous Submarine Energy Module has been developed in France by the Bertin Company under the direction of the French Directorate for Naval Construction for installation in the AM 2000 submarine The system is shown in Figure 416 and is simply a steam Rankine cycle with a fossil fuel source supplying heat for the steam generator The combustion 81 v process leads to high temperature corrosion problems similar to those already discussed for CCD and Stirling applications Bertin proposes that the exhaust gas and water be condensed and stored onboard with no net change in weight as the fuel is consumed which would also make the system depth independent However because of the high pressures at which the combustion cycle could be operated the exhaust can be discharged overboard 35 COMBUSTION PRODUCTS JTER MESMA Operating Cycle Figure 416 82 4232 SMALL NUCLEAR POWER This AIP option is not simply a scaled down version of a larger nuclear propulsion plant but rather a low power cycle designed to meet hotel load requirements and recharge batteries while submerged This system is being developed in Canada by Energy Conversion Systems under the title Autonomous Marine Power Source AMPS The obvious contribution of AMPS is that it can provide a conventional submarine with seemingly infinite endurance but not high sustained speed at what is hoped to be reduced cost As with a full sized nuclear power option the political climate and infrastructure development associated with a nuclear propulsion program may be too great for many countries 29 Illustrated in Figure 417 the AMPS concept features a low power low temperature pressurized water nuclear power source which is perceived as being safer than a high temperature concept Heat is transferred to a secondary Rankine cycle where electrical power is produced Current plans call for a 100 kW plant which could be scaled to 400 kW 23 4233 WALTER CYCLE The Walter Cycle is a power cycle based on hydrogen peroxide as an oxidizer and is included for a historical perspective since no countries presently show interest in such a power source for submarines although Sweden employs hydrogen peroxide and diesel fuel for torpedo propulsion 20 Developed in Germany during World War II Walter cycle power plants were installed in several experimental submarines proving their high power density limited only in their ability to carry reactants The Germans expected speeds of 24 knots in their Type XXVI submarines while the United Kingdom achieved 26 knot performance for periods of up to three hours in EXPLORER during the 1950s 83 WATER AMPS Power Cycle Figure 417 43 The United Kingdom abandoned Walter cycle development with the advent of nuclear propulsion Shown in Figure 418 the Walter cycle combines diesel fuel and high test 80 percent peroxide HTP to produce a high pressure and temperature mixture of carbon dioxide and steam HTP is first passed into a catalyst where it decomposes in an exothermic reaction producing oxygen and water steam The oxygen is then passed to a combustion chamber where it is combined with diesel fuel and ignited Water is also admitted to the combustion chamber to limit the temperature rise and form additional steam The resultant steam and exhaust product mixture is then directed to a turbine for propulsion power 84 Exhaust products are then condensed the water reclaimed and the remaining products discharged overboard 23 EXHAUST OVERBOARD S AWA IR COOLING Walter Power Cycle Figure 418 85 Blank Reverse CHAPTER FIVE 50 REACTANTS This chapter addresses the issue of reactants which include fuels oxidants and other fluids or solids necessary to operate any of the power system concepts discussed in Chapter 4 Table 51 summarizes the fuels and oxidants to be discussed Table 51 AlP Reactant Options What fuels can be used Which are the easiest most weight and volume efficient and safest to store These questions have been the subject of much debate in the AIP arena One such study illustrates the point that the most energy dense fuel may not be the best for AIP applications Consider the following fuels and oxidants and their energy density 87 Reactants Fuel Remarks Hydrogen Pure source hard to store Hydrocarbon Based Fuels With reformerbest hydrogen source Reactants Oxidants Oxygen Cryogenics best method Hydrogen Peroxide Potentially unstable if concentrated Chemical Reformation Competitive in some applications Fuel Energy content Energy storage density kWhrkq reactant and tankage kWhrkq Uranium235 5000 H2 347 H2 02 37 017 Diesel Fuel 127 Diesel Fuel 02 28 047 included to illustrate the high energy density of nuclear power From this data one might conclude that pure hydrogen would be a good choice as a fuel because it is the most energy dense however when the cost of storing the fuel and oxidant is included which is a metal hydride for hydrogen and cryogenics for oxygen in these cases the combination of Diesel Fuel 02 appears better 51 This is perhaps the most critical portion of the AIP concept Chapter 5 is divided into three parts fuels in Section 51 oxidants in Section 52 and because it is a significant concern for most power sources the management of the products of combustion will be addressed in Section 53 51 FUELS 511 HYDROGEN Hydrogen is the basic building block of all fuels and hydrogen in a pure form as H2 is required in the internal chemical processes of all fuel cells Hydrogen can be stored in one of several pure forms or reformed from a hydrogen based fuel as required by the power system 88 5111 HYDROGEN GASEOUS STORAGE Although the storage density for this form is very poor gaseous storage is used extensively in industry where transportation of small volumes of gas are required Increasing the gas pressure will allow more H2 to be stored but will also increase the size and weight of the storage cylinder A standard high pressure cylinder 425 liters at 6000 psi would contain only 123 kg of H2 while the cylinder plus H2 weighs 1388 kg for a H2 weight percentage of 087 percent At this high pressure the energy contained in the compressed gas represents a significant hazard should the tank rupture thus strong consideration would be given to placing the tank outsides the pressure hull Precautions must also be taken to prevent hydrogen embrittlement of the cylinders though the use of special materials and to ensure the cylinders meet established shock performance standards 57 5112 HYDROGEN CRYOGENIC STORAGE Cryogenic storage of any gas as a liquid is more beneficial from the perspective that more of the gas can be carried for a given available volume But as with gaseous storage the penalty of this form of storage lies in the extraordinary measures which must be taken to maintain the cryogenic conditions Storage of cryogenic liquids has been investigated extensively with super insulated dewars being the accepted form of cryogenic storage In this scenario liquid hydrogen LH would be loaded at the beginning of a mission and some boil off accepted due to inevitable heat conduction into the tank This phenomena is especially critical for LH whose boiling point is 200K Accounting for this boil off means that additional hydrogen beyond that for mission requirements must be loaded plus some method devised to deal with the 89 vaporized hydrogen gas itself either by discharge overboard detection risk or combustion One study conducted at Newport News Shipbuilding suggested that a reliquification plant be installed but this would require electrical power to run the required compressors and equipment a luxury not found in an AIP submarine 65 The exceptionally low temperatures bring special considerations associated with the of embrittlement of tanks the sealing of valves and connections and specially insulated hull penetrations should the tanks be stored outboard of the pressure hull their most likely location because of safety concerns In light of these considerations as with gaseous hydrogen meeting submarine shock standards will also be a challenge Also to be considered are the logistics of fueling the ship While LH can be transported safely its availability is not as wide spread as other fuels or even liquid oxygen so replenishment overseas or outside a specific port may prove difficult 5113 HYDROGEN METAL HYDRIDE Of the three pure hydrogen storage methods the HydrogenMetal Hydride hydride method is the only one than has been tested at sea An iron titanium hydride storage system was used in Germany in a Type 205 submarine during fuel cell tests in 1987 29 The principle of operation for a hydride is that a metal matrix of some form is saturated with hydrogen gas with the hydrogen bonding itself to the matrix The amount of hydrogen absorbed depends of the temperature and pressure in the matrix and varies by matrix type 57 This concept of charging the hydride with an over pressure of gas makes it an easy way to refuel the submarine and is considered to be the safest of all the hydrogen storage methods When the hydrogen is required for power generation a reduction in hydrogen gas pressure 90 along with heating the matrix in some forms will cause the hydrogen gas to be released for use This method of hydrogen storage is very volume efficient but brings with it a significant weight penalty The weight density weight of hydrogen to the total storage system weight for the hydride used in the Type 205 submarine was 15 percent and is typical for most known hydrides although researchers in India have claimed weight densities as high as 6 percent 56 65 Other issues involve improving the hydrogen storage density for low temperature hydrides and the sizing of storage containers which provide the proper amount of heat transfer when required IvlcLll nyul luG LVl cly Metal Hydride Storage in ExU1 German Type 205 Figure 51 Because of the tremendous weight associated with the hydride particular attention has to be given to the placement of this weight on the ship in terms of 91 buoyancy and stability Any large weights added should be placed low and will require additional displaced volume to carry the weight a weight limited design Some of this weight could be offset by using it in place of stability lead in the balancing of the ship Both of these concerns were addressed in the Type 205 modification as some lead was removed with the hydrides located external to and below the keel Figure 52 36 5114 HYDROGEN BY REFORMATION This method is one of the most popular hydrogen storage options and is being studied carefully by the research community Having reviewed the weight and volume penalties associated with pure hydrogen storage not to mention the complexities of the storage methods themselves the concept of storing some form of hydrogen based fuel and reforming it to a pure hydrogen fuel in situ is very attractive While the fuel is not pure hydrogen it is dense enough to overcome this difference and is in general much easier to handle and store The decision becomes what fuel to use and how to reform it To reform a fuel into hydrogen steam at high temperature approximately 8000F is brought into contact with the fuel causing for methanol a reaction similar to CH30H H20 C02 3H2 At issue is how to generate the required high temperature for reformation High temperature fuel cells can conduct the reformation internally but low temperature fuel cells require that this process be accomplished externally One possible source of heat comes from burning the tail gas of the reformate itself Incomplete reformation and impurities in the fuel can lead to the creation of other 92 gasses such as carbon monoxide nitrogen and methane Of these gasses carbon monoxide will poison the PEM cell severely decreasing its power output The elimination of carbon monoxide is a developmental issue for reformers 3 Typical candidate fuels for reformation include diesel fuel methanol and ethanol Diesel fuel is easy to handle fully compatible with submarine operations and available worldwide Reformation methods for diesel fuel have been developed but extra processes to ensure the elimination of carbon monoxide make this process more cumbersome Methanol and ethanol can be reformed while minimizing the production of carbon monoxide with methanol producing more hydrogen gas per mole of fuel 3 The ethanol reformation process also requires more water and produces more carbon dioxide which must be disposed of 13 Methanol is a synthetic fuel that is in ample supply because of its interest as a replacement fuel for automobiles Methanol however is immiscible in water requiring it to be stored in its own tank or in seawater compensated tanks with bladders separating the fuel and water One other reformation process has been suggested for AIP applications and involves the transformation of a hydrocarbon fuel form one form to another releasing hydrogen gas in the process A proven technology in the chemical industry one example fuel to be reformed is cyclohexane C6H12 C6H6 3H2 Reformer producing 56 grams of hydrogen per 780 grams of cyclohexane 7 H2 by weight 26 93 In summary of the hydrogen storage methods discussed above Figure 52 presents a comparison of the various options From this graphic it can be seen that while gaseous or cryogenic hydrogen contains 100 percent hydrogen the percentage weight of hydrogen stored is inferior to that for reformed methanol Even a metal hydride FeTiH15 stores more hydrogen per cubic meter however with a hydrogen storage weight percent compared to the storage system of less than 1 percent it clearly carries a weight penalty Additional details on hydrogen storage are contained in Appendix B I f Iw 80 60 40 20 0 IJ Z H2 Gas Uquid H2 Meihanol FeTiH 195 U Wt H2 from Fuel L Wt H2 fuel tank El H2 storage density kgm3 Hydrogen Content of Various Fuels 44 Figure 52 512 OTHER FUELS A variety of fuels have been considered for AIP applications The goal of these fuels can be summarized by saying they should have a high energy density be easy to handle and be readily available These fuels should also 94 produce a minimum amount of exhaust products so less has to be discharged overboard or stored onboard Marine diesel fuel is available world wide but is not an optimum fuel source As illustrated in Section 5113 marine diesel is difficult to reform and also contains sulfur which can lead to the formation of sulfuric acid and high temperature corrosion problems in synthetic atmosphere engines Desulfurized diesel fuel is common but not a regular fuel in standard logistic supply systems The use of JP5 C12 7H228 a standard aviation and gas turbine fuel has been considered in some applications because of its high energy density and logistic availability 70 The French MESMA system presently uses ethanol although other fuels are being considered and the Swedish Navy utilizes a sulfur free fuel Lacknafta which is similar to marine turpentine 20 35 52 OXIDANTS 521 OXYGEN Oxygen is required to complete the combustion process and can be provided in many different forms 5211 OXYGEN GASEOUS STORAGE Arguments similar to hydrogen above can be made against gaseous storage for oxygen when compared to other methods such as cryogenics Oxygen storage in high pressure flasks is very inefficient in terms of volume and weight As an example a study conducted at Newport News Shipbuilding evaluated methods of oxygen storage In an attempt to store 100MWhrs of oxygen 500 21 ft3 standard oxygen flasks at 3000 psi were required with a total weight of 475 Itons and a volume of 13400 ft3 A comparable liquid oxygen 95 system would weigh 109 Itons and displace 3348 ft3 illustrating the efficiency of liquid oxygen storage 65 One novel method of gaseous oxygen storage has been proposed by an Italian company Fincantieri employing torroidal gas cylinders which are welded together to form a pressure hull This method helps to alleviate the weight and volume penalties of gaseous oxygen storage by replacing ship structure with oxygen cylinders The cylinders are designed to store the oxygen at 4000 psi and also store exhaust products from a CCD engine 66 This principle is illustrated in Figure 53 One obvious concern with this design is that while the individual torroids are no doubt sturdy can the process of joining these torroids together form a pressure hull that is strong enough to withstand shock and can be adequately inspected for cracks and corrosion Pressure Hull r H Torroidal Cylinders Torroidal Gaseous Oxygen Storage Concept Figure 53 5212 OXYGEN CRYOGENIC STORAGE This method is considered to be the best option for storage onboard an AIP vessel More volume efficient than gaseous storage an extensive 96 experience base exists for the handling of liquid oxygen LOX Storage tanks would be comprised of super insulated dewars with a typical storage temperature of 900K 1830C Based on typical tank arrangements the boil off would be approximately one percent of the volume per day 7 Unlike hydrogen above this boil off is beneficial with the vaporized oxygen used as breathing oxygen for the crew In an effort to reduce the heat absorption of the LOX large tanks are more efficient but become more difficult to place on the submarine There are many safety concerns associated with LOX storage inside the pressure hull to include Failure of tank flooding the ship with oxygen oxygen poisoning Increased fire potential Cryogenic contact with sensitive materials such as HY steel hull 31 Sweden has adopted LOX storage for use in NAECKEN and has reported no operational problems to date Their concept is similar to that pictured in Figure 51 with two double insulated LOX tanks contained in an isolated LOX compartment equipped with monitoring equipment and an overboard venting system for emergencies In this arrangement all the LOX piping is completely shielded from the crew much the same as a reactor compartment onboard a nuclear submarine 20 A study conducted by Johns Hopkins University Applied Physics Laboratory in the 1980s investigated the replacement of oxygen generators with cryogenic oxygen tanks envisioning a storage system with tanks located in the ballast tanks external to the pressure hull In this study placement of the tanks in the corrosive environment of the sea was judged to be 97 a safer option than standard double insulated tanks located inside the pressure hull in place of the oxygen generators 7 5213 OXYGEN CHEMICAL REFORMATION There are a number of chemical compounds which can produce oxygen as a byproduct of a chemical reaction One compound that has found use in the AIP arena is Sodium Perchlorate NaCIO04 which is used to generate oxygen for the US Navys Oxygen Breathing Apparatus OBA units and is now proposed as an oxygen source in an aluminumoxygen power system for the 44 inch UUV In this concept Figure 54 oxygen candles are contained in a large