Fuel cell cooling system

Abstract

This fuel cell cooling system is provided with a first cooling flow path, a fuel cell, an ion exchanger, a second cooling flow path, a radiator, and an intermediate heat exchanger, and performs a first operation 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, and performs a second operation when the temperature of the refrigerant in the second cooling flow path is lower than the reference value. The refrigerant is circulated in the first cooling flow path according to a path through which the refrigerant that has passed through the intermediate heat exchanger flows side by side to the fuel cell and the ion exchanger, and the refrigerant is circulated in the second cooling flow path according to a path 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, the second operation is performed.

Description

Technical Field

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

[0002] The fuel cell system disclosed in Japanese Patent Application Laid-Open No. 2002-33108 includes a first cooling flow path and a second cooling flow path through which a refrigerant circulates. 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 performs heat exchange between the first and second cooling flow paths.

[0003] In some fuel cell systems, an ion exchanger is installed to remove ions from the refrigerant flowing through the cooling flow path. According to the technology of Japanese Patent Application Laid-Open No. 2002-33108, if an ion exchanger is installed in the first cooling flow path, high-temperature refrigerant may flow into the ion exchanger, causing it to degrade. This specification proposes a technology for suppressing thermal degradation of the ion exchanger. Summary of the Invention

[0004] Technical Solution 1

[0005] A fuel cell cooling system, wherein the fuel cell cooling system disclosed in this specification comprises: a first cooling flow path for circulating a refrigerant; a fuel cell arranged in the above-mentioned first cooling flow path; an ion exchanger arranged in the above-mentioned first cooling flow path; a second cooling flow path for circulating a refrigerant; a radiator arranged in the above-mentioned second cooling flow path; and an intermediate heat exchanger for performing heat exchange between the above-mentioned first cooling flow path and the above-mentioned second cooling flow path, wherein when the temperature of the refrigerant in the above-mentioned first cooling flow path is lower than a reference value during power generation of the above-mentioned fuel cell, a first action is performed, in which the refrigerant passing through the above-mentioned intermediate heat exchanger is discharged to the above-mentioned fuel cell. The refrigerant circulates in the first cooling flow path according to the path flowing through the pool and the above-mentioned ion exchanger, and circulates in the second cooling flow path according to the path passing through the above-mentioned intermediate heat exchanger and the above-mentioned radiator. When the temperature of the refrigerant in the above-mentioned first cooling flow path is higher than the above-mentioned reference value during power generation of the above-mentioned fuel cell, a second action is performed. In the second action, with the flow path of the above-mentioned ion exchanger closed, the refrigerant circulates in the first cooling flow path according to the path passing through the above-mentioned intermediate heat exchanger and the above-mentioned fuel cell, and circulates in the second cooling flow path according to the path passing through the above-mentioned intermediate heat exchanger and the above-mentioned radiator.

[0006] In the above-described fuel cell cooling system, when the temperature of the refrigerant in the first cooling flow path exceeds a reference value during fuel cell power generation, a second action is performed. In the second action, the refrigerant circulates through the first cooling flow path, passing through the intermediate heat exchanger and the fuel cell, while the flow path of the ion exchanger is closed. This prevents high-temperature refrigerant from flowing into the ion exchanger. As a result, thermal degradation of the ion exchanger can be suppressed.

[0007] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention are described below with reference to the accompanying drawings, wherein like reference numerals denote like elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a block diagram of a fuel cell cooling system according to Example 1;

[0009] Figure 2 This is a flowchart of the action selection process of the fuel cell cooling system of Example 1;

[0010] Figure 3 is a block diagram of a fuel cell cooling system according to Example 2;

[0011] Figure 4 This is a flowchart of the operation selection process of the fuel cell cooling system of the second embodiment. DETAILED DESCRIPTION

[0012] Following the above-mentioned technical solution 1, the additional structure of the fuel cell cooling system disclosed in this specification will be described below.

[0013] Technical Solution 2

[0014] In the fuel cell cooling system according to claim 1, the temperature of the reference value is 75° C. or higher.

[0015] Technical Solution 3

[0016] In the fuel cell cooling system according to claim 1 or 2, the first action 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.

