System for cooling fuel cell

Abstract

To provide technique that cools an intercooler while efficiently raising the temperature of a fuel cell.SOLUTION: A system for cooling a fuel cell comprises: a first cooling flow path; a fuel cell provided in the first cooling flow path; a second cooling flow path; a radiator provided in the second cooling flow path; an intercooler provided in the second cooling flow path; an intermediate heat exchanger performing heat exchange between the first and second cooling flow paths; and a bypass flow path provided in the second cooling flow path. When the temperature of the coolant in the first cooling flow path is lower than a first reference value during power generation performed by the fuel cell, a first operation is performed in which the coolant is circulated in the second cooling flow path via a path through the intermediate heat exchanger, intercooler, and bypass flow path. When the temperature of the coolant in the first cooling flow path is higher than the first reference value, a second operation is performed in which the coolant is circulated in the second cooling flow path via a path through the intermediate heat exchanger, intercooler, and radiator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a fuel cell cooling system. [Background technology]

[0002] The fuel cell system disclosed in Patent Document 1 has a first cooling flow path and a second cooling flow path that circulate a refrigerant. A fuel cell is provided in the first cooling flow path. A radiator is provided in the second cooling flow path. An intermediate heat exchanger is provided across the first and second cooling flow paths. The intermediate heat exchanger exchanges heat between the first and second cooling flow paths. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-33108 Summary of the Invention [Problem to be solved by the invention]

[0004] In a fuel cell system, an intercooler is provided to cool the compressed air supplied to the fuel cell. In the technology of Patent Document 1, providing an intercooler in the second cooling flow path allows the refrigerant cooled by the radiator to be supplied to the intercooler and the intermediate heat exchanger. During power generation by the fuel cell, the refrigerant can be circulated through the first cooling flow path and the second cooling flow path so as to pass through the radiator, the intermediate heat exchanger, and the intercooler. Heat generated in the fuel cell is transferred to the intermediate heat exchanger by the refrigerant flowing through the first cooling flow path. The intermediate heat exchanger cools the refrigerant in the first cooling flow path by heat exchange with the refrigerant in the second cooling flow path (i.e., the refrigerant cooled by the radiator). This allows the fuel cell to be efficiently cooled by the refrigerant in the first cooling flow path. Furthermore, the intercooler cools the compressed air by heat exchange with the refrigerant in the second cooling flow path (i.e., the refrigerant cooled by the radiator). This allows the compressed air to be efficiently cooled.

[0005] When a fuel cell is started in a low-temperature environment, the temperature of the fuel cell is low immediately after start-up, resulting in low power generation efficiency. Furthermore, when the fuel cell is started, it is necessary to supply refrigerant to the intercooler. In the above fuel cell system, when refrigerant is supplied to the intercooler, refrigerant is also supplied to the intermediate heat exchanger. As a result, the fuel cell is cooled by the refrigerant in the intermediate heat exchanger and the first cooling flow path, making it difficult for the temperature of the fuel cell to increase. This makes it difficult for the power generation efficiency of the fuel cell to increase. Thus, providing an intercooler in the second cooling flow path poses the problem of making it difficult for the temperature of the fuel cell to increase in a low-temperature environment. This specification proposes a technology that can raise the temperature of the fuel cell while supplying refrigerant to the intercooler. [Means for solving the problem]

[0006] (Aspect 1) The fuel cell cooling system disclosed in this specification includes a first cooling flow path that circulates a refrigerant, a fuel cell provided in the first cooling flow path, a second cooling flow path that circulates a refrigerant, a radiator provided in the second cooling flow path, an intercooler provided in the second cooling flow path, and an intermediate heat exchanger that exchanges heat between the first cooling flow path and the second cooling flow path, wherein the second cooling flow path includes a bypass flow path provided in parallel to the radiator, and when the temperature of the refrigerant in the first cooling flow path is lower than a first reference value during power generation by the fuel cell, A first operation is performed to circulate the refrigerant through the first cooling flow path through a path that passes through a battery and the intermediate heat exchanger, and to circulate the refrigerant through the second cooling flow path through a path that passes through the intermediate heat exchanger, the intercooler, and the bypass flow path, and when the temperature of the refrigerant in the first cooling flow path is higher than the first reference value during power generation by the fuel cell, a second operation is performed to circulate the refrigerant through the first cooling flow path through a path that passes through the fuel cell and the intermediate heat exchanger, and to circulate the refrigerant through the second cooling flow path through a path that passes through the intermediate heat exchanger, the intercooler, and the radiator.

