KR20070017134A - Subdivided cooling circuit for a fuel cell system - Google Patents

Abstract

Improvements in initiation time for electrochemical fuel cell systems from freezing and freezing temperatures can be observed by minimizing the amount of coolant in the coolant subsystem. In particular, this can be achieved by having two pumps 50, 55-double loop (A, B) cooling subsystems. During startup, one pump 55 guides the refrigerant through the starting refrigerant loop A, and after the temperature of either the fuel cell stack 20 or the refrigerant reaches a predetermined threshold, the main or standard refrigerant loop B Coolant is introduced into the fuel cell stack. In an embodiment, after reaching the predetermined temperature, the refrigerant in the standard loop B is mixed with the refrigerant in the initiating loop A.

Refrigerant, Fuel Cell Stack, Cooling Subsystem, Refrigerant Loop, Stack Valve.

Description

Split Cooling Circuit for Fuel Cell System {SUBDIVIDED COOLING CIRCUIT FOR A FUEL CELL SYSTEM}

This application is directed to Provisional US Patent Application 60 / 560,731, filed Feb. 9, 2004, and US Patent Application Non-provisional US Patent Application 10 / 936,461, filed Sep. 8, 2004. It is about claiming priority interests. The above applications are hereby incorporated by reference in their entirety.

The present invention relates to an electrochemical fuel cell, and more particularly to subsystems and methods for regulating the temperature of a fuel cell system during initiation.

Electrochemical fuel cells convert reactants, ie fuel and oxidant flow streams, to produce power and reactants. An electrochemical fuel cell uses an electrolyte disposed between two electrodes, a cathode and an anode. Each electrode includes an electrocatalyst disposed at the interface between the electrode and the electrolyte for inducing a predetermined electrochemical reaction. Usually the location of the electrocatalyst forms a range of electrochemical activity.

Usually, a polymer electrolyte membrane (PEM) fuel cell uses a membrane electrode assembly (MEA) composed of an ion-exchange membrane disposed between two electrode layers. The MEA comprises a porous electrically conductive sheet material as a flowable diffusion layer, such as carbon fiber paper or carbon cloth. In a typical MEA, the electrode layer provides structural support for the ion-exchange membrane, which support is typically thin and flexible. The membrane is ionically conductive (typically quantum conductive) and also acts as a barrier to separate the reactant streams from each other. Another function of the film acts as an electrical insulator between the two electrode layers. The electrodes must be electrically insulated from each other to prevent short circuits. Typical commercial PEMs are sulfonated perfluorocarbon membranes sold by the E.I.Du Pont de Nemours and Company under the NAFION® brand.

The MEA includes an electrocatalyst for inducing a predetermined electrochemical reaction. The electrocatalyst comprises finely pulverized platinum particles disposed in the layer at each membrane / electrode layer boundary. The electrodes are electrically coupled to provide a path for guiding electrons between the electrodes through an external force.

In a fuel cell stack, the MEA is typically placed between two separators that cannot physically penetrate the reactant flow stream. The separator acts as a current collector and provides a support for the electrode. To control the distribution of the reactant flow stream into the electrochemical range of activity, the surface of the separator facing the MEA may have open-faced chnnels formed in the range of electrochemical activity. Such channels generally form a flow field area consistent with the adjacent range of electrochemical activity. Such separators with reactant channels formed in a range of electrochemical activities are known as flow field plates. Most fuel cells in a fuel cell stack are connected together in series to increase the overall output of the assembly. In this arrangement, one side of the plate may serve as an anode plate for one cell and the other side may serve as a cathode plate for adjacent cells. In this arrangement, the plates may be referred to as positive plates.

The fuel flow stream fed to the anode typically contains hydrogen. For example, the fuel flow stream may be a gas such as a reformate stream containing substantially pure hydrogen or hydrogen. Alternatively, a liquid flow stream such as water soluble methanol may be used. The oxidant flow stream supplied to the cathode comprises substantially pure oxygen or oxygen, such as a dilute oxygen stream, such as air. In the fuel cell stack, the reactant stream is supplied and discharged by respective supply and discharge manifolds. Collector ports are provided to fluidly connect the collector tube to the flow field range and to the electrode. Aggregates and corresponding ports may also be provided to circulate the refrigerant fluid through internal passageways for absorbing heat generated by the pyrogenic fuel cell reaction in the stack. The preferred operating temperature range for PEM fuel cells is 50 ° C to 120 ° C, with the most typical temperature ranges between 75 ° C and 85 ° C.

