Heat exchanger

Abstract

To prevent a heat exchanger from being unnecessarily increased in size.SOLUTION: A heat exchanger may comprise: a first flow path; a second flow path that is adjacent to the first flow path and exchanges heat with the first flow path; a third flow path that is adjacent to the second flow path and exchanges heat with the second flow path; and a fourth flow path that is adjacent to the third flow path and exchanges heat with the third flow path. Each of the first flow path and the third flow path may be connected to any one of a flow path of a fuel gas supplied to a fuel battery and a flow path of cooling water supplied to the fuel battery, and each of the second flow path and the fourth flow path may be connected to any one of a flow path of fuel off-gas discharged from the fuel battery, a flow path of oxidant gas supplied to the fuel battery, a flow path of oxidant off-gas discharged from the fuel battery, and a flow path of the cooling water discharged from the fuel battery.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed in this specification relates to a heat exchanger for a fuel cell.

Background Art

[0002] Patent Document 1 describes a heat exchanger for a fuel cell. The heat exchanger includes a first flow path through which a relatively low-temperature fluid flows, and second, third, and fourth flow paths through which relatively high-temperature fluids flow. The second flow path is adjacent to the first flow path and exchanges heat with the first flow path. The third flow path is adjacent to the first flow path and exchanges heat with the first flow path. The fourth flow path is adjacent to the first flow path and exchanges heat with the first flow path.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described heat exchanger, for one flow path, three flow paths are arranged in a biased manner so as to exchange heat. Therefore, the heat exchanger is likely to be relatively large as a whole. In this specification, a technology for suppressing the useless enlargement of the heat exchanger is provided.

Means for Solving the Problems

[0005] The technology disclosed in this specification is embodied in a heat exchanger for a fuel cell. In a first aspect of this technology, the heat exchanger includes a first flow path, a second flow path adjacent to the first flow path and exchanging heat with the first flow path, a third flow path adjacent to the second flow path and exchanging heat with the second flow path, and a fourth flow path adjacent to the third flow path and exchanging heat with the third flow path. Each of the first flow path and the third flow path may be connected to either a flow path of fuel gas supplied to the fuel cell or a flow path of cooling water supplied to the fuel cell. Each of the second flow path and the fourth flow path may be connected to any one of a flow path of fuel off-gas discharged from the fuel cell, a flow path of oxidant gas supplied to the fuel cell, a flow path of oxidant off-gas discharged from the fuel cell, and a flow path of the cooling water discharged from the fuel cell.

[0006] In the heat exchanger described above, each of the first flow path and the third flow path is connected to either a flow path of fuel gas supplied to the fuel cell or a flow path of cooling water supplied to the fuel cell. On the other hand, each of the second flow path and the fourth flow path is connected to any one of a flow path of fuel off-gas discharged from the fuel cell, a flow path of oxidant gas supplied to the fuel cell, a flow path of oxidant off-gas discharged from the fuel cell, and a flow path of the cooling water discharged from the fuel cell. That is, a relatively low-temperature fluid flows through each of the first flow path and the third flow path, and a relatively high-temperature fluid flows through each of the second flow path and the fourth flow path. With such a configuration, the flow paths through which the low-temperature fluid flows and the flow paths through which the high-temperature fluid flows are alternately arranged, and efficient heat exchange can be performed between each adjacent pair of flow paths. Therefore, the heat exchanger is prevented from being unnecessarily enlarged.

[0007] In a second aspect of this technology, in addition to the first aspect described above, the first flow path may also be adjacent to the fourth flow path and exchange heat with the fourth flow path. With such a configuration, it is possible to make the other two flow paths adjacent to all of the first flow path to the fourth flow path. By further increasing the efficiency of heat exchange, further miniaturization of the heat exchanger can be achieved.

[0008] In the third aspect of the present technology, in addition to the above-described first aspect or second aspect, the second flow path and the third flow path may be surrounded by at least one of the first flow path and the fourth flow path. According to such a configuration, the area where the first flow path is adjacent to the second flow path and / or the area where the fourth flow path is adjacent to the third flow path can be increased, and the efficiency of heat exchange can be enhanced. Further, it is possible to suppress useless heat exchange between the second flow path and the third flow path and the outside.