[0017] Technical Solution 4

[0018] Based on the fuel cell cooling system described in any one of technical solutions 1 to 3, the above-mentioned first cooling flow path comprises: a fuel cell flow path, in which the above-mentioned fuel cell is provided; an ion exchanger flow path, in which the above-mentioned ion exchanger is provided; and an intermediate heat exchanger flow path, in which the above-mentioned intermediate heat exchanger is provided, the downstream end of the above-mentioned intermediate heat exchanger flow path is connected to the upstream end of the above-mentioned ion exchanger flow path and the upstream end of the above-mentioned fuel cell flow path, the upstream end of the above-mentioned intermediate heat exchanger flow path is connected to the downstream end of the above-mentioned ion exchanger flow path and the downstream end of the above-mentioned fuel cell flow path, and the fuel cell cooling system has a pump provided in the above-mentioned intermediate heat exchanger flow path.

[0019] According to the second aspect, degradation of the resin of the ion exchanger can be suppressed.

[0020] According to the third technical solution, even if the temperature of the refrigerant in the first cooling flow path is high, if the conductivity of the first cooling flow path is high, the refrigerant in the first cooling flow path is allowed to flow into the ion exchanger. As a result, thermal degradation of the ion exchanger can be minimized, and an increase in the conductivity of the refrigerant can be suppressed.

[0021] According to the fourth aspect, the refrigerant cooled in the intermediate heat exchanger flows into the ion exchanger, so that thermal degradation of the ion exchanger can be more effectively suppressed.

[0022] Example 1

[0023] The fuel cell cooling system of Example 1 will be described. Figure 1 The fuel cell cooling system 100 shown is installed in a device powered by a fuel cell (e.g., a fuel cell electric 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 .

[0024] The intermediate heat exchanger 30 includes a first heat exchange flow path 30a and a second heat exchange flow path 30b. The first heat exchange flow path 30a is part of the first cooling flow path 12, and the second heat exchange flow path 30b is part of the second cooling flow path 22. The intermediate heat exchanger 30 exchanges heat between the first heat exchange flow path 30a and the second heat exchange flow path 30b. In other words, the intermediate heat exchanger 30 exchanges heat between the first cooling flow path 12 and the second cooling flow path 22.

[0025] The first cooling flow path 12 includes 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 delivers refrigerant from its installation location toward the intermediate heat exchanger 30. When the pump 16 is operated, the refrigerant circulates in the first cooling flow path 12. The refrigerant having passed through the intermediate heat exchanger flow path 12 c flows in parallel to the ion exchanger flow path 12 b and the fuel cell flow path 12 a .

[0026] 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 electricity to a motor (not shown). The fuel cell 14 is cooled by a refrigerant flowing through the fuel cell flow path 12a.

[0027] The ion exchanger 32 removes ions from the refrigerant flowing in the ion exchanger flow path 12b. The ion exchanger 32 reduces the ion concentration in the refrigerant to reduce the electrical conductivity of the refrigerant.

[0028] A valve 38 is provided in the ion exchanger flow path 12b. Valve 38 is disposed between the upstream end of the ion exchanger flow path 12b and the ion exchanger 32. Valve 38 opens and closes the flow path of the ion exchanger flow path 12b. When valve 38 is open, refrigerant that has passed through the intermediate heat exchanger 30 flows side by side in the ion exchanger flow path 12b and the fuel cell flow path 12a. When valve 38 is closed, refrigerant that has passed through the intermediate heat exchanger 30 flows into the fuel cell flow path 12a instead of the ion exchanger flow path 12b.

[0029] The fuel cell cooling system 100 includes temperature sensors 18a and 18b. Temperature sensor 18a is located upstream of the fuel cell flow path 12a. Temperature sensor 18a detects the temperature of the refrigerant flowing into the fuel cell 14 (hereinafter also referred to as the FC inlet temperature). Temperature sensor 18b is located downstream of the fuel cell flow path 12a. Temperature sensor 18b detects the temperature of the refrigerant discharged from the fuel cell 14.

[0030] 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 in the second cooling flow path 22 by exchanging heat with the outside air. Furthermore, an intermediate heat exchanger 30 is provided in the second cooling flow path 22. A portion of the second cooling flow path 22 is formed by a second heat exchange flow path 30b of the intermediate heat exchanger 30.

[0031] The fuel cell cooling system 100 includes a pump 26 , a temperature sensor 28 a , and a temperature sensor 28 b .

[0032] The pump 26 is installed in the second cooling flow path 22. The pump 26 sends the refrigerant from the installation position toward the intermediate heat exchanger 30. When the pump 26 is operated, the refrigerant circulates in the second cooling flow path 22.