vessel and ignited sequentially to maintain a certain oxygen pressure in an accumulator thus supplying oxygen on demand without the issues of oxygen boil off over long periods of inactivity 59 PS Accumulator Actuation Control Oxygen Circuit Demand I Burned Candle Unburned Candle Oxygen Candle Vessel 44 Inch UUV Oxygen Supply Concept Figure 54 98 D 5214 OXYGEN GENERATION ONBOARD Generation oxygen onboard submarines is not a new concept as nuclear submarines have been doing this for many years with a reverse version of the alkaline fuel cell An oxygen generator can produce up to 134 kg of oxygen per hour while requiring 50 kW of electrical power Appendix B 7 For comparison a standard PEM cell requires approximately 25 kg of oxygen to produce 50 kW of electricity Based on this simple analysis Generation of oxygen by electrolysis is not a viable option One other onboard generation option is the extraction of oxygen for the ocean itself Artificial gill technology involves the use of a porous membrane which only passes gas molecules to extract the dissolved oxygen from the sea Oceans in the northern latitudes possess the required oxygen concentration greater than 4 mll of seawater necessary for this technology to be successful 1 The present state of development for this technology renders it as large and bulky requiring approximately 30 percent of the electricity that its oxygen can produce Further development may make this technology a viable option for the future 522 HIGH TEST HYDROGEN PEROXIDE Hydrogen Peroxide H202 is a versatile compound which has many uses Common in low strengths as a disinfectant H202 in high concentrations is extremely reactive and quite powerful For this thesis high test hydrogen peroxide HTP is defined to mean H202 of sufficient concentration to be used as an oxygen source for an AIP vehicle HTP decomposes by the following reaction 99 H202 H20 02 heat HzO 2 In very high concentrations ie greater than about 75 weight percent H202 the chemical reaction is very unstable and dissociation can occur very rapidly in the presence of a catalyst which can be almost anything In lower concentrations however HTP can be handled successfully An accepted method for storing H202 proposed in several studies is to contain the reactant in polyvinyl chloride bladders inside seawater compensated tanks 44 A 70 percent H202 solution can be expected to yield 33 percent oxygen by weight In summary of the oxidant storage methods discussed above Figure 55 compares the weights and volumes of the various sources 44 l fn Isw 80 cm 60 40 20 0 E 02Gas LOX 70 H202 1000 800 600 400 200 0 Z c E 0 co OWJ 0o NaCI04 Wt Oxfrom WtOxOxidant Oxslorage density Oxdant lank kgm3 Ii Comparison of Oxidant Storage Methods Figure 55 100 w Ie 53 WASTE PRODUCT MANAGEMENT Almost as much of an issue as what fuels to use is how to deal with the waste products of AIP From a design view management of the waste products affects the net power output of the plant since energy will be required to return the products to the sea or process them for retention onboard Operationally exhaust products may leave a trail that while invisible to the eye could be detected by other sophisticated means Since energy conversion generally involves hydrogen consumption any fuel that brings with it other elements such as carbon will have waste products to be processed such as carbon dioxide Some waste products are not really waste like the pure water generated from the PEM cell which is potable and can be easily stored for crew consumption or transferred to a variable ballast system for discharge overboard The aluminumoxygen cell generates hydrargillite but as water and potassium hydroxide are added to the system to compensate for the corrosion of the aluminum plates this waste can be stored in the empty reactant tanks for processing upon return to port Thus the primary concern of waste management is how to deal with carbon dioxide and other inert gasses In the torroidal oxygen storage design by Fincantieri of Italy the concept proposes compression and storage of the waste gas without discharging overboard 29 The other alternative is to discharge the gasses overboard After expending the energy to compress the gas to operating depth pressure 20 kW based on PEM cell with reformed methanol at 500 kW and 1000 ft operating depth Appendix B the gas must be diffused so that large bubbles dont trail the submarine One concept for distributing the gasses is shown in Figure 56 22 The most promising solution to the carbon dioxide discharge problem comes from a consortium headed by Cosworth Engineering of the United Kingdom In this Cosworth system exhaust gasses are scrubbed of carbon 101 dioxide which is soluble in water by passing the gas through an absorber unit where it is sprayed with low pressure seawater until the water is saturated The carbon dioxide saturated water is pumped to a water transfer unit where spools connecting a high pressure submergence pressure loop and the low pressure scrubbing loop are swapped The saturated water is then flushed to sea via the high pressure loop The system is effective quiet and has been demonstrated successfully at sea The system claims to minimize the power required to discharge carbon dioxide overboard because the seawater pumps work only against the differential pressure in their loop instead of against full sea pressure Porous Plates GAS DIFFUSER Direction of Flow Slowly narrowing flow area to prevent flow separation Liquid Gas Flow Mixer Figure 56 102 i ON M requiring only 6 percent of the output power of the plant 65 Using this estimate about 30 kW of power would be required to discharge carbon dioxide overboard from a 500 kW PEM plant with reformed methanol The Cosworth system is being strongly considered by almost every nation interested in processing carbon dioxide gas overboard Scrubbed Exhaust Out ENGINE ATMOSPHERE CYCLE Cooled Exhaust In LP Seawater HP Seawater SEAWATER TRANSFER SYSTEM ABSORBER Overboard Cosworth Exhaust Management System Figure 57 Blank Reverse CHAPTER SIX 60 THE SUBMARINE MODEL The modeling process for the weights and volumes which determine the shape of the final submarine hull are described in this chapter Section 61 describes the submarine envelope while Sections 62 and 63 describe the model for volumes and weights Section 64 outlines the method for ship powering and endurance calculations As stated in Chapter 2 the estimation of weights and volumes for a submarine concept design come from an extensive historical data base For this thesis the data base for weights and volumes is derived from a 1988 Massachusetts Institute of Technology MIT thesis by Stenard titled Comparative Naval Architecture of Modern Foreign Submarines 61 The approach for the model is based on the MIT Math Model for Conventional Submarines 53 MIT Math Model and several papers by Captain Jackson on submarine parametrics and concept design 33 34 The AIP submarine model builds from a baseline diesel electric submarine which was originally synthesized using the MIT Math Model 68 In this design a concept submarine Appendix C was developed using the math model and balanced in sufficient detail to gain confidence in the model evaluate the validity of the various coefficients and establish certain weights and volumes for use in this thesis This model therefore develops a Hybrid submarine one that retains full diesel electric capability and adds an AlP option rather than one that relies on AIP alone 105 61 HULL ENVELOPE It is well accepted that a streamlined form will offer less resistance to flow than one that is irregular in shape Because the modern submarine is optimized to operate below the water surface rather than above as in pre1960 designs the body of revolution or Albacore form has been adopted as the primary hull shape In describing its shape Jackson states that an optimum design will have a well rounded nose and a streamlined tail with an UD length to diameter ratio of about 6 and a maximum diameter about 40 aft of the forward end 33 It is seldom possible to achieve an optimum shape as the size of the hull envelope is driven by the weight and volume of the equipment contained inside the submarine and usually results in the addition of a section of hull constant in diameter between the forward and after parabolic sections Figure 61 The Afterbody Parallel Midbody Forebody The Submarine Envelope Figure 61 106 l l diameter is generally constrained by navigational restrictions imposed on the beam and draft by the harbors where the ship is expected to operate Thus an envelope balance must be achieved which contains sufficient volume for the ship does not pose too wide a beam and is an acceptable compromise with regards to LD ratio In addition to changing the length or diameter the hull shape can be made fuller of sleeker by varying certain constants which describe the parabolas making up the bodies of revolution and can be used to adjust the buoyancy contributed by the hull Appendix D contains details of the hull envelope model 62 VOLUME ESTIMATES The details of the volume estimates are contained in Appendix E 621 PRESSURE HULL VOLUME As shown in Figure 23 the volume inside the pressure hull Vph can be broken into the following categories Mobility Weapons Command and Control C31 Ship Support Auxiliaries Habitability and Storerooms The size of each of these items is dependent on different aspects of the owners statement of requirements and are described below 6211 MOBILITY VOLUME This volume describes that portion of the hull which involves propulsion and power generation to include tankage for any required fuel For 107 conventional diesel electric submarines the following relationship was developed in the MIT Math Model VDE SHPPDE where PDE represents the average mobility density This relationship varies with installed shaft horsepower which changes proportionately with ship size if the required speed performance of the hull is fixed For this model the relationship was modified to include terms which reflect the additional volume of the AIP plant ie energy converter fuel storage compensating water product management system and any change in battery size from the baseline VAIP SHPPDE AVBat VAIP 6212 WEAPONS and C31 VOLUME The weapons volume is based on the amount of ordnance carried by the submarine and the number of torpedo tubes thus the value is fixed by owners requirements and is unaffected by adding AIP capability VP No Torp Tubespw NoReloadsp The volume for C31 is likewise fixed by owners requirements and is a constant based on volume estimates from ships with similar capabilities 6213 SHIP SUPPORT VOLUME This volume is multifaceted and includes the remaining volume inside the pressure hull which is made up of berthing and messing facilities storerooms office spaces and auxiliary machinery spaces Berthing messing and office space are based on factors proportional to navy standards for crew size while 108 storage is proportional to the length of the mission These factors are then adjusted to add additional area for passageways compensate for unusable area due to hull curvature and incorporate a standard deck height of 7 feet Area Berthing Messing Ab Const Crew Size Area Storerooms Ar Const Mission Length Area Other Spaces Ao Const Const Crew Size The required auxiliary volume includes a wide range of items including but not limited to refrigeration and atmosphere control equipment nonAlP variable ballast tanks and piping as well as high pressure air and hydraulic systems This volume is therefore proportional to the size of the ship specifically Vph Because some auxiliary systems are sized for the crew this factor is also affected by manning Vau ConstVph ConstCrew Size Vss Vaux COnStAbm Asr Aos In summary Vph VAIP Vweps V 31 Vss 622 OTHER VOLUMES With parameters established for pressure hull determination estimation of the remaining volume between the pressure hull and hull envelope are based on the size of the ship similar to the auxiliary volume The outboard volume Vob accounts for items outside the pressure hull which are solid with respect to the 109 sea in that they will not flood with water such as high pressure air bottles and structural members Vob is proportional to Vph and when added to Vph the total is termed the everbuoyant volume Veb The free flood volume Vff is the space inside the envelope which floods on submerging and from a naval architecture viewpoint does not contribute to buoyancy when surfaced Vff is proportional to Veb Both factors are based on historical data Vob ConstVph Veb Vob Vph Vff ConstVph The remaining volume is allotted to reserve buoyancy and encompasses the main ballast tanks This volume is based on a percentage of the everbuoyant volume nominally 10 15 percent and is set by the owners requirements based on the expected mission of the submarine When added to the everbuoyant volume main ballast tank volume adds up to the submerged volume Vmbt Const Veb Vsub Veb Vmbt Verv Vsub Vif 63 WEIGHT ESTIMATES The details of the weight estimates are contained in Appendix F 110 631 SURFACED DISPLACEMENT Similar to the pressure hull volume the surfaced displacement or normal surfaced condition NSC is a summation point for the estimated weights in the ship Figure 23 listed seven weight groups that make up the NSC however this model combines some of the groups based on information which can be estimated from Stenard 6311 STRUCTURAL WEIGHT Structural weight includes the pressure hull itself as well as the scantlings necessary to provide the required hull stiffness As a result this factor is proportional both to the final size of the ship as well as the diving depth which is set by the owner Stenard gives the following relation for structural weight Wr NSCConst Diving Depth Const This weight is not directly affected by the addition of an AIP power plant 6312 MOBILITY WEIGHT For diesel electric submarines the following describes the relationship for the weight of mobility Wmob Battery Weight ConstSHP04 This relationship varies with the installed shaft horsepower and battery weight both of which will vary directly with ship size if the required speed performance of the hull is fixed Mobility weight is the one weight parameter which is directly 111 affected by the addition of AIP capability As described in Section 6211 the relationship is modified to include terms which reflect the additional weight of the AIP plant and any change in battery weight from the baseline Wmb Battery Weight Const SHPO AWBterr WAP 6313 WEAPONS AND C31 WEIGHT Similar to the weapons volume weapons weight is based on the number of torpedo tubes plus factors related to the volume of the weapons space The number of reloads do not figure into this weight because they are accounted for in the variable load of the ship Unlike the volume determination for C31 the best estimate of this weight is obtained by using a percentage of the weapons volume which is closely linked to the sensor and electronic capabilities of the ship Wweps ConstV ConstNo Torp Tubes Const Wc ConstV 6314 SHIP SUPPORT WEIGHT As described for ship support volume this weight encompasses auxiliaries and habitability items By similar reasoning auxiliary weights are proportional to the size of the ship and is scaled by NSC while habitability is proportional to the size of the crew The following describes the relation for ship support weight 112 W ConstNSC ConstCrew Size 6315 FIXED BALLAST AND VARIABLE LOAD WEIGHT All submarines are designed with added weight normally in the form of lead ballast to provide a margin for weight growth over the life of the ship margin lead and to help balance longitudinal moments stability lead The total amount of lead is set as a percentage of NSC and is normally greater than 5 percent Variable load weight represents a broad category of items which are not a fixed part of the ship but are weights that can be expected to vary from mission to mission such as the embarked crew and initial weapons load or items that are depleted over the course of a patrol such as fuel oil and provisions Because these weights will generally decrease over a mission an equal amount of weight must be added so the ship can maintain a neutrally buoyant condition This weight addition is accomplished via the variable ballast system Reference68 describes an investigation of the effect of AIP fuels on this factor and determined that the proportion of AIP fuel is similar to that for conventional diesel fuel allowances As a result this factor is adjusted such that the final weight of variable loads bunker diesel fuel and AIP fuel together represent the same percentage of the total variable load for conventional submarines Wo ConstNSC W ConstNSC In Summary NSC Wstr Wmob Wweps Wc3 Wss Wfb W 113 By solving the above equation for NSC the total weight to be supported by displaced water at all times is determined and must be equated to the everbuoyant volume determined earlier This balance is achieved by increasing the fixed ballast percentage if the equivalent weight of the displaced seawater volume is greater than NSC volume limited If the estimated ship weight is greater than the equivalent displaced seawater volume weight the dimensions of the hull envelope are increased which will proportionately increase the everbuoyant volume until the two values match weight limited 64 POWERING AND ENDURANCE Once the initial estimates of weight and volume are made a check must be made to see if sufficient allowance has been made for required propulsion and electrical hotel loads as well as endurance requirements This section describes the method used to model these estimates The details for this section can be found in Appendix G 641 POWERING 6411 HYDRODYNAMICS While the Albacore style hull helps to reduce resistance a certain amount of resistance must be overcome to push the hull form through the water This resistance can be divided into two broad categories hull resistance and appendage resistance Hull resistance has three component parts 114 Frictional Ca which is a function of ship length speed and the viscosity of the seawater An accepted correlation for C is given by 0075 Log0Rn 22 where Rn SpeedLength kinematic viscosity Residual C which represents the resistance generated by pressure differences along the hull Jackson gives the following relation for Cr 0000789 Cr L k2 D where k2 6 36DiaCsa 24DiaCsf Correlation Allowance Ca which represents an adjustment between results obtained by model testing and actual results obtained from full size ship tests Ca 0 0004 Because these resistance coefficients are all based on the size of the hull they are brought together with the wetted surface described in Appendix D Appendage resistance is made up of Bridge Sail