[0009] In the fourth aspect of the present technology, in addition to the above-described third aspect, the first flow path, the second flow path, the third flow path, and the fourth flow path may be provided concentrically. According to such a configuration, in all of the first flow path to the fourth flow path, the area adjacent to other flow paths can be increased, and the efficiency of heat exchange can be enhanced. Further, except for the outermost flow path, useless heat exchange between each flow path and the outside can be suppressed.

[0010] In the fifth aspect of the present technology, in addition to any one of the above-described first aspect to fourth aspect, a flow path of the fuel gas may be connected to the first flow path. And a flow path of the discharged cooling water may be connected to the second flow path. And a flow path of the supplied cooling water may be connected to the third flow path. And a flow path of the oxidant gas may be connected to the fourth flow path. According to such a configuration, in the arrangement of the four flow paths in the heat exchanger, the two flow paths through which the cooling water flows are arranged in the central portion of the arrangement. Compared with the fuel gas and its off-gas which are gases, the cooling water which is a liquid has a relatively high heat exchange capacity. Therefore, when the two flow paths through which the cooling water flows are arranged in the central portion in the arrangement of the four flow paths, the efficiency of heat exchange can be effectively enhanced.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0012] (First Embodiment) A heat exchanger 10 of a first embodiment will be described with reference to Figs. 1 and 2. As shown in Fig. 1, the heat exchanger 10 is used in a fuel cell system 100. As an example, the fuel cell system 100 is mounted on an electric vehicle. The fuel cell system 100 supplies generated electric power to a traction motor of the electric vehicle. Alternatively, the fuel cell system 100 charges a battery of the electric vehicle with the generated electric power. However, the heat exchanger 10 of the present technology is not limited to being mounted on an electric vehicle, and may be mounted on other mobility devices equipped with a fuel cell.

[0013] In addition to the heat exchanger 10, the fuel cell system 100 includes a fuel cell 12, a fuel gas supply unit 14, an oxidant gas supply unit 16, a radiator 18, and a plurality of flow paths 20, 22, 24, 26, 28, and 30.

[0014] A fuel gas and an oxidant gas are supplied to the fuel cell 12. In this embodiment, the fuel gas is hydrogen, and the oxidant gas is air (oxygen). The fuel cell 12 has a plurality of fuel cell units (not shown). In each of the plurality of fuel cell units (hereinafter simply referred to as a cell), the supplied fuel gas and oxidant gas react with each other to generate electricity.

[0015] The fuel cell 12 has each of a plurality of flow paths 20, 22, 24, 26, 28, 30 connected thereto. The plurality of flow paths 20, 22, 24, 26, 28, 30 include a fuel gas flow path 20, a fuel off-gas flow path 22, an oxidant gas flow path 24, an oxidant off-gas flow path 26, a first cooling water flow path 28, and a second cooling water flow path 30. The fuel gas flow path 20 is a flow path for the fuel gas supplied to the fuel cell 12. The fuel off-gas flow path 22 is a flow path for the fuel off-gas discharged from the fuel cell 12. The oxidant gas flow path 24 is a flow path for the oxidant gas supplied to the fuel cell 12. The oxidant off-gas flow path 26 is a flow path for the oxidant off-gas discharged from the fuel cell 12. The first cooling water flow path 28 is a flow path for the cooling water supplied to the fuel cell 12. The second cooling water flow path 30 is a flow path for the cooling water discharged from the fuel cell 12.

[0016] The fuel gas that has passed through each cell is discharged from the fuel cell 12 through the fuel off-gas flow path 22 as fuel off-gas. The oxidant gas that has passed through each cell is discharged from the fuel cell 12 through the fuel off-gas flow path 22 as oxidant off-gas. In the fuel off-gas flow path 22 and the oxidant off-gas flow path 26, relatively high-temperature fuel off-gas and oxidant off-gas heated for the fuel cell reaction flow as compared with the fluids in the other flow paths of the fuel cell system 100.

[0017] Although not particularly limited, the fuel off-gas flow path 22 may be connected to a gas-liquid separator (not shown), and impurities such as water generated by the reaction in each cell may be removed by the gas-liquid separator. Then, the fuel off-gas discharged from the fuel cell 12 may be returned to the fuel gas flow path 20 via the gas-liquid separator.

[0018] The fuel gas supply unit 14 has a fuel gas tank that stores fuel gas. The fuel gas supply unit 14 is connected to the fuel cell 12 via the fuel gas flow path 20. The fuel gas supply unit 14 supplies the fuel gas stored in the fuel gas tank to the fuel cell 12. Relatively low-temperature fuel gas flows in the fuel gas flow path 20.

