MXPA00000878A - Fuel cell gas management system - Google Patents

Abstract

A fuel cell gas management system (10) including a cathode humidification system (30) for transferring latent and sensible heat from an exhaust stream (16) to the cathode inlet stream (14) of the fuel cell (26);and anode humidity retention system (80) for maintaining the total enthalpy of the anode stream (20) exiting the fuel cell equal to the total enthalpy ofthe anode inlet stream (18);and a cooling water management system (130) having segregated deionized water and cooling water loops interconnected by means of a brazed plate heat exchanger.

Description

GAS FUEL CELL HANDLING SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is generally related to a method and apparatus for the management and control of various flow streams related to the operation and a fuel cell. The present invention relates more specifically to a gas fuel cell management system which includes subsystems for conditioning the temperature and humidity of the air or other oxidant supplied to the cathode of the fuel cell, for moisture retention of the fuel anodic and for the circulation of cooling water. 2. Description of Related Art Fuel cells generate electrical energy by chemical reaction without altering the electrodes or electrolytes of the cell itself. The utility of fuel cells has been known since at least 1939, when Grove demonstrated that water electrolysis could be reversed using platinum electrodes. Other developments in the fuel cell technology have included the development of fuel cells with proton exchange membrane (PEM) phosphoric acid fuel cells, alkaline fuel cells, and fuel cells that incorporate reforming technology in piezo hydrocarbons pyrolyzed as gasoline to obtain hydrogen to fuel the fuel cell. Fuel cells have found application in numerous fields. One area of particular interest has been the application of fuel cell technology in electric cars. In automotive applications, weight and space are very important, and therefore, the fuel cell and its support systems should be smaller and lighter as possible. On the other hand, because automotive applications subject the equipment to a wide and fast range of fluctuation of operating conditions such as temperature, humidity, etc., the equipment used in such applications must be capable of supporting and operating under a variety of conditions. The equipment used in automotive applications must also be strong enough to withstand the vibrations and stresses induced by use on the road. A cathode circuit to feed the oxidant, typically room air, to the fuel cells. In order to maintain adequate operating conditions for the fuel cell, the temperatures and humidities of the cathodic and anodic circuits must be precisely controlled to prevent the electrolyte from drying out or otherwise damaging the fuel cells, thereby stopping the electricity flow of the. fuel cell. Several systems to condition the gas flow circuits of a fuel cell have been proposed. For example, US Patent No. 3,516,867 to Dankese discloses a fuel cell system that includes a dehumidifier and a humidifier for conditioning the gas streams of the fuel cell. The humidification portion is this system achieves the transfer of moisture through a partition. It has been found that this type of humidification system is inefficient for automotive applications, mainly due to the large surface areas required to transfer the required amounts of moisture to the gas streams, and due to the undesirable weight of such large-scale systems. In addition, large amounts of heat energy are consumed to vaporize moisture in this type of humidification systems, whose energy consumption reduces the efficiency of the system. US Patent No. 3,669,751 to Richman discloses a fuel cell, a hydrogen generator and a heat exchanger system, wherein the reactive air to be supplied to the fuel cell comes into evaporative contact with the wet electrolyte to humidify the reactive air. The Ruchman system suffers disadvantages similar to that of Dankese; mainly, the requirement of large surface areas to effect the transfer of moisture and the resulting weight of system components, as well as the considerable energy consumption to evaporate moisture. In addition to cathodic humidification, existing fuel cell technology requires the humidification of the hydrogen fuel stream supply to the anode of the fuel cell, in order to prevent the electrolyte from drying out in the fuel cell. This anodic humidification requirement adds other components to the gas fuel cell handling system, resulting in an undesirable increased cost and weight. On the other hand, humidification systems known as membrane humidifiers or systems that use air flows through wetted-sphere beds consume considerable energy to vaporize the water to provide the required humidification. Therefore it has been found that the known methods of anodic humidification are not suitable for automotive applications. Thus, it can be seen that there is still a need for a light efficient medium to condition the oxidant flow to the cathodic supply of a fuel cell. There is a further need for a method and apparatus for conditioning the anodic supply to a fuel cell, which minimizes the weight and cost of the associated components.

The present invention is primarily directed to the provision of a method and apparatus for handling gas fuel cells that meet these and other needs.

