System for cooling fuel cell

Abstract

To provide technique that suppresses thermal degradation of an ion exchanger.SOLUTION: A system for cooling a fuel cell comprise: a first cooling flow path; a fuel cell; an ion exchanger; a second cooling flow path; a radiator; and an intermediate heat exchanger. When the temperature of the coolant in the first cooling flow path is lower than a reference value during power generation performed by the fuel cell, a first operation is performed in which the coolant is circulated through the intermediate heat exchanger into the first cooling flow path via a path where the coolant flows in parallel with the fuel cell and ion exchanger, and coolant is circulated into the second cooling flow path via a path through the intermediate heat exchanger and radiator. When the temperature of the coolant in the first cooling flow path is higher than the reference value during the power generation performed by the fuel cell, a second operation is performed in which the coolant is circulated in the first cooling flow path via a path through the intermediate heat exchanger and the fuel cell while closing the flow path of the ion exchanger, the coolant is circulated in the second cooling flow path via a path through the intermediate heat exchanger and the 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 ion exchanger may be provided to remove ions from the refrigerant flowing through the cooling channel. In the technology of Patent Document 1, if an ion exchanger is provided in the first cooling channel, high-temperature refrigerant may flow into the ion exchanger, causing deterioration of the ion exchanger. This specification proposes a technology to suppress thermal deterioration of the ion exchanger. [Means for solving the problem]

[0005] (Aspect 1) The fuel cell cooling system disclosed in this specification includes a first cooling flow path for circulating a refrigerant, a fuel cell provided in the first cooling flow path, an ion exchanger provided in the first cooling flow path, a second cooling flow path for circulating a refrigerant, a radiator provided in the second cooling flow path, and an intermediate heat exchanger for exchanging heat between the first cooling flow path and the second cooling flow path, and when the temperature of the refrigerant in the first cooling flow path is lower than a reference value during power generation by the fuel cell, the refrigerant that has passed through the intermediate heat exchanger flows in parallel to the fuel cell and the ion exchanger. and performing a first operation of circulating the refrigerant through the first cooling flow path through a path passing through the intermediate heat exchanger and the radiator, and circulating the refrigerant through the second cooling flow path through a path passing through the intermediate heat exchanger and the radiator, and when a temperature of the refrigerant in the first cooling flow path is higher than the reference value during power generation by the fuel cell, performing a second operation of circulating the refrigerant through the first cooling flow path through a path passing through the intermediate heat exchanger and the fuel cell with the flow path of the ion exchanger closed, and circulating the refrigerant through the second cooling flow path through a path passing through the intermediate heat exchanger and the radiator.

[0006] In the above fuel cell cooling system, when the temperature of the refrigerant in the first cooling flow path is higher than a reference value during power generation by the fuel cell, a second operation is performed. In the second operation, the refrigerant circulates through the first cooling flow path via a route that passes through the intermediate heat exchanger and the fuel cell while the flow path of the ion exchanger is closed. In other words, high-temperature refrigerant does not flow into the ion exchanger. As a result, thermal degradation of the ion exchanger can be suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a block diagram of a fuel cell cooling system according to a first embodiment. [Figure 2] 4 is a flowchart of an operation selection process of the fuel cell cooling system according to the first embodiment. [Figure 3] FIG. 10 is a block diagram of a fuel cell cooling system according to a second embodiment. [Figure 4] 10 is a flowchart of an operation selection process of a fuel cell cooling system according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Following the above-mentioned first embodiment, additional configurations of the fuel cell cooling system disclosed in this specification will be described below. (Aspect 2) 2. The fuel cell cooling system of claim 1, wherein the reference temperature is 75° C. or higher. (Aspect 3) A fuel cell cooling system as described in aspect 1 or 2, wherein the first operation is performed when the temperature of the refrigerant in the first cooling flow path is higher than the reference value and the conductivity of the refrigerant in the first cooling flow path is higher than a threshold value. (Aspect 4) 4. The fuel cell cooling system according to any one of aspects 1 to 3, wherein the first cooling flow path includes a fuel cell flow path in which the fuel cell is provided, an ion exchanger flow path in which the ion exchanger is provided, and an intermediate heat exchanger flow path in which the intermediate heat exchanger is provided, wherein a downstream end of the intermediate heat exchanger flow path is connected to an upstream end of the ion exchanger flow path and an upstream end of the fuel cell flow path, and wherein the upstream end of the intermediate heat exchanger flow path is connected to a downstream end of the ion exchanger flow path and a downstream end of the fuel cell flow path, and wherein the fuel cell cooling system further includes a pump provided in the intermediate heat exchanger flow path.