resistance which varies with the total surface area of both sides of the sail and is calculated by multiplying this area by the following drag coefficient CDB 0009 R CDBArea Sail 115 C Appendage resistance varies with the total surface area of the control surfaces bow planes stern planes and rudder Jackson has shown that for good existing submarine designs this resistance can be approximated by Rapp LengthDiameter 1000 With an estimate of the total resistance on the ship the effective horsepower EHP which is the power necessary to push the hull through the water can be calculated by the following EHP Const Speed3WSCf Cr Ca Rbridge Rappend EHP is translated into shaft horsepower SHP through the propulsive coefficient PC EHP SHP PC PC represents the efficiency of the propeller in transferring the power at the propeller to the ocean and is a function the open water characteristics of the propeller o the hull efficiency h the relative rotative efficiency rr which accounts for turbulence in the wake in the vicinity of the propeller PC ohX7 For this model the PC determined for a seven bladed 155 ft diameter fixed pitch propeller in Reference 68 is assumed Any comparisons made in the 116 model with various propeller options are accomplished by adjusting the value for PC 6412 PROPULSION MOTOR TURNDOWN The propulsion motor installed in any shipboard application must be sized to meet high end power requirements However in the case of AIP applications the motor will be operated at a power much less than its rated value Operation at this lower power may result in a lower motor efficiency and a lower overall transmission efficiency for the conversion of electrical power to shaft horsepower Conventional DC motors are presently installed in many diesel electric submarines Short of utilizing Permanent Magnet AC motor technology Section 312 AC synchronous motors employing power electronics technology are available now for use in propulsion applications These motors do not suffer from the same efficiency loss as conventinal DC motors 45 For this model motor efficiency was assumed to be constant over the range of operation 642 SNORKELING POWER AND BUNKER FUEL CALCULATION This power represents the additional resistance on the hull due to wavehull interactions near the surface while operating submerged with the snorkel mast extended The real effect on the ship is that more power is required while at periscope depth to maintain a given speed The additional power is given by SHPwave ConstWSC where Cwa Cont 117 and is used to determine the amount of bunker fuel required for the ship to make the stated diesel endurance The weight of bunker fuel is given by the following relationship which combines range diesel engine economy and total engine load RangesfcSHPwae sub 1 34HOTEL LOADDE Fuel Itons 2240tailpipe r Snorkel Speed 643 HOTEL LOADS Hotel loads represent all the parasitic electrical loads on the ship which are required to support essential ship functions Traditionally diesel submarine hotel loads are smaller than on nuclear submarines because electrical power is a premium coming directly from the battery while submerged AIP really does little to alleviate the problem completely because at low speeds the electrical hotel load is predicted to be several times larger than that required for propulsion Stenard gives the following relation for calculating hotel load HOTELDE kW 1 5VmOb 4Vc 15Vss VwEps 1000 Hotel load is a function of various ship volumes which grow as ship size increases While its absolute size is small the factor of four applied to the volume for C31 reflects the intensive power nature of electronic equipment Since hotel load scales with submarine size no adjustment was made for the AIP plant itself however a constant value of 15 kW was added to account for the power necessary to operate one COH2 burner and one CO2 scrubber for 118 atmosphere control equipment not normally found on dieselelectric submarines HOTELAIP HOTELDE 15kW Some additional relief that AIP may provide on hotel load comes from the pure water generated by some fuel cell plants or the potential for bottoming cycles or other use of waste heat eliminating some electrical heating requirements None of these considerations are incorporated in this model 644 BATTERY ENDURANCE AlP can provide relatively low power 500 kW for significant periods of time weeks AlP cannot provide the power 40005000 kW necessary for high speed bursts for any period of time The solution to this short term high power problem is the storage battery which can provide the burst energy necessary to make high speeds for several hours at a time Thus the battery endurance at a given speed is an important quantity to evaluate for any AIP model The general relationship for battery endurance is given by Batt SizeBatt Capacity Batt Endur hrs 0746 SHP HOTEL LOADAIP In this relationship battery capacity is the kW rating for the battery at a particular discharge rate assumed to be about 2 hours for burst conditions and 80 hours for creep calculations For any periods of time estimated to be greater that these two assumptions ie a burst period estimated as 25 hours the results are conservative as a battery will generally deliver more total energy when discharged at a slower rate 7coul represents the efficiency associated 119 with recovering energy stored in the battery In this model any battery can be represented as long as the rapid and slow discharge rates are known and an estimate of 7coul made This same relationship in a different form is used to calculate any change in battery weight and volume from the baseline submarine For a given endurance period the required battery size can be determined The difference in the number of batteries from the baseline is then determined and using weight and volume estimates for a standard battery a change in battery weight and volume can be calculated and applied to the mobility estimate for the ship 65 THE AIP PLANT The AIP plant is modeled using the data presented in Appendices A and B for the various plant and reactant options For a generic AIP plant the following component parts were considered Plant type PEM CCD etc Reformer required YES NO Oxidant type LOX H202 etc Fuel type H2 Diesel Methanol etc Other fluid KOHVATER ARGON Comp Water Product mgmt system YES NO Breathing oxygen YES NO Reqd if LOX not designated as the choice for oxidant For each item a weight g or kg or volume or khr factor as appropriate was determined so that an estimate of the total weight and volume of that part could be made The parts that are applicable to a given plant are then summed to give a total AIP weight and volume These values are then input to the weight and volume relations for mobility to give total AIP capable values 120 CHAPTER SEVEN 70 COMPUTER CODE DEVELOPMENT The computer code for this model was written using Turbo C Version 30 for DOS by Borland incorporating the submarine model concepts presented in Chapter Six Figure 71 provides an overview of the code titled SUBSIZE showing the flow path through the functions to achieve a balanced design Input data in file SUBSIZECPP is modified by the user before each run to establish the desired ship constraints The AIP plant is defined in file AIPSIZECPP for one of six different AlP plant options The computer code including the main program functions input data and sample output is contained in Appendix I 71 OVERVIEW Referring to figure 71 the user selects the desired parameters for the ship in the main program SUBSIZECPP The first functions called estimates the volumes and then the required hull envelope Weights are estimated next since some weight estimates are based on the volumes already determined Weights and volumes are then matched in a looping process which checks the value of NSC against a displacement equivalent to Veb AV Veb 35 NSC and Av are matched by the following process 121 INPUT DATA SUBSE CPP ESTIMATE WEIGHTS WEIGHT I I I BALANCE WEIGHT LIMITED WTLIMIT t I I VOLUME LIMITED VLLIMIT I SELECT AIP PLANT ESTIMATE POWER CALC SNORT POWERFUEL I CALC HOTEL LOAD I CALC BATTERY SIZE I CALC BATT ENDR INDESC RATIO CALC AIP PLANT SIZE II I POWER SNORT DIESFUEL HOTEL BATTDELT BATTENDR INDESCR AIPSIZ SUBSIZE Flowchart Figure 71 122 ESTIMATE VOLUMES VOLUME DETERMINE ENVELOPE ENVLEOPE mmomm I I WEIGHT LIMITED NSC Av The overall length of the hull envelope is increased in 01 foot increments until the resulting envelope displaces enough water to equal NSC Volumes are then recomputed VOLUME LIMITED NSC Av The amount of lead is increased by adjusting the lead margin in increments of 004 percent approximately 100 Itons until NSC equals Av Weights are then recalculated The weights and volumes are matched in this fashion rather than refining the estimates of weights or volumes because in this first look at a concept design not enough information is usually available to adjust weights and volumes Only after a complete trip around the design spiral can such adjustments be made With a balance achieved between weights and volumes the estimates for ship power fuel load hotel load and battery endurance and indiscretion ratio are made These parameters are calculated first because they will be used to provide the estimate of the size of the AIP plant and its required fuel as well as any increase in the size of the battery With the power requirements established the size of the particular AIP plant is calculated and an adjustment in the size of the battery estimated These values are then added to the weights and volumes for mobility which will typically increase these values Now that the estimates for weight and volume have changed the program enters an iterative loop where the process described above is repeated Each time through new values for ship powering hotel load and battery endurance and indiscretion ratio are calculated because as the ship changes in size so will 123 these values At the end of each loop a revised total AIP plant size is determined along with a revised change in battery size These new values then replace the previous values in the mobility weight and volume estimates Iterations are continued until the change in NSC from one iteration to the next is less than one percent Program output includes a restatement of the key input parameters as well as those parameters which were calculated or adjusted by the program such as lead margin The output also summarizes the volume and weight estimates for the submarine hull as well as weight and volume estimates for the AIP plant broken down by plant reactants and auxiliaries A sample program output sheet is contained in Appendix I 124 CHAPTER EIGHT 80 RESULTS AND CONCLUSIONS The goal of this thesis was to develop a computer code to evaluate various AIP propulsion options by synthesizing a submarine hull according to certain owners requirements for mission capability and performance This code can be used to support the concept design of AIP submarines The model developed gives good results when compared to other studies of AIP submarines Validation of the model is addressed in Section 81 with AIP and other technological impacts evaluated in section 82 Section 83 illustrates the usefulness of the tool in performing tradeoff studies as a part of the submarine design process 81 MODEL VALIDATION It is difficult to measure the accuracy of this model against real world submarines for several reasons The number of true nonnuclear AIP submarines is small and many of the technologies evaluated in this thesis are still theoretical in terms of full scale applications Additionally the details of any real or proposed ships are carefully guarded by the respective consortiums and governments conducting AIP investigations The AIP option has been investigated by several student submarine design teams in the Naval Construction and Engineering Program at the Massachusetts Institute of Technology MIT in a variety of scenarios and missions but AIP has always fallen short in tradeoff studies when compared to nuclear power and total ship performance One recent study at MIT evaluated the AIP option from the perspective that AIP was the only option for extending 125 underwater endurance forcing an detailed evaluation of AIP concerns and limitations 60 This study evaluated PEM fuel cell with methanol and Aluminum Oxygen semicell technologies selecting one option for a concept design In the concept design a detailed evaluation of discrete submarine weights and volumes and arrangements was made to validate the approach used and to verify the appropriateness of the margins assumed The approach to submarine synthesis used in that study was paralleled by this thesis with results presented in Figure 81 AC Uz 5000 4000 3000 2000 1000 0 BASE LINE PEM 25 day endurance PEM 35 day endurance ALOX 25 day endurance ALOX 35 day endurance CANADIAN HYBRID AIP SUBSIZE COMPUTER SUBMARINE MODEL Comparison of Canadian Hybrid Submarine and SUBSIZE results Figure 81 As can be seen the results of the SUBSIZE model for NSC closely follow the findings from the Canadian submarine study While the same margins and scaling factors used in the study were duplicated in the computer model 126 detailed design decisions in the Canadian submarine study had a significant impact on the final results for each variant Detailed decisions of this sort were not included in the SUBSIZE model results 82 GENERAL RESULTS For many of the figures presented results are compared by NSC between variants This attribute was chosen for comparison purposes because it represents the balancing point in the model between weights and volumes NSC also has a significant impact on other attributes such as installed SHP and AIP plant capacity Results showed each of the AIP options to be volume limited requiring the model to add lead ballast by increasing the lead margin to achieve a balanced design This is attributed to the fact that the overall AIP plant has an average density less than that of seawater 64 Ibsft3 Table 81 Table 81 Comparison of AIP Plant Densities 25 day endurance 8 kt AIP speed 20 kt burst speed 127 AIP Plant AIP Weight AIP Volume Plant Density Itons ft3 Ibft3 Aluminum 47699 2562763 4169 CBC 50047 4684182 2393 CCD 74434 678244 2458 MCFC 2524 2299155 2450 PEM 27812 233235 2671 Stirling 69911 6483188 2415 Supporting data for each of the figures in this chapter can be found in Appendix H 821 OVERALL AIP IMPACT Many investigations have been conducted regarding the benefits and limitations of different AlP options It is not unexpected that the results obtained with the SUBSIZE model should parallel results obtained by others Figure 82 presents the results by AlP plant for various ship and AlP attributes and shows that the MCFC plant results in the smallest ship for a common set of requirements The PEM plant is closely matched and given the shipboard suitability issues and operating experience for each plant it can be understood why the PEM fuel is being actively pursued by many nations The CCD engine is predicted to require the largest ship size of the three heat engines evaluated due to its generally higher specific plant weight and high specific reactant consumption rates Table A1 Despite these results the CCD is a popular option because diesel technology is readily available The Aluminum Oxygen plant ranked midway between the fuel cells and heat engines When the AlP endurance is varied as in Figure 83 the impact on ship size shows that the variance in ship weight is larger for those plants whose specific reactant consumption rates are higher specifically the heat engine plants The trends observed in Figure 83 are consistent with those presented in reference 52 128 X A c4 a m ALOX CBC CCD MCFC PEM STRLNG 8 kt AIP speed 20 kt burst speed 25 day AP endurance with LOX e LENGTH NSC SIZE AIP ft1000 io3ns10000 kW1000 Comparison of AIP Plants Figure 82 12000 10000 8000 6000 4000 CBC CCD MCFC PEM STRLNG 8 kt AIP speed 20 kt burst speed with LOX e 25 Days 30 Days 35 Days AIP Plant Variation with Endurance Figure 83 129 06 05 04 03 02 01 0 0 oc 0 Uzz 2000 0 ALOX 822 IMPACT OF REACTANTS Figures 84 and 85 show the effect of various reactant storage methods on NSC For comparison purposes the PEM plant with methanol was chosen for the oxidant storage variation and the PEM plant with LOX chosen for the fuel storage variation All other attributes for the ships were held constant Of the four oxidant storage methods evaluated LOX HTP and sodium perchlorate all have a similar impact on ship size while gaseous storage methods compare poorly These results are generally in agreement with figure 55 except that sodium perchlorate does not show the expected advantage in terms of oxygen density Gaseous storage is the worst because of the large weight of the oxygen flasks compared to oxygen Table B1 with the internal storage option suffering significantly because of the increased volume packing factor While competitive with LOX HTP suffers from a history of mishaps and difficulty in handling and will no doubt face significant opposition The use of sodium perchlorate in this size application may also be met with some skepticism Figure 85 presents the results for various hydrogen storage options and compares well to the trends of Figure 52 Next to methanol liquid hydrogen has the least impact on ship size but presents many practical engineering issues in its implementation Metal hydrides enjoy great volume efficiency but pay a significant penalty in weight forcing ship size to grow significantly to carry the high weight of the hydride bed Gaseous hydrogen storage is shown to be beyond the realm of practicality as expected due to the very low ratio of stored hydrogen weight to that of its vessel 130 2 1 I 15 1 05 O LOX H202 NaCIO3 Gas Ox External Gas Ox Internal PEM Plant with Methanol 8 ktAIP speed 20 kt burst speed NSC A AP Oxidant Oxidant ItDns Capacity Tank Tank 10000 kW Volft3 Wtlton 1000 100000 11000 Comparison of Oxidant Storage Methods Figure 84 LIQ H2 HYDRIDE GAS H2 PEM Plant with LOX 8 ktAIP speed 20 kt burst speed I NSC ItDns Fuel Tank Fuel Tank 10000 ft3 100000 Itons 1000 t Comparison of Hydrogen Storage Methods Figure 85 131 25 2 15 1 05 0 METH 823 IMPACT OF OTHER TECHNOLOGIES Because the model considers the impact of AIP on the total submarine design certain ship constraints can often mask expected results This concept is evident in the comparison of battery types on ship size In the model battery size is constrained to satisfy endurance requirements at both creep speed 90 hours and at burst speed 2 hours The general trend through all results shows that the creep requirement is limiting In Figure 86 the use of a LAIS battery which is assumed to have the same discharge characteristics as the lead acid battery but a higher