heat exchanger

Abstract

A heat exchanger may include: a first flow path; a second flow path that exchanges heat with the first flow path; a third flow path that exchanges heat with the second flow path; and a fourth flow path that exchanges heat with the third flow path, wherein each of the first and third flow paths is connectable to one of a flow path for fuel gas to be supplied to a fuel cell and a flow path for cooling water to be supplied to the fuel cell; and each of the second and fourth flow paths is connectable to one of the following: a flow path for fuel off-gas discharged from the fuel cell, a flow path for oxidant gas to be supplied to the fuel cell, a flow path for oxidant gas off-gas discharged from the fuel cell, and a flow path for cooling water discharged from the fuel cell.

Description

BACKGROUND

[0001] The technology disclosed here relates to a heat exchanger for a fuel cell.

[0002] Japanese patent application JP 2008-204834 A describes a heat exchanger for a fuel cell. The heat exchanger comprises a first flow path through which a relatively low-temperature fluid flows, and second, third, and fourth flow paths through which a relatively high-temperature fluid flows. 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, and the fourth flow path is adjacent to the first flow path and exchanges heat with the first flow path. SUMMARY

[0003] In the heat exchanger described above, the three flow paths are arranged disproportionately with respect to the one flow path intended for heat exchange. Therefore, the overall size of the heat exchanger is relatively large. The technology disclosed here prevents unnecessary enlargement of the heat exchanger.

[0004] The technology disclosed here is embodied as a heat exchanger for a fuel cell. In a first aspect of the technology, a heat exchanger may comprise: 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, wherein each of the first flow path and the third flow path may be connected to a flow path for fuel gas to be supplied to a fuel cell and a flow path for cooling water to be supplied to the fuel cell.and each of the second flow path and the fourth flow path may be connected to one of the following: a flow path for fuel gas off-gas discharged from the fuel cell, a flow path for oxidizing gas to be supplied to the fuel cell, a flow path for oxidizing gas off-gas discharged from the fuel cell, and a flow path for cooling water discharged from the fuel cell.;

[0005] In the heat exchanger described above, each of the first and third flow paths is connected to one of a flow path for fuel gas to be supplied to the fuel cell and a flow path for cooling water to be supplied to the fuel cell. Conversely, each of the second and fourth flow paths is connected to one of a flow path for the fuel gas off-gas discharged from the fuel cell, a flow path for the oxidizing gas to be supplied to the fuel cell, a flow path for the oxidizing gas off-gas discharged from the fuel cell, and a flow path for the cooling water discharged from the fuel cell. That is, a relatively low-temperature fluid flows through each of the first and third flow paths, while a relatively high-temperature fluid flows through each of the second and fourth flow paths.This configuration enables efficient heat exchange between two adjacent flow paths because the flow paths through which the low-temperature fluid flows and the flow paths through which the high-temperature fluid flows are arranged alternately. This prevents unnecessary enlargement of the heat exchanger.

[0006] In a second aspect of the technology according to the first aspect, the first flow path can also be adjacent to the fourth flow path and also exchange heat with the fourth flow path. According to this configuration, the other two flow paths can be adjacent to all of the first to fourth flow paths. This enables more efficient heat exchange and thus a reduction in the size of the heat exchanger.

[0007] In a third aspect of the technology according to the first 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. This configuration enlarges an area where the first flow path is adjacent to the second flow path and / or an area where the fourth flow path is adjacent to the third flow path, thus increasing heat exchange efficiency. Furthermore, the configuration prevents the second and third flow paths from unnecessarily exchanging heat with the outside environment.

[0008] In a fourth aspect of the technology according to the third aspect, the first flow path, the second flow path, the third flow path, and the fourth flow path may be arranged concentrically. This configuration allows all of the first to fourth flow paths to be adjacent to the other flow path(s) over larger areas, thereby increasing heat exchange efficiency. Furthermore, the configuration prevents the flow paths (except for the outermost flow path) from unnecessarily exchanging heat with the outside environment.

