FUEL CELLS ON THE NASA SPACE SHUTTLE.   Term Paper ID:29355 Click to get this paper Essay Subject: Reviews the fuel cells used on the orbiter vehicles.... More... 17 Pages / 3825 Words 8 sources, 55 Citations, MLA Format $68.00 Return to List of Papers Paper Abstract: Reviews the fuel cells used on the orbiter vehicles. Table comparing fuel cell types. Fuel cell structure. Fuel cell components; the three fuel cell system on a space shuttle. Fuel cell reactants, storage and distribution. Fuel cell operation including consideration of parameter and processing. 3 Figures. Paper Introduction: FUEL CELLS ON THE NASA SPACE SHUTTLE ORBITER Introduction This research reviews the fuel cells used on the NASA space shuttle orbiter vehicles. The presentation of the review focuses on (1) fuel cell structure, (2) fuel cell components, (3) fuel cell reactants, (4) fuel cell storage and distribution, and (5) fuel cell operation. The review of fuel cell operation includes consideration of (a) parameter and (b) processing. Fuel Cell Structure The concept of the fuel cell is not a new technology. The fuel cell dates to 1839 and British scientist Sir William Grove. The first fuel cell appeared in 1842 (Connelley 1). Practical applications of the fuel cell concept proved elusive, however, until the National Aeronautics and Space Administration (NASA) funded the Text of the Paper: The entire text of the paper is shown below. However, the text is somewhat scrambled. We want to give you as much information as we possibly can about our papers and essays, but we cannot give them away for free. In the text below you will find that while disordered, many of the phrases are essentially intact. From this text you will be able to get a solid sense of the writing style, the concepts addressed, and the sources used in the research paper. fuel cell reactants fuel cellstorage and distribution and fuel to and British scientist Sir William Grove The first flights The Soviet space program also components required to support the fuel cellprocess orbiterconsists of fuel cells contained accessory section monitors the reactant flow removes electrical control unit Hoogers Fuel Cell Reactants Fuel cells typically Fuel cell technology today works Cell Storage and Distribution Fuel cells electrical energy in a continuous process Specifically a fuelcell asindependent electrical power sources Each fuel cell system power section is where hydrogen and oxygen aretransformed into electrical Fuel cells produce energy The fuel cells used in light and heat Thechemical reaction is flows over a second electrode An electrolytesubstance One of the mission critical problems toxic Further batteries had a finite celltechnology was its cost of were relativelyinsignificant because the spacecraft engines used far greater electrochemical reactions In a typical fuel cell hydrogen gas produce hydroxyl ions The overall led toincreasingly reliable fuel cell functioning fossil fuels Bakker and Cohn In is a KOH potassiumhydroxide solution In the alkaline fuel e The electrons move through the electricalcircuit attached to is as follows O H e OH electrons to producehydroxyl ions The hydroxyl ions water and heat The electrons are routed through the space shuttle orbiter Dicks and Larminie An mixed the hydrogen enters a condenser thewater vapor to water droplets A centrifugal water separator then water for the space shuttleorbiter crew consumption and cools the the cell stack through thefuel cell heat exchanger the circulatingfluid maintains the cell stack at a temperature to a minimum of C from cryogenictemperature oxygen pressure to a range of to psia and and hydrogen's pressuredecreases the coolant's pressure also decreases to prevent cell stack Theresulting saturated gas mixture moves through a condenser hydrogen-water mixture Dicks andLarminie The fuel cell stack removing the product watervapor formed module flows directly throughtwo ports into operations Dicks and Larminie Reactant current produced Anappreciable amount of excess reactants used indicates a decreases theefficiency of the reactions water linetemperature above C when required The normal temperature of of to Temperature sensors located on the fuel a pH sensor located downstream of the are percent consumed in the production daily to cleanse the cells When a pick up the contaminants and blow them outoverboard through the pre-heater limitations Dicks and Larminie Fuel cell purge can be Thehydrogen reactant is the more likely to current is checked to ensure a load of lessthan and the pre-heaters raise the temperature ofthe reactants to a from the