[0019] The oxidant gas supply unit 16 has a compressor that delivers the oxidant gas. The oxidant gas supply unit 16 is connected to the fuel cell 12 via the oxidant gas flow path 24. The oxidant gas supply unit 16 compresses outside air with the compressor and supplies air as an oxidant to the fuel cell 12. In the oxidant gas flow path 24, a relatively high-temperature oxidant gas flows due to the compression by the compressor.

[0020] The radiator 18 is a heat exchanger that exchanges heat between outside air and cooling water. The radiator 18 is connected to the first cooling water flow path 28. Therefore, the radiator 18 is connected to the fuel cell 12 via the first cooling water flow path 28. As a result, in the first cooling water flow path 28, the cooling water supplied from the radiator 18 flows toward the fuel cell 12. In the first cooling water flow path 28, relatively low-temperature cooling water cooled by the radiator 18 flows. The radiator 18 is connected to the second cooling water flow path 30. Therefore, the radiator 18 is connected to the fuel cell 12 via the second cooling water flow path 30. As a result, in the second cooling water flow path 30, the cooling water discharged from the fuel cell 12 flows toward the radiator 18. Therefore, in the second cooling water flow path 30, relatively low-temperature cooling water heated by the fuel cell 12 flows. Note that a pump (not shown) for circulating the cooling water between the radiator 18 and the fuel cell 12 is provided.

[0021] As shown in FIGS. 1 and 2, the heat exchanger 10 has a first end 10a and a second end 10b, and includes a plurality of flow paths 32, 34, 36, 38 extending between the first end 10a and the second end 10b. The plurality of flow paths 32, 34, 36, 38 extend parallel to each other. The plurality of flow paths 32, 34, 36, 38 include a first flow path 32, a second flow path 34, a third flow path 36, and a fourth flow path 38. The second flow path 34 is adjacent to the first flow path 32 and exchanges heat with the first flow path 32. The third flow path 36 is adjacent to the second flow path 34 and exchanges heat with the second flow path 34. The fourth flow path 38 is adjacent to the third flow path 36 and exchanges heat with the third flow path 36. The plurality of flow paths 32, 34, 36, 38 are arranged in a line in the order of the first flow path 32, the second flow path 34, the third flow path 36, and the fourth flow path 38.

[0022] The fuel gas flow path 20 is connected to the first flow path 32. Specifically, the fuel gas flow path 20 is divided into an upstream portion and a downstream portion by the first flow path 32. More specifically, the downstream end of the upstream portion of the fuel gas flow path 20 is connected to the first flow path 32 at the first end 10a of the heat exchanger 10. The upstream end of the downstream portion of the fuel gas flow path 20 is connected to the first flow path 32 at the second end 10b of the heat exchanger 10. That is, in the heat exchanger 10, in the first flow path 32, the fluid flows from the first end 10a toward the second end 10b (in the depth direction of the paper of FIG. 2).

[0023] The oxidant gas flow path 24 is connected to the second flow path 34. Specifically, the oxidant gas flow path 24 is divided into an upstream portion and a downstream portion by the first flow path 32. More specifically, the downstream end of the upstream portion of the oxidant gas flow path 24 is connected to the second flow path 34 at the second end 10b of the heat exchanger 10. The upstream end of the downstream portion of the oxidant gas flow path 24 is connected to the second flow path 34 at the first end 10a of the heat exchanger 10. That is, in the heat exchanger 10, in the second flow path 34, the fluid flows from the second end 10b toward the first end 10a (in the front direction of the paper of FIG. 2).

[0024] The first cooling water flow path 28 is connected to the third flow path 36. Specifically, the first cooling water flow path 28 is divided into an upstream portion and a downstream portion by the third flow path 36. More specifically, the downstream end of the upstream portion of the first cooling water flow path 28 is connected to the third flow path 36 at the first end 10a of the heat exchanger 10. The upstream end of the downstream portion of the first cooling water flow path 28 is connected to the third flow path 36 at the second end 10b of the heat exchanger 10. That is, in the heat exchanger 10, in the third flow path 36, the fluid flows from the first end 10a toward the second end 10b (in the depth direction of the paper of FIG. 2).