Under typical conditions, the initiation of an electrochemical fuel cell stack is subject to high ambient temperatures, and the fuel cell stack can be initiated at an appropriate amount of time and quickly reach the desired operating temperature. In some fuel cell applications, it is necessary or required to initiate the operation of the electrochemical fuel cell stack when the stack core temperature is below the freezing point of water and even below the freezing point below -25 ° C. However, at such low temperatures, the fuel cell stack does not operate smoothly, and the quick start of the fuel cell stack becomes more difficult. Thus, this may require energy to efficiently operate the electrochemical fuel cell stack from a significant amount of time and / or cold start temperature below the freezing point of water.

U. S. Patent No. 6,358, 638 discloses a method of heating a cold MEA to accelerate cold start of a PEM fuel cell. The patent discloses one of the contents where the fuel is directed into the oxidant stream or the oxidant is directed into the fuel stream. The presence of a platinum catalyst on the electrode promotes an exothermic chemical reaction between hydrogen and oxygen and locally heats the ion exchange membrane from below freezing point to an appropriate operating temperature. However, there is still a need in the art for more effective methods of efficiently initiating fuel cell stacks at low temperatures and below freezing points. The present invention fulfills this need and provides further related advantages.

Notable improvements in start-up time at freezing or below freezing temperatures can be achieved using two pump-double loop cooling subsystems. For example, in an electrochemical fuel cell system, the cooling subsystem includes an initiating refrigerant loop comprising an initiation pump fluidly connected to the electrochemical fuel cell stack; It can include both standard refrigerant loops including standard pumps and stack valves. The amount of refrigerant in the starting refrigerant loop is less than the amount of refrigerant in the standard refrigerant loop. During initiation, the stack valve is closed and the electrochemical fuel cell stack is fluidly separated from the standard refrigerant loop. Refrigerant in the initiating loop circulates through the fuel cell stack and allows the stack to quickly reach a predetermined temperature. If refrigerant does not circulate through the stack, local heating in the stack may adversely affect the stack. More efficient heating can occur by minimizing the amount of refrigerant in the initiating loop, and in particular with less refrigerant than in the standard refrigerant loop.

In another embodiment, the cooling subsystem for the electrochemical fuel cell system may include an initiating refrigerant loop fluidly connected to the electrochemical fuel cell. The starting refrigerant loop comprises an starting pump. The cooling subsystem also includes a standard refrigerant loop that includes a standard pump and a stack valve. When the stack valve is closed, only the starting refrigerant loop is fluidly connected to the electrochemical fuel cell stack. However, when the stack valve is opened, both the starting refrigerant loop and the standard refrigerant loop are fluidly connected to the fuel cell stack. Thus, a small amount of refrigerant is useful for the fuel cell stack during startup when efficient heating is required, and a large amount of refrigerant from both refrigerant loops is useful during normal operation. In a preferred embodiment, the starting refrigerant loop is also fluidly connected to the standard refrigerant loop when the stack valve is opened. This is simpler to manufacture and mixes the refrigerant, thereby reducing the heat shock as the cooler refrigerant in the standard refrigerant loop enters the fuel cell stack. Nevertheless, both refrigerant loops remain fluidly separated throughout.

During initiation, a method for operating a refrigerant subsystem for an electrochemical fuel cell system includes the steps of: (a) inducing a first refrigerant through a fuel cell stack; (b) the temperature of either the fuel cell or the first refrigerant is first Inducing a second refrigerant through said fuel cell stack when said predetermined temperature is reached. During the step (a), the first refrigerant is fluidly separated from the second refrigerant. When the temperature of one of the refrigerants in the fuel cell stack or initiation loop reaches a predetermined threshold, the stack valve can be opened so that the electrochemical fuel cell is fluidly connected to the standard refrigerant loop, allowing further cooling of the fuel cell stack. Make it possible. In an embodiment, the refrigerant in the standard refrigerant loop is mixed with the refrigerant in the initiation loop when the stack valve is opened.