[0007] In the above fuel cell cooling system, when the temperature of the refrigerant in the first cooling flow path is lower than a first reference value while the fuel cell is generating electricity, a first operation is performed. In the first operation, the refrigerant circulates through the second cooling flow path via a path that passes through the intermediate heat exchanger, the intercooler, and the bypass flow path. Because the refrigerant circulates through a path that bypasses the radiator, the temperature of the refrigerant in the second cooling flow path is less likely to drop. This reduces the amount of heat transfer between the first and second cooling flow paths within the intermediate heat exchanger. As a result, the temperature of the refrigerant in the first cooling flow path is less likely to drop, allowing the temperature of the fuel cell to be increased efficiently. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a block diagram of a fuel cell cooling system. [Figure 2] FIG. 4 is an explanatory diagram of a first circulation flow path. [Figure 3] FIG. 4 is an explanatory diagram of a second circulation flow path. [Figure 4] 4 is a flowchart of an operation selection process of the fuel cell cooling system. DETAILED DESCRIPTION OF THE INVENTION

[0009] Following the above-mentioned first embodiment, additional configurations of the fuel cell cooling system disclosed in this specification will be described below. (Aspect 2) Aspect 2. The fuel cell cooling system according to aspect 1, wherein in the first operation and the second operation, the refrigerant flows in parallel through the intermediate heat exchanger and the intercooler in the second cooling flow path. (Aspect 3) A fuel cell cooling system as described in aspect 1 or 2, wherein, in the first operation, when the temperature of the refrigerant in the first cooling flow path is lower than a second reference value, the circulation speed of the refrigerant in the first cooling flow path is slower than when the temperature of the refrigerant in the first cooling flow path is higher than the second reference value. (Aspect 4) A fuel cell cooling system according to any one of aspects 1 to 3, wherein, in the first operation, when the temperature of the refrigerant in the first cooling flow path is lower than the second reference value, the circulation speed of the refrigerant in the second cooling flow path is slower than when the temperature of the refrigerant in the first cooling flow path is higher than the second reference value.

[0010] According to the second aspect, the refrigerant flowing through the second cooling passage flows into the intermediate heat exchanger and also flows into the intercooler. That is, the intermediate heat exchanger performs heat exchange between the first cooling passage and the second cooling passage and also cools the intercooler.

[0011] 1 is mounted on a device powered by a fuel cell (for example, a fuel cell vehicle). The fuel cell cooling system 100 includes a first cooling system 10, a second cooling system 20, and an intermediate heat exchanger 30.

[0012] A refrigerant circulates through the first cooling system 10. A refrigerant circulates through the second cooling system 20. The intermediate heat exchanger 30 has a first heat exchange passage 30a and a second heat exchange passage 30b. The first heat exchange passage 30a is part of the first cooling system 10, and the second heat exchange passage 30b is part of the second cooling system 20. The intermediate heat exchanger 30 causes heat exchange to occur between the first heat exchange passage 30a and the second heat exchange passage 30b.

[0013] The first cooling system 10 has a fuel cell 14 and a first cooling flow path 12. The fuel cell 14 is provided in the first cooling flow path 12. Compressed air is supplied to the fuel cell 14 from an air compressor (not shown), and hydrogen is supplied from a tank (not shown). The fuel cell 14 generates electricity by reacting oxygen and hydrogen, and supplies the electricity to a motor (not shown).

[0014] The first cooling flow path 12 has a flow path 12a and a flow path 12b. The flow path 12a is connected to the downstream end of the first heat exchange flow path 30a and the upstream end of the refrigerant flow path in the fuel cell 14. The flow path 12b is connected to the downstream end of the refrigerant flow path in the fuel cell 14 and the upstream end of the first heat exchange flow path 30a. The first cooling flow path 12 is made up of the flow path 12a, a refrigerant flow path provided inside the fuel cell 14, the flow path 12b, and the first heat exchange flow path 30a. In other words, the first cooling flow path 12 is an annular flow path through which the refrigerant circulates.