BRIEF DESCRIPTION OF THE INVENTION Briefly described, in a preferred form, the present invention comprises a cathodic humidification system, an anodic moisture retention system, and a cooling water processing system. The present invention provides greatly reduced weight and complexity in comparison with known gas fuel cell management and systems and techniques, and is well suited for automotive applications. The cathodic humidification system of the present invention preferably comprises a compression means for pressurizing the air and supplying it to the cathode of the fuel cell to be used as an oxidant of the fuel cell, and a latent and sensitive heat transfer device as is an enthalpy wheel, to condition the pressurized oxidant. The cathodic humidification system may additionally comprise an adiabatic cooling medium for controlling the temperature of the dry bulb of the air, by vaporizing the cooled water within the air stream, before its introduction to the enthalpy wheel. The enthalpy wheel operates by removing both latent and sensible heat from the cathodic discharge current of the fuel cell to heat and humidify the cathodic supply current. Because the water vapor collected from the cathodic discharge never condenses on the enthalpy wheel, but is trapped as vapor inside the enthalpy wheel, it is unnecessary to provide energy (in the form of heat of vaporization) to transfer the moisture removed from the cathodic expulsion to the cathodic supply by the enthalpy wheel. The adiabatic cooling medium of the present invention preferably comprises means for collecting liquids from cathodic expulsion, transfer means for transport. The cooling rate in the cathodic supply controls the dry bulb temperature of the air supply stream, while the enthalpy wheel speed controls the temperature of the wet bulb, and thus the relative humidity of the cathodic supply. By varying the speed of the enthalpy wheel rotation, the amount of moisture transferred to the cathodic supply may vary. Relative humidity, pressure and temperature detectors are preferably provided to verify cathodic supply conditions and provide a feedback control, through a computerized control system, for the adiabatic cooling speed and the rotational speed of the enthalpy wheel .