In an embodiment, said first predetermined temperature is an operating temperature of a fuel cell system, for example, between 60 ° C and 80 ° C. In another embodiment, the predetermined temperature is less than an operating temperature, for example 60 ° C., more specifically less than 50 ° C. Typically, this predetermined temperature is greater than 30 ° C or 40 ° C.

The initiation loop further includes a heater that helps to quickly reach the temperature of the refrigerant to a predetermined temperature. In order to further minimize the amount of refrigerant in the starting refrigerant loop, the loop can be integrated into the stack assembly. Other components of the refrigerant subsystem may include a compressor, a cathode feed heat exchanger or a radiator. If the fuel cell system is used in an automobile, the cooling subsystem may further include a propulsion system and / or a vehicle heating system.

These and other aspects of the present invention will become apparent with reference to the accompanying drawings and the following detailed description.

1 is a conceptual diagram of a prior art refrigerant subsystem for an electrochemical fuel cell system.

2 is a conceptual diagram of an embodiment of a refrigerant subsystem for an electrochemical fuel cell system.

3 is a conceptual diagram of an embodiment of a refrigerant subsystem for an electrochemical fuel cell system.

4 is a conceptual diagram of a refrigerant subsystem testing a chamber for an embodiment of the present invention.

5 is a refrigerant temperature graph as a function of time for three different fuel cell systems using a refrigerant subsystem testing the chamber of FIG.

 6 is a graph of power achieved for a fuel cell system as a function of time for three different fuel cell systems using a refrigerant subsystem testing the chamber of FIG.

In the drawings, like reference numerals are used in different drawings to refer to like elements.

Typically temperature control of the fuel cell system is performed with refrigerant circulated through the refrigerant subsystem. Typical refrigerants are, for example, water, ethylene, glycols, propylene glycols, fluoroinerts, alcohols or combinations thereof. The choice of refrigerant is largely determined by the expected physical state of the fuel cell. For example, if the fuel cell stack is operated at a freezing point or below freezing point, a freezing refrigerant will be selected. The main purpose of the refrigerant is to regulate the temperature and to prevent overheating not only of the fuel cell stack but also of other components of the fuel cell system, for example compressors, cathode feeds, propulsion systems, car heaters, motors, electrical appliances, etc. It is. Also during startup, and particularly when the fuel cell stack is at freezing or below freezing temperatures, the refrigerant may assist the fuel cell stack in reaching an optimal operating temperature.

1 is a conceptual diagram of a conventional refrigerant subsystem 10 for an electrochemical fuel cell system. The refrigerant subsystem may include a pump 50, a compressor 30, a cathode feed heat exchanger 40, and a refrigerant reservoir 60 fluidly connected to the fuel cell stack 20. Refrigerant in the refrigerant reservoir 60 may be circulated through the fuel cell stack 20, the compressor 30, and the cathode feed heat exchanger 40, which supports temperature control of these components. In particular, for the compressor 30, the temperature control of the compressor motor and the compressor inverter (not shown) can be designed separately or together. A temperature sensor (not shown) may measure the temperature of the fuel cell stack 20 and / or the temperature of the refrigerant circulating through the refrigerant subsystem 10. The refrigerant subsystem 10 may also include a radiator 70 and a radiator valve 75. Once the temperature of the fuel cell stack 20 or the coolant exceeds a predetermined threshold, the radiator valve 75 may direct coolant through the radiator 70 to achieve additional cooling of the fuel cell system.

Other components may also be coupled to the refrigerant subsystem 10 when needed, especially as used in automotive applications. For example, propulsion system 80 may be reversibly and fluidly connected to refrigerant subsystem 10 by propulsion valve 85. Similarly, the vehicle heating system 95 may be reversibly and fluidly connected to the refrigerant subsystem 10 by the vehicle heating valve 95. Thus, the same refrigerant subsystem 10 used to adjust the temperature of the fuel cell stack 20 can be used to adjust the temperature of many other components when needed.