[0009] According to the second aspect, deterioration of the resin of the ion exchanger can be suppressed.

[0010] According to the third aspect, even if the temperature of the refrigerant in the first cooling channel is high, if the conductivity of the first cooling channel is high, the refrigerant in the first cooling channel is allowed to flow into the ion exchanger, thereby suppressing an increase in the conductivity of the refrigerant while minimizing thermal degradation of the ion exchanger.

[0011] According to the fourth aspect, the refrigerant cooled in the intermediate heat exchanger flows into the ion exchanger, so that thermal deterioration of the ion exchanger can be more effectively suppressed.

[0012] Example 1 A fuel cell cooling system according to a first embodiment will be described. The fuel cell cooling system 100 shown in Fig. 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 flow path 12, a second cooling flow path 22, an intermediate heat exchanger 30, a fuel cell 14, an ion exchanger 32, and a radiator 24.

[0013] 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 passage 12, and the second heat exchange passage 30b is part of the second cooling passage 22. The intermediate heat exchanger 30 causes heat exchange between the first heat exchange passage 30a and the second heat exchange passage 30b. That is, the intermediate heat exchanger 30 causes heat exchange between the first cooling passage 12 and the second cooling passage 22.

[0014] The first cooling flow path 12 has a fuel cell flow path 12a, an ion exchanger flow path 12b, and an intermediate heat exchanger flow path 12c. A fuel cell 14 is provided in the fuel cell flow path 12a. An ion exchanger 32 is provided in the ion exchanger flow path 12b. An intermediate heat exchanger 30 is provided in the intermediate heat exchanger flow path 12c. A portion of the intermediate heat exchanger flow path 12c is formed by the first heat exchange flow path 30a of the intermediate heat exchanger 30. The downstream end of the intermediate heat exchanger flow path 12c is connected to the upstream end of the ion exchanger flow path 12b and the upstream end of the fuel cell flow path 12a. Furthermore, the upstream end of the intermediate heat exchanger flow path 12c is connected to the downstream end of the ion exchanger flow path 12b and the downstream end of the fuel cell flow path 12a. A pump 16 is provided in the intermediate heat exchanger flow path 12c. The pump 16 pumps refrigerant from its installation position toward the intermediate heat exchanger 30. When the pump 16 is operated, the refrigerant circulates through the first cooling flow path 12. The refrigerant that has passed through the intermediate heat exchanger flow path 12c flows in parallel to the ion exchanger flow path 12b and the fuel cell flow path 12a.

[0015] 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). The fuel cell 14 is cooled by a refrigerant flowing through the fuel cell flow path 12a.

[0016] The ion exchanger 32 removes ions from the refrigerant flowing through the ion exchanger flow path 12b. The ion exchanger 32 reduces the ion concentration in the refrigerant, thereby reducing the conductivity of the refrigerant.

[0017] A valve 38 is provided in the ion exchanger flow path 12b. The valve 38 is provided between the upstream end of the ion exchanger flow path 12b and the ion exchanger 32. The valve 38 opens and closes the flow path of the ion exchanger flow path 12b. When the valve 38 is open, the refrigerant that has passed through the intermediate heat exchanger 30 flows in parallel through the ion exchanger flow path 12b and the fuel cell flow path 12a. When the valve 38 is closed, the refrigerant that has passed through the intermediate heat exchanger 30 does not flow through the ion exchanger flow path 12b, but flows through the fuel cell flow path 12a.