As a further refinement to the invention, the size of the openings in the enthalpy wheel can be chosen to selectively filter the nitrogen and other components of the cathodic supply air stream, thereby increasing the partial pressure of the oxygen in the flow of supply air to increase the efficiency of the fuel cell. Alternatively, two or more porous wheels may be provided in series, having aperture sizes to selectively filter various components of the ejection and / or cathodic supply streams. The anodic moisture retention system of the present invention preferably comprises one or more eductors or other means for recirculating the anodic expulsion stream to the anodic supply. By mixing the anodic ejection with the hydrogen supply from the storage tanks, the cold dry hydrogen from the tanks is humidified by an amount approximately equal to the wet exhaust hydrogen from the fuel cell. The operating conditions of the fuel cell are controlled to control an excess of hydrogen (preferably at a stoichiometric rate of about 2.0) to the anodic supply and to control the temperature of the anodic supply hydrogen stream. In this way, the total enthalpy of the anodic expulsion is controlled to be approximately equal to the total enthalpy of supply, with this, in effect, using excess hydrogen to transport the anodic moisture through the fuel cells, back to the current of anodic supply and prevent moisture from condensing out of the anodic current in the fuel cell. In this way, the need for an anode humidifier, and its associated equipment, is eliminated, thereby reducing weight. The fuel cell, sometimes referred to as a "cell", is cooled by deionized water flowing through the cell. Deionized water is an aggressive corrosive agent and, therefore, stainless steel pipe and equipment must be used to handle this deionized water. Because stainless steel is a poor thermal conductor, and is heavy and expensive, the use of a stainless radiator to effect the transfer of heat from water to air has been found to be undesirable, especially in automotive applications. Therefore, the present invention uses a brazed plate heat exchanger to effect the transfer of water to water from the stack heat, from a closed deionized water circuit to a cooling stream of water and ethylene glycol. Next, a standard commercial automotive radiator system can be used for water-to-air heat transfer from the glycolate stream. In this way, the heat of the deionized water is transferred by convention of water to water through the thin stainless plates of the brazed plate heat exchanger, at a much higher heat transfer rate than what could be obtained through of heat exchange of stainless steel to air through a stainless steel radiator. This aspect of the present invention allows the use of a less expensive, lighter, more efficient aluminum air-to-air water radiator and minimizes the amount of deionized water required. The use of a more efficient aluminum radiator also reduces the surface area required to effect heat transfer, thereby minimizing the aerodynamic drag associated with the radiator. Accordingly, it is an object of the present invention to provide a gas handling system for conditioning the reactive streams of a fuel cell, which is compact, lightweight and inexpensive. Another object of the present invention is to provide a gas fuel cell handling system which allows cathodic air humidification, anodic hydrogen moisture retention, and cooling water processing for a fuel cell. A further object of the present invention is to provide a method and apparatus for transferring the latent and sensible heat of the cathodic discharge current from the fuel cell to the cathodic supply stream. A further object of the present invention is to provide a method and apparatus for retaining moisture within the hydrogen fuel stream supplied to the anode supply of a fuel cell. Still another object of the present invention is to provide a method and apparatus for processing the deionized cooling water for a fuel cell, which method and apparatus minimizes the amount of deionized water needed, and minimizes the total weight, the surface area and the aerodynamic drag of the cooling system. This and other objects, features and advantages of the present invention will be more obvious from the reading of the following specification in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic diagram showing the gas fuel cell management system of the present invention, according to a preferred form. A - Fuel cell Figure 2 is a schematic diagram showing in preferred form the cathodic humidification system of the present invention in more detail. A - Fuel Cell B - Drain C - Water DI D - Manual filler of anodic tank E - Ambient air ^^ MMHÉaiÍi_i F - From the H2 G purge window - Expulsion to the environment. Figure 3 is a schematic diagram showing a preferred form of the anodic moisture retention system of the cooling water processing system of the present invention in more detail. A - Fuel cell B - Drain vent C - Drain. Figure 4 is a schematic diagram showing the cathodic humidification system of Figure 1 in more detail. A - Fuel cell Figure 5 shows a preferred form of the cathodic humidification portion of the cathodic humidification system of Figure 2. A - A ejection B - From stack C - A stack D - From the environment DETAILED DESCRIPTION OF THE PREFERRED MODALITY Referring now in detail to the Figures in which the reference numerals represent similar parts through them, Figure 1 shows the gas fuel cell handling system 10 of the present invention, according to a preferred form. The gas handling system 10 generally comprises a cathodic humidification system 30, an anodic moisture retention system 80, and a cooling water processing system 130, all connected to a fuel cell 12. The fuel cell 12 generally comprises a cathodic supply 14, a cathodic ejection 16, an anode supply 18, an anodic discharge 20, a supply 22 of cooling water and a discharge 24 of cooling water. The electricity generated by the fuel cell 12 is conducted to a load. The fuel cell 12 operates according to known methods, and can have any number of known fuel cell manifolds. In the described embodiment, the fuel cell will be described as a proton exchange membrane (PEM) fuel cell. However, the present invention is not limited to this, and can be applied to reactive currents of other types of fuel cells equally. In a typical proton exchange membrane fuel cell, the hydrogen is supplied to the anode supply 18 of the fuel cell, to be used as the fuel, and the air is supplied to the cathodic supply 14 of the fuel cell 12 for use as the fuel. as the oxidant- of the fuel cell. Inside the fuel cell or the battery, the oxidant and the fuel react to generate water and electrical energy. An electrolyte solution, maintained between the catalytic membranes inside the fuel cell, conducts a flow of electrons through the fuel cell to the conductors 26. The electrolyte solution must be kept in a wet condition in order to maintain the conductivity. The fuel and the oxidant are passed through alternate layers in the pile. The layers are separated by catalytic membranes, which promote the reaction between the fuel and the oxidant. Cathodic Humidification System Because the fuel cell 12 operates best at elevated temperatures, it has been found desirable to heat and humidify the oxidizing air supplied to the cathodic supply 14 in order to prevent the electrolytes in the cathodic air stream from drying out in the cell. gas. The cathodic humidification system 30 of the present invention is shown in detail in Figures 2 and 4. Ambient air is sucked through filter means 32, such as a commercially available automotive air filter., and within a pressurization medium 34. The pressurizing means 34 is preferably a compressor activated by a motor, and preferably compresses the supply air to approximately two atmospheres. It will be understood to those of ordinary skill in the art that the pressurizing means 32 can pressurize the supply air through a pressure range above the ambient pressure. An electrically activated twin screw compressor, such as the motorcycle supercharger manufactured by Opcon Autorotor AB of Nacka. The supply air supplied to the cathodic supply 14 to be at 70 ° C dew point and 75 ° C dry bulb. In this way, it is necessary to introduce moisture into the supply air stream and reduce its dry bulb temperature. The present invention reduces the dry bulb temperature and, to a lesser extent, humidification of the cathodic supply air stream begins through the use of a carefully controlled adiabatic coolant