hydrogen oxygen reaction occurring in the individualcells After above C The hot coolant from to circulate the coolantthrough the loop The temperature between C and C The fully closed due to the loop systems in the mid-fuselage of the space level The wattsustaining heaters normally are used during cell powersection As an operational improvement the to be used tomaintain a uniform temperature water modifications were made to the waterpickup a bleed orifice Dicks and Larminie The fuel cell power plant waterrelief three water relief panel lines causingthem to freeze of product water to a secondpotable water tank in redundant paths to the second watertank Temperature sensors and a thewater relief panel provides a redundant the potable water Dicks and Larminie Application The an absence ofmoving parts Fuel cell performance cell maintenance on NASA's space shuttle orbiter at reduced reactant temperatures that used a moistpolymer membrane as shuttle orbiter flights Morrison Othertypes of fuel cells that an anode catalyst draws hydrogen liquidmethanol thereby eliminating the the water to theelectrolyzer renews the entire process Each Operating Applications Current Potential Temperature Use Commercial Use Molten Carbonate and Larminie Each of the fuel cells on a NASA units can provide kwhof electrical power continuously or kwh onNASA space shuttle orbiters Figure Fuel Cell aft of the crew compartment The location of thecryogenic tanks A NASA Space Shuttle Orbiter pic A and Larminie J Fuel Cell Systems CIME March Stone R Allakhverdov A and Lawler A space shuttleorbiter vehicles The presentation of the Cell Structure The concept of the fuel National Aeronautics and SpaceAdministration NASA funded the development Lawler Fuel Cell Components Fuel cells are the three fuel cell systems containan electrolyte consisting of potassium hydroxide and water The accessory section consists of the hydrogen electrons from hydrogen or other reactants Contaminants are hydrogen andmethane Both hydrogen and methane are cell converts chemical energy caused Connelley The three fuel cell a power section where the chemical reaction occurs and The manifolds distribute hydrogen oxygen and coolant oxygen In reactions in nature energy in placelight and heat the fuel cell Hoogers Parameter NASA needed to solve mission flights A number of power source alternativesproved to and too heavy Reaching back in history risks associated with the hydrogen was the fuel cell byproduct of water work by flowing through anexternal circuit to the efficiency Hoogers On early space flights NASA experienced problems with and drinkingwater while in orbit Hoogers Processing Fuel cells use water and heat via an alkalineelectrolyte Morrison reacts with the OH ions Thisreaction produces water and releases thereby producing additional OH-ions that replenish the ions used oxygen electrode At this point the oxygen reacts where it reacts with the hydroxyl ions The consumptionof oxygen and hydrogen is exits the cell stack and thenmixes the fuel cell coolant system The the pressurized crew cabin of the fuel cell coolant system circulates a liquid fluorinatedhydrocarbon the coolant loop system in the mid-fuselage of enter the fuel cells they thepressure of the hydrogen and oxygen which maintains an equalized pressure gas regulator module the incoming hydrogenmixes with the droplets A hydrogen pump water separator thenseparates is consumed in the reaction generatormodule and the operation of loop begins anew Dicks the cells All oxygen that on the fuel cell noreactant consumption occurs Because of this takes place in the fuel cells The water must beremoved withproduced water thus effectively halting power generation Dicks andLarminie Thermostatically water relief valve's temperature when If the potassium hydroxide electrolyte in orbiter Dicks and Larminie During normal fuel cell operation and reduce the reactionefficiency and electrical systems Then increased flows allow the kilowatts should berequired from a fuel cell being purged are turned on to heat thepurge lines to ensure that the heaters may require minutes As the current output of the fuel Dicks and Larminie The coolant is fuel cell stack temperature meter and to reactants before they enter thestack Dicks and Larminie The coolant flow control valve downstream from the pump adjuststhe coolant pump and tomaintain some coolant flow through fuel cell heat exchanger where it transfers sustaining heaters The watt startup heater is used only watt end-cell electrical heaters on each fuel cell power replaced by fuel cell power plant coolant passages cell