[0015] The first cooling system 10 has a pump 16 and temperature sensors 18a and 18b. The pump 16 is provided in the flow path 12b. The pump 16 pumps the refrigerant from its installation position toward the intermediate heat exchanger 30. When the pump 16 operates, the refrigerant circulates within the first cooling flow path 12 in the following order: the intermediate heat exchanger 30, the flow path 12a, the fuel cell 14, and the flow path 12b.

[0016] Temperature sensor 18a is provided in flow path 12a. Temperature sensor 18a detects the temperature of the coolant flowing into fuel cell 14. Temperature sensor 18b is provided in flow path 12b. Temperature sensor 18b detects the temperature of the coolant discharged from fuel cell 14 (hereinafter referred to as FC outlet temperature).

[0017] The second cooling system 20 includes a radiator 24, a second cooling passage 22, an intercooler 32, and a three-way valve .

[0018] The radiator 24 is provided in the second cooling flow path 22. The radiator 24 cools the refrigerant flowing through the second cooling flow path 22 by heat exchange with outside air.

[0019] The second cooling flow path 22 has a flow path 22a, a flow path 22b, a flow path 22c, an intercooler flow path 34, and a bypass flow path 36. The flow path 22a is connected to the upstream end of the second heat exchange flow path 30b and the downstream end of the refrigerant flow path in the radiator 24. The flow path 22b is connected to a three-way valve 38 and the downstream end of the second heat exchange flow path 30b. The flow path 22c is connected to the three-way valve 38 and the upstream end of the refrigerant flow path in the radiator 24. The upstream end of the intercooler flow path 34 is connected to the flow path 22a. The downstream end of the intercooler flow path 34 is connected to the flow path 22b. The intercooler flow path 34 is a flow path provided so that the refrigerant flows in parallel with the intermediate heat exchanger 30. The upstream end of the bypass flow path 36 is connected to the three-way valve 38. The downstream end of the bypass flow path 36 is connected to the flow path 22a upstream of the intercooler flow path 34. The second cooling flow path 22 is made up of a flow path 22b, a flow path 22c, a refrigerant flow path in the radiator 24, a flow path 22a, an intercooler flow path 34, a bypass flow path 36, and a second heat exchange flow path 30b. The second cooling flow path 22 is an annular flow path through which the refrigerant circulates.

[0020] The intercooler 32 is provided in an intercooler flow path 34. The intercooler 32 cools the compressed air supplied to the fuel cell 14 by heat exchange with the refrigerant flowing through the intercooler flow path 34.

[0021] The three-way valve switches between a state in which the flow path 22b is connected to the flow path 22c and a state in which the flow path 22b is connected to the bypass flow path .

[0022] The second cooling system 20 has a pump 26. The pump 26 is provided in the flow path 22a. The pump 26 is provided downstream of a connection between the flow path 22a and a bypass flow path 36 and upstream of a connection between the flow path 22a and an intercooler flow path 34. The pump 26 sends out refrigerant from its installation position toward the intermediate heat exchanger 30 and the intercooler 32.

[0023] The second cooling system 20 has a temperature sensor 28a and a temperature sensor 28b. The temperature sensor 28a is provided in the flow path 22a. The temperature sensor 28a detects the temperature of the coolant discharged from the radiator 24. The temperature sensor 28b is provided in the flow path 22c. The temperature sensor 28b detects the temperature of the coolant flowing into the radiator 24.

[0024] The fuel cell cooling system 100 includes a control device 40. The control device 40 controls the pump 16, the pump 26, and the three-way valve 38 based on the temperature of the coolant in the first cooling flow path 12.

[0025] The fuel cell 14 is supplied with compressed air from an air compressor (not shown) and hydrogen from a tank (not shown). The fuel cell 14 generates electricity by reacting oxygen with hydrogen. While the fuel cell 14 is generating electricity, the fuel cell cooling system 100 can execute warm-up control and normal control, which will be described below.