means. The adiabatic coolant means 36 preferably comprises an ultrasonic nozzle 38, which supplies a fine spray of chill water to the compressed air from a cathodic water reservoir 40 by means of a cooling water measuring pump 42. The heat of the vaporization consumed to evaporate the cooling water reduces the dry bulb temperature of the air. By controlling the metering pump 42, the speed of the chiller water supplied to the air stream, and in this way, the amount of dry bulb cooling is controlled. The liquid water collected from the cathodic ejection 16 can be collected in the reservoir 40 for use in the cooling step. After the cooling step, the cooled compressed air is introduced into an enthalpy transfer medium 44 to transfer the latent and sensible heat of the cathodic discharge stream to the cathodic supply stream. In a preferred form, the enthalpy transfer medium 44 comprises a rotationally activated enthalpy wheel 46 comprising an acrylic fiber structure or other material which is resistant to attack by deionized water, coated with a selective molecular sieve desiccant. water or zeolite. The mass of the wheel transports sensible heat, while the desiccant traps and transfers the water vapor molecules and, with this, the latent heat. The synthetic fiber-based energy conservation wheels manufactured by LaRoche Air Systems, Inc. have been found to provide acceptable heat transfer performance, and to resist attack by deionized water. A variable speed electric motor 48 is preferably provided to activate the enthalpy wheel 46. The saturated expulsion air of the cathodic discharge 16 is directed through a first side of the enthalpy wheel 46, where the latent and sensible heat is collected by the enthalpy wheel as the exhaust air passes through this . As the enthalpy wheel rotates, latent and sensitive heat is released into the supply air stream being supplied to the cathode supply 14. Controlling the rotation speed of the enthalpy wheel 46, the heat transfer rate, and thus the relative humidity (and the wet bulb temperature) is controlled. The detectors such as a relative humidity detector 50, a temperature sensor 52 and a pressure sensor 54 are preferably provided to verify the conditions of the air discharged from the enthalpy transfer medium 44 within the cathodic fuel cell supply 14. By means of a computer feedback control system not shown, the dry bulb temperature and the relative humidity of the cathodic supply air stream can be selectively controlled by adjusting the cooling speed and / or the rotation speed of the wheel 46 of enthalpy. A moderate valve or orifice fitting 56 'is preferably provided in the cathodic expulsion duct as the enthalpy transfer medium 44, to maintain the operating pressure in the cathodic air stream. Any liquid water condensed in the cell is collected and drained to the cathodic water reservoir 40 for the use of the chiller pump, and for the periodic automatic or manual anodic supply. Although an enthalpy wheel is the preferred enthalpy transfer medium, alternative enthalpy transfer media can be used. For example, two or more beds or zeolite towers can be operated, by continuous sequence valves, to alternate between a charge mode where the fuel cell exhaust air heats and humidifies the zeolite, and a discharge mode wherein the moisture and heat trapped in the beds or towers of zeolite are released from the cathodic supply air. The use of an enthalpy wheel, however, has been found to provide very good performance and to minimize space and weight requirements. The pore sizes in the zeolite of the enthalpy wheel 46 can be chosen to selectively trap or filter one or more components of the exhaust or supply air streams. Alternatively, additional molecular sieve wheels can be installed in the airstream (s) for selective filtering. In this way, for example, by selectively filtering the nitrogen from the supply air stream, the partial pressure of the oxygen in the supply air stream can be increased, thereby providing a more efficient fuel cell operation. The components of the cathodic humidification system, including the enthalpy wheel 46, the cathodic water reservoir 40, the metering pump 42 and the ultrasonic nozzle 38 can be physically combined, according to a preferred form of the present invention. The saturated expulsion air passes up through the enthalpy wheel 46 and the condensed liquid is collected under the enthalpy wheel 46 for use by the extinguishing pump. A labyrinth seal 68 can be provided between the enthalpy wheel and the housing 70 of the humidifier 60. A gear motor 48 is mounted on the top of the cathode humidifier and is connected to the enthalpy wheel 46 through an axis of motor 66. Anodic Moisture Retention System Figure 3 schematically shows the anodic moisture retention system 80 of the present invention, according to a preferred form. The hydrogen gas used as fuel in a PEM fuel cell is preferably stored in one or more high-pressure storage media such as tanks 82. A regulating means such as a high-pressure solenoid operated reduction valve 84, reduces the pressure of hydrogen supplied from tanks 82 to a usable level. A computer controlled digital control valve 85 is preferably provided to regulate the flow of hydrogen supply to the fuel cell of the tanks 84. In order to efficiently use the hydrogen supplied to the fuel cell 12, it has been found desirable to recirculate the hydrogen in excess expelled by the anodic expulsion of the fuel cell 12 back to the anodic supply of the fuel cell. However, due to the small molecular size of hydrogen, it is difficult to pump and contain hydrogen by compressors or standard pumps having rotating axes and mechanical seals. Accordingly, in a preferred form, the present invention utilizes one or more eductors to recirculate the hydrogen through an anodic loop. These eductors incorporate a converging-diverging nozzle and an injection port for injecting a high velocity flow adjacent to the point of the shrinkage nozzle, to induce a flow in the recirculated hydrogen. An eductor 86 first or "operant", activated by high pressure hydrogen injection of storage tanks, serves to recirculate hydrogen when the fuel cell is operating in a standard operating mode. The use of eductors, instead of pumps, eliminates the presence of moving parts in the hydrogen loop, which can create sparks and result in an explosion. It circulates hydrogen fuel through the anodic loop. However, during startup, all or none of the hydrogen is consumed by the fuel cell, and the operating eductor 86 provides insufficient recirculation. Therefore, the anodic moisture retention system of the present invention preferably further comprises a second or "start" eductor 84. The start eductor 88 is activated by the injection of water or other activation liquid, which is preferably supplied by a start pump 90 activated by electric motor, which provides the motor flow and begins to circulate and humidify the anodic loop. As the fuel cell begins to consume the hydrogen fuel, the high pressure hydrogen from the tanks 82 begins to be sucked through the operating eductor 86. Both eductors 86 and 88 then operate in parallel, until the operating conditions are achieved. At that point, the starter eductor 88 can be turned off, and the operating eductor 86 then begins with the recirculation of the anode loop. The recirculation of hydrogen in the anodic loop during initiation is desirable, since hydrogen venting during onset can result in an undesirable accumulation of explosive hydrogen. The recirculated hydrogen expelled from the cell is mixed with the fresh high pressure hydrogen from the tanks 82 in the operating eductor 86, and is discharged into the anode reservoir 92, where any liquid water retained in the hydrogen flow is collected. Also, the high vapor pressure of the cooling water of the cell within the anonymous reservoir 92 serves to dampen the moisture of the hydrogen stream. Anodic reservoir 92 preferably has a safety valve 94 for protection against excessive pressurization, and a timed computer controlled purge vent 96 which periodically purges the anode circuit to eliminate any accumulation of inert gas or air at the anode. which can lead to an explosive condition. Due to the constant recycling of the hydrogen loop, air that can leak through the fuel cell on the cathode side can accumulate and develop an explosive atmosphere in the anodic hydrogen loop. Therefore it is - »- < «--- periodically necessary to ventilate a portion of the hydrogen from the anodic loop through the purge vent 96. The hydrogen that is not consumed in the