[0018] The fuel cell cooling system 100 has temperature sensors 18a and 18b. The temperature sensor 18a is provided upstream of the fuel cell flow path 12a. The temperature sensor 18a detects the temperature of the coolant flowing into the fuel cell 14 (hereinafter referred to as the FC inlet temperature). The temperature sensor 18b is provided downstream of the fuel cell flow path 12a. The temperature sensor 18b detects the temperature of the coolant discharged from the fuel cell 14.

[0019] The second cooling flow path 22 is an annular flow path. A 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. An intermediate heat exchanger 30 is also provided in the second cooling flow path 22. A portion of the second cooling flow path 22 is configured by the second heat exchange flow path 30b of the intermediate heat exchanger 30.

[0020] The fuel cell cooling system 100 includes a pump 26, a temperature sensor 28a, and a temperature sensor 28b.

[0021] The pump 26 is provided in the second cooling flow path 22. The pump 26 sends out the refrigerant from its installation position toward the intermediate heat exchanger 30. When the pump 26 operates, the refrigerant circulates within the second cooling flow path 22.

[0022] Temperature sensor 28a is provided in second cooling flow path 22, downstream of radiator 24. Temperature sensor 28a detects the temperature of the refrigerant discharged from radiator 24. Temperature sensor 28b is provided in second cooling flow path 22, upstream of radiator 24. Temperature sensor 28b detects the temperature of the refrigerant flowing into radiator 24.

[0023] The fuel cell cooling system 100 includes a control device 40. The control device 40 controls the pump 16, the pump 26, and the valve 38 based on the temperature of the coolant in the first cooling flow path 12.

[0024] When the fuel cell 14 generates power, the fuel cell 14 generates heat. The control device 40 operates the pumps 16 and 26 while the fuel cell 14 is generating power. When the pump 16 operates, a refrigerant circulates through the first cooling flow path 12. When the pump 26 operates, a refrigerant circulates through the second cooling flow path 22. The fuel cell 14 is cooled by heat exchange between the refrigerant in the first cooling flow path 12 and the fuel cell 14. 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. The heat is transferred from the intermediate heat exchanger 30 to the radiator 24 by the refrigerant in the second cooling flow path 22. The refrigerant in the second cooling flow path 22 is cooled by the radiator 24 exchanging heat with outside air.

[0025] The fuel cell cooling system 100 controls the valve 38 according to the flowchart shown in FIG. 2 while the fuel cell 14 is generating electricity.

[0026] In step S2, the control device 40 determines whether the FC inlet temperature is equal to or lower than a judgment temperature T1. The judgment temperature T1 is set to a temperature (e.g., 75°C or higher) that can ensure the performance of the ion exchanger 32. For example, the temperature at which the resin in the ion exchanger 32 starts to deteriorate can be used as the judgment temperature T1.

[0027] If the FC inlet temperature is equal to or lower than the judgment temperature T1 (YES in step S2), the control device 40 opens the valve 38 (step S4). When the valve 38 is opened, the refrigerant that has passed through the intermediate heat exchanger 30 flows in parallel to the ion exchanger 32 and the fuel cell 14 in the first cooling flow path 12. In this case, the temperature of the refrigerant in the first cooling flow path 12 is low, so the low-temperature refrigerant flows into the ion exchanger 32. Therefore, the ion exchanger 32 is less likely to be deteriorated by the heat of the refrigerant that flows in. In particular, because the low-temperature refrigerant immediately after passing through the intermediate heat exchanger 30 flows into the ion exchanger 32, thermal deterioration of the ion exchanger 32 can be effectively suppressed. Furthermore, if the judgment temperature T1 is set to the resin deterioration start temperature, deterioration of the resin in the ion exchanger 32 can be effectively suppressed. When the refrigerant flows into the ion exchanger 32, the ion exchanger 32 removes ions from the refrigerant. This reduces the ion concentration in the refrigerant and the conductivity of the refrigerant. Furthermore, the fuel cell 14 is efficiently cooled by the inflowing coolant.