[0026] Warm-up control is performed when the temperature of the fuel cell 14 is low. In warm-up control, the control device 40 operates the pump 16. When the pump 16 operates, the refrigerant circulates through the first cooling flow path 12 in the following order: intermediate heat exchanger 30, flow path 12a, fuel cell 14, and flow path 12b. Therefore, heat generated by power generation in the fuel cell 14 is transferred to the intermediate heat exchanger 30 (i.e., first heat exchange flow path 30a) by the refrigerant in the first cooling flow path 12. The intermediate heat exchanger 30 transfers the heat generated by power generation in the fuel cell 14 from the first heat exchange flow path 30a to the second heat exchange flow path 30b.

[0027] Furthermore, in the warm-up control, the control device 40 operates the pump 26. Furthermore, the control device 40 connects the flow path 22b to the bypass flow path 36 using the three-way valve 38. Therefore, the refrigerant circulates through the first circulation flow path 101 indicated by the arrow in FIG. 2. That is, the refrigerant sent out by the pump 26 flows in parallel through the intermediate heat exchanger 30 and the intercooler 32. The refrigerant that has passed through the intermediate heat exchanger 30 and the intercooler 32 then flows into the bypass flow path 36 via the three-way valve 38. Therefore, the refrigerant does not flow through the radiator 24. The intermediate heat exchanger 30 cools the refrigerant in the first cooling flow path 12 by heat exchange between the first cooling flow path 12 and the second cooling flow path 22. Furthermore, the intercooler 32 cools the compressed air supplied to the fuel cell 14 by heat exchange with the refrigerant flowing through the intercooler flow path 34.

[0028] As explained above, during warm-up control, the fuel cell 14 is cooled, and the compressed air supplied to the fuel cell 14 is cooled by the intercooler 32. Furthermore, during warm-up control, the refrigerant does not flow through the radiator 24, so the refrigerant in the second cooling flow path 22 is not easily cooled. This makes it difficult for heat exchange to occur in the intermediate heat exchanger 30, and the refrigerant in the first cooling flow path 12 is also not easily cooled. Therefore, the temperature of the fuel cell 14 is likely to rise.

[0029] Normal control is executed when the temperature of the fuel cell 14 is higher than a reference value. In normal control, the control device 40 operates the pump 16. Therefore, similar to warm-up control, the refrigerant circulates through the first cooling flow path 12. Therefore, heat generated by power generation in the fuel cell 14 is transferred to the intermediate heat exchanger 30 (i.e., the first heat exchange flow path 30a) by the refrigerant in the first cooling flow path 12. The intermediate heat exchanger 30 transfers the heat generated by power generation in the fuel cell 14 from the first heat exchange flow path 30a to the second heat exchange flow path 30b.

[0030] Furthermore, in normal control, the control device 40 operates the pump 26. Furthermore, the control device 40 connects the flow path 22b to the flow path 22c using the three-way valve 38. Therefore, the refrigerant circulates through the second circulation flow path 102 indicated by the arrow in FIG. 3 . That is, the refrigerant pumped out by the pump 26 flows in parallel through the intermediate heat exchanger 30 and the intercooler 32. The refrigerant that has passed through the intermediate heat exchanger 30 and the intercooler 32 then flows to the radiator 24 via the three-way valve 38. Therefore, the refrigerant does not flow through the bypass flow path 36. The radiator 24 cools the refrigerant in the second cooling flow path 22 by heat exchange with outside air. Therefore, the refrigerant cooled by the radiator 24 flows through the intermediate heat exchanger 30 and the intercooler 32. The intermediate heat exchanger 30 cools the refrigerant in the first cooling flow path 12 by heat exchange between the first cooling flow path 12 and the second cooling flow path 22. Because the refrigerant in the second cooling flow path 22 is cooled by the radiator 24, the intermediate heat exchanger 30 can efficiently cool the refrigerant in the first cooling flow path 12. In addition, the intercooler 32 cools the compressed air supplied to the fuel cell 14 by heat exchange with the refrigerant flowing through the intercooler flow path 34.

[0031] As described above, under normal control, the fuel cell 14 is cooled, and the compressed air supplied to the fuel cell 14 is cooled by the intercooler 32. Also, under normal control, the radiator 24 cools the refrigerant in the second cooling flow path 22. Therefore, the intermediate heat exchanger 30 can effectively cool the refrigerant in the first cooling flow path 12. Therefore, the fuel cell 14 can be effectively cooled.

[0032] The control device 40 executes the process shown in the flowchart of FIG.