fuel cell 12 is then expelled through the anodic discharge, and is recirculated through the eductors 86, 88 as described above. The stoichiometric ratio of the hydrogen fuel supplied to the anode of the fuel cell 12 is controlled by a moderator 98 in the anode discharge conduit 20. Under standard operating conditions, the fresh hydrogen from the tanks 82 is introduced through eductors at a rate approximately equal to that of the recirculated hydrogen of the anodic discharge. It has been found that the need for anodic humidification (and the resulting need for humidifying equipment) can be eliminated by adjusting the supply hydrogen temperature and the stoichiometric ratio to maintain the total enthalpy of the fuel cell hydrogen exhaust stream. equal to the total enthalpy of the hydrogen supply stream of the fuel cell. For example, it has been found that under the following anodic fuel conditions, the enthalpy of the exhaust hydrogen is equal to the enthalpy of the hydrogen supply and, therefore, the recirculated hydrogen carries enough latent and sensible heat to mix with the hydrogen fresh from tanks 82 and maintain the desired anodic supply conditions: Anodic Expulsion H? Fresh from Mixed to Recirculated Tanks Nickname 0.08 Ib / min 0.08 Ib / min 0.16 Ib / min 83.4 ° C db 25 ° C db 70 ° C db 100% RH 0% RH 100% RH (113 gr / min H20) (0 gr / min H20) 113 gr / min H20 Q = + 2.6 kW Q = -2.6 kW Q = 0.0 Under these conditions, with a cuff temperature of 83.4 ° C, and a stoichiometric ratio of 2.0 Stolch (ie supply of two times the amount of H2 required for the fuel cell), the recirculated ejection hydrogen fuel from the fuel cell exhaust will have a total enthalpy approximately equal to the total desired enthalpy of the recirculated and fresh hydrogen supply mixture of the fuel cell. It should be understood that the above operating parameters are examples only, and that any number of combinations of operating conditions may allow exploitation of the excess anodic expulsion energy, limited only by the pumping capacity of the eductors and the temperature range of allowable operation of fuel cell 12. By suitably adjusting the temperature and the stoichiometric ratio of the hydrogen stream in the anodic supply 18, the moisture is retained in the hydrogen stream instead of condensing in the fuel cell. This eliminates the need to add moisture to the anodic supply stream, as well as eliminating the need to handle the condensate waste water in the fuel cell 12. Because the anodic fuel stream is recirculated through the anodic reservoir 92, which also functions as the deionized water reservoir for the cooling system (as will be described in detail below), the pressure of the anodic fuel stream and the cooling water stream are automatically maintained in equilibrium, thereby avoiding potential damage by pressure differentials between these two systems within the fuel cell. The anodic hydrogen current pressure, on the other hand, is preferably controlled by computer by regulating means such as the reducing valve 84 and the digital regulating valve 85, to match the cathodic air current pressure discharged from the compressor 34. In this way , the pressures of the three systems are kept in balance, thereby reducing the potential for damage to the fuel cell Cooling Water Management Systems Deionized water is necessary to cool the cell 12 fuel, since the standard water would cause a short circuit in the fuel cell. Deionized water, however, is highly corrosive and requires stainless steel equipment for handling. Because stainless steel is a poor heat conductor, providing a stainless steel radiator to reject the heat absorbed by the deionized cooling water from fuel cell 12 to ambient air requires a stainless steel radiator having a very large surface area. This large surface area would result in high aerodynamic drag in the vehicle activated by the fuel cell, and would result in costly and very heavy radiating. On the other hand, because antifreeze agents can not be added to deionized water, it is desirable to minimize the amount of deionized water present in the fuel cell cooling system to simplify the required antifreeze protection. The cooling water management system 130 of the present invention is shown schematically, in a preferred form, in Figure 3. The cooling water system 130 of the present invention addresses the above-identified problems inherent in water cooling systems. stainless steel handling for deionized cooling water providing a "double stage" cooling water system. This double stage system preferably comprises two closed loops, ie a loop 132 of deionized water and a standard 134 water-glycol loop. A brazed plate heat exchanger 136 provides heat transfer of water to water between the deionized water loop 132 and the standard water loop 134 without g ^^^^ jj ^ tó ^^^^^^^^^ j ^^^^^^^ g ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ mixed of two loops. The brazed plate heat exchanger 136 is preferably provided in the supply line 138 of the deionized water loop 132 between the anodic reservoir 92 and the deionized cooling water supply 140 to the fuel cell 12. The deionized cooling water is discharged from the fuel cell 12 through a deionized cooling water discharge line 142 and returned to the anodic tank 92. A deionized cooling water pump 144 circulates the deionized cooling water through loop 132 of deionized water. The loop 134 of deionized water circulates through the heat exchanger 136 of brazed plate heat to absorb the heat rejected from the loop 132 of deionized water. A standard cooling water pump 148 circulates standard cooling water, which may include an antifreeze agent such as ethylene glycol, through the standard water loop 134. A radiator 150 is preferably provided in the standard water loop 134 to reject the heat into the ambient air. The brazed plate heat exchanger 136 preferably comprises a stacked range of thin stainless plates with deionized water and standard cooling water circulating in the alternating layers between the thin stainless plates. In this way, heat is transferred from the deionized cooling water to the standard cooling water by forced convection and conduction of water to metal to water through the thin stainless plates, with this resulting in a much higher rate of heat transfer. of what could be obtained through the use of a fin radiator stainless steel air. Once heat has been transferred to the standard water / glycol cooling mixture in loop 134 of standard cooling water, pipe and non-stainless equipment. Also, automotive aluminum radiators are commercially available, thus eliminating the requirement of costly custom fabrication. In this way, the cooling system of the present invention allows the use of a less expensive radiator, lighter, and smaller, requiring a smaller surface area and, therefore, less aerodynamic drag, than would be possible with heat transfer from stainless to air. The provision of two separate cooling water loops 132 134 also minimizes the amount of deionized water necessary for the fuel cell to cool and therefore reduces the freezing potential. In addition, in the preferred form, the present invention takes advantage of the separate cooling water loops by consolidating the anodic deposit 92 and other deionized water handling piping and equipment in a heated and / or thermally insulated location to further minimize the probability of the freezing In a preferred form, the deionized water pump 144 and the standard cooling water pump 138 comprise a pump with double termination activated by a single motor. The thermostat is preferably provided in the deionized water loop 132 or the cooling water sleeve of the fuel cell to maintain the desired outlet temperature of the stack as required for anodic moisture retention, as described above. The radiator 150 may additionally comprise a fan to assist in expelling the heat to the ambient air. A standard automotive cabin fan coil unit can also be provided to heat the cabin of a vehicle activated by a fuel cell. During startup, the deionized cooling water discharged from the fuel cell 12 can be diverted through the starter conduit 146 and be pumped, by means of the standard starter pump 90 through the starter eductor 88 to provide motor flow. of the anodic recirculation during the start. Since the invention has been described in its preferred forms, it will be obvious to those skilled in the art that many modifications, additions, and exclusions can be made therein without departing from the spirit and scope of the invention and its equivalents as set forth in following claims.