2 is a conceptual diagram of an embodiment of a refrigerant subsystem 100. The pump 50 may circulate the refrigerant in the refrigerant reservoir 60 through components of the fuel cell system, such as the compressor 30, the cathode feed heat exchanger 40, and as in the refrigerant subsystem shown in FIG. The other direction can be circulated through other components such as the radiator 70, the propulsion system 80 and the vehicle heating system 90. This is shown in FIG. 2 as a standard refrigerant loop (B). Refrigerant subsystem 100 further includes a second starting refrigerant loop (A). The loop A can be reversibly and fluidly separated from the standard refrigerant loop B by the stack valve 65. Stack valve 65 may be, for example, a thermostatic valve or a proportional valve. In particular, the starting refrigerant loop A may comprise a fuel cell stack 20, a pump 55 and an optional heater 25. During start up of the fuel cell system, in particular when the system is at a freezing point or below freezing point, the stack valve 65 can be closed such that the refrigerant loop A and the refrigerant loop B are fluidly separated. During the initiation process, the refrigerant loop A and the refrigerant loop B may increase in temperature. The relatively small amount of refrigerant in the refrigerant loop A enables fast and efficient heating, in particular compared to the refrigerant in the refrigerant loop B. This can reduce the time required for the fuel cell stack 20 to reach the appropriate temperature at which the fuel cell stack 20 is started. In fact, no preheating is necessary in the embodiment with the reduced amount of refrigerant in the refrigerant loop A, and at freezing point the fuel cell stack 20 can be started by itself. Typically, a suitable temperature at which power may be generated from fuel cell stack 20 may be about 5 ° C. In another embodiment, the heater 25 may also be used to heat the refrigerant in the refrigerant loop A and support the fuel cell stack 20 to reach the temperature.

At significantly cold temperatures, the viscosity of the refrigerant in the refrigerant loop A may be higher than the viscosity at the warm temperature. This increased viscosity can affect the refrigerant flow rate and care must be taken to ensure that the pump 55 maintains a sufficient refrigerant flow rate in the refrigerant loop A. Otherwise, concentrated heating in fuel cell stack 20 can cause damage to individual cells from local overheating. However, at the freezing point and below the freezing point, less heat is generated by the fuel cell stack 20, and the individual fuel cells in the stack 20 can absorb significant amounts of heat generated with increased viscosity. The flow rate of the refrigerant can be significantly reduced than the flow rate required in normal operating conditions. The flow rate is highly dependent on the stack design, the material and the amount of heat generated within the fuel cell stack 20 and can be readily determined by one skilled in the art. Nevertheless, during the cold-start phase for a typical automated fuel cell system, the refrigerant flow rate of the refrigerant loop (A) can be as low as 5 to 25 slpm (standard litre per minute), more specifically 85 kW. It can be 15 to 25 slpm for the total fuel cell stack. The refrigerant flow rate is consistent with the cell cooling requirement without local hot spots.

As the fuel cell stack 20 is heated and the refrigerant in the refrigerant loop A is heated similarly, the viscosity drops and the flow rate according to the pump design (e.g. positive displacement or mixed flow) Increases naturally. This natural increase in refrigerant flow rate may be sufficient in certain fuel cell systems to match the increased cooling requirements of the fuel cell stack 20 during startup. Thus, the low cost of a fixed speed pump can be all that is needed for the pump 55 in the refrigerant loop A. In contrast, the pump 50 of the refrigerant loop B may still have a speed control for adjusting the flow rate of the refrigerant during normal operation. In addition, during normal operation, the pump 55 may be used to increase the refrigerant flow rate through the fuel cell stack 20 and may be a smaller pump 50 than the pump required for conventional cooling subsystems.

As the refrigerant in the refrigerant loop A is heated, the refrigerant may expand and an expansion reservoir (not shown) in the refrigerant loop A may be used to accommodate the increased amount of refrigerant. In the embodiment shown in FIG. 2, this expansion reservoir may be unnecessary as any excess refrigerant amount may leak directly into the refrigerant loop B as only one valve. That is, the stack valve 65 separates the refrigerant loop A from the refrigerant loop B. In any case, the pressure increase in the refrigerant loop A due to the increased amount of refrigerant will be minimal.