energy density results in a smaller ship while the NiCd option which has an energy density between the two does not follow the same trend This difference can be explained by the relatively flat discharge curve for NiCd batteries over a range of discharge rates Figure 49 which results is a slightly larger installed battery and significantly more burst endurance 1 08 06 04 02 0 Lead Acid NiCd LAIS PEM Plant 4 kt creep speed 20 kt burst speed I NSC llns 10000 for creep Burst Endurance hours 10 endurance of 90 hours for creep endurance of 90 hours Comparison of Battery Options with Fixed Creep Endurance Requirement Figure 86 132 By adjusting the model to fix burst endurance at two hours Figure 87 ship size is decreased by approximately 5 and 15 percent respectively for lead acid and NiCd options but not for LAIS which had the closest balance between the battery endurance scenarios These results show that next to the AIP plant battery endurance requirements have a significant impact on the overall submarine design 1 08 06 04 02 0 Lead Acid NiCd LAJS PEM Plant 4 kt creep speed 20 kt burst speed NSC lions 10000 for burst Creep Endurance hours 10 endur of 2 hrs for burst endur of 2 hrs Comparison of Battery Options with Fixed Burst Endurance Requirement Figure 87 For shaft propulsion options variations in propulsive coefficient and motor type were evaluated For the different motor types the real impact on ship synthesis is in the weight required for each option with results in Table 81 While both advanced motor options have less actual motor weight the model adds back lead ballast due to the volume limited nature of the AlP submarine which results in a heavier submarine in the synthesized model The true impact 133 Table 82 Effect of Propulsion Motor Type on NSC Motor Type NSC Itons Final Lead Margin Conventional 256436 0112 Permanent Magnet AC 266392 0147 Superconducting 266067 0137 Homopolar DC 25 day endurance 8 kt AIP speed 20 kt burst speed of this weight reduction would have to be evaluated in detail when the first reconciliation of weights is done in the concept design process In varying the propulsor type an improvement in propulsive coefficient is evident in smaller plant sizes and fuel volumes Figure 88 shows the results of increasing the propulsive coefficient by 10 percent As before for varied endurance the reduction in NSC is more significant for ships with higher specific reactant consumptions 0 Uz 5000 4000 3000 2000 1000 0 AL A A 7 T Ox CBC CCD MCFC PEM 25 day endurance 8 ktAIP speed 20 kt burst speed STRLNG A Fixed Pilch Prop PC 086 Conta Rotatng PC 096 Effect of Propulsive Coefficient on NSC Figure 88 134 I I 83 SHIP TRADEOFFS As explained in Chapter 2 the design process is iterative with many tradeoffs and compromises conducted to achieve a balanced design which meets the owners requirements The usefulness of the SUBSIZE model is illustrated here with several examples which show how varying certain requirements can affect the ship design Chapter 6 showed how decreasing the length to diameter LD ratio can improve the powering of the submarine which results in a reduction in installed SHP Figure 89 illustrates the effect of increasing the hull diameter for one of the larger AIP variants with its resulting decrease in NSC and SHP 140 120 100 080 060 040 30 31 32 33 34 35 36 37 38 39 40 Hull Diameter feet NSC I1Dns LOD10 SHP10000 10000 Effect of LD ratio on NSC and SHP Figure 89 The effect of increasing the desired AIP speed is shown in Figure 810 While this curve is similar to the trend for increasing AIP endurance the point where increasing AIP speed has a significant impact on NSC is instructive A 135 curve of this type tells the designer that a change in AIP speed of 1 knot below a threshold of about 7 knots is relatively insignificant when compared to a similar 1 knot increase in speed above 7 knots 08 06 04 02 0 c I d 4 5 6 7 8 9 10 AIP Speed knots i NSC AP A AAIPWt AP Ions Power Iions Volume 10000 kW 1000 ft3 1000 100000 Effect of AIP Speed on NSC Figure 810 One final operational parameter considered important for submarine operations is the indiscretion ratio which is the amount of time spent snorkeling to recharge batteries divided by the total time for a chargedischarge cycle While on AIP this ratio will be essentially zero however while transiting this ratio may be significant The goal of reduced intersection ratio must be balanced by the owners requirement to maintain an acceptable average speed of advance when transiting Table 83 shows how SUBSIZE may be used to evaluate the effect of various transit and snorting speeds on indiscretion ratio and speed of advance 136 Table 83 Indescretion Ratio and Speed of Advance 3 Knot Snort Speed Transit Charge Speed of 3 Endurance Time Advance Ratio hours hours i knots 8 01 4002 475 731 9 013 3214 475 j 801 10 015 2584 475 1 863 11 018 2088 475 1 916 12 021 1699 475 i 959 13 024 1394 475 i 993 14 3ii 027 101717 4 not Snort Speed Transit Charge I Speed of Indesc 4 R Endurance Time Advance hours hours knots 8 010 4002 479 741 9 013 3214 479 813 10 015 2584 479 878 11 018 2088 479 933 12 021 1699 479 979 13 1 94 4 79 1016 15 4J9 1061 5 not Snort Speed Indesc Transit Charge i Speed of 5 Endurance Time Advance hours hours knots 8 011 4002 485 751 9 013 3214 485 825 10 015 2584 485 892 11 018 2088 485 950 t2 ii1 0 217 16 1 4 85 999 13 025 1394 485 1038 14 028 115 8 1068 16 035 811 485 1103 6 not Snort Speed Transit Charge Speed of Indesc 6 Ratio Endurance Time Advance hours hours knots 8 011 4002 495 761 9 013 3214 495 837 10 016 2584 495 906 11 018 2088 495 967 ti 1 i 9 6 18 0 11 5 1094 15 032 963 495 1118 035i 81 1 i 495 I 1134 137 Blank Reverse CHAPTER NINE 90 AREAS FOR FUTURE STUDY Beyond the effort here to model the AIP submarine further study in the area of AIP submarine design is warranted Two possible areas for future study include SUBMARINE COST SUBSIZE does not attempt to answer the question of cost of construction The cost to build a submarine is well documented but in the United States is based on nuclear submarine data and is compounded by the desire by private shipbuilders to hold this type of data closely As with the estimated parameters for the AlP plants there are no operational units in production thus the true cost of the AIP option is currently very difficult to estimate DETAILED POWER PLANT DESIGN SUBSIZE assumes that an AIP plant will follow the same rules for arrangements as the conventional submarines used in its database This assumption may not be strictly true since these plants bring with them components such as closed cycle gas turbines LOX tanks and fuel tanks with bladders components not presently found if at all on many submarines Once more detailed plant data is made available an effort to arrange several AIP propulsion plants would be instructive in refining the estimates of this model 139 Blank Reverse REFERENCES 1 Adams V W Possible Future Propulsion Systems for Submarines Journal of Naval Enaineerina Vol 31 No 2 1988 2 Air Independent NonNuclear Propulsion U Anon Office of the Chief of Naval Research Arlington VA July 1991 3 Amphlett J C Methanol Diesel Oil and Ethanol as Liquid Sources of Hydrogen for PEM Fuel Cells Proceedings of the 28th Intersociety Energy Conversion Engineering Conference Vol1 Atlanta GA 1993 4 Anderson E Briefing notes NAVSEA 03E2 November 1993 5 ApDlication of Solid Oxide Fuel Cell SOFC Technoloav to Navy Propulsion and ShiD Service Systems Briefing Notes February 1993 6 BagleyD et al Integrated Electric Propulsion System for Minimum Signatures Submarine Technology Illustrative Concept unpublished paper 7 Blackburn C M et al Cryogenic Storage of Submarine Breathing Oxygen OnBoard Design Concept The Johns Hopkins UniversityApplied Physics Laboratory Report JHUAPL 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Heemskerk KA Airindependent Propulsion for Submarines A Canadian Perspective Maritime Engineering Journal Canada 1991 30 Hellquist K Submarines with Air Independent Propulsion in the Present and Future Environment Paper presented at INEC 92 Solutions to the Challenge of a New Defence Environment September 1992 31 Hereford L G et al Cryogenic Storage of Submarine Breathing Oxygen Preliminary Safety and Hazard Analysis Johns Hopkins University Applied Physics Laboratory Report JHUAPL TG 1338B August 1983 142 32 Heywood J B Internal Combustion Enqine Fundamentals New York McGrawHill 1988 33 Jackson H A CAPT USN Ret P E Submarine Parametrics Paper presented at the Royal Institute of Naval Architects International Symposium on Naval Submarines London England 1983 34 Jackson H A CAPT USN Ret P E Fundamentals of Submarine Concept Design Paper presented at the annual meeting of the Society of Naval Architects and Marine Engineers New York 1992 35 Kerros P Leroy P Grouset D MESMA AIP System for 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24th Intersociety Energy Conversion Engineering Conference Washington DC 1989 70 Urbach H BKnauss D T Quandt E R Advanced Concepts in Chermical Propulsion Systems for a 500Ton Submersible Naval Engineers Journal Vol93 No 1 February 1981 71 Whitcomb C Briefing notes NSWC Carderock Bethesda MD October 1993 72 Whitcomb C Cervi M Air Independent Propulsion AIP System Evaluation U NSWC Carderock Bethesda MD Report Number NSWCSSD9317 June 1993 73 Whitcomb C Price S Submarine Special Warfare Submarine Design Project Course 13414 Ocean Engineering Department Massachusetts Institute of Technology May 1992 74 Wilson M S et al Electrocatalysis Issues in Polymer Electrolyte Fuel Cells Proceedings of the 28th Intersociety Energy Conversion Engineering Conference Vol1 Atlanta GA 1993 145 Blank Reverse APPENDIX A POWER SOURCE DOCUMENTATION A0 OVERVIEW This appendix contains supporting data and calculations for the energy conversion devices and batteries discussed in Chapter 4 and modeled in Chapter 6 Material properties are taken from References 3248 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 Section Summary of Energy Conversion Devices Proton Exchange Membrane Fuel Cell PEM Molten Carbonate Fuel Cell MCFC AluminumOxygen SemiCell Aluminum Closed Cycle Diesel CCD Stirling Engines Closed Brayton Cycle CBC Lead Acid Battery NickelCadmium Battery NiCd LithiumAluminum IronSulfide Battery LAIS Page No 148 149 150 152 153 155 157 158 159 161 147 A1 SUMMARY OF ENERGY CONVERSION DEVICES Table A1 Summary of Energy Conversion Devices AIP Plant PEM MCFC ALOX CCD STIRLING CBC Attribute Plant Weight 180 246 5533 117 1154 40 kgkW Plant Volume 0343 108 35 0389 0487 0151 ft3kW Reformer 180 Weight kgkW Reformer 0424 Volume ft3kW Oxidant 0511 0554 0263 0988 10 0872 Weight kgkWhr Oxidant 0016 0017 0008 0031 0031 0027 Volume ft3kWhr Fuel Weight METHANOL DIESEL ALUMINUM DIESEL DIESEL DIESEL kgkWhr 034 0165 028 0247 026 0195 Fuel Volume 0015 0007 0000 0011 0011 0008 ft3kWhr Other Weight COMP COMP KOH ARGON COMP COMP kgkWhr WATER WATER WATER WATER WATER WATER 0163 0177 0898 0413 0319 0278 Other 00176 00191 00318 00806 00345 003 Volume ft3kWhr Product 167 167 167 167 167 Weight kgkW Product 2354 2354 2354 2354 2354 Volume ft3kW Fuel volume is included in plant volume 148 A2 PEM FUEL CELL The following summarizes the weight and volume factors applied to the modeling of the PEM AlP plant Plant weights and volumes as well as reactant consumption rates were gathered from several sources The assumed value includes the authors judgement of the validity of the source Methanol Pure Hydrogen 149 Type Weight Volume Volume Weight Factor Factor Factor Factor kg ft3 Plant type PEM 180 0343 10 10 kW Reformer YES 180 0424 10 10 kW Oxidant LOX 0511 0016 146 30 kWhr Fuel METHANOL 034 0015 10 10 kWhr Other COMP 0163 00176 23 10 kWhr WATER Prod Mgmt COS 167 2354 10 10 kW WORTH Reference Efficiency Weight Volume Oxidant Fuel Rate Remarks PEM Density Density Rate kg kgkW ft 3kW kgkWhr kWhr 12 1587 10 0403 005 58 70 Sys Effic H2 38 55 Sys Effic Meth 1 50 0136 05 0047 70 60 397 0118 Sys Effic 13 1853 0338 062 035 40 0511 34 73 0367 046 72 136 11 Average 11394 0538 0480 Assumed 180 0343 0511 34 Value 064 Each reference was reviewed for its consistency with other sources and to evaluate the basis of how the data was presented From the estimates of reactant consumption in kgkWhr the volumetric consumption rate was computed assuming a density for the form of the reactant For the PEM plant with methanol and LOX Oxidant volume factor 0511 kgWhr 2205 lb 0014 1 0016 kWhr Fuel volume factor kg 3 1 0 34 hr 2205 kb 0020 0015 kWhr To allocate volumes for the compensating water tanks and the weight of the empty tank structure the following factors were calculated using standard tank data from Reference 12 Compensating water volume 0 511 hr 2205 00156 b 00176 fkPr Compensating water weight 0511 k 0n0156ft3 204 Ib of tank 1 kg 0511 0156b l ft3 of reactant kWhr Other fuel and oxidant options for the PEM plant are detailed in Appendix B Reformer and product management estimates are contained in Appendix B A3 MOLTEN CARBONATE FUEL CELL The following summarizes the weight and volume factors applied to the modeling of the MCFC AIP plant 150 As before plant weights volumes and reactant consumption rates were gathered from several sources The assumed value source includes the authors judgement of the validity of the Each reference was evaluated and the volumetric consumption rate computed assuming a density for the form of the reactant For the MCFC plant with diesel fuel and LOX Oxidant volume factor 0554 k2205b 0014 b 0017 kWhr Fuel volume factor 0165 kW 2205 b 0 1 9 ft3 0007 9 kh kg lb t 0 151 Type Weight Volume Volume Weight Factor Factor Factor Factor kg ft3 Plant type MCFC 246 108 10 10 kW Reformer NONE 00 00 kW Oxidant LOX 0554 0017 146 30 kWhr Fuel DIESEL 0165 0007 10 10 kWhr Other COMP 0177 00191 23 10 kWhr WATER Prod Mgmt COS 167 2354 10 10 kW WORTH Reference Efficiency Weight Volume Oxidant Fuel Rate Remarks MCFC Density Density Rate kg kgkW ft3kW kgkWhr kWhr 58 35 System Effic 38 65 132 0425 0128 Cell Efficiency 60 182 082 0683 0199 65 426 133 0553 0167 73 60 0485 014 Cell Efficiency 72 48 272 13 0381 System Effic 40 0533 0154 Average 253 115 0536 0195 Assumed 246 108 0554 0165 Value Compensating water volume 0554 Whr2205 b 00156b 00191 kW Compensating water weight Compensating water weight 0554 k 00156 t3 20 4 lb of tank A4 ALUMINUM OXYGEN SEMICb ft3 tanELL A4 ALUMINUM OXYGEN SEMICELL 0177 kg kWhr The table above summarizes the weight and volume information gathered from several sources Reference Efficiency Weight Volume Oxidant Fuel Rate Remarks ALOX Density Density Rate kg kgkW ft3kW kgkWhr kWhr 12 5533 35 026 028 KOH H20 0898kgkWhr 72 862 46 13 1173 0276 KOHH20 0896kgkWhr 40 0263 KOH H20 0898kgkWhr Average 405 0266 0280 Assumed 5533 350 0263 0280 0898 KOH H20 Value I The assumed value includes the source without aluminum includes aluminum in cell authors judgement of the validity of the 152 Type Weight Volume Volume Weight Factor Factor Factor Factor kg ft3 Plant type ALOX 553 35 10 10 kW Reformer NONE 00 00 kW Oxidant LOX 0263 0008 146 30 kWhr Fuel ALUMINUM 028 00 10 10 kWhr Other KOH 0898 00318 133 23 kWhr WATER Prod Mgmt NONE 00 00 kW Again each reference was evaluated and the volumetric consumption rate computed assuming a density for the form of the reactant For the Aluminum plant with LOX Oxidant volume factor 0263 2205 lb 0014 0008 kWhr No fuel volume factor was computed because the plant volume factor already includes the aluminum fuel No compensating water factors were determined because the products are retained on board A5 CCD ENGINES The following summarizes the weight and volume factors applied to the modeling of the CCD AIP plant Plant weights and volumes as well as reactant consumption rates were gathered from several sources 153 Type Weight Volume Volume Weight Factor Factor Factor Factor kg ft3 Plant type CCD 117 0389 10 10 kW Reformer NONE 00 00 kW Oxidant LOX 0988 0031 146 30 kWhr Fuel DIESEL 0247 0011 10 10 kWhr Other ARGON 0413 00806 10 10 kWhr WATER Prod Mgmt COS 167 2354 10 10 kW WORTH The assumed value source includes the authors judgement of the validity of the The volumetric consumption rate was computed assuming a density for the form of the reactant For the CCD plant with diesel fuel and LOX Oxidant volume factor 0 988 kWhr 2205 b 0014 fe 0 031 kWhr Fuel volume factor O247 hkg 2205o 019 l 0011 r kg 09i Mr Argon volume factor 0038 kr 06165kg q3281 t 0827 hr The Argon weight and volume factors are combined with the compensating water factors for entry into the other reactant category of the model Argon volume Argon weight 0827 kWhr 000274 0 00227 kWhr O kW6i0098kWhr 0038 gr 26 00988 kg kWhr Comp water volume 0 988 hr 2205 b 0 01 56 23 0 078 kWhr Comp water weight 0988 khr 00156 204 lb of tank kWhr2 lbJ ft of reactant 0314 kg kVhr 154 Reference Efficiency Weight Volume Oxidant Fuel Rate Remarks CCD Density Density Rate kg kgkW ft3kW kgkWhr kWhr 38 30 System Effic 1 588 025 10 03 47 184 357 0985 028 70 106 063 0284 65 61 0388 114 0187 29 084 024 Ar0038 kgkWhr 73 33 0873 0252 System Effic 72 33 1814 10 System Effic 40 0642 0185 Average 118 1118 0913 0247 Assumed 117 0389 0988 0247 Value I I Combined volume Combined weight 0 00227 0078 0 0806 kWhr 00988 0314 0413kWhr Because argon and compensating water are combined volume and weight factors are applied before the two are added See Appendix B for argon weight and volume factors A6 STIRLING ENGINES The following summarizes the weight and volume factors applied to the modeling of the Stirling AIP plant The following plant weights and volumes and reactant consumption rates were gathered from several sources 155 Type Weight Volume Volume Weight Factor Factor Factor Factor kg ft 3 Plant type STIRLING 1154 0487 10 15 kW Reformer NONE 00 00 kW Oxidant LOX 10 0031 146 30 kWhr Fuel DIESEL 026 0011 10 10 kWhr Other COMP 0319 00345 23 10 kWhr WATER Prod Mgmt COS 167 2354 10 10 kW WORTH The assumed value includes the authors judgement of the validity of the source Volume packing factor of 15 applied in model due to data uncertainty The following volumetric consumption rates for the Stirling plant with diesel fuel and LOX were computed assuming a density for the form of the reactant Oxidant volume factor 10 kr 2205 b 0014 0 031 kWhr Fuel volume factor 026 kr 2205 kb 0019 lb0011 kWhr Compensating water volume 10 r 2205 kb 00156 00345 kWhr Mr kg lb kV345 hr Compensating water weight 10 kWhr 00156 204 lb of tank 0319 kg ft3 of reactantr Because of the uncertainty of the data collected for the Stirling engine and its auxiliaries a plant volume packing factor of 15 was assumed 156 Reference Efficiency Weight Volume Oxidant Fuel Rate Remarks STIRLING Density Density Rate kg kgkW ft 3kW kgkWhr kWhr 1 39 8 0353 10 03 System