Claims (24)

1. A system to control the cooling and reactive currents to and from a fuel cell, the fuel cell is of the variety that has a first reactive input, a first reactive output, a second reactive input, a second reactive output, an input of cooler, a cooler outlet, the system comprises: (a) a first reactive humidification subsystem for supplying a first reactive supply stream to the first reactive input of the fuel cell and receiving a first reactive ejection stream of the first Reactive output of the fuel cell, the first reactive humidification subsystem comprises enthalpy transfer means for collecting moisture from the first reactive ejection stream and transferring a portion of the collected moisture to the first reactive input stream; (b) a second reagent moisture retention subsystem comprising a recirculation loop for collecting the excess of the second reagent from the second reactive outlet of the fuel cell, a source of the second reagent, mixing means for mixing the second reagent with the source with a second reagent collected from the second reactive outlet of the combusible cell, and motive means for circulating the second reagent in the recirculation loop and for introducing the second reagent into the second reactive entrance of the fuel cell; and (c) a cooling system comprising a first cooling loop communicating with the cooler inlet and the cooler outlet, a second cooling loop, a heat exchanger for transferring heat between the first and second cooling loop. , the first cooling loop is segregated from the second cooling loop.

2. The system according to claim 1, characterized in that the enthalpy transfer means of the first reactive humidification subsystem comprises an enthalpy wheel.