[0009] In a fifth aspect of the technology according to any one of the first to fourth aspects, the first flow path may be connected to the flow path for the fuel gas, the second flow path may be connected to the flow path for the discharged cooling water, the third flow path may be connected to the flow path for the cooling water to be supplied, and the fourth flow path may be connected to the flow path for the oxidizing gas. According to this configuration, in the arrangement of the above-mentioned four flow paths of the heat exchanger, the two flow paths through which the cooling water flows are centrally located in the arrangement. Compared with gases such as fuel gas and its exhaust gas, cooling water, which is a liquid, has a relatively high heat exchange capacity. Therefore, the arrangement in which the two flow paths through which the cooling water flows are centrally located in the arrangement of the four flow paths effectively increases the heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a configuration of a fuel cell system. Fig. Figure 2 shows a cross section of a heat exchanger according to a first embodiment along the line II-II in Fig. 1. Fig. 3A shows a cross section of a heat exchanger according to a second embodiment. Fig. 3B shows a cross-sectional view of a heat exchanger according to a third embodiment. Fig. 4A shows a cross-sectional view of a heat exchanger according to a fourth embodiment. Fig. 4B shows a cross-sectional view of a heat exchanger according to a fifth embodiment. Fig. 5 shows a cross-sectional view of the heat exchanger according to a sixth embodiment. Fig. 6 shows a configuration of a heat exchanger according to a seventh embodiment. DESCRIPTION[FIRST EMBODIMENT]

[0010] With reference to the Fig. 1 and Fig. 2, a heat exchanger 10 according to a first embodiment is described. As in Fig. 1, the heat exchanger 10 is used in a fuel cell system 100. In one example, the fuel cell system 100 is installed in an electric vehicle. The fuel cell system 100 supplies generated electrical power to the electric vehicle's drive motor. Alternatively, the fuel cell system 100 charges the electric vehicle's battery with generated electrical power. The heat exchanger 10 in the present technology does not need to be installed in an electric vehicle, but can be installed in another mobility device equipped with a fuel cell stack.

[0011] In addition to the heat exchanger 10, the fuel cell system 100 also includes a fuel cell stack 12, a fuel gas supply 14, an oxidizing gas supply 16, a cooler 18, and a plurality of flow paths 20, 22, 24, 26, 28, 30.

[0012] Fuel gas and oxidizing gas are supplied to the fuel cell stack 12. In this embodiment, the fuel gas is hydrogen, and the oxidizing gas is air (oxygen). The fuel cell stack 12 includes a plurality of fuel cells (not shown). In each of the plurality of fuel cells (hereinafter referred to simply as "cells"), electrical energy or power is generated through the reaction between the supplied fuel gas and the oxidizing gas.

[0013] Each of the plurality of flow paths 20, 22, 24, 26, 28, 30 is connected to the fuel cell stack 12. The plurality of flow paths 20, 22, 24, 26, 28, 30 includes a fuel gas flow path 20, a fuel gas off-gas flow path 22, an oxidizing gas flow path 24, an oxidizing gas 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 to be supplied to the fuel cell stack 12. The fuel gas off-gas flow path 22 is a flow path for the fuel gas off-gas discharged from the fuel cell stack 12. The oxidizing gas flow path 24 is a flow path for the oxidizing gas to be supplied to the fuel cell stack 12. The oxidizing gas off-gas flow path 26 is a flow path for the oxidizing gas off-gas discharged from the fuel cell stack 12.The first cooling water flow path 28 is a flow path for cooling water supplied to the fuel cell stack 12. The second cooling water flow path 30 is a flow path for cooling water discharged from the fuel cell stack 12.

[0014] After flowing through the cells, the fuel gas is discharged as fuel gas off-gas from the fuel cell stack 12 through the fuel gas off-gas flow path 22. After flowing through the cells, the oxidation gas is discharged as oxidation gas off-gas from the fuel cell stack 12 through the oxidation gas off-gas flow path 26. The fuel gas off-gas and the oxidation gas off-gas flowing through the fuel gas off-gas flow path 22 and the oxidation gas off-gas flow path 26 have a relatively high temperature compared to the fluids flowing in the other flow paths of the fuel cell system 100 due to heating by the reactions in the fuel cell stack.