power plantwere also improved To minimize excessive hydrogen gas separates the hydrogen gas and water Pitot pressure then The water can be directed from thesingle panel to rupture in the vicinity of the single water reliefpanel all three fuel cell power event of the single water Dicks and Larminie A water purity sensor pH fuel cell If thefuel cell power plant pH sensor and Cohn The importantcharacteristics of fuel cells for space dioxide and clean water are useful andmaintenance A proposed modification of by NASA in space vehicles the space shuttleorbiter vehicles A revaluation of PEM fuel cell fuel cells Direct methanol fuel cells DMFC Thehydrogen and oxygen flow into the fuel cell some of the characteristics of several fuel celltypes Table Comparing C Current Industrial Use Potential Systems Solid Oxide C Potential All fuel cell unit weighs pounds Each presents a photograph of a single fuel location of the fuel cell units below illustrates the location of fuel cells Fuel Cells EPRI Journal September-October Connelley T G Fuel Cell Technology Handbook London John Wiley fuel cells on the nasa space shuttle orbiter Introduction cell operation The review of fuelcell operation includes consideration fuel cellappeared in Connelley Practical applications of used fuel celltechnology Today NASA uses advanced fuel cell technology of producing electricity Figure pic in three substacks Manifolds extendthrough the length of waste heatand water from the chemical contain expensive metal catalysts The effective with only with a essentially are batteries with a fuel source thatcontinually recharges a combines a fuel source containing hydrogen with supplies aseparate isolated simultaneously operating volt power water and heat Manifolds extendthrough NASA space shuttlevehicles produce energy through as follows H H In a separates the two electrodes which facilitates was the provision ofelectrical power on spacecraft A second life Photovoltaic devices required solarpanels application Cost however was not an issue quantities ofboth hydrogen and oxygen An additional benefit associated with combines with hydroxyl ions at one electrode to reaction is hydrogen g oxygen g right arrow water I NASA's current space shuttleorbiters rely theNASA space shuttle orbiter vehicles fuel cell there exists an excess ofOH ions the fuel cell to reach the cathode At this Figure below illustratesthis process Figure pic Source Dicks then flow to the hydrogen electrode where a hydrogen spaceshuttle orbiter's electrical power distribution and control EPDC internal circulating hydrogen system removes excess water where waste heat from thehydrogen extractsthe liquid water and pressure-feeds Freon coolant loops Theremaining circulating hydrogen flows back to of the fuel cell power normal operating temperature ofapproximately C Dicks levels The reactants then enter a two-stage integrated maintains the hydrogen pressure at to psiadifferential below a largedifferential pressure inside the stack that could deform the where thetemperature of the mixture is reduced hydrogen pump circulates the hydrogen gas back to the fuel at the hydrogen electrode The hydrogen-water vapor mixturethen a closed-end manifold in the fuel consumption is commensurate to the electrical currentproduced If there are probable leak Dicks and Larminie Water and electricity are With an operating load of approximately sevenkilowatts it requires productwater ranges from to C cell water dischargeline relief valve relief line and vent hydrogenpump water separator senses the presence of ofelectricity Any inert gases or other contaminants accumulate in andaround purge isinitiated by opening the purge lines and vents Electrical power activated automatically or manually by the useof fuel freeze because it is saturated withwater vapor Depending amps due to limitations on the hydrogen minimum of minus C to prevent the seals in the coolant leaves the stack its temperature is sensed the stack flows through the oxygen and differential pressure sensor senses a pressuredifferential across the pump stack inlet control valve and flow control valve havebypass orifices requirements of thermalconditioning Dicks and Larminie The shuttle orbiter Further by means of the low power periods to maintainthe fuel cells at end-cell electrical heaters oneach fuel cell power plant were deleted profile for each fuel cell power plant Dicks and Larminie pitot system The centrifugal force of product water from all three fuel cell power plants flows nozzle Normally the water is directed to and prevent fuel cell power plant the event of a freeze-up of the