[0028] The control device 40 repeatedly executes steps S2 to S6 while the FC inlet temperature is equal to or lower than the judgment temperature T1. Therefore, while the FC inlet temperature is equal to or lower than the judgment temperature T1, the control device 40 keeps the valve 38 open until the vehicle power is turned off.

[0029] If the FC inlet temperature exceeds the judgment temperature T1 (NO in step S2), the control device 40 closes the valve 38 (step S8). With the valve 38 closed, the refrigerant that has passed through the intermediate heat exchanger 30 does not flow to the ion exchanger 32 in the first cooling flow path 12. Therefore, in the first cooling flow path 12, the refrigerant circulates between the intermediate heat exchanger 30 and the fuel cell 14. In this way, when the temperature of the refrigerant in the first cooling flow path 12 is high, closing the valve 38 prevents the high-temperature refrigerant from flowing into the ion exchanger 32. Therefore, the ion exchanger 32 is less likely to deteriorate due to the heat of the refrigerant. Furthermore, the fuel cell 14 is cooled by the refrigerant.

[0030] The control device 40 repeatedly executes steps S2, S8, and S10 while the FC inlet temperature exceeds the determination temperature T1. Therefore, while the FC inlet temperature exceeds the determination temperature T1, the control device 40 keeps the valve 38 closed until the vehicle power is turned off.

[0031] As described above, in the first embodiment, the control device 40 closes the valve 38 when the FC inlet temperature is high, thereby preventing high-temperature refrigerant from flowing into the ion exchanger 32. Therefore, deterioration of the ion exchanger 32 can be suppressed.

[0032] Example 2 A fuel cell cooling system according to the second embodiment will be described. As shown in Fig. 3, the fuel cell cooling system 200 according to the second embodiment has a configuration in which a conductivity meter 50 is added to the fuel cell cooling system 100 according to the first embodiment. The conductivity meter 50 measures the conductivity C2 of the refrigerant flowing through the first cooling flow path 12.

[0033] The fuel cell cooling system 200 controls the valve 38 according to the flowchart shown in Fig. 4 while the fuel cell 14 is generating electricity. Steps S2, S4, S6, and S8 shown in Fig. 4 are the same as steps S2, S4, S6, and S8 shown in Fig. 2.

[0034] In the second embodiment, after performing step S8, the control device 40 determines in step S20 whether the conductivity C2 exceeds the conductivity upper limit C1.

[0035] If the electrical conductivity C2 exceeds the electrical conductivity upper limit C1 (YES in step S20), the control device 40 opens the valve 38 (step S22). When the valve 38 opens, the refrigerant that has passed through the intermediate heat exchanger 30 flows in parallel to the ion exchanger 32 and the fuel cell 14 in the first cooling flow path 12. When the refrigerant flows through the ion exchanger 32, the ion exchanger 32 removes ions from the refrigerant. This reduces the ion concentration in the refrigerant. As a result, the electrical conductivity C2 of the refrigerant flowing through the first cooling flow path 12 decreases.

[0036] The control device 40 repeatedly executes steps S20 to S24 while the conductivity C2 exceeds the conductivity upper limit C1. Therefore, while the conductivity C2 exceeds the conductivity upper limit C1, the control device 40 keeps the valve 38 open until the vehicle power is turned off. This causes the conductivity C2 to decrease.