[0033] In step S2, the control device 40 measures the outside air temperature using a temperature sensor (not shown). The control device 40 determines whether the outside air temperature is equal to or lower than a cold temperature determination temperature T1 (e.g., 0°C). When the vehicle is stopped, the temperature of the refrigerant is approximately equal to the outside air temperature. Therefore, the processing of step S2 is equivalent to determining whether the temperature of the refrigerant flowing through the first cooling flow path 12 is equal to or lower than the cold temperature determination temperature T1.

[0034] If the outside air temperature is below the cold temperature determination temperature T1 (YES in step S2), the control device 40 performs cold temperature warm-up control in step S4. In cold temperature warm-up control, the control device 40 performs the warm-up control described above. In cold temperature warm-up control, the control device 40 controls the output current of the fuel cell 14 to a high value. Also, in cold temperature warm-up control, the control device 40 controls the discharge flow rates of the pumps 16 and 26 to a low value. As described above, the temperature of the fuel cell 14 is likely to rise during warm-up control. In particular, in cold temperature warm-up control, the output current of the fuel cell 14 is high, so heat is likely to be generated in the fuel cell 14. Also, because the discharge flow rates of the pumps 16 and 26 are low, heat is unlikely to be transferred from the fuel cell 14 to the refrigerant. For this reason, the temperature of the fuel cell 14 is particularly likely to rise. In this way, when the air temperature is below the cold temperature determination temperature T1, the cold temperature warm-up control is performed, and the temperature of the fuel cell 14 rises quickly. This increases the power generation efficiency of the fuel cell 14.

[0035] If the FC outlet temperature is lower than the cold weather warm-up control termination temperature T2, the control device 40 performs cold weather warm-up control until the vehicle power is turned off (i.e., YES in step S6, NO in step S8).If the FC outlet temperature exceeds the cold weather warm-up control termination temperature T2 (NO in step S6), the control device 40 performs step S12.

[0036] If the outside air temperature is higher than the cold temperature determination temperature T1 in step S2, the control device 40 determines in step S10 whether the FC outlet temperature is lower than the warm-up control end temperature T3. That is, the control device 40 determines whether the temperature of the refrigerant flowing through the first cooling flow path 12 is lower than the warm-up control end temperature T3. The warm-up control end temperature T3 is a temperature higher than the cold temperature determination temperature T1.

[0037] If the FC outlet temperature is lower than the warm-up control termination temperature T3 (YES in step S10), the control device 40 performs normal warm-up control in step S12. In normal warm-up control, the control device 40 performs the warm-up control described above. In normal warm-up control, the control device 40 controls the output current of the fuel cell 14 to a low value (i.e., a value lower than that in step S4). Also, in normal warm-up control, the control device 40 controls the discharge flow rates of the pumps 16, 26 to a high value (i.e., a value higher than that in step S4). As described above, the temperature of the fuel cell 14 is likely to rise in warm-up control. However, in normal warm-up control, the output current of the fuel cell 14 is low and the discharge flow rates of the pumps 16, 26 are high, so the temperature of the fuel cell 14 is less likely to rise than in cold weather warm-up control. In this way, when the temperature of the fuel cell 14 is relatively high, the amount of power generated by the fuel cell 14 is reduced and the flow rate of the coolant is increased compared to cold weather warm-up control, thereby mitigating the temperature gradient within the fuel cell 14.

[0038] If the FC outlet temperature is lower than the warm-up control end temperature T3, the control device 40 performs normal warm-up control until the vehicle power is turned off (i.e., YES in S10, NO in step S14). If the FC outlet temperature exceeds the warm-up control end temperature T3 (NO in step S10), the control device 40 performs step S16.

[0039] In step S16, the control device 40 performs the normal control described above, thereby efficiently cooling the fuel cell 14 and efficiently cooling the compressed air by the intercooler 32.

[0040] If the FC outlet temperature is higher than the warm-up control resumption temperature T4, the control device 40 performs normal control until the vehicle power is turned off (i.e., NO in step S18, NO in S20). Note that the warm-up control resumption temperature T4 is a temperature lower than the warm-up control end temperature T3. If the FC outlet temperature becomes lower than the warm-up control resumption temperature T4 (YES in step S18), the control device 40 performs normal warm-up control in step S12.