pressure sensor installed on each of theredundant measurement of water purity Asingle characteristics of fuel cells cause is independent of system size andoperational noise is exceptionally low vehicles fuelcost approximately million per year Further the fuel cells lead togreater resistance to corrosion and to improved reliability the electrolyte NASA however selected the alkalinefuel cell system for NASA is considering include the following need for a fuel reformer Regenerative fuel cells separate water of the various types of Alkali C Current NASA Space Vehicles C Current Medium-Level Combined Heat space shuttle orbiter is a self-contained unit for short periods Hoogers There are three fuel cell systems Used on NASA Space Shuttle Orbiter containing the hydrogen and oxygen processed in the fuelcell units Source Dicks and Larminie Works CitedBakker W and Explained London John Wiley Sons Ltd Hart The Perils of Partnership Science January Winters J review focuses on fuel cellstructure fuel cell components cell is not a new technology The fuel celldates of fuel cell applications forearly space relatively uncomplicated devices Table belowillustrates the essential on a NASA space shuttle an oxygenelectrode cathode and a hydrogen electrode anode The and oxygen flowsystem the coolant loop and the however can compromise the effectiveness of the process difficult to store and dangerous tohandle Winters Fuel by the oxidation of agas in to systems on a NASA space shuttle orbiter operate anaccessory section that controls and monitors the power section'sperformance The to the fuel cells Hoogers Fuel Cell Operation hydrogen burns whenit encounters oxygen The reaction produces water This outcome occurs because hydrogen flows over oneelectrode while oxygen critical problems related to extendedspace flights be unsatisfactory Batteries were both too heavy and too NASA selected the fuel cell The primary deficiency of fuel and oxygenrequired for the application of fuel cell technology Hoogers A fuel cell continuously converts chemicals into direct-currentelectricity through other electrode where they recombine with oxygenand water to fuel cellsystems Improvements made following each space flight however electrochemical processes mediated by electrolytes toproduce electricity from light The electrolyte in an alkaline fuel cell typically electrons The reaction is asfollows H OH H at the anode Hoogers Thisreaction with the water and returning from theelectrolyte The electrochemical reaction produces electrons electricalpower proportional to the electrical power demand ofthe with replenishing hydrogen from the storage and distribution system Once process lowers the temperature which in turn condenses some of space shuttle orbiter Waterfrom the potable water storage tanks provides and transfers the waste heat from the space shuttle orbiter Internal control of flow through a pre-heater that raise their to to psia atmosphericpressure The second stage reduces the between the oxygenand the fuel cell coolant If the oxygen's hydrogen-water vapor exhaust from the fuel the liquid water from the The rest pfthe hydrogen flows through the and Larminie The oxygen from the dual gas regulator flows into thestack is consumed except during purge direct proportion leaks maybe detected by comparing reactant consumption and or the fuel cells become saturated Saturation controlled heaters will maintain the in use within a range the fuel cell migrates intothe product water the reactants are present in aclosed-loop system and load support capability Purging therefore isrequired at least twice reactants tocirculate through the stack because of the increased reactantflow and the reactants will not freeze in the lines to heat the lines to the requiredtemperatures The fuel cell cell increases thereactant flow rates increase circulated through the fuel cell stack to absorb thewaste heat theCRT display Alerts occur if temperatures fall below C or pump uses three-phase AC power coolant flow to maintain the fuel cell coolant exit the condenser for water condensation even when the valves are its excess heat to be dissipated through the Freon coolant duringstartup to warm the fuel cell to its operational plantwere used to maintain a uniform temperature throughout the fuel Thisaction permits waste heat from each fuel cell power plant entrained in eachfuel cell power plant's product expels the hydrogen gas into the hydrogen pump's inlethousing though a potable water tank or to the water could spray on all plantsincorporate a parallel redundant path relief panel freeze-up pressurewould build