3. The system according to claim 2, characterized in that the first reactive humidification subsystem further comprises first verification means for verifying the relative humidity of the first reactive input stream supplied to the first reactive input of the fuel cell, and first means control to control the speed of rotation of the enthalpy wheel in response to the verified relative humidity of the first reactive input current. , -? - 3um?.?! IM? L? ^? ^ R lfíßHMUti¡i? I ^ - ^ S »?? ißa? ^ A ^. -.- __ »._« - ». *« _. «* A -.- jh¿_ < ? __-,

4. The system according to claim 3, characterized in that the first reactive humidification subsystem further comprises cooling means for adjusting the dry bulb temperature of the first reactive input stream.

5. The system according to claim 4, characterized in that the cooling means comprise an ultrasonic nozzle for introducing a coolant liquid into the first reactive input stream at a cooler supply speed, wherein the evaporation of the coolant liquid cools the first stream Reactive input.

6. The system according to claim 5, characterized in that the first reactive humidification subsystem further comprises second verification means for verifying the dry bulb temperature of the first reactive input stream supplied to the first reactive input of the fuel cell, and second control means for controlling the supply speed of the cooler in response to the verified dry bulb temperature of the first reactive input stream.

^^ 7. The system according to claim 2, characterized in that the enthalpy wheel comprises an acrylic base and a ceramic zeolite.

8. The system according to claim 1, characterized in that the first reactive humidification subsystem further comprises filter means for selectively filtering at least one component of the first reactive input stream.

9. The system according to claim 8, characterized in that the filter means comprise a molecular sieve for filtering the nitrogen of the first reactive input stream.

10. The system according to claim 1, characterized in that the mixing means of the second reagent moisture retention subsystem further comprises means for controlling the stoichiometric amount of the second reagent supplied to the fuel cell.