[0015] The fuel gas off-gas flow path 22 may be connected to a gas-liquid separator (not shown), and impurities such as water generated by reactions in each cell may be removed by the gas-liquid separator, although this is not required. The fuel gas off-gas discharged from the fuel cell stack 12 may be recirculated to the fuel gas flow path 20 via the gas-liquid separator.

[0016] The fuel gas supply 14 includes a fuel gas tank that stores the fuel gas. The fuel gas supply 14 is connected to the fuel cell stack 12 via the fuel gas flow path 20. The fuel gas supply 14 delivers the fuel gas stored in the fuel gas tank to the fuel cell stack 12. The fuel gas flowing through the fuel gas flow path 20 has a relatively low temperature.

[0017] The oxidizing gas supply 16 includes a compressor that supplies the oxidizing gas. The oxidizing gas supply 16 is connected to the fuel cell stack 12 via the oxidizing gas flow path 24. The oxidizing gas supply 16 compresses the outside air through the compressor and supplies air as an oxidant to the fuel cell stack 12. The oxidizing gas flowing through the oxidizing gas flow path 24 has a relatively high temperature due to the compression by the compressor.

[0018] The cooler 18 is a heat exchanger that exchanges heat between the outside air and the cooling water. The cooler 18 is connected to the first cooling water flow path 28. Thus, the cooler 18 is connected to the fuel cell stack 12 via the first cooling water flow path 28. The cooling water supplied from the cooler 18 flows through the first cooling water flow path 28 toward the fuel cell stack 12. The cooling water flowing through the first cooling water flow path 28 has a relatively low temperature because it is cooled by the cooler. The cooler 18 is connected to the second cooling water flow path 30. Thus, the cooler 18 is connected to the fuel cell stack 12 via the second cooling water flow path 30. The cooling water flowing out of the fuel cell stack 12 flows through the second cooling water flow path 30 to the cooler 18.Therefore, the cooling water flowing through the second cooling water flow path 30 has a relatively high temperature because it is heated in the fuel cell stack 12. A pump (not shown) is provided between the radiator 18 and the fuel cell stack 12 to circulate the cooling water between them.

[0019] As in the Fig. 1 and Fig. 2, the heat exchanger 10 includes a first end 10a, a second end 10b, and a plurality of flow paths 32, 34, 36, 38 extending between the first end 10a and the second end 10b. The flow paths 32, 34, 36, 38 run parallel to one another. 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 flow paths 32, 34, 36, 38 are arranged in a row 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.

[0020] The first flow path 32 is connected to the fuel gas flow path 20. In particular, the fuel gas flow path 20 is divided into an upstream section and a downstream section by the first flow path 32. More specifically, the downstream end of the upstream section 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 section 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 first flow path 32 of the heat exchanger 10, the fluid flows from the first end 10a to the second end 10b (toward the back of the drawing in Fig. 2).

[0021] The second flow path 34 is connected to the oxidizing gas flow path 24. In particular, the oxidizing gas flow path 24 is divided into an upstream portion and a downstream portion by the second flow path 34. More specifically, the downstream end of the upstream portion of the oxidizing 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 oxidizing 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 second flow path 34 of the heat exchanger 10, the fluid flows from the second end 10b to the first end 10a (toward the front of the drawing in Fig. 2).

[0022] The third flow path 36 is connected to the first cooling water flow path 28. 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 third flow path 36 of the heat exchanger 10, the fluid flows from the first end 10a to the second end 10b (toward the back of the drawing in Fig. 2).

[0023] The fourth flow path 38 is connected to the second cooling water flow path 30. 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 fourth flow path 38 of the heat exchanger 10, the fluid flows from the second end 10b to the first end 10a (toward the front of the drawing in Fig. 2).