Effic 30 65kW per engine 17 1154 0487 095 0199 64 0949 026 65 118 07 107 0175 40 0836 0241 Average 1045 0513 0961 0235 Assumed 1154 0487 1000 0260 Value A7 CBC ENGINES The following summarizes the weight and volume factors applied to the modeling of the CBC AIP plant The plant weights volumes and reactant consumption rates gathered from several sources are The assumed value includes the authors judgement of the validity of the source The volumetric consumption rates were computed assuming a density for the form of the reactant For the CBC plant with diesel fuel and LOX 157 Type Weight Volume Volume Weight Factor Factor Factor Factor kg ft3 Plant type CBC 40 0151 10 10 kW Reformer NONE 00 00 kW Oxidant LOX 0872 0027 146 30 kWhr Fuel DIESEL 0195 0008 10 10 kWhr Other COMP 0278 003 23 10 kWhr WATER Prod Mgmt COS 167 2354 10 10 kW WORTH Reference Efficiency Weight Volume Oxidant Fuel Rate Remarks CBC Density Density Rate kg kgkW ft 3kW kgkWhr kWhr 12 4050 454 012 151 0218 System Effic 69 System Effic 70 295 016 65 459 0173 106 0378 2 549 0175 40 0906 0261 Average 439 0157 1159 0286 Assumed 40 0151 0872 0195 Value Oxidant volume factor 0872 kr 2205lb0014 0027 kGhr Fuel volume factor rkg lb t3 0 195 kVVhr 2205 k 0 019 if O 008 kWhr Compensating water volume 0872 kg 2205 b 00156 003 kW Compensating water weight 0872 k00156 204 of tank Mlr ft3 of reactant kg IkWr A8 LEAD ACID BATTERY The data taken is the same used in the baseline submarine battery determination in Appendix C with the final results repeated here for ease in comparison to other battery types LEAD ACID BATTERY DATA 2 hour capacity kWhr 1600 5 hour capacity kWhr 2035 80 hour capacity kWhr 26455 Weight Itons 764 Volume ft3 800 No Batteries Burst 551 No Batteries Creep 508 Coulombic Efficiency 09 158 A9 NiCd BATTERY For comparison purposes the lead acid battery was developed based on a standard battery unit having a nominal total voltage of 240 VDC A standard NiCd battery will be determined based on the same total battery voltage The following summarizes data sources and their estimates for weights volumes and battery capacity The assumed value includes the authors judgment of the validity of the source As a result a standard characteristics NiCd battery is determined to have the following 1 hr capacity 5000 Amphr231V 1155 kWhr Weight 155 k Whr 1000Wh o 2b2 3438 Itons Volume 115 r 642 ft3 Reference 23 gives the following figure for NiCd battery capacities other than a standard 1hour 1 C rate 159 Reference Efficiency Energy Energy Remarks NiCd Density Density kWhft 3 Whlb 71 172 1357 5000 A 231 VDC 1 hour rate 4 18 150 1 hour rate Average 176 1429 Assumed 90 18 15 Value 120 0 100 I U Ilo C 80 a 01C IC IOC DISCHARGE RATE NiCd Capacity vs Discharge Rate Figure A1 From this figure the following scaling factors for battery capacity are assumed 1 hour rate 2 hour rate of 1 hour rate 80 hour rate of 1 hour rate factor 10 104 11 Capacitv 1155 kWhr 1201 kWhr 1270 kWhr Using the required energy required for a 4 knot 90 hour transit and 20 knot 2 hour burst from Appendix C the following number of standard batteries are required 8814 kVWhr 734 Batteries burst 1201 Wbhs 13692 kWhr 1078 Batteries 1270 kWhr 1078 Batteries creep Batte 160 l C n SUMMARY OF NiCd BATTERY DATA 1 hour capacity kWhr 1155 2 hour capacity kWhr 1201 80 hour capacity kWhr 1270 Weight Itons 38 Volume ft3 670 No Batteries Burst 734 No Batteries Creep 1078 Coulombic Efficiency 09 A10 LAIS BATTERY The standard LAIS battery will be determined based on a total battery voltage of 240VDC From the data presented on the next sheet a standard LAIS battery is determined to have the following characteristics 240 Vos 1 0 Cells45kWhr 450kWhr 2 40 Mr 1000 Wh Cell l 36 Itn 45 1s k r l Wh 2205 lb ons 369 Itons Weight cWr120 kWhr kg J 2240 lb Volume 45h0 kWr 1000 wh m3 t 7224 ft 3 220 r kWr 1000 1 03048 m The following summarizes data sources and their estimates for weights volumes and battery capacity 161 The assumed value includes the authors judgment of the validity of the source Because the LAIS battery is projected to have similar discharge characteristics to the lead acid battery the following scaling factors are assumed 5 hour rate 2 hour rate of 5 hour rate 80 hour rate of 5 hour rate factor 10 083 13 Capacity 450kWhr 369 kWhr 858 kWhr Using the required energy required for a 4 knot 90 hour transit and 20 knot 2 hour burst from Appendix C the following number of standard batteries are required 8814 kWhr 2389 Batteries burst aftery 13692 kWhr 2341 Batteries creep 585BatRtey SUMMARY OF LAIS BATTERY DATA 2 hour capacity kWhr 369 5 hour capacity kWhr 450 80 hour capacity kWhr 858 Weight Itons 369 Volume ft3 7224 No Batteries Burst 2389 No Batteries Creep 2341 Coulombic Efficiency 10 162 Reference Efficiency Energy Energy Remarks LAIS Density Density Whl Whkg 58 200 43 100 350 130 45 kWhr at 24 VDC 10 122 7056 15 160 190 4 Average 208 13019 Assumed 220 120 Value APPENDIX B REACTANT DOCUMENTATION B0 OVERVIEW This appendix contains supporting data and calculations for the reactants and discussed in Chapter 5 and modeled in Chapter 6 Material properties taken from References 3248 Section Summary of reactant packing factors Reformer Exhaust Product Management Oxidants Liquid Oxygen LOX Gaseous Oxygen High Test Hydrogen Peroxide HTP Sodium Perchlorate Hydrogen Liquid Hydrogen Gaseous Hydrogen Metal Hydride Other Fuels Other Reactants Paqe No 164 164 165 167 167 169 170 170 171 171 172 172 173 173 163 B1 B2 B3 B4 B41 B42 B43 B44 B5 B51 B52 B53 B6 B7 B1 SUMMARY OF REACTANT PACKING FACTORS Table B1 Reactant Packing Factors Reactant Weight Packing Volume Packing Factor Factor Liquid Oxygen 146 30 Gaseous Oxygen Int 496 384 Gaseous Oxygen Ext 496 128 High Test Peroxide 70 10 10 Sodium Perchlorate 134 23 Liquid Hydrogen 110 30 Gaseous Hydrogen 650 128 Metal Hydride 500 10 Diesel Fuel 10 10 Methanol 10 10 Aluminum Included in cells Included in cells Argon 26 000274 KOHWater 133 23 Compensating Water Incl in Wt Fac 23 B2 REFORMER A reformer is required for any energy conversion device requiring pure hydrogen if the fuel not supplied in a pure form Of the AIP plants considered only the PEM cell may require a reformer As discussed in Chapter 5 the reformer decomposes a hydrogen based fuel to produce hydrogen gas usually through the use of steam generated by the fuel being reformed Methanol was the reformed fuel used in this model but diesel as well as other fuels could be used instead Reference 3 gives the following volumes for reformers Methanol 0012 0424 164 Diesel 0043kW 1W52 While no weight was given a weight density equal to the PEM cell 18 kgkW is assumed Because the reformer is a relatively compact item no penalty ie a packing factor equal to one is assumed for equipment arrangement B3 EXHAUST PRODUCT MANAGEMENT Whether reformed or burned directly by the AIP plant fuels such as methanol and diesel will produce CO2 and other gasses as a byproduct For this model overboard discharge is assumed by the use of the Cosworth system Section 53 Reference 29 gives the following weights and volumes for such a system Weight 167 kg Volume 2354 w The discharge of gas overboard requires significant energy to raise the CO2 gas pressure to that of the ocean Assuming a 500 kW PEM plant with methanol operating at a 400 ft depth governing reaction 2CH3OH H20 02 hea 4H2 2C0 2 H20 CO2 production 034750 kWj kW CO 23375 kg CO 32 CH3OH hr 165 ocean back pressure at a depth of 400 ft 400 feet100 feet ofdepth 147 psia 1907 psia Assuming an ideal gas withy 133 initial temperature of 3000K and 147 psia T2 300K 190 7psia 14 7psia 1331 133 5666 K the change in enthalpy for CO2 is 32 At 5660K hco 2720 kcal mole At 3000K hco 0016 kcal mole A hco 2704 kcal 11C 2 7O4 mole Assuming a compressor efficiency of 080 the work required to compress the gas is 2704 kcal 08 moleC 02 1000 44g kg 4 184 9 321e 5 kg 3 21e k23375 360 209J kW which amounts to 42 percent of the AIP plant output Fuel consumption rates for AlP plants include this penalty The other major byproduct of fuel cells is pure water which is assumed to be stored on board for consumption or transferred to the variable ballast system 166 T2 T 1 P2 r 1 B4 OXIDANTS B41 LIQUID OXYGEN In the model LOX was assumed to be stored inside the pressure hull in an arrangement similar to Figure B1 If the oxygen compartment takes up one half the crosssection of a 31 ft diameter hull and the external diameter of each LOX tank is 12 ft then the ratio of area A to the total crosssection of the LOX tanks is Liquid Oxygen Tank Arrangement Figure B1 Area A 312 7548 ft2 167 Area of LOX tanks 2 2 2262 ft2 Ratio of areas 7548 7548 167 2262 Reference 73 gives a factor for the ratio of the outside LOX tank volume to LOX weight as 0024 ft 3 o ex te al tank and LOX tank weight to LOX weight as 046 b f LOXtank Reference 70 gives this ratio of weights as 125 For weights a ratio of 146 is assumed For the ratio of LOX tank to actual LOX volume the result is 0024 of etank 7123 lb of LOX 171 Combining these two factors the overall volume packing factor for LOX becomes 171167 285 Reference64 suggests a factor of 337 while reference12 suggests a factor of 30 The value of 30 is assumed In addition to the ship endurance requirements for oxygen the breathing oxygen for the crew is added to the AIP requirement since an AIP submarine may not be exchanging air with the atmosphere for weeks at a time The following factors for breathing oxygen from reference 7 are assumed Factor Use rate of LOX LOX density Ullage Factor of Safety Value 003 ft3manday 7123 Ibft3 095 11 For a crew size of 44 and a mission length of 60 days 168 cubic feet of LOX 003 mf3day 44 men60 days10511 9171 ft3 tons of LOX 7123 9171 ft3 2240 292 Itons This total is added to the total LOX for AIP endurance before the volume and weight packing factors are applied For applications where LOX was not specified as the AIP oxidant LOX was still assumed for breathing with packing factors applied B42 GASEOUS OXYGEN The storage of oxygen as a gas was assumed to be in high pressure cylinders at 3000 psi The volumetric consumption of oxygen based on the specific oxygen consumption of the PEM cell in Appendix A is 0511 kgr 2 2 05 059 0 066 kWhr kW kg khr lb and is used in the oxidant storage method comparison Reference 65 gives the following factors for tank weight and volume Ratio Factor Wt Tank Oxygen Wt Oxygen 496 Vol Tank Oxygen Vol Oxygen 128 This storage of oxygen could be either internal or external to the pressure hull An internal area analysis similar to the LOX case in Section B41 gives a ratio of gas cylinder crosssection to area A of 30 and when multiplied by the volume factor above a final packing factor of 384 is obtained If the cylinders are stored outside the pressure hull ie in a main ballast tank then 100 percent 169 utilization of the area around the cylinders is assumed and the factor of 128 alone is applied The weight factor of 496 is assumed to include the weight of the tank supports B43 HIGH TEST PEROXIDE HTP 70 percent contains 33 wo oxygen and is the concentration assumed in the model At this concentration HTP is considered to be safe to handle with care HTP decomposes by H22 H20 H 20 0 2 For 70 percent HTP there are 206 moles of H20 2 and also 0 per 100 grams of solution Therefore based on the specific oxygen consumption of the PEM cell the volumetric consumption of HTP is kg 100 grams H20 2 0 012 F 2205 lb 0 0399 r 0kwhr I 206 moles l15994 grams b of K kg kWhr Lgr mole of Storage of HTP is assumed to be in plastic bladders in self compensating tanks external to the pressure hull with 100 percent utilization of the space resulting in a packing factor of 10 for weight and volume B44 SODIUM PERCHLORATE The storage of sodium perchlorate is modeled as contained in pressure vessels similar in construction to other steel tanks found onboard a submarine and containing approximately 39 wo Oxygen Assuming the specific oxygen consumption rate for the PEM cell the volumetric rate is 0511 kg Ox 256 kg Na 04 m1000 9 0061 in 0 083 00186 r hrReference 12 givesOx standard tank factors for volume and weight Reference 12 gives the following standard tank factors for volume and weight 170 Ratio Factor lb of tank ft3 of reactant 204 ft3 of arrangeable tank volume 23 ft3 of reactant For weight the tank factor now becomes 1kg Ox256 kg NaCO 400ml353e 24ft3 elbtank 0 336 kg tank kg Ox kgI 4k tank045 0336 tank factor 134 B5 HYDROGEN B51 LIQUID HYDROGEN Similar ideas apply to Liquid Hydrogen LH as they did to LOX except that LH must be stored at a much colder temperature so the insulation will probably be thicker and that LH requires more volume to store a given weight of reactant First the specific consumption of pure hydrogen must be calculated Assuming the methanol flow rate for the PEM cell and the following reaction CH3OH H2 0 CO2 3H2 specific H2 consumption 34 kg CHH 6048 grams H2 064kg H2 kWhr 320414 grams CH 3OH kWhr To calculate the volumetric consumption 0064 kr 14 1 1000 g 0 061 0083 0032 khr kWhr 9k g nkl 171 Reference 73 gives the value of 0043 kWhr SO an average value of 0038 1T is assumed Reference 73 also gives a tank to hydrogen weight ratio of 10 thus a factor of 11 is assumed for the ratio of total tank plus LH weight to LH weight The same volume packing factor that was used for LOX is assumed for LH B52 GASEOUS HYDROGEN The storage of hydrogen as a gas was assumed to be in high pressure cylinders at 3000 psi similar to the gaseous oxygen storage in Section B42 A significant difference however involves the density of hydrogen which is much lower than for oxygen Assuming the specific hydrogen consumption rate of Section B51 the volumetric consumption is 0064 Whr 2205 g1 b 0141 khr Reference 57 gives a ratio of 90 lb of HTank while reference 73 gives 551 lbofHTank A value of 65 was assumed in the model The storage cylinders are assumed to be similar in construction and arrangement to those for oxygen except that due to safety considerations only external storage was considered with a volume packing factor of 128 B53 METAL HYDRIDE A regenerable metal hydride similar to the form FeTiMg was assumed For an estimate of the volumetric consumption rate the hydrogen consumption rate of Section B51 was assumed and the following storage densities were considered Reference Storage density ft3lb 36 0188 56 0812 73 0333 assumed value 04 172 resulting in 0064 kr 04 2205 kg 0056 r kVh lb kg kWhr The weight percent of hydrogen in a hydride is estimated by many sources to be between 1 and 35 wo depending on the storage medium 56 For the model a weight percent of 20 was assumed yielding a weight factor for hydride storage of 50 Because the volume estimate includes the storage medium no additional volume penalty is required B6 OTHER FUELS The volume factors for other fuels were calculated in Appendix A with its particular AIP application Methanol is immiscible in water thus is stored in a seawater compensated tank external to the pressure hull bladders similar to those used for HTP must be employed In this case the volume and weight packing factors are assumed to be 10 because 100 percent of the volume in the tank can be used and the tank weight is included as a part of the hull structure which scales with the size of the submarine The same argument applies for diesel fuel except that bladders are not required because diesel fuel and water do not mix The weight and volume factors for aluminum are a default value of 10 While the specific aluminum consumption is computed the volume is included in the size of the cell stacks thus there is no additional weight or volume penalty B7 OTHER REACTANTS The storage of potassium hydroxide KOH and water for the aluminum cell is assumed to be in standard steel tanks with typical internal arrangements Using the tankage weight and volume ratios for Section B44 for a specific consumption rate for KOHH20 of 0898 k the volumetric consumption rate is 173 0898 kWhr 0 001 g 328 0318 r with a weight factor of 1kg KOH H2Oo0001 m 328 204 lbrtan 0 454tn 033 k g tank factor 133 The volume packing factor is 23 The only other fluid modeled is argon for the CCD engine Reference 49 gives data for standard 2500 psi gas storage cylinders For storage of 2700 m3 of gas at STP Tank weight 7000 kg Tank external volume 74 m3 Gas volume at STP 2700 m3 For a specific consumption rate for argon of 0038 kg the volumetric consumption rate is 0038 kWhr 0617 3 28 3 0827 kWhr the weight factor is 3 7000 kg of tank 1 kg Ar0617328k3 2700 m3 of gas factor 26 and the volume packing factor is 74 m3 of tank 000274 1700 m3 of gas 174 APPENDIX C BASELINE DIESEL ELECTRIC SUBMARINE CO INTRODUCTION This appendix presents information on the baseline diesel electric submarine used as a basis for the AIP model in this thesis 68 C1 Baseline Submarine Summary 175 C2 Propeller Selection Summary 175 C3 Lead Acid Battery Selection 179 C4 MIT Math Model for the Baseline Submarine 180 C1 BASELINE SUBMARINE SUMMARY Table C1 gives specific details on the performance and characteristics of the baseline submarine with a profile view in Figure C 1 C2 PROPELLER SELECTION SUMMARY The standard propeller chosen for the model was the same as selected for the Canadian Hybrid Submarine Design This propeller was chosen by hand calculation Figure C2 and Table C3 and validated using MANEUVERING TOOL software available from the US Navy Hydrodynamic Office through Draper Laboratory in Cambridge MA The general propeller characteristics are summarized In Table C2 175 Profile View of the Baseline Submarine Figure C1 176 Table C1 Baseline Diesel Electric Submarine Characteristic Value Length 210 feet Diameter 31 feet Displacement Surfaced 2325 Itons Submerged 2670 Itons Diving Depth 900 feet Range Snorting 10000 nm Submerged 4 knots 965 hours Submerged max speed 2 hours Maximum Submerged Speed 20 knots Weapons Number of Torpedo Tubes 6 Number of Reloads 19 Crew 44 Endurance 90 days Mobility Installed SHP 5000 PC 7 blade fixed pitch prop 0863 3 12V 652 MB MTU Diesels 990 kWe each Lead Acid Battery 2 hr Cap 1600 kWhr 80 hr Cap 2645 kWhr Volume 4408 ft3 Weight 421 Itons Table C2 Summary of Propeller Characteristics Propeller Diameter Design Speed Hull Efficiency Rotational Efficiency Open Water Efficiency Advance Coefficient PD Ratio Propulsive Coefficient 155 feet 20 knots 127 103 066 077 11 0862 177 Propeller Curve 7 Blade Type B Figure C2 Table C3 Propeller Selection Spreadsheet C3 LEAD ACID BATTERY SELECTION The Lead Acid Battery was sized according to the advanced lead acid battery data provided in References 4 71 The baseline submarine was determined to have the following propulsive plus hotel loads Endurance 90 hours 2 hours Enerav Required 13692 kWhrs 8814 A standard battery