[0033] 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.

[0034] The fuel cell cooling system 100 includes a control device 40 . The control device 40 controls the pumps 16 and 26 and the valve 38 based on the temperature of the coolant in the first cooling flow path 12 .

[0035] When the fuel cell 14 generates electricity, the fuel cell 14 generates heat. The control device 40 operates the pumps 16 and 26 while the fuel cell 14 is generating electricity. When the pump 16 is operating, the refrigerant circulates in the first cooling flow path 12. When the pump 26 is operating, the refrigerant circulates in 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. The heat generated by the power generation of 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 the power generation of 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 via the refrigerant in the second cooling flow path 22. The radiator 24 cools the refrigerant in the second cooling flow path 22 by exchanging heat with the outside air.

[0036] The fuel cell cooling system 100 is used in accordance with the fuel cell 14 during power generation. Figure 2 The flow chart shown controls valve 38 .

[0037] In S2, the control device 40 determines whether the FC inlet temperature is equal to or lower than the determination temperature T1. The determination 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 degradation starting temperature of the resin in the ion exchanger 32 can be used as the determination temperature T1.

[0038] When the FC inlet temperature is below the judgment temperature T1 (if the answer is yes in S2), the control device 40 opens the valve 38 (S4). If the valve 38 is open, the refrigerant that has passed through the intermediate heat exchanger 30 in the first cooling flow path 12 flows side by side toward the ion exchanger 32 and the fuel cell 14. In this case, the temperature of the refrigerant in the first cooling flow path 12 is relatively low, so the low-temperature refrigerant flows into the ion exchanger 32. Therefore, the ion exchanger 32 is less likely to deteriorate due to the heat of the flowing refrigerant. In particular, the low-temperature refrigerant flows into the ion exchanger 32 shortly after passing through the intermediate heat exchanger 30, so thermal degradation of the ion exchanger 32 can be effectively suppressed. In addition, when the judgment temperature T1 is set to the resin degradation start temperature, degradation 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. As a result, the ion concentration in the refrigerant decreases, and the electrical conductivity of the refrigerant decreases. In addition, the fuel cell 14 is efficiently cooled by the inflowing refrigerant.

[0039] While the FC inlet temperature is below the determination temperature T1, the control device 40 repeatedly executes S2 to S6. Therefore, while the FC inlet temperature is below the determination temperature T1, the control device 40 opens the valve 38 until the vehicle power is turned off.

[0040] If the FC inlet temperature exceeds the determination temperature T1 (if S2 is negative), the control device 40 closes the valve 38 (S8). When the valve 38 is closed, the refrigerant that has passed through the intermediate heat exchanger 30 in the first cooling flow path 12 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, the valve 38 is closed, thereby preventing 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. In addition, the fuel cell 14 is cooled by the refrigerant.

[0041] While the FC inlet temperature exceeds the determination temperature T1, the control device 40 repeatedly executes S2, S8, and S10. Therefore, while the FC inlet temperature exceeds the determination temperature T1, the control device 40 closes the valve 38 until the vehicle power is turned off.

[0042] As described above, in the first embodiment, the control device 40 closes the valve 38 when the FC inlet temperature is high, thereby preventing the high-temperature refrigerant from flowing into the ion exchanger 32. Therefore, the deterioration of the ion exchanger 32 can be suppressed.

[0043] Example 2

[0044] The fuel cell cooling system of Example 2 is described. Figure 3 As shown, the fuel cell cooling system 200 of the second embodiment has a configuration in which a conductivity meter 50 is added to the fuel cell cooling system 100 of the first embodiment. The conductivity meter 50 measures the conductivity C2 of the coolant flowing in the first cooling flow path 12 .

[0045] The fuel cell cooling system 200 is used in accordance with the fuel cell 14 during power generation. Figure 4 As shown in the flow chart, the control valve 38 is controlled. Figure 4 S2, S4, S6 and S8 shown are Figure 2 S2, S4, S6 and S8 shown are the same.

[0046] In the second embodiment, after executing S8 , the control device 40 determines in S20 whether the conductivity C2 exceeds the conductivity upper limit value C1 .

[0047] When the conductivity C2 exceeds the conductivity upper limit C1 (if the answer is yes in S20), the control device 40 opens the valve 38 (S22). If the valve 38 is open, the refrigerant that has passed through the intermediate heat exchanger 30 in the first cooling flow path 12 flows side by side into the ion exchanger 32 and the fuel cell 14. If 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. As a result, the conductivity C2 of the refrigerant flowing in the first cooling flow path 12 is reduced.