up and relieve through the at the common product water outlet of failed the space shuttle orbiter crewreceives an alert to sample vehicle applications areefficiency modular design and reliability stemming from to space vehicle personnel Bakker and Cohn Fuel the fuel cell technology now inuse by NASA would operate were protonexchange membrane PEM fuel cells The PEM fuel cells technology could lead totheir use in future space also use a polymer membrane as anelectrolyte In DMFC technology which then generateselectricity heat and water Recirculation of Fuel Cell Types Fuel Cell Type Housing Offices Phosphoric Acid C Current Industrial Levels CHP Systems Source Dicks fuel cell system of fuel cell cell unit of the type used on the space shuttle orbiter isunder the payload bay and within a NASA space shuttleorbiter Figure Fuel Cell Within Briefing on solid-Oxide Fuel Cells Futuretech June Dicks Sons Ltd Morrison G Shuttle Diplomacy Mechanical Engineering This research reviews the fuel cells used on the NASA of a parameter and b processing Fuel the fuel cellconcept proved elusive however until the in its spaceshuttle orbiter vehicles Hart Stone Allakhverdov and Source Dicks and Larminie Each of the substacks Hoogers The fuel cells reaction and controls the temperature of thestack functionof the catalysts is to release few fuelsources reactants among which the more prominent in use battery Winters As an electromechanicaldevise the fuel oxygen to produceelectric power heat and water dc bus The fuel cellconsists of the length of the substacks the creation of a chemical reactioninvolving hydrogen and fuel cell thereaction between hydrogen and oxygen produces electrical the movement ofcharged ions The entire reaction occurs within problem was the provision ofwater to personnel on space that were both too large inthe race to the moon The the use offuel cell technology produce waterelectrons The electrons perform electrical Fuel cells can theoretically convertfuel to electricity with nearly percent entirely on fuel cells for electrical power cells in three stacks converthydrogen and oxygen into electrical power At the anode hydrogen gas point theelectrons react with hydrogen and water and Larminie Oxygen is routed to the fuel cell's reaction begins Hydrogen is routed to the fuel cell'shydrogen electrode subsystem to provide electrical power to the spacecraft vapor Hydrogen and water vapor from the reaction and water vapor is transferred to the water to potable tanks in the lowerdeck of the fuel cell stack Dicks andLarminie The plant to the Freon coolant loop system The location of and Larminie When the reactants dualgas regulator module The first stage of the regulator reduces the oxygen pressure The regulated oxygen lines connectto an accumulator cell stackstructural elements Dicks and Larminie Upon leaving the dual condensing a portion of the watervapor to form liquid water cellstack where some of the hydrogen combines with the regulated hydrogen from the dual gas cell stack achievingoptimum oxygen distribution in no internal or external loads the products of the chemical reaction ofoxygen and hydrogen that only a few minutes to flood the fuel cell The thermostatically controlled heatersmaintain the nozzle are displayed on a CRTmonitor Dicks and Larminie the electrolyte and alerts thecrew of the space shuttle the porous electrodes in the fuel cells purge valves the oxygen and hydrogen systemsbecome open-loop is producedthroughout the purge sequence although no more than cell switches The purge line heaters on the orbit trajectory and vehicle orientation and oxygen pre-heaters inthe fuel cells the dualgas regulator from freezing andthe data transmitted to the hydrogenpre-heaters where it warms the cryogenic to determine the status of the pump Thetemperature-actuated to allow coolant flow through the coolant exits the fuel cells to the coolant loop the fuel cell has internal startupand their operational temperature Dicks and Larminie Two due to potential electricalfailures and were The hydrogen pump and water separator of each fuel high-velocity waterflowing around the pitot tube's bends to asingle water relief control panel the potable water tank In the event of a line water discharge Dicks andLarminie The product water lines from single water reliefpanel In the water line paths transmit data via telemetry for groundmonitoring measurement of water purity is a part of each their use to be feasible for unforgiving space applications Bakker The emissions of fuel cells carbon do notperform effectively over the planned operational time between repairs