with a volume of 800 ft3 and a weight of 764 Itons was determined to have a capacity of 407 kWhr at the 5 hour rate for a total energy 179 Hull Dia 311 LDK 1 6128 EHP 5000 i Des Spd 20 Ms EHPN3 0129485 density 19905 Dp 155 1 091 1w 0721 eta h 1271 ertrr 1031 J Kt Ea o 066 01 0003179 J 077 02 0012717 PD 11 03 0028613 04 0050868 PC 0862 05 0079481 i 06 01144531 07 01557831 08 0203472 09 0257519 1 0317925 11 0384689i 12 0457812i 13 0537293 14 06231331 15 0715331 Speed 4 knots 20 knots capacity of 2035 kWhrs The following scaling factors were used to estimate the battery capacity at burst 2 hours and creep 80 hours endurance rates 5 hour rate 2 hour rate 80 hour rate factor 10 08 of 5 hr rate 13 of 5 hr rate Capacity 2035 kWhr 1628 kWhr 26455 kWhr Dividing the capacities into the required energy battery size Endurance Requirement Numt Burst Creep above results in the following 3er of Batteries 551 518 In order to meet both requirements the larger battery was chosen thus the total battery weight and volume is Weight 42096 Itons Volume 4408 ft3 C4 MIT MATH MODEL FOR THE BASELINE SUBMARINE The MIT Math model developed with MATHCAD 40 software by mathsoft follows The model is self explanatory and employs the same methodology used in SUBSIZE 180 MIT MATH MODEL SS Mode with increased battery 5294 h 33000ft lb min I OWNERS REQUIREMENTS Enter the following owners requirements Diving Depth ft D D 900ft SHP CREW Size Range 10 knots snorting Stores Period Number of Torpedo Tubes Number of Reloads Iton 2240 1b knt 515 m sec SHP 5000hp N T44 E 10000knt hr TS 90 TT 6 RL 19 II VOLUME REQUIREMENTS Using owners requirements and Figs 13 determine the densities for Mobility Tubes and Reloads for your Boat Mobility Density DensityTubes DensityReloads ft 3 PMOB 67 hp PTT 0042 RL ft3 0036 V MOB SHP MOB V WEAIS TT pTT RLPRL V C3I 5300ft3 V MOB 335 104 It3 V WEAPS 6706 10 1t3 V C3I 53 103 fit3 SHIP SUPPORT Area Analysis assume a 7 deck height and consider factors for passageway 108 and hull curvature 112 VPH 5961 104 V aux 03Rf3V pH 93fi3N T V ux 2198 103 ft aUX Berth Mess Storerooms Other Spaces offices etc Volume for ship support Pressure Hull VPH Abm 1011 2 N T A sr 85 fi2tTS A bnm 440 It2 A sr 7651t 2 sr Aos 120ft2 6ft2N T Aos 1464ft 2 V SS V aux 1 127 ft 108 A bm A sr Aos V SS 1364 1 4 ft 3 93ft3 NTt Abm AsrAos 7tl 8112 VMOBt VWEAPS VC3 1 97 VPH 5913 104 181 MOBILITY WEAPONS C3 I Auxiliaries OUTBOARD V ob 2 3 V PH V ob 13 6 1 0 4 ft3 EVERBUOYANT VOLUME Veb V PH Vob Veb 7273 104 ft3 BALLAST TANK VOLUME SUBMERGED VOLUME FREEFLOOD VOLUME ENVELOPE VOLUME A ebr V eb64 lb ft3 Vbt 13V eb Vs V eb V bt lb Ar V 64 ft3 V ff 0 6 V eb Venv VsV f A ebr 2078 103 Iton V bt 9455103 fi3 Vs 8219104 ft3 as 2348 103 Iton V ff 4364 103 ft3 V 8655 104 ft3 env A envr V e 64lb ft3 A 2473 10 Iton envr Ill VOLUME AVAILABLE Using the formulae developed by CAPT Jackson the volume requirements calculated in Section II above and Figures 4 5 select LD and length of parallel midbody and forward aft shape factors Also extract coefficients As a starting point use the following shape factors 1 f 25 C pf 75 1 a 3 C pa 6429 pa C wsf 8452 C wsa 75 wsa KI 6 24C pf 36C pa KI 1886 Select LD LOD 76 D 28ft L LODD L 2128fl nD 3 Iton A enva LOD K1 435 ft3 LpM B LOD 6 D LpMB 448fl A enva 2815 103 Iton envl ck The tolerance for this volume balance is available volume must be greater than required volume but by no more than 5 A enva A envr Err v envr Errv 0138 182 Entrance Run Select D IV WEIGHT ESTIMATION A surf 2325 Iton The following weight formula are taken from LT Stennards 1988 SM Thesis Appendix I WSTR sds 00055 15 WMOB 596N cell 20 64 lton hp 6 4 Input number of battery cells N cell 702 W STR 699537 lIton W MOB 884376 Iton V WEAPS W WEAPS 002 ft3 6TT 5lton W WEAPS 54413 lIton V WEAPS WC3I 00836 lton ft3 W C3I 56065 lIton WFB 05 Asurf W SS 0336 A surf N T4lton W VL 18Asurf W VL 4185 lton Write in terms of Surfaced Displacement to get Weights yields the following expression for Submerged Displacement U DD00055 15 m I W MOB oB 54413 56065 05A surf 0336Asurft 4N T 1 8A surf Iton DD kl 00055 m 5 0 05 0336 18 W MOB k2 54 4 13 5606 5 4 N T Iton k2 A surf lton 1 kl A surf 2325 103 lIton V OVERALL BALANCE This is the first opportunity to bring Weight and Volume calculations together There are many different ways to compare the two we will use everbuoyant volume Veb and NSC Dsurf weights NOTE All use of volumes in this section will be expressed in terms of Itons A enva A eba 119 A eba 2365X 103 lton A eba A sur Err Aeba A surf 2325 10 Iton Err 0017 The tolerance at this point is 01 Err 05 If out of tolerance continue reading 183 ck A WEIGHT LIMITED CASE Veb Dsurf Due to the uncertainty in your design at this point you do not have the luxury of shaving weight Therefore you must add buoyancy Return to Section ill and change shape factors LOD adding parallel midbody or D as appropriate for the magnitude of your imbalance B VOLUME LIMITED CASE Veb Dsurf Due to the uncertainty in your design you do not have the luxury of tightening up the design At this point add lead fixed ballast you will have what is termed as a lead mine C Veb Dsurf After a couple iteration you should rewash this condition of designers bliss The next step is to determine wetted surface and confirm final envelope Wetted Surface K2 6 24C wsf 36 C wsa WS nD2LOD K2 K2 1272 WS 1559104 ft2 Check wetted surface 1 Entrance Lf 24D Lf672ft xf 01l1672 L PMB 448ft yfx I ft D yfx f2 ft dxf 2 Run WS f 4995 103 It2 La 3 6D La 1008ft a 0 11 1008 yaxa xaftl D La2 La WSa o yaxa2ftndx a WSa 665103 f 2 WSfaWSfa WSa WSfa 1165104 1fl2 Final Envelope Displacement A e enva WS WS f DL PMB WS 1559104 t2 A 2815103 Ilton e This portion of the Math Model was deleted for brevity and does not affect the result 184 Lf 1t WSf 0 ck This portion of the Math Model was deleted for brevity and does not affect the result VIII SPEED POWER Section IX provides a methodology consistent with that described on pages 1 8 through 1 10 of ref a A Effective Horsepower 1 Resistance calculation parameters 2 2 TSW 59 Psw 99051bvSW 12817 10 t SW t sec V 0530 RNV etted Surface previously calculated Correlation Allowance C a 0004 2 Frictional resistance calculation c tV lol 3 Cr calculation using e uation 11 from refa V 16889 see vSW WS 1559 1 t2 075 gR NV 22 00789 r LOD K2 4 Appendage drag including sail calculation a From your arrangement drawing enter surface area of the sail As 8001t2 C Ds 009 185 A s C Ds 721 fi b For the remaining appendages use the expression on pg 159 for AACdA App LD 1000 App 5958ft 2 5 Lets put it all together well use equation 9 from refa EHPV 15104 1104 EHPV 5000 0 00872 v3 WS C r C V C a t A s CDs App 2 0 10 20 30 V B Shaft Horsepower 1 Propeller Selection Use series re Propeller Open Water Efficiency 2 Hull Efficiency Use ref a Fig 13 3 Relative Rotative efficiency Assume rr 103 4 PC PCtloIhqrr 5 SHP SHPV 15104 SHPV 5000 0 0 f a section 6 or other method to determine o 7 LOD K2 6328 lh 124 EHPV PC 5 10 15186 20 V 25 30 SHP4 33255 SHP5 63734 SHP8 251281 SHP 10 48235 SHP12 822073 SHP15 1579 103 SHP20 3667 103 c Vnl A OA n I n 3 I I I I I I I I I I I I SHP23 5524 103 C Snorkelinq Shaft Horsepower Using Stenards Appendix D method and assuming a 10 kt snort speed 10 16889fi 5 FN 322 i322 L SHP20 3667 103 F N 0204 09 C 624310 4 4LOD 3606 C w SHP w 00872 10 W S ft2 SHP sn SHP W SHP 10 SHP sn 567205 D Endurance Calculation Using Stenards Appendices EP M 1 Specific Fuel Consumption App P 2 Hotel Load Includes a correction for the differences in the results gained from Appendix M and Table 91 SFC 55 l hp hr Vaux 03V PH993fl 3NT V SS 1127 108Abm Asrt Aos fl V aux Lh I5V MOB 4 V C3i 15 V SS V WEAPSlO f L h 98595 The Battery Endurance at 4 knots is approximately BattEND 4 20664N cell 0997 90 BattEND 4 92353 Lh 134 hours 097 Transmission 090 Turndown 090 Battery 11 The Battery Endurance at 20 knots is approximately BattEND 25 20664 N cell 09097 SHP25 L L 134 BattEND 25 2362 FV F 624 lb 085 ft3 3 Bunker Fuel Requirements App E E SFC 109 SP sl t 134 L h ih p F 0 1n 08010 knt F 98810 3 ft3 F E 6083 107 ft F 233953 ton ig 0 16054 lt3 imperiagallons 22 SHP Cw 11 615410 187 4 Endurance at 8 knots snorting 816889fi 5 FN 322L Cw SHP 00872103WS 2 FN 0163 05 4 LOD 13 606 L CW 346810 4 SHP sn SHP w SHP8 SHP 298423 sn F0808knt 1299 104 knt hr SFC 109 SHP sn 134L h hp 5 Endurance at 12 knots snorting 12 16889 ft 5 FN 322 L F N 0245 16 4LOD 13 6 0 6 L 2 DJ CW 3468 10 4 C SHP 00872 103 WS ft2 SHP sn SHP W SHP12 SHP sn 972925 F 080 12knt 7594 103 knt hr SFC109 SHP sn 134 L h hp Based on this fuel calculation and the results of part V and Il new volume estimates are computed as follows is adjusted V PH 59 13 104 fl3 the old figure VPH 5913104f311473 V PH 6 7 8 4 104 of3 OUTBOARD Vob F V 8 3 1280 ft3 06V PH V ob 1 3 5 5 104 Ift EVERBUOYANT VOLUME V eb V PHV H Vob V eb 8139 104 ft3 A ebr V eb 6 4 lb ft3 BALLAST TANK VOLUME SUBMERGED VOLUME FREEFLOOD VOLUME Vbt 15Veb Vs Veb Vbt 64 lb r V s fi3 V ff 06 V eb A ebr 2325 10 lton A stu 2325 103 Ilton V bt 1221 10 ft3 V 936 104 ft3 A sr 2674 103 It V ff 4883 1l03 ft3 188 C W V ob 02 V PH A surf 2325 103 Ilton L W ENVELOPE VOLUME env V s Vff V 9848 104 113 A env V env 64 lb ft3 A envr 2814 103 1ton Err v 4058 1 04 ie the new pressure hull volume agrees Now adjust the components of pressure hull volume so that their total matches our new figure Auxiliaries Vaux 03VpH 93ft3NT V PH 6 7 84 104 ft3 V aux 2444 103 ft3 Berth Mess Storerooms Other Spaces offices etc A bm I0ft 2 N T1 Asr 85f 2 T s1O Aos 120ft2 6 2 NT Abm 440 ft2 A r 765ft 2 A 14641t 2 os Volume for ship support V 8 V aux 1 127ftl 108 A bm r Asr r A os V 1389 104 fi3 V MOB 5000hp PMOB125 V MOB 4 1 8 8 104 ft3 V WEAPS 6706 It C3 I V C31 5300ft 10 Now check to see if pressure hull volume OK V C31 53 103 ft3 V PH 67841 04 lit3 93 ft3 NTt AbmA sr Aos 7 fl 108112 VMOB VWEAPS VC31 97 SHP4 33255 SHP20 3667 103 SHP 10 48235 SHP21 4231 103 SHP22 4849 103 SHP23 5524 103 V PH 6777 104 It3 V ob 1355 104 fi3 V eb 8139 104 1i3 V bt 12 2 1 104 ft3 V 936 104 I3 V ff 4883 10 i3 V 9848 104I t 3 env V bt 015 V eb BattEND 4 92353 BattEND 5 2362 W STR 69944 Iton W MOB 884376 Iton W WEAPS 54413 Iton W C3I 56065 Iton WFB 116234 Iton W 781 17 Iton W VL 418442 Ion Vff 006 V eb V 02 PH WVL 018 A surf A enva A enva enr envr MOBILITY WEAPONS VpH W FB B 005 A surl V WEAPS TT PTT fRLp RL O Ih Blank Reverse APPENDIX D HULL ENVELOPE The envelope is first developed as a pure teardrop shape with the forward body comprising 40 percent of the length and the after body comprising the remaining 60 percent The forward body is formed by revolving an ellipse about its major axis and is described by the following equation Yf b1 l Lf D1 The after body is formed by revolving a line parallel to the directrix and is described by Ti nd YL ae D2 The quantities Yf and Ya are the local radii of the respective body of revolution with Xa and Xf describing the local position of the radius along the body Figure D1 If parallel midbody is added to the envelope then cylindrical section with a radius equal to the maximum radius of the fore and after body is inserted in between The local radii represent the offsets for drawing the submarine hull and also determine the prismatic coefficient for the hull section The prismatic coefficient Cpis a hull form parameter for fullness and is the ratio of the volume of the body of revolution divided by the volume of a right cylinder with the same maximum radius For an optimum shape the fore and after bodies will have 191 different values for Cp C is used to determine the total hull volume by the following relation Volume 36DCa 6D 24DC 4 YVV1 D J V The Body of Revolution Hull Figure D1 where the added term 6D accounts for the volume of the parallel midbody where Cp 1 Just as the volume of the envelope can be determined the surface area for the body can be described by the following relation Wetted Surface nzD236DCsa 6D 24DCf Defined as the wetted surface the surface area of the hull is a key determinant of the power required to drive the hull form though the water and involves the surface coefficient Csf which describes the ratio of the surface area of the body 192 of revolution to the surface area of a right cylinder with the same maximum radius The factors nf and na in equations D1 and D2 describe the fullness of the body by affecting the curvature of the parabolas Table D1 lists some representative values for nf and na along with their resultant Cp and Csf Figure D2 illustrates the effect of varying nf and na on the hull geometry Table D1 Selected values for Cp and Csf Fore body 20 25 30 35 6667 7493 8056 8443 7999 8590 8952 9200 After body 20 25 30 35 5333 5954 6429 6808 6715 7264 7643 7934 A f Od Yf C voon nz 2 n 3 tPo a 1 1 2 40 t 3 A t t 9 o LA 4 I i I I I I I i I I I Ia 4 0 r 7 L 5 4 5 2 Z 0 Effect of nf and na on Hull Geometry Figure D2 The details of this appendix were derived from reference 33 193 n na CP Cs I w Blank Reverse APPENDIX E VOLUME DATA E0 OVERVIEW This appendix contains the details of the volume estimates used in SUBSIZE The volume data is based on the thesis by Stenard 61 which was further analyzed by Professor J Reed for presentation in a special submarine design course at the Massachusetts Institute of Technology during the Independent Activities Period January 1994 Table E1 summarizes the volume data form Stenard A discussion of the various factors chosen for the model follows E1 FACTOR ANALYSIS To build the submarine model estimates of ship volumes must be made Trends in this data must then be evaluated to develop parametrics from which predictions of submarine attributes can be made These parametrics form the basis of the volume analysis below Mobility Volume Reference 53 analysis of Stenards data yields the parametric curve shown in Figure E1 With an estimate of SHP for the baseline ship of 5000 SHP a mobility density diesel electric PDE of 67 ft3SHP was selected Because this density accounts only for the diesel electric plant the additional volume for the AIP plant and any increased battery size from the baseline is added to determine the overall AIP volume of mobility VAIP SHPpDE AVBattry VAIP 195 Table E1 Volume Data For Use in SUBSIZE VOLUMES ft3 KILO WALRUS BBEL 2 1700 200 AVG MOBILITY 33000 33527 25630 37044 150021 i 44000 37204 WEAPONS 10000 9281 7290 6724 5676 6000 7495 C3 1 11000 5900 6701 9127 4806 5300 7139 SHIP SUPPORT 14000 27752 14562 11428 10043 i 10000 14631 VOL ph 68000 76460 54183 64323 70546 65300 66469 OB ITEMS 19500 9290 20895 11277 4354 6940 12043 VOLeb 87500 85750 75078 75600 74900 72240 78511 MBT 24500 12250 11340 8400 7350 9310 12192 SUB VOL 112000 98000 86418 84000 82250 81550 90703 FREEFLOOD 5600 4900 4618 4200 4112 4078 4585 ENVELOPE 117600 102900 91036 88200 86362 85628 95288 VOLUMES EQUIVALENT DISPLACEMENTS lions KILO WALRUS BARBEL 2400 1700 2000 AVG VOL ph 1943 2185 1548 1838 2016 1866 1899 OB ITEMS 557 265 597 322 124 198 344 VOLeb 2500 2450 2145 2160 2140 2064 2243 MBT 700 350 324 240 210 266 348 SUB VOL 3200 2800 2469 2400 2350 2330 2592 FREEFLOOD 160 140 132 120 117 117 131 ENVELOPE 3360 2940 2601 2520 2467 244 7 2723 VOLUMES OF VOL ph KILO WALRUS BARBEL 2400 1700 2000 AVG MOBILITY 038 039 034 049 067 061 0479 WEAPONS 011 011 010 009 008 008 0095 C3 1 013 007 009 012 006 007 0090 SHIP SUPPORT 016 032 019 015 013 i 014 0184 VOL ph 078 089 072 085 094 090 0848 OB ITEMS 022 011 028 015 006 1 010 0152 VOLeb 100 100 100 100 100 100 1000 MBT 028 014 015 011 010 013 0152 SUB VOL 128 114 115 111 110 113 1152 FREEFLOOD 006 006 006 006 005 006 0058 ENVELOPE 134 1 121 117 115 119 1210 196 to 8 P MOB a 6 4 SHP I Mobility Density Figure E1 Ill U UU4 0003 PRL a pL RLi b RL 0002 0001 0 5 10 15 20 0008 0006 a PTrTi b PT 1 0004 0002 RL I Torpedo Tube and Reload Densities Figure E2 197 I I X l J g J J 6 TT l I I I I 8 4 Weapons The weapons volume is based on similar parametric relationships for those weapons items that remain fixed in the ship specifically the number of torpedo tubes installed and the room set aside for rack storage of weaDons Figure E2 above presents the parametric curves for the torpedo tube PuT and reload PRL densities 53 The densities are then multiplied against values set down in the owners requirements Vweps No Torp Tubesp NoReloadspR For this model values of 00042 and 00036 respectively were selected C31 Volume The volume selected for C31 5300 ft3 was that of the British Type 2000 submarine based on the desire to have a ship with similar weapons and sensor capabilities Ship Support Volume Four factors combine to provide input for this volume Attribute Factor Area Berthing and Messing Abm 10crew size Area Storeroom Asr 85mission length Area Office Spaces Aos 120 06crew size Volume Auxiliaries Vax a function of the above plus Vph 198 These constants were selected based on design experience and requirements for habitability adjusted for the fact that diesel submarines are generally not as spacious as nuclear powered ships The areas above are converted to volumes by three multiplicitive factors 108 to account for added area for passageways 112 to account for wasted space in the vicinity of the curved hull and a standard deck height of 7 feet The values are based on proven submarine designs Other Volumes The volumes outside the pressure hull are also based on design experience and the data presented by Stenard For SUBSIZE the following factors were selected Outboard Margin Vph 018 Volume Main Ballast Tanks Veb 015 Volume Freeflood Veb 006 199 Blank Reverse APPENDIX F WEIGHT DATA F0 OVERVIEW This appendix contains the weight data base for SUBSIZE Table F 1 as well as a discussion of the weight formulae presented by Stenard 61 The weight data was further adjusted by Professor J Reed for presentation in a special submarine design course presented at the Massachusetts Institute of Technology during the Independent Activities Period January 1994 F1 FACTOR ANALYSIS In his thesis Stenard developed parametric equations for ship weights based on the data in Table F1 In general these equations were used with some modifications Structural Weight Stenard gives the following relation for structural weight Wstr NSC000055Diving Depth 015 in meters which is a function of diving depth sizing the pressure hull to withstand the pressure exerted by the sea The formula was accepted with the factor 000055 changed to 000017 to allow the use of depth in feet Mobility Weight Again Stenard gives a relationship which is accepted except that the battery weight for the baseline submarine 42096 Itons is substituted for the battery weight factor Wmob0572 battery cells 21SHP0 64 201 Table F1 Weight Data For Use in SUBSIZE KILO WALRUS BARBEL 2400 1700 2000 AVG STRUCTURE 825 787 820 618 544 611 701 MOBILITY 700 792 575 