Heater 25 may be used to heat the refrigerant in refrigerant loop A and bring fuel cell stack 20 to operating temperature. The heater may be used in a conventional refrigerant design or refrigerant loop B. (not shown) Heater 25 may be useful in a fuel cell system, and some heaters increase the amount of refrigerant needed to house the heater itself. It may not have the required heat flux to compensate for the total heat generated.

The total amount of heat of the refrigerant in the refrigerant loop A can be minimized by further integration of the refrigerant loop A into the fuel cell stack assembly (not shown).

When the refrigerant in the refrigerant loop A or the temperature of the fuel cell stack 20 reaches a critical temperature, the stack valve 65 may be opened to direct the refrigerant in the refrigerant loop B to the fuel cell stack 20. have. This critical temperature may be, for example, between 30 ° C and 80 ° C. In an embodiment, the threshold temperature is between 60 ° C. and 80 ° C., that is, the normal operating temperature of the fuel cell stack 20. In this embodiment, the fuel cell stack 20 reaches a predetermined operating temperature at the minimum time, leading to greater power density from the fuel cell stack 20 at an earlier time. In another embodiment, the threshold temperature is 60 degrees, more specifically 50 degrees or less. As the cold refrigerant in the refrigerant loop B is directed into the warm refrigerant in the refrigerant loop A, the temperature gradient can be developed. At low temperatures, the fuel cell stack 20 may be at a high temperature gradient without adverse effects (eg, a temperature gradient up to 30 ° C.) However, at 60 ° C. to 80 ° C., only the typical fuel cell stack 20 is Safely, for example, it can be a temperature gradient less than 10 ° C. Thus, by having a low threshold temperature (ie, 30 ° C. to 60 ° C. instead of 60 ° C. to 80 ° C.) for transferring the refrigerant in the refrigerant loop B into the fuel cell stack 20, the fuel cell stack may be subjected to thermal shock. The risk of damage is reduced. Regardless of the critical temperature, care is required to reduce the risk of heat shock. This can be done, for example, by adjusting the rate at which the refrigerant in the refrigerant loop B is guided into the refrigerant loop A.

In the further embodiment of FIG. 3, the heat shock hazard of the fuel cell stack 20 can be reduced or eliminated by using a heat exchanger 45 instead of a thermostatic valve, such as the stack valve 65. The refrigerant loop A and the refrigerant loop B are arranged as shown in FIG. 2, and as such many components of the loop are arranged, but not clearly shown in FIG. 3. In the embodiment shown in FIG. 3, the refrigerant in the refrigerant loop B is led to the refrigerant loop C by the valve 15. Refrigerant loop (C) comprises a heat exchanger (45) in thermal contact with the refrigerant loop (A). In particular, during the initial starting state, the valve 15 is closed, whereby only the refrigerant is circulated in the refrigerant loop A and the refrigerant loop B excluding the refrigerant loop C. Although the refrigerant temperature may increase faster in the refrigerant loop A than in the refrigerant loop B, the refrigerant temperature may increase in both the refrigerant loop A and the refrigerant loop B. FIG. When either the fuel cell stack 20 or the refrigerant in the refrigerant loop A has reached a first predetermined threshold, the valve 15 opens to circulate the refrigerant in the refrigerant loop B in the refrigerant loop C. It is possible to further increase the temperature of the refrigerant in the refrigerant loop (B) to return the refrigerant through the valve. Once the refrigerant in the refrigerant loop B has reached the second predetermined threshold, the stack valve 65 can be opened. Another way to consider this operation is to provide a stack valve such that refrigerant B mixes with refrigerant A when the temperature difference between the refrigerant in refrigerant loop A and the refrigerant in refrigerant loop B is less than a predetermined predetermined heat shock value. 65 may be opened. Thus, when there is a relatively small temperature difference between the refrigerant in the refrigerant loop A and the refrigerant in the refrigerant loop B, the risk of the fuel cell stack 20 becoming thermal shock is reduced or eliminated.