[0048] While conductivity C2 exceeds conductivity upper limit C1, control device 40 repeatedly executes steps S20 to S24. Therefore, while conductivity C2 exceeds conductivity upper limit C1, control device 40 opens valve 38 until the vehicle is powered off. This reduces conductivity C2.

[0049] When the conductivity C2 is less than the conductivity upper limit value C1 (in the case of no in S20), the control device 40 keeps the valve 38 in a closed state. 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 conductivity C2 is less than the conductivity upper limit value C1, the control device 40 prevents the high-temperature refrigerant from flowing into the ion exchanger 32 by closing the valve 38. Therefore, deterioration caused by the heat of the refrigerant is less likely to occur in the ion exchanger 32. During the period when the conductivity C2 is less than the conductivity upper limit value C1, the control device 40 repeatedly executes S2, S8, S20 and S26. Therefore, during the period when the conductivity C2 is less than the conductivity upper limit value C1, the control device 40 keeps the valve 38 in a closed state until the power of the vehicle is disconnected.

[0050] As described above, in Example 2, even if the temperature of the refrigerant in the first cooling flow path 12 is high, if the conductivity C2 of the refrigerant in the first cooling flow path 12 is high, the controller 40 opens the valve 38. This prevents the conductivity C2 of the refrigerant flowing in the first cooling flow path 12 from becoming excessively high.

[0051] In Examples 1 and 2, valve 38 constitutes the flow path changing device that changes the refrigerant flow path within first cooling flow path 12. However, the flow path changing device may also be constituted by another device (e.g., a three-way valve). Furthermore, in Example 1, valve 38 is a solenoid valve, but the flow path changing device may also be constituted by a device that does not utilize electricity. For example, the flow path changing device may also be constituted by a device such as a thermostat that switches the flow path based on the thermal expansion of a material.

[0052] The process of opening the valve 38 in the first and second embodiments is an example of the first operation. The process of closing the valve 38 in the first and second embodiments is an example of the second operation.

[0053] The determination temperature T1 in Examples 1 and 2 is an example of a reference value. In addition, the conductivity upper limit value C1 in Example 2 is an example of a threshold value.

[0054] While 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 encompasses various variations and modifications of the specific examples exemplified above. The technical elements described in this specification or the accompanying drawings may exhibit technical utility individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies exemplified in this specification or the accompanying drawings may achieve multiple objectives simultaneously, and achieving one of these objectives alone may be technically useful.

Claims

1. A fuel cell cooling system, wherein: The fuel cell cooling system comprises: A first cooling flow path for circulating the refrigerant; A fuel cell is provided in the first cooling flow path; an ion exchanger, disposed in the first cooling flow path; A second cooling flow path for circulating the refrigerant; a radiator, disposed in the second cooling flow path; as well as an intermediate heat exchanger for performing heat exchange between the first cooling flow path and the second cooling flow path, 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 action is performed. In the first action, the refrigerant is circulated in the first cooling flow path along a path in which the refrigerant having passed through the intermediate heat exchanger flows in parallel to the fuel cell and the ion exchanger, and the refrigerant is circulated in the second cooling flow path along a path in which the refrigerant 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 action is performed. In the second action, with the flow path of the ion exchanger closed, the refrigerant is circulated in the first cooling flow path along a path passing through the intermediate heat exchanger and the fuel cell, and the refrigerant is circulated in the second cooling flow path along a path passing through the intermediate heat exchanger and the radiator.

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

3. The fuel cell cooling system according to claim 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 electrical conductivity of the refrigerant in the first cooling flow path is higher than a threshold value.

4. The fuel cell cooling system according to claim 1 or 2, wherein: The first cooling flow path includes: A fuel cell flow path provided with the fuel cell; an ion exchanger flow path provided with the ion exchanger; and The intermediate heat exchanger flow path is provided with the intermediate heat exchanger, The downstream end of the intermediate heat exchanger flow path is connected to the upstream end of the ion exchanger flow path and the upstream end of the fuel cell flow path. The upstream end of the intermediate heat exchanger flow path is connected to the downstream end of the ion exchanger flow path and the downstream end of the fuel cell flow path. The fuel cell cooling system includes a pump provided in the intermediate heat exchanger flow path.

Images