868 988 922 808 WEAPONS 78 48 53 60 42 59 57 C3 1 67 50 56 84 32 40 55 SHIP SUPPORT 101 98 117 101 67 76 93 A1 1771 1775 1621 1731 1673 1708 1713 FIXED BALLAST 128 129 123 119 86 93 113 A 1899 1904 1744 1850 1759 1801 1826 VARIABLE LOAD 600 550 401 310 380 264 418 NSC 2499 2454 2145 2160 2139 2065 2244 MBT 700 350 324 240 210 266 348 SUB DISPL 3199 2804 2469 2400 2348 2331 348 WEIGHlS OF A 1 Ions KILO WALRUS BARBEL 2400 1700 2000 AVG STRUCTURE 047 044 051 036 033 036 0409 MOBILITY 040 045 035 050 059 054 0471 WEAPONS 004 003 003 003 003 0 0033 C 3 1 004 003 003 005 002 002 0032 SHIP SUPPORT 006 006 007 006 i 004 004 0055 A1 100 100 100 100 i 100 100 1000 FIXED BALLAST 007 007 008 007 005 005 0066 A 107 107 108 107 1 105 105 1066 VARIABLE LOAD 034 031 025 018 023 015 0243 NSC 141 138 132 125 128 121 1309 MBT 040 020 020 014 013 016 0202 SUB DISPL 181 158 152 139 140 136 0202 WEIGHTS OF NSCQ KILO WALRUS BARBEL 2400 1700 2000 AVG STRUCTURE 033 032 038 029 025 030 0312 MOBILITY 028 032 027 040 046 045 0364 WEAPONS 003 002 002 003 002 003 0025 C3 1 003 002 003 004 001 002 0024 SHIP SUPPORT 004 004 005 00305 004 0042 A1 071 072 076 080 078 083 0766 FIXED BALLAST 005 005 006 006 004 005 0050 A 076 078 081 086 082 087 0817 VARIABLE LOAD 024 022 019 014 018 013 0183 NSC 100 100 100 100 100 100 1000 MBT 028 014 015 011 010 013 0152 SUB DISPL 128 1T14 115 111 i 110 113 0152 CV3 WEtC 00067 00054 00077 00125 00056 00067 00074 202 As was the case for mobility volume the overall mobility weight is further adjusted to account for AIP weight and the change in battery weight Wmob Battery Weight 21SHP6 AWBattery WAP Weapons Weight The following formula for weapons weight based on the number of torpedo tubes and a factor for the size of the weapons spaces is given and accepted Wweps 0002Vweps 6No Torp Tubes 5 C31 Weight Here Stenard gives a formula based on the volume of the C31 space 000836 Volume C31 For SUBSIZE a more traditional approach that being a weight for C31 based on NSC is taken with the following factor taken developed from Stenards data WC3 0025NSC Ship Support Weight Again the parametric relationship presented by Stenard is used Ws 00336 NSC 0 4Crew Size Other Weights The remaining weights that make up NSC are margins based on historical trends These values become real numbers in the later stages of design as detailed design is conducted and better estimates for these values are obtained For SUBSIZE an initial value of 005 was selected for the lead margin which is consistent with Table F 1 The value of variable load should total to be 203 about 018 of NSC but as explained in Chapter 6 fuel is included in the variable load weight thus variable load must now consider the impact of AIP During the validation of the model it was observed that selecting a value for variable load fraction equal to 005 would yield a final variable load fraction of about 018 204 APPENDIX G SNORKEL POWERING G0 OVERVIEW Chapter 6 provided the required formula constants applied to the hydrodynamic powering equations which are well established This appendix focuses on the method used to determine the required snorkel power for the submarine G1 PROCEDURE When operating near the surface but not broached ship powering is still governed by the effects of a body of revolution hull moving through a fluid However due to the bodys proximity to the surface the additional effects of making a disturbance on the free surface must be considered As in surface ship powering relationships this additional power is a function of the Froude Number for the ship determined by 169Speed in knots 322 Length This value is then used to enter Figure G1 along with a ratio hL to obtain a chart number which is proportional to the wave making resistance of the hull In the ratio L represents the length of the body of revolution while h is distance from the center of the body of revolution to the surface of the fluid which is also illustrated in Figure G1 this chart number is then applied to the following relationship to obtain the wave resistance coefficient Chart No 4 k2 2 Cwave is then converted to SHP by the relation SHPwaVe 872WSCw 205 This additional SHP due to wave action is added directly to SHP due to the body of revolution 1 I i t TIIII Z i I i i iT I 1 X T t 11 I ri i 1 X Z N d I o L 2 IV I V i e L 00 t 2 6t G r 4w V3 L Wave Drag Coefficient Figure G1 206 10 4 2 0 APPENDIX H DATA TABLES This Appendix contains the data tables to support the results presented in Chapter 8 Compare Plants at 25 day endurance Figure 82 PLANT LENGTH LOD NSC SHP AIP ALOX 23483 758 314214 447978 41034 i CBC 27412 884 384231 514619 47856 CCD 33032 1066 484522 608474 5753 iMCFC 20135 65 254597 390328 35169 PEM 20235 653 256436 392066 35345 iiSTRLNG 32771 1057 479836 604143 57082 207 Figure 81 NSC NSC Itons Itons BASELINE 2325 2316 PEM 25 day 3048 2804 endurance PEM 35 day 3207 3316 endurance ALOX 25 day 3449 endurance ALOX 35 day 4544 endurance Differenc 0 8 3 1 18 t Figure 83 PLANT 25 days 30 days 35 days ALOX 314214 372737 450383 CBC 384231 501015 674092 CCD 484522 681733 1029486 MCFC 254597 294908 344022 PEM 256436 297956 351817 STRLNG 479836 672482 1010478 PEM NSC AIP Cap Ox Vol Ox Wt LOX 256436 35345 1017947 15575 H202 24267 33987 813644 10258 NaCI03 247751 34494 885396 1395 GasOxEt 5582 64597 3274289 967 GasOxln 1982867 196746 2991804 294524 Figure 85 PEM NSC AIP Cap Fuel Vol Fuel Wt METH 256436 35345 318109 7098 LIQ H2 476883 56811 3272323 23622 HYDRIDE 1107998 11635 1815057 219901 GAS H2 1945932 193376 2094025 438576 Figures 86 and 87 PEM PEM NSC Burst End NSC Creep End Lead Acid 256436 294 236184 6198 NiCd 258794 46 216579 4017 LAIS 236905 207 236625 8714 208 Figure 84 Blank Reverse PLANT FPP CR APPENDIX I COMPUTER PROGRAM 10 OVERVIEW This appendix contains the computer code written in Turbo C using Borland Turbo C 30 and contains the following sections Section Page No 11 Main Program SUBSIZECPP 212 12 Header File AIPH 228 13 Powering Functions POWERINGCPP 229 14 Printer File PRINTERCPP 233 15 AIP Sizing Functions and Plant Input Files AIPSIZECPP 235 16 Sample Output 243 211 11 MAIN PROGRAM SUBSIZECPP SUBSIZE This program determines the size of a concept hybrid AIP submarine include aiph char pausel To pause program at predetemined spots Ship parameters float divingdepth 9000 float maxshp 50000 float crewsize 440 float torpedotubes 40 in ft Iinitial installed shaft horsepower float torpedoreloads 210 float missionlength 600 I in days float maxspeed 200 I in knots float burstendurance 20 II in hours float snortspeed 100 I in knots float maxrange 100000 nm total float aipspeed 80 in knots float aip endurance 250 in days float snortrange maxrangeaipenduranceaipspeed240 determines snort range balance to acheive max range float creepspeed 40 I in knots float rechargespeed 40 speed while recharging batteries float transitspeed 130 speed while running on batteries float creependurance 900 I in hours float pc 0863 ratio EHPSHP float transeff 096 Envelope float subdiameter 310 float priscoef fwd 075 float priscoefaft 06429 float wetsurf coef fwd 08452 float wetsurf coef aft 075 I in ft3 determines forebody shape determines forebody shape deter forebody wetted surface deter afterbody wetted surface 212 float float float float float float float float float float Margins and weightsvolumes volume c cubedi 53000 fixedballastmargin 005 variableloadmargin 005 c cubed i factor 0025 mobilitydensity 67 torpedotubedensity 10042 torpedoreloaddensity 10036 outboardmargin 0 18 mbtmargin 0 15 freefloodmargin 006 Battery char batterytype30 Lead Acid float batt wt 764 float batt vol 8000 float batttwo hrcapacity 16000 float batteightyhrcapacity 26455 float battcaptransit 24556 float num batt init 551 float couleff 09 char batterytype30 LAIS Ifloat battwt 369 float battvol 7224 float batttwo hr capacity 3690 float batteightyhrcapacity 8580 Ifloat battcaptransit 00 float num batt init 2389 float couleff 10 char batterytype30 NiCd float batt wt 380 Ifloat batt vol 6700 float batttwo hr capacity 12010 float batteightyhrcapacity 12700 float battcaptransit 00 Ifloat numbattinit 1078 Ifloat couleff 09 I in ft3 deter initial lead margin estimate of variable load fraction estimate of C3I fraction of nsc in ftA3hp Iin ftA3TT in ftA3reload deter otbd item vol deter reserve buoyancy deter freeflood vol I in Itons in ft3 in kWhr I in kWhr Iin kWhrs effic of extracting battery energy in Itons in ft3 I in kWhr I in kWhr effic of extracting battery energy I in Itons I in ftA3 in kWhr I in kWhr effic of extracting battery energy extern float battendurburst battendurcreep extern float numbatt 213 float volumeweapons in ft3 float volumemobility in ft3 float volumeaux in ftA3 float volumeshipsupport in ftA3 float volumepressurehull in ftA3 float volumeoutboard in ft3 float volumeeverbuoyant in ftA 3 float volumemainballasttank in ftA3 float volumesubmerged in ftA3 float volumefreeflood in ft3 float volumeenvelopereq in ftA3 float weightstructure ltons float weightmobility ltons float weightccubedi ltons float weightweapons ltons float weightfixedballast ltons float weightshipsupport ltons float weightvariableload ltons float nsc ltons float oldnsc ltons float sublength feet float speed knots float wetsurf ft2 Declarations from aip header files float ehpaip float shpaip float reqdcapacityaip in kW float plantwt float plantvol float reformerwt float reformervol float oxidantwt float oxidantvol float fuelwt float fuelvol float otherwt float othervol float productwt float productvol extern float loxwt extern float loxvol 214 char planttype30 char reformer5 char oxidanttype30 char fueltype30 char othertype30 char productmgmt30 char breathingoxygen5 Declarations from powerO float nusw 128171000000 float reynoldsnum float corr allow 00004 float frictcoef float residcoef float area sail 8000 float coefdragsail 0009 float resistbridge float resistapp extern float ehp shp effective and shaft horsepower Declarations from hotel float hotelload float float float float Declarations from diesel dieselsfc 055 dieselmech eta 090 fuelallow 08 bunkerfuel hphr fuel use during mission Declarations from indesc float ehprecharge float shprecharge float timerecharge float battendurtransit float indescratio float shptransit float ehptransit float soa float coef wave float shpwave 215 extern extern extern extern extern extern extern include iostreamh include mathh include iomaniph include fstreamh include stringh float pi 4atan10 float kl 6036priscoef aft 24priscoeffwd float k2 6036wet surf coef aft 24wetsurf coef fwd float aipvol 00 float aipwt 00 float deltabattwt 00 float deltabattvol 00 mainO cout setiosflagsios fixed setprecision2 defines pi for hull shape calculations for wetted surf calculations initally zero for baseline calc initally zero for baseline calc initally zero for baseline calc initally zero for baseline calc Estimate required volume of the submarine with volume function volume Determine envelope dimensions for a body of revolution based on the estimated volume and curve factors envelopeO Estimate the required weight of the submarine with weight function weight0 This loop adds hull length if weight limited and is skipped if volume limited wtlimitO This loop adds lead weight if volume limited and is skipped if weight limited vllimitO 216 Determine the power required to push the body of revolution speed maxspeed powerO maxshp shp Determine the propulsion power required while snorting for the body of revolution snortO Determine the hotel load for the ship hotelO Determine diesel fuel required to transit the required snort distance diesfuel Determine battery size difference from the baseline battdelt0 Determine battery endurance battendr User select the AIP plant to evaluate int type cout Select AIP type cout PEM F C l cout Molten Carbonate F C 2 cout Al Ox Cell 3 cout Closed Diesel 4 cout Closed Brayton 5n cout Closed Stirling 6 cin type switch type case 1 pemdeclO break case 2 mfcdecl break case 3 aludeclO break case 4 ccddeclO break case 5 cbcdecl break case 6 strdeclO break default cout invalid entry should break be integer between 1 and 6 217 Determine the size of the AIP plant aipsizeO Now that the AIP plant has been sized rerun weights and volumes do oldnscnsc Rerun volume estimate volumeO Rerun envelope dimensions envelopeO Rerun weight estimate weights This loop grows the envelope volume if weight limited and is skipped if volume limited wtlimitO This loop adds lead weight if volume limited Hand is skipped if weight limited vllimitO Determine the propulsion power required for la given speed for the body of revolution speed maxspeed power0 maxshp shp Determine the propulsion power required while snorting for the body of revolution snort Determine the hotel load for the ship hotelO Determine diesel fuel required diesfuelO 218 Determine battery size difference from the baseline battdelt0 Determine battery endurance battendr0 Redetermine the AIP plant size aipsize0 Determine indescretion ratio parameters indesc0 while nscoldnscnscO0 1 Prepare Screen Output cout AIP SIZING PROGRAM OUTPUT cout INPUT DATA cout Range Total Ship Range nm maxrange cout Snort snortspeed kts nm snort range n cout Submerged aipspeed kts AIP days aipendurance cout Submerged creep creepspeed kts on battery hours battendurcreep cout Submerged burst maxspeed kts on battery hours battendurburst cout Submerged transit transitspeed kts on battery hours battendurtransit cout Recharge time rechargespeed kts hours timerecharge cout SOA kts soa Indescretion Ratio indesc ratio cout Diving Depth ft divingdepth Crew Size crew size n cout Torpedo Tubes torpedotubes Reloads torpedoreloads cout MARGINS cout Fixed Ballast NSC setprecision3 fixed ballast marginsetprecision2 Variable Load NSC variableloadmargin cout Outboard Items Vph outboardmargin Res Buoyancy Veb mbtmargin n cout Freeflood Volume Veb freefloodmargin 219 cout ENVELOPE cout Length ft sublength Diameter ft subdiameter LD sublengthsubdiameter cout Cpf setprecision4priscoef fwd Cpa priscoefaft Cwsf wetsurfcoeffwd Cwsa wetsurfcoefaftsetprecision2 icin pause cout VOLUMES ft3 cout Weapons volumeweapons Mobility volumemobility cout Ship Support volumeshipsupport CA3I volumec cubed i cout Pressure Hull volumep ressurehull Outboard volume outboard cout Everbuoyant volumeeverbuoyant Main Ballast Tanks volumemainballasttank cout Submerged volumesubmerged Freeflood volume freeflood cout Envelope volumeenvelopereq cout WEIGHTS Itons cout Structure weightstructure Mobility weightmobility cout Weapons weightweapons CA3I weightccubedi n cout Ship Support weightshipsupport Fixed Ballast weightfixedballast cout Variable Load weightvariableload Normal Surf Condition nsc cout MOBILITY cout Battery Type batterytype Number of Batteries numbatt cout Battery Weightlton numbattbattwt VolumeftA3 numbattbattvol cout CapacitykWhr 2hr rate numbattbatttwo hrcapacity cout Propulsive Coeff pc Installed SHP maxshp cout Hotel Load kW hotelload Bunker Fuel Itons bunkerfuel cin pause 220 cout AIP cout AIP Plant Size kW reqdcapacityaip cout Type planttype Weightltons plantwt VolumeftA3plantvol cout Reformer reformer Weightltons reformerwt VolumeftA3reformervol cout Oxidant oxidanttype Weighttons oxidantwt VolumeftA3oxidantvol cout Breath LOX breathingoxygen Weightltons loxwt Volumeft3loxvol cout Fuel fueltype Weightltons fuelwt VolumeftA3 fuelvol n cout Other othertype Weightltons otherwt Volumeft3 othervol cout Cosworth productmgmt Weightltons productwt VolumeftA3 product vol cout Totals Weightltons aip wt VolumeftA3 aipvol Send data to printer include printercpp return 0 END OF MAIN PROGRAM SUBSIZE DIESFUEL diesfuelO This subroutine calculates the amount of diesel fuel required to transit snort range at periscope depth extern float shpsnort bunkerfuel snortrangedieselsfcshpsnort 134hotelload 22400fuelallowtransef snortspeed return 0 END OF DIESFUELO 221 ENVELOPE envelope0 This function calculates a body of revolution length given the envelope displacement and a diameter sublength subdiameterkl1400volumeenvelopereq35 pipowsubdiameter3 return 0 END OF ENVELOPE HOTEL hotelO This subroutine calculates hotel load based on volume estimates hotelload 15015volumemobility40volumeccubedi 15 volumeshipsupportvolumeweapons10000 return 0 END OF HOTEL 222 INDESCO indescO This subroutine calculates the indiscretion ratio for an assumed snort speed while recharging batteries calculate the shp at recharge speed speed rechargespeed power0 shprecharge shp coef wave 0240sublengthsubdiameter 13606 powsublengthsubdiameter2 02 determined from Jackson notes pg 623A shpwave 872wetsurfcoefwave shprecharge shprechargeshpwave calculate the hotel load during recharge hotel calculate time to recharge timerecharge numbattbattcaptransit080 3 09900shprecharge 134hotelload0 80 calculate endurance on battery at transit speed speed transitspeed power0 shptransit shp battendurtransit numbattbattcaptransit 1000 coulefftranseffshptransit0746hotelload 100 accounts for 100 kWhrs consumed while preparing for periscope depth operations Calculate indescretion ratio and speed of advance indescratio timerechargetimerechargebattendurtransit 10 10 accounts for 1 hour of periscope depth preparation Itime with no distance travelled soa timerechargerechargespeedbattendurtransittransitspeed timerechargebattendurtransit 10 return0 END OF INDESC0 223 VOLUMEO volumeO This function calculates volumes for SUBSIZECPP float volumeaux in ftA3 volumeweapons torpedotubestorpedotubedensity torpedoreloadstorpedoreloaddensity volumemobility maxshpmobilitydensityaipvoldeltabattvol volumeccubedi is defined in subsizecpp float areaberthmess 10crewsize in ft2 float areastoreroom 85missionlength in ft2 float areaotherspaces 12006crewsize in ft2 volumeauxiliary is a function of volume pressure hull volumepressurehull 93 crewsize areaberthmessareastoreroomareaotherspaces70 108 112 volumemobilityvolumeweaponsvolumeccubed i097 volumeaux 003 volumepressurehull93 crewsize volumeshipsupport volumeauxl1270108areaberthmess areastoreroomareaotherspaces volumeoutboard outboardmarginvolumepressurehull volumeeverbuoyant volumeoutboardvolumepressurehull volumemainballasttank mbtmarginvolumeeverbuoyant volumesubmerged volumemainballasttankvolumeeverbuoyant volumefreeflood freefloodmarginvolumeeverbuoyant volumeenvelopereq volumesubmergedvolumefreeflood returnO END OF VOLUME0 224 WEIGHTO weightO This subroutine calculates weights for SUBSIZECPP weightstructure is a function of Normal Surfaced Condition nsc weightmobility 42096420powmaxshp 064 aipwtdeltabattwt weightweapons 0002volumeweapons60torpedotubes5 weightccubedi is a function of nsc weightshipsupport is a function of nsc weightfixedballast is a function of nsc weightvariableload is a function of nsc nsc weightmobilityweightweapons04crewsize 