[0024] The heat exchanger 10 includes a housing 40. The housing 40 is a tubular member. The housing 40 includes a peripheral wall 42 defining the tube and a plurality of plate-shaped 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 within 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 peripheral wall 42 has a generally rectangular cross-section and includes a first wall 42a, a second wall 42b, a third wall 42c, and a fourth wall 42d. The cross-section here refers to the cross-section perpendicular to the direction in which the tube defined by the peripheral wall 42 extends.In another embodiment, the peripheral wall 42 may have a polygonal or circular cross-section. The first wall 42a is opposite the third wall 42c, and the second wall 42b is opposite the fourth wall 42d. The second wall 42b and the fourth wall 42d extend between the first wall 42a and the third wall 42c.

[0025] 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 partition walls 44 are arranged at predetermined intervals within the peripheral wall 42. Each of the partition walls 44 includes a plurality of ribs 44f. The ribs 44f protrude from both surfaces of each partition wall 44 facing two adjacent flow paths. This increases the area over which both the first flow path 32 and the second flow path 34 contact the partition wall 44, thus increasing the heat exchange efficiency. The shape of the plurality of ribs 44f is not particularly limited. Each rib 44f may have an elongated plate shape or a pin shape.

[0026] In the heat exchanger 10 according to this embodiment, the fuel gas flow path 20 for the fuel gas to be supplied to the fuel cell stack 12 is connected to the first flow path 32, and the first cooling water flow path 28 for the cooling water to be supplied to the fuel cell stack 12 is connected to the third flow path 36. In contrast, the oxidizing gas flow path 24 for the oxidizing gas to be supplied to the fuel cell stack 12 is connected to the second flow path 34, and the second cooling water flow path 30 for the cooling water draining from the fuel cell stack 12 is connected to the fourth flow path. That is, the fluids with relatively low temperatures flow through the first flow path 32 and the third flow path 36, while the fluids with relatively high temperatures flow through the second flow path 34 and the fourth flow path 38.In this configuration, flow paths 32 and 36, through which the low-temperature fluids flow, and flow paths 34 and 38, through which the high-temperature fluids flow, are arranged alternately, allowing heat to be efficiently exchanged between two adjacent flow paths. This avoids unnecessary enlargement of the heat exchanger 10.

[0027] Specifically, in this embodiment, the flow paths 32, 34, 36, 28 of the heat exchanger 10 are arranged such that the directions of the fluids flowing in two adjacent flow paths are opposite to each other. That is, the directions of the fluids flowing in the first flow path 32 and the second flow path 34 are opposite to each other, the directions of the fluids flowing in the second flow path 34 and the third flow path 36 are opposite to each other, and the directions of the fluids flowing in the third flow path 36 and the fourth flow path 38 are opposite to each other. This configuration enables efficient heat exchange between two adjacent flow paths over a range from the first end 10a to the second end 10b of the heat exchanger 10. However, in another embodiment, the directions of the fluids flowing in two adjacent flow paths may be the same.

[0028] Furthermore, in this embodiment, the fuel gas flows in the first flow path 32, and the oxidizing gas flows in the second flow path 34. In contrast, the cooling water flows in the third flow path 36 and the fourth flow path 38. That is, the fluids flowing in two adjacent flow paths of the plurality of flow paths 32, 34, 36, and 38 of the heat exchanger 10 are both gases or water. This configuration enables efficient heat exchange between the two adjacent flow paths. However, in another embodiment, with respect to two adjacent flow paths, the fluid flowing in one flow path may be a gas, and the fluid flowing in the other flow path may be water. [SECOND EMBODIMENT]

[0029] With reference to Fig. 3A, a heat exchanger 110 according to a second embodiment is described. As in Fig. As shown in Figure 3A, the heat exchanger 110 according to the second embodiment includes eight flow paths, including two sets of flow paths 32, 34, 36, and 38 described in connection with the first embodiment, and this is the difference from the heat exchanger 10 of the first embodiment. Apart from this difference, the configuration of the heat exchanger 110 of the second embodiment is the same as that of the heat exchanger 10 of the first embodiment. In the configuration of the second embodiment, the flow paths 32 and 36 through which the low-temperature fluids flow and the flow paths 34 and 38 through which the high-temperature fluids flow are arranged alternately, thereby efficiently exchanging heat between two adjacent flow paths.The number of flow paths is not limited to four in the first embodiment or eight in the second embodiment, but may be any number as long as the number is four or more.