As shown in FIG. 3, additional precautions to avoid heat shock in the embodiment of FIG. 2 may be unnecessary. When the refrigerant loop A reaches a predetermined operating temperature, only the stack valve 65 may be opened to be sufficient to maintain the operating temperature of the fuel cell stack 20. When the refrigerant in the refrigerant loop B is slowly mixed with the refrigerant in the refrigerant loop A, the fuel cell stack 20 maintains the mixing temperature and the refrigerant in the refrigerant loop B continuously increases in temperature. When the refrigerant temperatures of the refrigerant loop A and the refrigerant loop B become equal, the stack valve 65 is completely opened. Radiator valve 75 is also open to maintain the cooling subsystem at the desired operating temperature. Thus, it may be possible to avoid heat shock without using additional refrigerant loops.

As shown in FIG. 4, the test chamber is assembled to account for the effect of the reduced amount of refrigerant and the time for the fuel cell system to reach its normal operating temperature from temperatures below freezing and freezing. Three refrigerant paths, that is, refrigerant path D, refrigerant path E and refrigerant path F, are assembled. The pump 50 supplies the refrigerant through the flow meter 35, and pumps the fuel cell stack 20 through the refrigerant paths D and E. Refrigerant path E further includes a refrigerant reservoir 60, a heater 25 and a heat exchanger 45. Cold refrigerant from the station is led through heat exchanger 45 as shown by the arrow. Refrigerant path E shows a conventional fuel cell system, and refrigerant path D represents a reduced amount of refrigerant achieved by avoiding unnecessary components in the fuel cell stack, although still using a one-pump system. have. A separate refrigerant path F with a stack pump 55 was used to compare the effects of the two pump systems and the small amount of refrigerant during initiation.

Three different amounts of refrigerant were tested: standard amount of refrigerant (5000 mL) for refrigerant path E, low amount of refrigerant (1000 mL) for refrigerant path D and very small amount of refrigerant (100 mL) for refrigerant path F.

FIG. 5 is a graph of coolant temperature as a function of time for three different amounts of coolant using the coolant subsystem testing the chamber of FIG. 4. A temperature sensor (not shown in FIG. 4) was installed at the coolant inlet and at the coolant outlet of the fuel cell stack 20. The starting temperature for the test was -5 ° C for the standard amount of refrigerant and -15 ° C for the small amount and the minimum amount of refrigerant. As can be seen in FIG. 5, the amount of refrigerant has a significant effect on the length of time required for the fuel cell stack to reach operating temperature. After 16 minutes, the standard refrigerant amount only had a temperature increase between 20 ° C and 40 ° C. In comparison, the small amount of refrigerant had a temperature increase between 60 ° C. and 75 ° C. after only 6 minutes, and the very small amount of refrigerant took only 3 minutes to increase in temperature between 75 ° C. and 80 ° C. This temperature increase has a significant effect on the amount of power that can be produced by the fuel cell stack 20, as shown in FIG.

6 is a graph of the power achieved for a fuel cell system as a function of time. In particular, FIG. 6 shows the percentage of total power produced by the fuel cell stack as a function of time. After 16 minutes, the fuel cell stack 20 operating with the standard refrigerant amount could only produce approximately 35% of the total power. In comparison, the fuel cell stack 20 only took 6.5 minutes to produce more than 60% of the total power when a small amount of coolant was used, and the fuel cell stack 20 was more than 80% of the total power when the amount of very coolant was used. It only took 2 minutes to generate. The magnitude of this effect is important as a roughly rapid amount of time.

While the embodiment is described in terms of automatic fuel cell applications, it is understood that the embodiment can be applied to any fuel cell application and in particular can be applied to any generator application located outside or at temperatures below freezing or freezing. do.

Although specific embodiments have been described for purposes of explanation, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not limited by the appended claims.

All of the above-mentioned U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patents mentioned in this specification and / or written in an application data sheet non-patent publications are incorporated herein by reference in their entirety.