[0025] The second cooling water flow path 30 is connected to the fourth flow path 38. Specifically, the second cooling water flow path 30 is divided into an upstream portion and a downstream portion by the fourth flow path 38. More specifically, the downstream end of the upstream portion of the second cooling water flow path 30 is connected to the fourth flow path 38 at the second end 10b of the heat exchanger 10. The upstream end of the downstream portion of the second cooling water flow path 30 is connected to the fourth flow path 38 at the first end 10a of the heat exchanger 10. That is, in the heat exchanger 10, in the fourth flow path 38, the fluid flows from the second end 10b toward the first end 10a (in the direction toward the front of the paper in FIG. 2).

[0026] The heat exchanger 10 includes a casing 40. The casing 40 is a cylindrical member. The casing 40 has a cylindrical peripheral wall 42 and a plurality of plate-like partition walls 44 located within the peripheral wall 42. The peripheral wall 42 and the plurality of partition walls 44 extend between the first end 10a and the second end 10b in the heat exchanger 10. The plurality of partition walls 44 define the first flow path 32, the second flow path 34, the third flow path 36, and the fourth flow path 38 within the peripheral wall 42. The cross section of the peripheral wall 42 generally has a rectangular shape and has a first wall 42a, a second wall 42b, a third wall 42c, and a fourth wall 42d. Here, the cross section refers to a cross section perpendicular to the direction in which the peripheral wall 42 extends cylindrically. However, in another embodiment, the cross section of the peripheral wall 42 may be polygonal or circular. The first wall 42a faces the third wall 42c, and the second wall 42b faces the fourth wall 42d. The second wall 42b and the fourth wall 42d extend between the first wall 42a and the third wall 42c.

[0027] The plurality of partition walls 44 extend between the first end 10a and the second end 10b of the heat exchanger 10. The plurality of partition walls 44 extend between the first wall 42a and the third wall 42c. The plurality of partition walls 44 are arranged at a predetermined interval within the peripheral wall 42. Each of the plurality of partition walls 44 has a plurality of fins 44f. The plurality of fins 44f protrude from both side surfaces located on two adjacent flow path sides in the plurality of partition walls 44. Thereby, the area of contact between both the first flow path 32 and the second flow path 34 and the partition wall 44 increases, and the heat exchange efficiency can be enhanced. The shape of each of the plurality of fins 44f is not particularly limited. Each of the plurality of fins 44f may have an elongated plate shape or a pin shape.

[0028] In the heat exchanger 10 of the present embodiment, the fuel gas flow path 20 of the fuel gas supplied to the fuel cell 12 is connected to the first flow path 32, and the first cooling water flow path 28 of the cooling water supplied to the fuel cell 12 is connected to the third flow path 36. On the other hand, the oxidant gas flow path 24 of the oxidant gas supplied to the fuel cell 12 is connected to the second flow path 34, and the second cooling water flow path 30 of the cooling water discharged from the fuel cell 12 is connected to the fourth flow path. That is, a relatively low-temperature fluid flows through each of the first flow path 32 and the third flow path 36, and a relatively high-temperature fluid flows through each of the second flow path 34 and the fourth flow path 38. According to such a configuration, the flow paths 32, 36 through which the low-temperature fluid flows and the flow paths 34, 38 through which the high-temperature fluid flows are alternately arranged, and efficient heat exchange can be performed between each two adjacent flow paths. Therefore, the heat exchanger 10 is prevented from being unnecessarily enlarged.

[0029] Particularly in this embodiment, the plurality of flow paths 32, 34, 36, 28 of the heat exchanger 10 are arranged such that the flow directions of each fluid are opposite to each other between every two adjacent flow paths. That is, in the first flow path 32 and the second flow path 34, the flow directions of each fluid are opposite to each other; in the second flow path 34 and the third flow path 36, the flow directions of each fluid are opposite to each other; and in the third flow path 36 and the fourth flow path 38, the flow directions of each fluid are opposite to each other. According to such a configuration, efficient heat exchange can be performed between two adjacent flow paths throughout the entire length from the first end 10a to the second end 10b of the heat exchanger 10. However, in another embodiment, the flow directions of each fluid may be the same between every two adjacent flow paths.

[0030] Furthermore, in this embodiment, in the first flow path 32, fuel gas flows, and in the second flow path 34, oxidant gas flows. On the other hand, in the third flow path 36 and the fourth flow path 38, cooling water flows. That is, each fluid flowing through two adjacent flow paths among the plurality of flow paths 32, 34, 36, 28 of the heat exchanger 10 is either gas-gas or water-water. According to such a configuration, efficient heat exchange can be performed between two adjacent flow paths. However, in another embodiment, between every two adjacent flow paths, the fluid flowing through one flow path may be gas and the fluid flowing through the other flow path may be water.