[0030] When the two first flow paths 32 are connected to the fuel gas flow path 20 as in the above configuration, the two first flow paths 32 can be connected in parallel to the fuel gas flow path 20. This configuration enables efficient heat exchange between each of the first flow paths 32 and the adjacent second flow path 34. In another embodiment, the two first flow paths 32 can be connected in series to the fuel gas flow path 20. The two second flow paths 34, the two third flow paths 36, and the two fourth flow paths 38 can be connected in the same manner as the two first flow paths 32. [THIRD EMBODIMENT]

[0031] With reference to Fig. 3B, a heat exchanger 210 according to a third embodiment is described. As in Fig. As shown in Figure 3B, the arrangement of the plurality of flow paths 32, 34, 36, 38 in the heat exchanger 210 of the third embodiment differs from that of the heat exchanger 10 of the first embodiment. In the heat exchanger 210, the flow paths 32, 34, 36, 38 are arranged such that each of the flow paths 32, 34, 36, 38 is adjacent to two other flow paths. The first flow path 32 is adjacent not only to the second flow path 34 but also to the fourth flow path 38. That is, the first flow path 32 can also exchange heat with the fourth flow path 38. In this configuration, all of the flow paths 32, 34, 36, 38 are adjacent to two other flow paths, respectively. This increases the efficiency of heat exchange and thus enables a downsizing of the heat exchanger 210.

[0032] In particular, the heat exchanger 210 includes a housing 240. The housing 240 includes a tubular peripheral wall 42, which is the same as that described in connection with the first embodiment, and a plurality of plate-shaped partition walls 244 located within the peripheral wall 42. The partition walls 244 are connected to each other at one end, and the other ends of the partition walls 244 are connected to the peripheral wall 42. [FOURTH EMBODIMENT]

[0033] With reference to Fig. 4A, a heat exchanger 310 according to a fourth embodiment is described. As in Fig. 4A, the heat exchanger 310 of the fourth embodiment includes, in addition to the plurality of flow paths 32, 34, 36, 38 described in connection with the first embodiment, a second first flow path 332 and a second second flow path 334. In this respect, the heat exchanger 310 of the fourth embodiment differs from the heat exchanger 10 of the first embodiment. The second first flow path 332 is adjacent to and exchanges heat with the fourth flow path 38. The second first flow path 332 is connected to the fuel gas flow path 20, as is the case with the first flow path 32 in the first embodiment. The second second flow path 334 is adjacent to and exchanges heat with the second first flow path 332. The second flow path 334 is connected to the oxidizing gas flow path 24, as is the case with the second flow path 34 in the first embodiment.

[0034] In the configuration of the fourth embodiment, the third flow path 36 and the fourth flow path 38 in which the cooling water flows are arranged centrally in the arrangement of the flow paths 32, 34, 36, 38, 332, and 334. Compared with the fuel gas and its exhaust gas, which are gases, the cooling water, which is a liquid, has a relatively high heat exchange capacity. Therefore, the heat exchange efficiency can be effectively increased by centrally arranging the two flow paths 36 and 38 in which the cooling water flows in the arrangement of the flow paths 32, 34, 36, 38, 332, and 334. The second first flow path 332 in this embodiment is an example of a "first flow path" in the present technology. The fourth flow path 38 in this embodiment is an example of a "second flow path" in the present technology.The third flow path 36 in this embodiment is an example of a "third flow path" in the present technology. The fourth flow path 38 in this embodiment is an example of a "fourth flow path" in the present technology. [FIFTH EMBODIMENT]