[0037] If the electrical conductivity C2 is less than the upper limit C1 (NO in step S20), the control device 40 keeps the valve 38 closed. Therefore, in the first cooling flow path 12, the refrigerant that has passed through the intermediate heat exchanger 30 does not flow to the ion exchanger 32. Therefore, in the first cooling flow path 12, the refrigerant circulates between the intermediate heat exchanger 30 and the fuel cell 14. In this way, when the temperature of the refrigerant in the first cooling flow path 12 is high and the electrical conductivity C2 is less than the upper limit C1, the control device 40 closes the valve 38 to prevent the high-temperature refrigerant from flowing into the ion exchanger 32. Therefore, deterioration of the ion exchanger 32 due to heat of the refrigerant is unlikely to occur. The control device 40 repeatedly executes steps S2, S8, S20, and S26 while the electrical conductivity C2 is less than the upper limit C1. Therefore, while the electrical conductivity C2 is less than the upper limit C1, the control device 40 keeps the valve 38 closed until the vehicle is turned off.

[0038] As described above, in the second embodiment, the control device 40 opens the valve 38 when the conductivity C2 of the refrigerant in the first cooling flow path 12 is high, even if the temperature of the refrigerant in the first cooling flow path 12 is high. This prevents the conductivity C2 of the refrigerant flowing through the first cooling flow path 12 from becoming excessively high.

[0039] In the first and second embodiments, the flow path changing device that changes the path through which the refrigerant flows in the first cooling flow path 12 is configured by the valve 38, but the flow path changing device may be configured by other devices (for example, a three-way valve, etc.). Also, in the first embodiment, the valve 38 is a solenoid 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.

[0040] The process of opening the valve 38 in the first and second embodiments is an example of a first operation. The process of closing the valve 38 in the first and second embodiments is an example of a second operation.

[0041] The determination temperature T1 in the first and second embodiments is an example of a reference value, and the conductivity upper limit C1 in the second embodiment is an example of a threshold value.

[0042] 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]

[0043] 12: First cooling channel 12a: fuel cell flow path 12b: Ion exchanger flow path 12c: Intermediate heat exchanger flow path 14:Fuel cell 16: Pump 22: Second cooling channel 24: Radiator 26: Pump 30: Intermediate heat exchanger 32: Ion exchanger 38: Valve 40: Control device 50: Conductivity meter 100: Fuel cell cooling system 200: Fuel cell cooling system

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; an ion exchanger 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 intermediate heat exchanger that exchanges heat between the first cooling flow path and the second cooling flow path; Equipped with when the temperature of the refrigerant in the first cooling flow path is lower than a reference value during power generation by the fuel cell, a first operation is performed in which the refrigerant that has passed through the intermediate heat exchanger is circulated in the first cooling flow path through a path that flows in parallel to the fuel cell and the ion exchanger, and the refrigerant is circulated in the second cooling flow path through a path that passes through the intermediate heat exchanger and the radiator, When the temperature of the refrigerant in the first cooling flow path is higher than the 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 intermediate heat exchanger and the fuel cell while the flow path of the ion exchanger is closed, and the refrigerant is circulated in the second cooling flow path through a path passing through the intermediate heat exchanger and the radiator. Fuel cell cooling system.

2. The fuel cell cooling system according to claim 1 , wherein the reference value is 75° C. or higher.

3. 3. The fuel cell cooling system according to claim 1, wherein the first operation is performed when the temperature of the coolant in the first cooling flow path is higher than the reference value and the conductivity of the coolant in the first cooling flow path is higher than a threshold value.

4. The first cooling channel is a fuel cell flow path in which the fuel cell is provided; an ion exchanger flow path provided with the ion exchanger; an intermediate heat exchanger flow path provided with the intermediate heat exchanger; Equipped with a downstream end of the intermediate heat exchanger flow path is connected to an upstream end of the ion exchanger flow path and an upstream end of the fuel cell flow path; an upstream end of the intermediate heat exchanger flow path is connected to a downstream end of the ion exchanger flow path and a downstream end of the fuel cell flow path; A pump is provided in the intermediate heat exchanger flow path.

3. The fuel cell cooling system according to claim 1.

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