[0031] (Embodiment 2) Referring to FIG. 3(A), the heat exchanger 110 of Embodiment 2 will be described. As shown in FIG. 3(A), the heat exchanger 110 of Embodiment 2 includes eight flow paths in which a plurality of flow paths 32, 34, 36, 38 similar to those in Embodiment 1 are arranged in a row and repeatedly arranged. In this regard, it is different from the heat exchanger 10 of Embodiment 1. Regarding other configurations of the heat exchanger 110 of Embodiment 2, they can be configured in the same manner as in Embodiment 1. Even with such a configuration, the flow paths 32, 36 through which low-temperature fluid flows and the flow paths 34, 38 through which high-temperature fluid flows are alternately arranged, and efficient heat exchange can be performed between every two adjacent flow paths. However, the number of the plurality of flow paths is not limited to four or eight in Embodiments 1 and 2, and the plurality of flow paths 32, 34, 36, 38 only need to have at least four flow paths.

[0032] In addition, when a plurality of first channels 32 are connected to the fuel gas channel 20 as in the above configuration, the two first channels 32 may be connected to the fuel gas channel 20 in parallel. According to such a configuration, efficient heat exchange can be performed between any of the first channels 32 and the adjacent second channels 34. However, in another embodiment, the two first channels 32 may be connected to the fuel gas channel 20 in series. The two second channels 34, the two third channels 36, and the two fourth channels 38 can be configured in the same manner as the two first channels 32.

[0033] (Example 3) Referring to FIG. 3(B), the heat exchanger 210 of Example 3 will be described. As shown in FIG. 3(B), in the heat exchanger 210 of Example 3, the channel arrangement pattern of the plurality of channels 32, 34, 36, 38 is different from that of the heat exchanger 10 of Example 1. In the heat exchanger 210, the plurality of channels 32, 34, 36, 38 are arranged so as to make one round from the first channel 32 to the fourth channel 38. The first channel 32 is also adjacent to the fourth channel 38. That is, the first channel 32 is configured to perform heat exchange with the fourth channel 38 as well. According to such a configuration, the other two channels can be made adjacent to all of the first channel 32 to the fourth channel 38. By further increasing the efficiency of heat exchange, further miniaturization of the heat exchanger 210 can be achieved.

[0034] Specifically, the heat exchanger 210 includes a casing 240. The casing 240 has a cylindrical peripheral wall 42 similar to that of Example 1 and a plurality of plate-like partition walls 244 located inside the peripheral wall 42. In the plurality of partition walls 244, one end of each is joined to each other, and the other end of each is joined to the peripheral wall 42.

[0035] (Example 4) With reference to FIG. 4(A), the heat exchanger 310 of Example 4 will be described. As shown in FIG. 4(A), in the heat exchanger 310 of Example 4, in addition to the plurality of flow paths 32, 34, 36, 38 in Example 1, the heat exchanger 310 further includes a second first flow path 332 and a second second flow path 334. In this regard, the heat exchanger 310 of Example 4 is different from the heat exchanger 10 of Example 1. The second first flow path 332 is adjacent to the fourth flow path 38 and exchanges heat with the fourth flow path 38. The second first flow path 332 is connected to the fuel gas flow path 20 in the same manner as the first flow path 32 of Example 1. The second second flow path 334 is adjacent to the second first flow path 332 and exchanges heat with the second first flow path 332. The second second flow path 334 is connected to the oxidant gas flow path 24 in the same manner as the second flow path 34 of Example 1.

[0036] In the configuration of Example 4, the third flow path 36 and the fourth flow path 38 through which the cooling water flows are located in the central portion of the flow path arrangement in which the plurality of flow paths 32, 34, 36, 38, 332, 334 are arranged. Compared with the fuel gas or its off-gas which is a gas, the cooling water which is a liquid has a relatively high heat exchange capacity. Therefore, when the two flow paths 36, 38 through which the cooling water flows are arranged in the central portion in the arrangement of the plurality of flow paths 32, 34, 36, 38, 332, 334, the efficiency of heat exchange can be effectively increased. Note that the second first flow path 332 in the present embodiment is an example of the "first flow path" in the present technology. The fourth flow path 38 in the present embodiment is an example of the "second flow path" in the present technology. The third flow path 36 in the present embodiment is an example of the "third flow path" in the present technology. The fourth flow path 38 in the present embodiment is an example of the "fourth flow path" in the present technology.