11. The system according to claim 10, characterized in that the second reagent circulates.

The system according to claim 11, characterized in that the motor means further comprise a second eductor for receiving a high-speed current of motor fluid to circulate the second reagent during the start of the motor. the fuel cell.

13. The system according to claim 10, characterized in that the stoichiometric amount of the second reagent supplied to the fuel cell is controlled at approximately twice the amount of the second reagent required for the fuel cell.

14. The system according to claim 10, characterized in that the stoichiometric amount of the second reactant delivered to the fuel cell is controlled at a rate where the total enthalpy of the excess of the second reactant collected from the second reactive outlet of the fuel cell is approximately equal to the total enthalpy of the second reactant introduced in the second reactive input of the fuel cell.

15. The system according to claim 1, characterized in that the first cooling loop comprises deionized water and the second cooling loop comprises a cooler, and wherein the second cooling loop further comprises a radiator for expelling the heat from the second cooling loop to the environment.

16. The system according to claim 1, characterized in that the fuel cell is a proton exchange membrane fuel cell, and wherein the first reagent comprises air supplied to the cathode of the fuel cell as an oxidant, and wherein the second reagent comprises hydrogen supplied to the anode of the fuel cell as fuel.

17. A method for controlling the chiller and reactive streams to and from a fuel cell, the fuel cell has a first reactive inlet, a first reactive outlet, a second reactive inlet, a chiller inlet and a chiller outlet, the method comprises : (a) providing a first reagent supply stream to be introduced into the first reactive input; (b) receiving a first reactive ejection stream from the first reactive stream (e) collecting an excess of the second reactant from the second reactive outlet; (f) mixing the collected excess of the second reagent with a second reagent supply from an external source to form a second reagent mixture; (g) circulating the second reagent mixture under a driving force to introduce it into the second reactive entrance; (h) recirculating in cooler through a first coolant loop in communication with the inlet of the cooler and the outlet of the cooler; (i) transferring the heat from the first cooler loop to the second segregated cooler loop; and (j) expelling the heat from the second cooling loop to the environment.

18. A system for conditioning a reactant stream supplied to a fuel cell, the system comprises: (a) ejection collection means for collecting an ejection stream from the reagent of the fuel cell; (b) supply means for supplying a reactant supply stream to the fuel cell; and (c) enthalpy transfer to collect latent and sensible heat from the ejection stream and transfer the latent and sensible heat to the inrush current.

19. The system according to claim 18, characterized in that the enthalpy transfer means comprise an enthalpy wheel which rotates at a rotation speed through an ejection zone adjacent to the ejection collection means and a supply zone. adjacent to the means of supply.

20. The system according to claim 19, characterized in that the fuel cell is a proton exchange membrane fuel cell, and wherein the reagent comprises supplied air. (a) collecting moisture from the cathodic expulsion in an enthalpy wheel; and (b) transferring at least a portion of the moisture collected from the enthalpy wheel to the cathode input.

21. The system according to claim 19, characterized in that it comprises:

22. A system for conditioning a reagent stream supplied to a fuel cell, characterized in that the system comprises: (a) a recirculation loop for collecting excessive reagent from the fuel cell; (b) mixing means for mixing the excess reagent harvested with a reagent supply from an external source to form a reactive mixture; g ^ gjjj ^^^ g ^^^^ - ^ üS5tí. ^ .- f ± (c) engine means to recirculate the reagent through the recirculation loop and introduce the reactive mixture into the fuel cell; and (d) control means for controlling the stoichiometric amount of the reagent introduced into the fuel cell.

23. A method for retaining moisture in a flow of hydrogen at an anode of a fuel cell, characterized in that the method comprises: (a) collecting excess hydrogen discharged from the fuel cell; (b) mixing a first quantity of fresh hydrogen from an external source with a second amount of excess hydrogen collected from the fuel cell to form a mixture of hydrogen; (c) controlling the first and second amount of hydrogen to control the total enthalpy of the mixture; and (d) introducing the mixture into a fuel cell.

24. A cooling system for cooling a fuel cell, characterized in that the cooling system comprises: (a) a first cooling loop communicating with the fuel cell; -.8¡ «Bi« ~ a.a & iaiSaJ¡l_L • & -. »», _. '(b) a second cooling loop isolated from the first cooling loop; (c) a heat exchanger for transferring heat between the first cooling loop and the second cooling loop; and (d) a radiator for expelling the heat from the second cooling loop.