1 00001 6764divingdepth0 1500336 fixedballast marginc cubed ifactor variableloadmargin ltons weightstructure nsc000016764divingdepth015 ltons weightshipsupport 00336nsc04crewsize ltons weightfixedballast fixedballastmarginnsc ltons weightvariableload variableloadmarginnsc ltons weightccubedi c cubed i factornsc ltons return 0 END OF WEIGHT 225 VLLIMIT vllimitO This function balances weights and volumes if volume limited while volumeeverbuoyant35nsc volumeeverbuoyant35nscnsc0001 while volumeeverbuoyant35nsc volumeeverbuoyant35nscnsc0 001 fixedballastmargin fixedballastmargin 00004 weight return 0 END OF VLLIMIT WTLIMIT wtlimitO This subroutine balances weights and volumes if weight limited while nscvolumeeverbuoyant3 5 while nscvolumeeverbuoyant35 sublength sublength0 1 volumeenvelopereq pipowsubdiameter34 sublengthsubdiameterk 1 volumeeverbuoyant volumeenvelopereq 1mbtmarginfreefloodmargin 226 Recalcuate the volumes that changed on matching weights and volumes volumemainballasttank mbtmarginvolumeeverbuoyant volumefreeflood freefloodmarginvolumeeverbuoyant volumesubmerged volumemainballasttank volumeeverbuoyant volumepressurehull volumeeverbuoyant 1 outboardmargin volumeshipsupport volumepressurehull volumemobility volumeweaponsvolumeccubedi volumeoutboard volumepressurehulloutboardmargin return 0 END OF WTLIMIT0 227 12 HEADER FILE AIPH program aiph function prototypes int volume int envelope0 int diesfuel0 int hotel0 int battendr int battdelt0 nt power int aipsize0 int weight0 int wtlimit int vllimit0 int snort int aludecl0 int cbcdecl int ccddecl0 int mfcdeclO int pemdecl0 int strdecl0 int indesc 228 13 POWERING FUNCTIONS POWERINGCPP POWERINGCPP include mathh include fstreamh include stringh include aiph float shpbattcreep ehpbattcreep battendurcreep float battendurburst ehpbattburst shpbattburst float ehpshp numbatt extern float maxspeed speed wetsurf pi extern float subdiameter sublength k2 reynoldsnum nusw extern float frictcoef residcoef resistbridge areasail extern float coefdragsail resistapp corrallow pc numbatt extern float numbattinit batttwohrcapacity extern float batteightyhrcapacity couleff transeff extern float hotelload creepspeed motoreff battendurcreep extern float creependurance battwt deltabattvol extern float deltabattwt battvol burstendurance extern float coefwave shpwave Declarations from snort float chartnumber 09 obtained from Jackson notes pg 623A float shpsnort ehpsnort extern float snortspeed BATTDELTO battdeltO This subroutine calculates the change in battery size from a baseline diesel electric lead acid battery float reqdcapacityburst float numbatt burst float deltabattburst float reqdcapacitycreep float numbattcreep float deltabattcreep float deltabatt 229 numbatt numbatt init Calculate battery delta based on burst speed speed maxspeed powerO ehpbattburst ehp shpbattburst shp reqdcapacityburst burstenduranceshpbattburst0746 hotelloadcoulefftranseff numbattburst reqdcapacityburstbatttwohr capacity deltabattburst numbattburst numbatt Calculate battery delta based on creep speed speed creepspeed power0 ehpbattcreep ehp shpbattcreep shp reqdcapacitycreep creependuranceshpbattcreep0746 hotelloadcoulefftranseff numbattcreep reqdcapacitycreepbatteightyhr capacity deltabatt creep numbattcreep numbatt if deltabattburstdeltabattcreep delta batt delta batt burst else deltabatt deltabattcreep numbatt numbattdeltabatt deltabatt wt deltabattbatt wt deltabatt vol deltabattbattvol return 0 END OF BATTDELT 230 BATTENDRO battendrO This subroutine calculates endurance on the installed battery Calculate burst endurance speed maxspeed power0 ehpbattburst ehp shpbattburst shp battendurburst numbattbatttwohrcapacitycoulefftranseff shpbattburst0 746hotelload Calculate creep endurance speed creepspeed power ehpbattcreep ehp shpbattcreep shp battendurcreep numbattbatteightyhrcapacitycouleff transeffshpbattcreep0746hotelload return 0 END OF BATTENDR POWER power This subroutine calculates the propulsive power required for a given hull User must designate what speed is to be used before calling POWER0 by the following sequence II speed speed II power 231 Assumed seawater properties 11 Temperature 59 deg F rho 19905 sec2ftA4 nu 12817e5 ftA2sec wetsurf pipowsubdiameter2sub lengthsubdiameterk2 reynoldsnum sublengthspeed 16889nusw frictcoef 0075powlogIOreynoldsnum22 residcoef 0000789sublengthsubdiameterk2 resistbridge areasailcoef dragsail resistapp sublengthsubdiameter10000 ehp 000872powspeed3 wetsurf fiictcoefresidcoefcorrallow resistbridgeresistapp shp ehppc return 0 END OF POWER SNORT snort This subroutine calculates the propulsive power required while snorting for a given hull speed snortspeed powerO ehpsnort ehp shpsnort shp coefwave chartnumber40sublengthsubdiameter 13606 powsublengthsubdiameter2 shpwave 872wetsurfcoefwave shpsnort shpsnortshpwave return0 END OF SNORT 232 14 PRINTER FILE PRINTERCPP ofstream prnPRN prn setiosflagsios fixed setprecision2 pm AIP SIZING PROGRAM OUTPUT r pm AIP SIZING PROGRAM OUTPUT pm INPUT DATA planttype pm Range Total Ship Range nm maxrange prn Snort snortspeed kts nm snortrange prn Submerged aipspeed kts AIP days aipendurance prn Submerged creep creepspeed kts on battery hours battendurcreep prn Submerged burst maxspeed kts on battery hours battendurburst prn Submerged transit transitspeed kts on battery hours battendurtransit prn Recharge time rechargespeed kts hours timerecharge prn SOA kts soa Indescretion Ratio indescratio prn Diving Depth ft divingdepth Crew Size crew size pm Torpedo Tubes torpedotubes Reloads torpedoreloads pm Mission Length days missionlength pm MARGINS prn Fixed Ballast NSC setprecision3 fixedballast marginsetprecision2 Variable Load NSC variableloadmargin prn Outboard Items Vph outboardmargin Res Buoyancy Veb mbtmargin prn Freeflood Volume Veb freefloodmargin prn ENVELOPE prn Length ft sublength Diameter ft subdiameter LD sub lengthsubdiameter prn Cpf setprecision4priscoef fwd Cpa priscoefaft Cwsf wetsurfcoeffwd Cwsa wetsurfcoefaftsetprecision2 prn VOLUMES ft3 pm Weapons volumeweapons Mobility volumemobility pm Ship Support volumeshipsupport CA3I volumec cubed i n 233 pm Pressure Hull volumepressurehull Outboard volumeoutboard n prn Everbuoyant volumeeverbuoyant Main Ballast Tanks volumemainballasttank prn Submerged volumesubmerged Freeflood volume freeflood n pm Envelope volumeenvelopereq n n pm WEIGHTS ltons pm Structure weightstructure Mobility weightmobility n pm Weapons weightweapons CA3I weightccubedi n pm Ship Support weightshipsupport Fixed Ballast weightfixedballast pm Variable Load weightvariableload Normal Surf Condition nsc pm MOBILITY pm Battery Type batterytype Number of Batteries num batt pm Battery Weightlton numbattbattwt VolumeftA3 numbattbattvol pm CapacitykWhr 2hr rate numbattbatttwo hr capacity pm Propulsive Coeff pc Installed SHP maxshp pm Hotel Load kW hotelload Bunker Fuel ltons bunker fuel pm AIP pm AIP Plant Size kW reqdcapacityaip pm Type planttype Weightltons plantwt VolumeftA3plantvol pm Reformer reformer Weightltons reformerwt VolumeftA3reformervol pm Oxidant oxidanttype Weightltons oxidantwt Volumeft3oxidantvol pm Breath LOX breathingoxygen Weightltons loxwt VolumeftA3loxvol pm Fuel fueltype Weightltons fuelwt Volumeft3 fuelvol pm Other othertype Weightltons otherwt VolumeftA3 othervol pm Cosworth productmgmt Weightltons product wt VolumeftA3productvol pm Totals Weightltons aipwt Volumeft3aipvol 234 15 AIP SIZING FUNCTIONS AND PLANT INPUT FILES AIPSIZECPP AIPSIZCPP include mathh include fstreamh include stringh include aiph float loxwt loxvol extern float hotelload transeff motoreff plantwt extern float reqdcapacityaip plantvol reformerwt reformervol extern float oxidantwt oxidantvol fuelwt fuelvol crewsize extern float missionlength speed aipspeed ehpaip ehp shpaip extern float shp aipendurance otherwt othervol product wt extern float aipwt aipvol productvol char planttype30 float plantwtfactor plantvol factor plantwtpackingfactor float plantvolpackingfactor reformerwtfactor char reformer5 float reformervolfactor reformerwtpackingfactor float reformervolpackingfactor char oxidanttype30 float oxidantwtfactor oxidantvolfactor float oxidantwtpackingfactor oxidantvolpackingfactor char fueltype30 float fuelwtfactor fuelvolfactor fuelwtpackingfactor float fuelvolpackingfactor char othertype30 float otherwtfactor othervolfactor float otherwtpackingfactor othervolackingfactor char productmgmt30 float productwtfactor productvolfactor float productwtpackingfactor productvolpackingfactor char breathingoxygen5 float oxuserate loxdensity loxullage loxsafetymargin float loxvolpackingfactor loxwtpackingfactor 235 aipsizeO AIPSIZEO This function calculates the size of the AIP plant as well as breathing oxygen calculate the required liquid oxygen for the mission loxvol crewsizemissionlengthloxsafetymarginox use rate loxullage loxwt loxvolloxdensity22400 loxvol loxvolloxvolpackingfactor loxwt loxwtloxwtpackingfactor Calculate AlP parameters based on AIP speed speed aipspeed power0 ehpaip ehp shpaip shp reqdcapacityaip shpaip0746hotelloadtranseff plantwt reqdcapacityaipplantwtfactor220522400 plant wtpackingfactor plantvol reqdcapacityaipplantvolfactor plantvolpackingfactor reformerwt reqdcapacityaipreformerwtfactor220522400 reformerwtpackingfactor reformervol reqdcapacityaipreformervolfactor reformervolpackingfactor oxidantwt aipendurance240reqdcapacity aipoxidantwtfactor 220522400oxidantwtpackingfactor oxidantvol aipendurance240 reqdcapacityaipoxidantvolfactor oxidantvolpackingfactor fuelwt aip endurance240reqdcapacityaipfuelwtfactor 220522400fuelwtpackingfactor fuelvol aipendurance240reqdcapacityaipfuelvolfactor fuelvolpackingfactor otherwt aipendurance240reqdcapacityaipotherwtfactor 220522400otherwtpackingfactor othervol aip endurance240reqdcapacityaipothervolfactor othervolpackingfactor productwt reqdcapacityaipproductwtfactor220522400 productwtackingfactor productvol reqdcapacityaipproductvolfactor productvolpackingfactor aipwt plantwtreformerwtoxidantwtfuelwtotherwt productwtloxwt aipvol plantvolreformervoloxidantvolfuelvolothervol productvolloxvol return 0 END OF AIPSIZE 236 aludeclO ALUDECL This file contains the declarations AIP Plant strcpyplanttype ALOX plantwtfactor 5533 plantvolfactor 35 plantwtpackingfactor 10 plantvolpackingfactor 10 strcpy reformer NO reformer wt factor 00 reformervolfactor 00 reformerwtpackingfactor 10 reformervolpackingfactor 10 strcpy oxidanttype LOX oxidant wt factor 0263 oxidantvol factor 0008 oxidantwtpackingfactor 146 oxidantvolpackingfactor 30 strcpy fueltype ALUMINUM fuelwtfactor 028 fuelvolfactor 00 fuelwtpacking factor 10 fuelvol packing factor 10 strcpy othertype KOHIWATER otherwtfactor 0898 othervolfactor 00318 otherwtpackingfactor 133 othervolpackingfactor 23 strcpy productmgmtNO productwtfactor 00 productvolfactor 00 productwtpackingfactor 10 productvolpackingfactor 10 strcpy breathingoxygen NO oxuserate 003 loxdensity 7123 loxullage 095 loxsafetymargin 11 loxvolackingfactor 30 loxwtpackingfactor 146 return 0 for the AluminumOxygen in kgkW in ftA3kW enter yesno If no enter 00 in factors I in kgkW I in ftA3kW I in kgkWhr in ftA3kWhr in kgkWhr I in ftA3kWhr in kgkWhr I in ftA3kWhr I in kgkW in ft3kW enter yes if oxidant type not LOX ft3manday ft3 END OF ALUDECL 237 This file contains the declarations AIP Plant strcpy planttype CBC plantwtfactor 40 plantvolfactor 0151 plantwtpackingfactor 10 plantvolpackingfactor 10 strcpy reformer NO reformer wtfactor 00 reformer vol factor 00 reformerwtpackingfactor 10 reformervolpackingfactor 10 strcpy oxidanttype LOX oxidant wt factor 0872 oxidant vol factor 0027 oxidantwtpackingfactor 146 oxidantvolpackingfactor 30 strcpy fueltype DIESEL fuel wt factor 0195 fuel vol factor 0008 fuel wtpackingfactor 10 fuelvolpackingfactor 10 strcpy othertype COMP WATER other wt factor 0278 other vol factor 003 otherwtpackingfactor 10 othervolpackingfactor 23 strcpy productmgmt YES productwtfactor 167 productvolfactor 2354 productwtpackingfactor 10 productvolpackingfactor 10 strcpy breathingoxygen NO ox use rate 003 lox density 7123 loxullage 095 loxsafetymargin 11 loxvolpackingfactor 30 loxwtpackingfactor 146 return0 for the Closed Brayton Cycle I in kgkW I in ftA3kW I enter yesno If no enter 00 in factors I in kgkW in ft3kW in kgkWhr in ft3kWhr in kgkWhr in ftA3kWhr I in kgkWhr in ftA3kWhr I in kgkW I in ftA3kW enter yes if oxidant type not LOX ftA3manday ft3 END OF CBCDECLO 238 cbcdeclo0 HCBCDECL This file contains the declarations for the Closed Cycle Diesel AIP Plant strcpy planttype CCD plantwtfactor 117 in kgkW plantvolfactor 0389 in ftA3kW plantwtpackingfactor 10 plantvolpackingfactor 10 strcpy reformer NO reformerwtfactor 00 reformervolfactor 00 reformerwtpackingfactor 10 reformervolpackingfactor 10 strcpy oxidanttype LOX oxidant wt factor 0988 oxidant vol factor 0031 oxidantwtpackingfactor 146 oxidantvolpackingfactor 30 strcpy fueltype DIESEL fuelwtfactor 0247 fuel vol factor 0011 fuel wtpackingfactor 10 fuelvolpackingfactor 10 strcpy othertype COMP WTR otherwtfactor 0413 othervolfactor 00806 otherwtpackingfactor 10 othervolpacking factor 10 strcpy productmgmt YES productwtfactor 167 productvolfactor 2354 productwtpackingfactor 10 productvolpackingfactor 10 strcpy breathingoxygen NO oxuserate 003 loxdensity 7123 loxullage 095 loxsafetymargin 11 loxvolpackingfactor 30 lox wtpacking factor 146 return0 enter yesno If no enter 00 in factors I in kgkW in ft3kW I in kgkWhr in ft3kWhr I in kgkWhr in ft3kWhr ARGON I in kgkWhr Includes I in ftA3kWhr conversion of STP argon to high press storage in kgkW I in ftA3kW enter yes if oxidant type not LOX ftA3manday ft3 END OF CCDDECL 239 ccddecl HCCDDECL This file contains the declarations for the Molten Carbonate FC AIP Plant strcpy planttype MCFC plantwtfactor 246 in kgkW plantvolfactor 108 in ftA3kW plantwtpackingfactor 10 plantvolpackingfactor 10 strcpy reformer NO reformer wt factor 00 reformervolfactor 00 reformerwtpackingfactor 10 reformervolpackingfactor 10 strcpy oxidanttype LOX oxidantwtfactor 0554 oxidant volfactor 0017 oxidantwtpackingfactor 146 oxidantvolpackingfactor 30 strcpy fueltype DIESEL fuel wtfactor 0165 fuelvolfactor 0007 fuelwtpackingfactor 10 fuelvolpackingfactor 10 strcpy othertype COMP WATER otherwtfactor 0177 other vol factor 00191 otherwtpackingfactor 10 othervolpackingfactor 23 strcpy productmgmt YES productwtfactor 167 productvolfactor 2354 productwtpackingfactor 10 productvolpackingfactor 10 strcpy breathingoxygen NO oxuserate 003 loxdensity 7123 loxullage 095 lox safetymargin 11 loxvolpackingfactor 30 loxwtpackingfactor 146 return0 END OF MFCDECL0 enter yesno If no enter 00 in factors I in kgkW I in ft3kW in kgkWhr I in ftA3kWhr I in kgkWhr I in ftA3kWhr I in kgkWhr i in ftA3kWhr in kgkW in ftA3kW enter yes if oxidant type not LOX ftA3manday ftA3 240 mfcdeclo0 MCFCDEC This function contains the declarations for the PEM AIP Plant strcpyplanttype PEM plantwtfactor 180 in kgkW plantvolfactor 0343 in ftA3kW plantwtpackingfactor 10 plantvolpackingfactor 10 strcpyreformer YES reformer wtfactor 180 reformervolfactor 0424 reformerwtpackingfactor 10 reformervolpackingfactor 10 strcpyoxidanttype LOX oxidantwtfactor 0511 oxidant vol factor 0016 oxidantwt packingfactor 146 oxidantvolpackingfactor 30 strcpyfueltype METHANOL fuelwtfactor 034 fuelvolfactor 0015 fuelwtpackingfactor 10 fuelvol packingfactor 10 strcpyothertype COMP WATER otherwtfactor 0163 othervolfactor 00176 otherwtqackingfactor 10 othervolpackingfactor 23 strcpyproductmgmt YES productwtfactor 167 productvolfactor 2354 productwtpackingfactor 10 productvolpackingfactor 10 strcpybreathingoxygen NO oxuserate 003 loxdensity 7123 loxullage 095 loxsafetymargin 11 loxvolpackingfactor 30 loxwtpackingfactor 146 return 0 END OF PEMDECL0 I enter yesno If no enter 00 in factors I in kgkW in ftA3kW I in kgkWhr in ftA3kWhr in kgkWhr I in ftA3kWhr in kgkWhr I in ftA3kWhr I in kgkW I in ftA3kW enter yes if oxidant type not LOX ftA3manday ftA3 241 pemdeclO PEMDECL strdeclo STRDECL0 This file contains the declarations for the Stirling AIP Plant strcpyplanttype STRLNG plantwtfactor 1154 I in kgkW plantvolfactor 0487 in ftA3kW plantwtpackingfactor 10 plantvolpackingfactor 15 strcpyreformer NO enter yesno If no enter 00 in factors reformerwtfactor 00 1 in kgkW reformervolfactor 00 in ftA3kW reformerwtpackingfactor 10 reformervolpackingfactor 10 strcpyoxidanttype LOX oxidantwtfactor 10 in kgkWhr oxidant vol factor 0031 in ftA3kWhr oxidantwtpackingfactor 146 oxidantvolpackingfactor 30 strcpyfueltype DIESEL fuelwtfactor 026 I in kgkWhr fuel volfactor 0011 I in ftA3kWhr fuelwtpackingfactor 10 fuelvol packingfactor 10 strcpyothertype COMP WATER otherwtfactor 0319 in kgkWhr othervolfactor 00345 I in ftA3kWhr otherwtpackingfactor 10 othervolpackingfactor 23 strcpyproductmgmt YES productwtfactor 167 in kgkW productvolfactor 2354 I in ftA3kW productwtpackingfactor 10 productvolpackingfactor 10 strcpybreathingoxygen NO enter yes if oxidant type not LOX oxuserate 003 ft3manday lox density 7123 ftA3 loxullage 095 lox safetymargin 11 loxvol in ft3 loxvolpackingfactor 30 loxwt in ltons loxwtpackingfactor 146 return0 END OF STRDECL 242 16 SAMPLE OUTPUT AIP SIZING PROGRAM OUTPUT INPUT DATA PEM Range Total Ship Range nm Snort 10 kts nm Submerged 8 kts AIP days Submerged creep 4 kts on battery hours Submerged burst 20 kts on battery hours Submerged transit 13 kts on battery hours Recharge time 4 kts hours SOA kts 1004 Indescretion Ratio 10000 5200 25 90 294 142 53 026 Diving Depth ft Torpedo Tubes Mission Length days 900 4 Crew Size Reloads 60 44 21 MARGINS Fixed Ballast NSC Outboard Items I VDh Freeflood Volume Veb 0112 Variable Load NSC 018 Res Buovancy Veb 006 ENVELOPE Length ft Cpf 075 20235 Cpa Diameter ft 06429 Cwsf 08452 VOLUMES ft3 Weapons Ship Support Pressure Hull Everbuoyant Submerged Envelope 678571 1392336 760702 Outboarc 8976284 10322727 10861304 Mobility C3I i 1369264 Main Ballast Tanks Freeflood WEIGHTS ltons Structure Weapons Ship Support Variable Load 77156 4257 10376 12822 Mobility C3I Fixed Ballast Normal Surf Condition MOBILITY Battery Type Lead Acid Battery WeightltonJ 49779 CapacitykWhr 2hr rate Propulsive Coeff 086 Hotel Load kW 13896 Number of Batteries Volumeift3 1042487 Installed SHP Bunker Fuel ltons AIP AIP Plant Size kW Type PEM Reformer YES Oxidant LOX Breath LOX NO Fuel METHANOL Other COMP WATER Cosworth YES 35345 Weightltons Weightltons Weightltons Weightltons Weihtltons Weightltons Weightltons 626 626 15575 426 7098 3403 058 Volumeft312123 Volumeft314986 Volumeft31017947 Volumeft327512 Volumeft3318109 Volumeft3858469 Volumeft383203 Weightltons 27812 Volumeft3233235 243 005 015 31 Cwsa LD 075 653 5006113 5300 1346443 538577 116796 6411 28618 256436 652 521243 392066 14018 Totals Reverse Blank