[0037] (Embodiment 5) With reference to FIG. 4(B), the heat exchanger 410 of Embodiment 5 will be described. As shown in FIG. 4(B), the heat exchanger 410 of Embodiment 5 includes a plurality of flow paths 32, 434, 36, 438 including the first flow path 32 and the third flow path 36 similar to those of Embodiment 1, and the second flow path 434 and the fourth flow path 438. The second flow path 434 is connected to the second cooling water flow path 30. The fourth flow path 438 is connected to the oxidant gas flow path 24. In these respects, the configuration of the heat exchanger 410 of Embodiment 5 is different from that of the heat exchanger 10 of Embodiment 1. In the configuration of Embodiment 5 described above, in the flow path arrangement of the four flow paths 32, 434, 36, 438 in the heat exchanger 410, the two flow paths 434, 36 through which the cooling water flows are arranged in the central portion of the flow path arrangement. Therefore, the efficiency of heat exchange can be effectively increased.

[0038] In the heat exchanger 410 of Embodiment 5, the flow path arrangement pattern of the plurality of flow paths 32, 434, 36, 438 is also different from that of the heat exchanger 10 of Embodiment 1. The second flow path 434 is adjacent to the first flow path 32 and exchanges heat with the first flow path 32. The third flow path 36 is adjacent to the second flow path 434 and exchanges heat with the second flow path 434. The fourth flow path 438 is adjacent to the third flow path 36 and exchanges heat with the third flow path 36. Further, in the heat exchanger 410, the first flow path 32 is also adjacent to the fourth flow path 438 and is configured to exchange heat with the fourth flow path 438. According to such a configuration, for all of the first flow path 32 to the fourth flow path 438, the other two flow paths can be made adjacent. By further increasing the efficiency of heat exchange, further miniaturization of the heat exchanger 410 can be achieved.

[0039] Furthermore, the second flow path 434 is surrounded by the first flow path 32 outside the range adjacent to the third flow path 36. The third flow path 36 is surrounded by the fourth flow path 438 outside the range adjacent to the second flow path 434. According to such a configuration, the area where the first flow path 32 is adjacent to the second flow path 434 and the area where the fourth flow path 438 is adjacent to the third flow path 36 can be increased, and the efficiency of heat exchange can be increased. Also, it is possible to suppress the second flow path 434 and the third flow path 36 from exchanging heat uselessly with the outside.

[0040] Although not particularly limited, the heat exchanger 410 includes a casing 240. The casing 240 has a cylindrical peripheral wall 42 similar to that of the first embodiment and a plurality of partition walls 444 located within the peripheral wall 42. The plurality of partition walls 444 include a cylindrical first partition wall 444a and a plate-shaped second partition wall 444b. The first partition wall 444a extends along the inner surface of the peripheral wall 42. A gap is provided between the first partition wall 444a and the peripheral wall 42. The second partition wall 444b extends between the second wall 42b and the fourth wall 42d of the peripheral wall 42. The second partition wall 444b is arranged to divide both the space defined by the first partition wall 444a and the space defined by the peripheral wall 42.

[0041] (Embodiment 6) Referring to FIG. 5, the heat exchanger 510 of Embodiment 6 will be described. As shown in FIG. 5, in the heat exchanger 510 of Embodiment 6, the flow path arrangement patterns of the plurality of flow paths 32, 434, 36, 438 are different from those of the heat exchanger 410 of Embodiment 5. Each of the first flow path 32, the second flow path 434, the third flow path 36, and the fourth flow path 438 extends along the same central axis C. The first flow path 32 is located innermost, and the second flow path 434, the third flow path 36, and the fourth flow path 438 are arranged outward in this order. The entire outer periphery of the first flow path 32 is surrounded by the second flow path 434. The entire outer periphery of the second flow path 434 is surrounded by the third flow path 36. The entire outer periphery of the third flow path 36 is surrounded by the fourth flow path 438. Specifically, the first flow path 32, the second flow path 434, the third flow path 36, and the fourth flow path 438 are provided concentrically around the central axis C. According to such a configuration, in all of the first flow path 32 to the fourth flow path 438, the area adjacent to other flow paths can be increased, and the efficiency of heat exchange can be enhanced. Further, except for the outermost fourth flow path 438, useless heat exchange between each of the flow paths 32, 434, 36 and the outside can be suppressed.