[0041] In the embodiment, the intercooler 32 is provided in the intercooler flow path 34. However, the intercooler 32 may be provided in the flow path 22b. The intercooler 32 may also be provided between the pump 26 and the intermediate heat exchanger 30. That is, the refrigerant may flow in series through the intermediate heat exchanger 30 and the intercooler 32.

[0042] The cold warm-up control and normal warm-up control of the embodiment are examples of the first operation, and the normal control of the embodiment is an example of the second operation.

[0043] The warm-up control end temperature T3 in the embodiment is an example of a first reference value, and the cold temperature determination temperature T1 in the embodiment is an example of a second reference value.

[0044] In the embodiment, the flow path changing device that changes the path through which the refrigerant flows in the second cooling flow path 22 is configured by the three-way valve 38, but the flow path changing device may be configured by other devices. Also, in the embodiment, the three-way valve 38 is an electromagnetic valve, but the flow path changing device may be configured by a device that does not use electricity. For example, the flow path changing device may be configured by a device that switches the flow path by thermal expansion of a material, such as a thermostat.

[0045] In the embodiment, the temperature sensor 18a detects the temperature of the coolant flowing into the fuel cell 14. However, the temperature sensor 18a may be provided near the outlet or inlet of the intermediate heat exchanger 30.

[0046] The temperature sensor 18b detects the temperature of the coolant discharged from the fuel cell 14. However, the temperature sensor 18b may be provided near the outlet or inlet of the intermediate heat exchanger 30.

[0047] In the embodiment, the temperature sensor 28a detects the temperature of the refrigerant discharged from the radiator 24. However, the temperature sensor 28a may be provided near the outlet or inlet of the intermediate heat exchanger 30.

[0048] In the embodiment, the temperature sensor 28b is provided in the flow path 22c. However, the temperature sensor 28b may be provided near the outlet or inlet of the intermediate heat exchanger 30.

[0049] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0050] 10: 1st cooling system 12: First cooling channel 14:Fuel cell 16: Pump 20:Second cooling system 22: Second cooling channel 24: Radiator 26: Pump 30: Intermediate heat exchanger 32: Intercooler 34: Intercooler flow passage 36: Bypass flow path 38: Three-way valve 40: Control device 100: Fuel cell cooling system 101: First circulation channel 102: Second circulation flow path

Claims

1. 1. A fuel cell cooling system, comprising: a first cooling flow path through which a coolant is circulated; a fuel cell provided in the first cooling flow path; a second cooling flow path through which a coolant is circulated; a radiator provided in the second cooling flow path; an intercooler provided in the second cooling flow path; an intermediate heat exchanger that exchanges heat between the first cooling flow path and the second cooling flow path; Equipped with the second cooling flow path includes a bypass flow path provided in parallel with the radiator, when a temperature of the refrigerant in the first cooling flow path is lower than a first reference value during power generation by the fuel cell, a first operation is performed to circulate the refrigerant in the first cooling flow path through a path passing through the fuel cell and the intermediate heat exchanger, and to circulate the refrigerant in the second cooling flow path through a path passing through the intermediate heat exchanger, the intercooler, and the bypass flow path, When the temperature of the refrigerant in the first cooling flow path is higher than the first reference value during power generation by the fuel cell, a second operation is performed in which the refrigerant is circulated in the first cooling flow path through a path passing through the fuel cell and the intermediate heat exchanger, and the refrigerant is circulated in the second cooling flow path through a path passing through the intermediate heat exchanger, the intercooler, and the radiator. Fuel cell cooling system.

2. In the first operation and the second operation, the refrigerant flows in parallel through the intermediate heat exchanger and the intercooler in the second cooling flow path. The fuel cell cooling system of claim 1 .

3. 3. The fuel cell cooling system according to claim 1, wherein, in the first operation, when the temperature of the refrigerant in the first cooling flow path is lower than a second reference value, the circulation speed of the refrigerant in the first cooling flow path is slower than when the temperature of the refrigerant in the first cooling flow path is higher than the second reference value.

4. 4. The fuel cell cooling system of claim 3, wherein, in the first operation, when the temperature of the refrigerant in the first cooling flow path is lower than the second reference value, the circulation speed of the refrigerant in the second cooling flow path is slower than when the temperature of the refrigerant in the first cooling flow path is higher than the second reference value.

Images