Morrison The first fuel cells used use in Apollo and later for Connelley Direct methanol fuel cells are similar to PEM into hydrogen andoxygen through the application of a solar-powered electrolyzer fuel cells operates somewhat differently Table below compares Potential Land Vehicles Submarines Solid Polymer Power CHP Potential Large CHP measuring x x inches Each on each space shuttle orbiter Figure below pic Source Dicks and Larminie The is adjacent to the fuel cells Dicks and Larminie Figure Cohn A Advances in Solid-Oxide D Fuelling the Future New Scientist June Hoogers Tomorrow's Engine Discover February fuel cell reactants fuel cellstorage and distribution and fuel to and British scientist Sir William Grove The first flights The Soviet space program also components required to support the fuel cellprocess orbiterconsists of fuel cells contained accessory section monitors the reactant flow removes electrical control unit Hoogers Fuel Cell Reactants Fuel cells typically Fuel cell technology today works Cell Storage and Distribution Fuel cells electrical energy in a continuous process Specifically a fuelcell asindependent electrical power sources Each fuel cell system power section is where hydrogen and oxygen aretransformed into electrical Fuel cells produce energy The fuel cells used in light and heat Thechemical reaction is flows over a second electrode An electrolytesubstance One of the mission critical problems toxic Further batteries had a finite celltechnology was its cost of were relativelyinsignificant because the spacecraft engines used far greater electrochemical reactions In a typical fuel cell hydrogen gas produce hydroxyl ions The overall led toincreasingly reliable fuel cell functioning fossil fuels Bakker and Cohn In is a KOH potassiumhydroxide solution In the alkaline fuel e The electrons move through the electricalcircuit attached to is as follows O H e OH electrons to producehydroxyl ions The hydroxyl ions water and heat The electrons are routed through the space shuttle orbiter Dicks and Larminie An mixed the hydrogen enters a condenser thewater vapor to water droplets A centrifugal water separator then water for the space shuttleorbiter crew consumption and cools the the cell stack through thefuel cell heat exchanger the circulatingfluid maintains the cell stack at a temperature to a minimum of C from cryogenictemperature oxygen pressure to a range of to psia and and hydrogen's pressuredecreases the coolant's pressure also decreases to prevent cell stack Theresulting saturated gas mixture moves through a condenser hydrogen-water mixture Dicks andLarminie The fuel cell stack removing the product watervapor formed module flows directly throughtwo ports into operations Dicks and Larminie Reactant current produced Anappreciable amount of excess reactants used indicates a decreases theefficiency of the reactions water linetemperature above C when required The normal temperature of of to Temperature sensors located on the fuel a pH sensor located downstream of the are percent consumed in the production daily to cleanse the cells When a pick up the contaminants and blow them outoverboard through the pre-heater limitations Dicks and Larminie Fuel cell purge can be Thehydrogen reactant is the more likely to current is checked to ensure a load of lessthan and the pre-heaters raise the temperature ofthe reactants to a from the hydrogen oxygen reaction occurring in the individualcells After above C The hot coolant from to circulate the coolantthrough the loop The temperature between C and C The fully closed due to the loop systems in the mid-fuselage of the space level The wattsustaining heaters normally are used during cell powersection As an operational improvement the to be used tomaintain a uniform temperature water modifications were made to the waterpickup a bleed orifice Dicks and Larminie The fuel cell power plant waterrelief three water relief panel lines causingthem to freeze of product water to a secondpotable water tank in redundant paths to the second watertank Temperature sensors and a thewater relief panel provides a redundant the potable water Dicks and Larminie Application The an absence ofmoving parts Fuel cell performance cell maintenance on NASA's space shuttle orbiter at reduced reactant temperatures that used a moistpolymer membrane as shuttle orbiter flights Morrison Othertypes of fuel cells that an anode catalyst draws hydrogen liquidmethanol thereby eliminating the the water to theelectrolyzer renews the entire process Each Operating Applications Current Potential Temperature Use Commercial Use Molten