Claims (31)

A cooling subsystem for an electrochemical fuel cell system having an electrochemical fuel cell stack, An initiating refrigerant loop comprising an initiation pump and fluidly connected to the electrochemical fuel cell stack; A standard refrigerant loop comprising a standard pump and a stack valve, wherein the standard refrigerant loop is fluidly connected to the electrochemical fuel cell stack when the stack valve is opened, and the standard refrigerant loop is electrochemical fuel when the stack valve is closed. Fluidly separated from the cell stack; Wherein the amount of refrigerant in the starting refrigerant loop is less than the amount of refrigerant in the standard refrigerant loop. The method of claim 1, When the stack valve is opened, the starting refrigerant loop is fluidly connected to a standard refrigerant loop. The method of claim 1, And when the stack valve is open, the starting refrigerant loop is fluidly connected to an electrochemical fuel cell stack. The method of claim 1, The standard refrigerant loop further comprises a compressor fluidly connected to the standard pump. The method of claim 1, The starting refrigerant loop further comprises a heater. The method of claim 1, The stack valve is a cooling subsystem which is a thermostatic valve. The method of claim 1, Stack valves are cooling subsystems that are proportional valves. The method of claim 1, Wherein said electrochemical fuel cell stack comprises a stack assembly and said starting refrigerant loop is integrated into said stack assembly. The method of claim 1, The standard refrigerant loop further comprises a cathode feed heat exchanger. The method of claim 1, The standard refrigerant loop further comprises a refrigerant reservoir. The method of claim 1, The standard refrigerant loop further comprises a radiator. The method of claim 11, And the radiator is fluidly connected to the standard refrigerant loop when the radiator valve is opened and the radiator further comprises a radiator valve that is fluidly separated from the standard refrigerant loop when the radiator valve is closed. The method of claim 1, The standard refrigerant loop further comprises a propulsion system. The method of claim 13, The propulsion system is fluidly connected to the standard refrigerant loop when the propulsion valve is opened and the propulsion system further comprises a propulsion valve that is fluidly separated from the standard refrigerant loop when the propulsion valve is closed. The method of claim 1, The standard refrigerant loop further comprises a vehicle heating system. The method of claim 15, The vehicle heating system is fluidly connected to the standard refrigerant loop when the vehicle heating valve is opened, and the vehicle heating system further comprises a vehicle heating valve that is fluidly separated from the standard refrigerant loop when the vehicle heating valve is closed. Subsystem. An electrochemical fuel cell system comprising the cooling subsystem of claim 1. A cooling subsystem for an electrochemical fuel cell system having an electrochemical fuel cell stack, An initiating refrigerant loop comprising an initiation pump and fluidly connected to the electrochemical fuel cell stack; A standard refrigerant loop comprising a standard pump and a stack valve, wherein both the starting refrigerant loop and the standard refrigerant loop are fluidly connected to the electrochemical fuel cell stack when the stack valve is opened, but when the stack valve is closed, the starting refrigerant A cooling subsystem in which only loops are fluidly connected from the electrochemical fuel cell stack. The method of claim 18, When the stack valve is opened, the starting refrigerant loop is fluidly connected to a standard refrigerant loop. The method of claim 18, The cooling amount of the starting refrigerant loop is less than that of the standard refrigerant loop. A method for operating a refrigerant subsystem for an electrochemical fuel cell system during initiation, (a) inducing a first refrigerant through the fuel cell stack; (b) inducing a second refrigerant through the fuel cell stack when the temperature of one of the electrochemical fuel cell stack or the first refrigerant reaches a first predetermined temperature, Wherein the second refrigerant is fluidly separated from the fuel cell stack while the first refrigerant is guided through the fuel cell stack. The method of claim 21, And the first refrigerant amount is smaller than the second refrigerant amount. The method of claim 21, Method of mixing the first refrigerant and the second refrigerant in step (b). The method of claim 21, The temperature of the fuel cell stack before start is 0 degrees C or less. The method of claim 21, The temperature of the fuel cell stack before start-up is -25 degrees C or less. The method of claim 21, Wherein the first predetermined temperature is between 30 ° C. and 60 ° C. The method of claim 21, Wherein the first predetermined temperature is less than 50 ° C. The method of claim 21, Wherein the first predetermined temperature is between 60 ° C. and 80 ° C. The method of claim 21, And when the second refrigerant reaches a second predetermined temperature, inducing the second refrigerant through the radiator. The method of claim 29, The second predetermined temperature is a predetermined operating temperature of the fuel cell stack. The method of claim 29, The second predetermined temperature is between 60 ° C and 80 ° C.

Images