[0042] Also, even in the above-described channel array pattern, in the channel arrays of the four channels 32, 434, 36, and 438 in the heat exchanger 510, the two channels 434 and 36 through which the cooling water flows are arranged in the central portion of the channel array. Therefore, the efficiency of heat exchange can be effectively increased.

[0043] Although not particularly limited, the heat exchanger 510 includes a casing 540. The casing 540 has a cylindrical peripheral wall 542 and a plurality of cylindrical partition walls 544 located within the peripheral wall 542. The plurality of partition walls 544 include a first partition wall 544a, a second partition wall 544b surrounding the entire outer peripheral surface of the first partition wall 544a, and a third partition wall 544c surrounding the entire outer peripheral surface of the second partition wall 544b.

[0044] (Example 7) Referring to FIG. 6, the heat exchanger 610 of Example 7 will be described. As shown in FIG. 6, the heat exchanger 610 of Example 6 includes a plurality of channels 32, 634, 36, 638 including the first channel 32 and the third channel 36 similar to those of Example 1, and the second channel 634 and the fourth channel 638. The second channel 634 is connected to the fuel off-gas channel 22, and the fourth channel 638 is connected to the oxidant off-gas channel 26. In this regard, the heat exchanger 610 of Example 6 is different from the heat exchanger 10 of Example 1. Also in this case, a relatively low-temperature fluid flows through each of the first channel 32 and the third channel 36, and a relatively high-temperature fluid flows through each of the second channel 634 and the fourth channel 638. Therefore, the channels 32 and 36 through which the low-temperature fluid flows and the channels 634 and 638 through which the high-temperature fluid flows are alternately arranged, and efficient heat exchange can be performed between each adjacent pair of channels.

[0045] In Examples 1 to 7, various combinations of a plurality of flow paths in the heat exchangers 10, 110, 210, 310, 410, 510, and 610 were described, but the combinations of the plurality of flow paths are not particularly limited. In each of the first flow path and the third flow path, any one of the fuel gas flow path 20 and the first cooling water flow path 28 may be connected. And in each of the second flow path and the fourth flow path, any one of the fuel off-gas flow path 22, the oxidant gas flow path 24, the oxidant off-gas flow path 26, and the second cooling water flow path 30 may be connected.

Explanation of Reference Numerals

[0046] 10, 110, 210, 310, 410, 510, 610: Heat exchanger, 12: Fuel cell, 20: Fuel gas flow path, 22: Fuel off-gas flow path, 24: Oxidant gas flow path, 26: Oxidant off-gas flow path, 28: First cooling water flow path, 30: Second cooling water flow path, 32, 332: First flow path, 34, 334, 434, 634: Second flow path, 36: Third flow path, 38, 438, 638: Fourth flow path, C: Central axis

Claims

1. A heat exchanger for a fuel cell, a first flow path, a second flow path adjacent to the first flow path and exchanging heat with the first flow path, a third flow path adjacent to the second flow path and exchanging heat with the second flow path, a fourth flow path adjacent to the third flow path and exchanging heat with the third flow path, comprising: In each of the first flow path and the third flow path, either a flow path of fuel gas supplied to the fuel cell or a flow path of cooling water supplied to the fuel cell is connected; In each of the second flow path and the fourth flow path, either a flow path of fuel off-gas discharged from the fuel cell, a flow path of oxidant gas supplied to the fuel cell, a flow path of oxidant off-gas discharged from the fuel cell, or a flow path of the cooling water discharged from the fuel cell is connected. Heat exchanger.

2. The heat exchanger according to Claim 1, wherein the first flow path is also adjacent to the fourth flow path and exchanges heat with the fourth flow path.

3. The heat exchanger according to Claim 1, wherein the second flow path and the third flow path are surrounded by at least one of the first flow path and the fourth flow path.

4. The heat exchanger according to Claim 3, wherein the first flow path, the second flow path, the third flow path, and the fourth flow path are provided concentrically.

5. A flow path of the fuel gas is connected to the first flow path, a flow path of the discharged cooling water is connected to the second flow path, a flow path of the supplied cooling water is connected to the third flow path, a flow path of the oxidant gas is connected to the fourth flow path. The heat exchanger according to any one of Claims 1 to 4.

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