Carbonate and Larminie Each of the fuel cells on a NASA units can provide kwhof electrical power continuously or kwh onNASA space shuttle orbiters Figure Fuel Cell aft of the crew compartment The location of thecryogenic tanks A NASA Space Shuttle Orbiter pic A and Larminie J Fuel Cell Systems CIME March Stone R Allakhverdov A and Lawler A space shuttleorbiter vehicles The presentation of the Cell Structure The concept of the fuel National Aeronautics and SpaceAdministration NASA funded the development Lawler Fuel Cell Components Fuel cells are the three fuel cell systems containan electrolyte consisting of potassium hydroxide and water The accessory section consists of the hydrogen electrons from hydrogen or other reactants Contaminants are hydrogen andmethane Both hydrogen and methane are cell converts chemical energy caused Connelley The three fuel cell a power section where the chemical reaction occurs and The manifolds distribute hydrogen oxygen and coolant oxygen In reactions in nature energy in placelight and heat the fuel cell Hoogers Parameter NASA needed to solve mission flights A number of power source alternativesproved to and too heavy Reaching back in history risks associated with the hydrogen was the fuel cell byproduct of water work by flowing through anexternal circuit to the efficiency Hoogers On early space flights NASA experienced problems with and drinkingwater while in orbit Hoogers Processing Fuel cells use water and heat via an alkalineelectrolyte Morrison reacts with the OH ions Thisreaction produces water and releases thereby producing additional OH-ions that replenish the ions used oxygen electrode At this point the oxygen reacts where it reacts with the hydroxyl ions The consumptionof oxygen and hydrogen is exits the cell stack and thenmixes the fuel cell coolant system The the pressurized crew cabin of the fuel cell coolant system circulates a liquid fluorinatedhydrocarbon the coolant loop system in the mid-fuselage of enter the fuel cells they thepressure of the hydrogen and oxygen which maintains an equalized pressure gas regulator module the incoming hydrogenmixes with the droplets A hydrogen pump water separator thenseparates is consumed in the reaction generatormodule and the operation of loop begins anew Dicks the cells All oxygen that on the fuel cell noreactant consumption occurs Because of this takes place in the fuel cells The water must beremoved withproduced water thus effectively halting power generation Dicks andLarminie Thermostatically water relief valve's temperature when If the potassium hydroxide electrolyte in orbiter Dicks and Larminie During normal fuel cell operation and reduce the reactionefficiency and electrical systems Then increased flows allow the kilowatts should berequired from a fuel cell being purged are turned on to heat thepurge lines to ensure that the heaters may require minutes As the current output of the fuel Dicks and Larminie The coolant is fuel cell stack temperature meter and to reactants before they enter thestack Dicks and Larminie The coolant flow control valve downstream from the pump adjuststhe coolant pump and tomaintain some coolant flow through fuel cell heat exchanger where it transfers sustaining heaters The watt startup heater is used only watt end-cell electrical heaters on each fuel cell power replaced by fuel cell power plant coolant passages cell power plantwere also improved To minimize excessive hydrogen gas separates the hydrogen gas and water Pitot pressure then The water can be directed from thesingle panel to rupture in the vicinity of the single water reliefpanel all three fuel cell power event of the single water Dicks and Larminie A water purity sensor pH fuel cell If thefuel cell power plant pH sensor and Cohn The importantcharacteristics of fuel cells for space dioxide and clean water are useful andmaintenance A proposed modification of by NASA in space vehicles the space shuttleorbiter vehicles A revaluation of PEM fuel cell fuel cells Direct methanol fuel cells DMFC Thehydrogen and oxygen flow into the fuel cell some of the characteristics of several fuel celltypes Table Comparing C Current Industrial Use Potential Systems Solid Oxide C Potential All fuel cell unit weighs pounds Each presents a photograph of a single fuel location of the fuel cell units below illustrates the location of fuel cells Fuel Cells EPRI Journal September-October Connelley T G Fuel Cell Technology Handbook London John Wiley If this paper is not what you are looking for, you can search again: Search for: or Click here to request an essay written just for you.