[0035] With reference to Fig. 4B, a heat exchanger 410 according to a fifth embodiment is described. As in Fig. 4B, the heat exchanger 410 of the fifth embodiment includes a plurality of flow paths, including a first flow path 32 and a third flow path 36, which are the same as those described in connection with the first embodiment, as well as a second flow path 434 and a 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 oxidizing gas flow path 24. In this respect, the configuration of the heat exchanger 410 of the fifth embodiment differs from the heat exchanger 10 of the first embodiment. In the above-described configuration of the fifth embodiment, the two flow paths 434 and 36 in which the cooling water flows are centrally located in the arrangement of the four flow paths 32, 434, 36, 438. This can effectively increase the heat exchange efficiency.

[0036] In the heat exchanger 410 of the fifth embodiment, the arrangement of the flow paths 32, 434, 36, 438 also differs from that of the heat exchanger 10 of the first embodiment. 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. Furthermore, in the heat exchanger 410, the first flow path 32 is also adjacent to the fourth flow path 438 and also exchanges heat with the fourth flow path 438. In this configuration, all flow paths 32, 36, 434, 438 are each adjacent to two other flow paths. This increases the efficiency of heat exchange and thus enables a reduction in the size of the heat exchanger 410.

[0037] Furthermore, the second flow path 434 is surrounded by the first flow path 32, except for a portion thereof adjacent to the third flow path 36. The third flow path 36 is surrounded by the fourth flow path 438, except for a portion thereof adjacent to the second flow path 434. In this configuration, the first flow path 32 borders the second flow path 434 over a large area, and the fourth flow path 438 borders the third flow path 36 over a large area. This increases the efficiency of heat exchange and prevents the second flow path 434 and the third flow path 36 from unnecessarily exchanging heat with the outside environment.

[0038] The heat exchanger 410 includes a housing 440, although this need not be the case. The housing 440 includes a peripheral wall 42 defining a tube, which is the same as that described in connection with the first embodiment, and a plurality of partition walls 444 located within the peripheral wall 42. The plurality of partition walls 444 includes a first partition wall 444a defining a tube and a plate-shaped second partition wall 444b. The first partition wall 444a extends along the inner surface of the peripheral wall 42. The first partition wall 444a is separate from 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 separate the space defined by the first partition wall 444a and the space defined by the peripheral wall 42. [SIXTH EMBODIMENT]

[0039] With reference to Fig. 5, a heat exchanger 510 according to a sixth embodiment is described. As in Fig. 5, the arrangement of the flow paths 32, 434, 36, 438 in the heat exchanger 510 of the sixth embodiment differs from that of the heat exchanger 410 of the fifth embodiment. The first flow path 32, the second flow path 434, the third flow path 36, and the fourth flow path 438 all run along the same central axis C. The first flow path 32 is located innermost, the second flow path 434 is outside the first flow path 32, the third flow path 36 is outside the second flow path 434, and the fourth flow path 438 is outside the third flow path 36. The first flow path 32 is surrounded by the second flow path 434 over its entire circumference. The second flow path 434 is surrounded by the third flow path 36 over its entire circumference. The third flow path 36 is surrounded over its entire circumference by the fourth flow path 438.In particular, the first flow path 32, the second flow path 434, the third flow path 36, and the fourth flow path 438 are arranged concentrically around the central axis C. In this configuration, all flow paths, from the first flow path 32 to the fourth flow path 438, are adjacent to other flow paths over large areas. This increases the efficiency of heat exchange and prevents the flow paths 32, 434, and 36, with the exception of the fourth outermost flow path, from unnecessarily exchanging heat with the outside environment.

[0040] In the above arrangement of the four flow paths 32, 434, 36, 438 of the heat exchanger 510, the two flow paths 434 and 36 through which the cooling water flows are arranged centrally in the arrangement. This can effectively increase the efficiency of heat exchange.

[0041] The heat exchanger 510 includes a housing 540, although this is not required. The housing 540 includes a peripheral wall 542 defining a cylinder and a plurality of cylindrical partition walls 544 located within the peripheral wall 542.

[0042] The plurality of partition walls 544 includes a first partition wall 544a, a second partition wall 544b surrounding the entire periphery of the first partition wall 544a, and a third partition wall 544c surrounding the entire periphery of the second partition wall 544b. [SEVENTH EXECUTION]

[0043] With reference to Fig. 6, a heat exchanger 610 according to a seventh embodiment is described. As in Fig.6, the heat exchanger 610 of the seventh embodiment includes a plurality of flow paths, including a first flow path 32 and a third flow path 36, which are the same as those described in connection with the first embodiment, as well as a second flow path 634 and a fourth flow path 638. The second flow path 634 is connected to the fuel gas exhaust flow path 22, and the fourth flow path 638 is connected to the oxidizer gas exhaust flow path 26. In this respect, the heat exchanger 610 of the sixth embodiment differs from the heat exchanger 10 of the first embodiment. Also in this embodiment, fluids with relatively low temperatures flow through the first flow path 32 and the third flow path 36, while fluids with relatively high temperatures flow through the second flow path 634 and the fourth flow path 638.Thus, the flow paths 32 and 36 through which the low-temperature fluids flow and the flow paths 634 and 638 through which the high-temperature fluids flow are arranged alternately, which enables efficient heat exchange between two adjacent flow paths.

[0044] The various combinations of flow paths in the heat exchangers 10, 110, 210, 310, 410, 510, and 610 have been described in connection with the first to seventh embodiments, but the combinations of flow paths are not particularly limited. Each of the first and third flow paths can be connected to one of the fuel gas flow path 20 and the first cooling water flow path 28. Each of the second and fourth flow paths can be connected to one of the fuel gas off-gas flow path 22, the oxidizing gas flow path 24, the oxidizing gas off-gas flow path 26, and the second cooling water flow path 30. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2008 - 204 834 A

[0002]

Claims

[1] Heat exchanger (10, 110, 210, 310, 410, 510, 610) for a fuel cell (12), comprising: a first flow path (32, 332); a second flow path (34, 334, 434, 634) adjacent to the first flow path (32, 332) and exchanging heat with the first flow path (32, 332); a third flow path (36) adjacent to the second flow path (34, 334, 434, 634) and exchanging heat with the second flow path (34, 334, 434, 634); and a fourth flow path (38, 438, 638) adjacent to the third flow path (36) and exchanging heat with the third flow path (36), wherein each of the first flow path (32, 332) and the third flow path (36) is connected to one of a flow path for fuel gas (20) to be supplied to the fuel cell (12) and a flow path for cooling water (28) to be supplied to the fuel cell (12); and each of the second flow path (34, 334, 434, 634) and the fourth flow path (38, 438, 638) is connected to one of the following: a flow path for fuel off-gas (22) discharged from the fuel cell (12), a flow path for oxidizing gas (24) to be supplied to the fuel cell, a flow path for oxidizing gas off-gas (26) discharged from the fuel cell (12), and a flow path for cooling water (30) discharged from the fuel cell (12). [2] The heat exchanger (210, 410) of claim 1, wherein the first flow path (32) is also adjacent to the fourth flow path (38, 438) and also exchanges heat with the fourth flow path (38, 438). [3] The heat exchanger (410, 510) of claim 1 or 2, wherein the second flow path (434) and the third flow path (36) are surrounded by at least one of the first flow path (32) and the fourth flow path (438). [4] The heat exchanger (510) of claim 3, wherein the first flow path (32), the second flow path (434), the third flow path (36) and the fourth flow path (438) are arranged concentrically. [5] Heat exchanger (410, 510) according to one of claims 1 to 4, wherein the first flow path (32) is connected to the flow path for the fuel gas (20), the second flow path (434) is connected to the flow path for the discharged cooling water (30), the third flow path (36) is connected to the flow path for the cooling water (28) to be supplied, and the fourth flow path (438) is connected to the flow path for the oxidizing gas (24).

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