Fuel cell unit

Abstract

The present invention relates to a fuel cell unit. The problem is to reduce the temperature gradient within each fuel cell stack. A fuel cell unit including a plurality of fuel cell stacks arranged side by side along a first axis, and including: a plurality of unit cells stacked along a second axis perpendicular to the first axis; a cooling liquid passage provided along a third axis perpendicular to the first and second axes; a cooling liquid supply path that supplies cooling liquid to the cooling liquid passage; and a cooling liquid discharge path that discharges cooling liquid from the cooling liquid passage. The plurality of fuel cell stacks includes: a first fuel cell stack having the cooling liquid supply path on one end side of the third axis and the cooling liquid discharge path on the other end side of the third axis; and a second fuel cell stack having the cooling liquid discharge path on one end side of the third axis and the cooling liquid supply path on the other end side of the third axis, the second fuel cell stack being adjacent to the first fuel cell stack.

Description

Technical Field

[0001] This disclosure relates to fuel cell units. Background Technology

[0002] A fuel cell stack with two single-cell stacks arranged in parallel is known (e.g., Patent Document 1).

[0003] [Existing Technical Documents]

[0004] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2007-149362 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] When the temperature gradient within a fuel cell stack increases, there is a possibility of flooding in the low-temperature regions and dry-up in the high-temperature regions. Both flooding and dry-up reduce the power generation performance of the fuel cell stack. Therefore, technologies to suppress the increase in temperature gradient within the fuel cell stack are needed.

[0008] Means for solving technical problems

[0009] This disclosure may be implemented in the following ways.

[0010] (1) According to one aspect of the present disclosure, a fuel cell unit is provided. The fuel cell unit includes a plurality of fuel cell stacks arranged side-by-side along a first axis, and each of the plurality of fuel cell stacks includes: a plurality of single cells stacked along a second axis perpendicular to the first axis; a coolant channel disposed along a third axis perpendicular to the first axis and the second axis; a coolant supply path supplying coolant to the coolant channel; and a coolant discharge path discharging coolant from the coolant channel to the coolant discharge path. The plurality of fuel cell stacks include: a first fuel cell stack having the coolant supply path at one end of the third axis and the coolant discharge path at the other end of the third axis; and a second fuel cell stack having the coolant discharge path at the one end of the third axis and the coolant supply path at the other end of the third axis, the second fuel cell stack being adjacent to the first fuel cell stack.

[0011] According to this method, the coolant flow direction can be reversed in the coolant channels of the adjacent first and second fuel cell stacks. Therefore, it is possible to suppress the increase of temperature gradients within each fuel cell stack.

[0012] (2) The fuel cell unit of the above method may also include a heat conduction component, which is arranged between the first fuel cell stack and the second fuel cell stack, in contact with the first fuel cell stack and the second fuel cell stack, and has a heat conduction rate higher than that of air.

[0013] According to this method, heat transfer can be easily achieved between the first fuel cell stack and the second fuel cell stack. Therefore, the increase in temperature gradient within each fuel cell stack can be effectively suppressed.

[0014] (3) In the fuel cell unit of the above method, the plurality of fuel cell stacks may also include a third fuel cell stack, the third fuel cell stack having the coolant supply path at one end of the third shaft and the coolant discharge path at the other end of the third shaft, and the second fuel cell stack being arranged between the first fuel cell stack and the third fuel cell stack.

[0015] According to this method, in fuel cell units comprising three or more fuel cell stacks, the increase in temperature gradient within each fuel cell stack can be suppressed. Attached Figure Description

[0016] Figure 1 This is an explanatory diagram showing the structure of the fuel cell unit according to the first embodiment.

[0017] Figure 2 This is an explanatory diagram showing the flow of coolant in the fuel cell unit of the first embodiment.

[0018] Figure 3 This is a cross-sectional view of the fuel cell unit according to the first embodiment.

[0019] Figure 4 This is a cross-sectional view of the fuel cell unit according to the second embodiment.

[0020] Figure 5 This is a cross-sectional view of the fuel cell unit according to the third embodiment. Detailed Implementation

[0021] A. First implementation method:

[0022] Figure 1This is an explanatory diagram showing the structure of the fuel cell unit 10 in the first embodiment. In this embodiment, the fuel cell unit 10 includes two fuel cell stacks 100A and 100B and a stack housing 200. In the following description, fuel cell stack 100A will be referred to as the first fuel cell stack 100A, and fuel cell stack 100B will be referred to as the second fuel cell stack 100B. However, without specifically distinguishing between the first fuel cell stack 100A and the second fuel cell stack 100B, it is sometimes simply referred to as fuel cell stack 100. Figure 1 The figure shows the X-axis, Y-axis, and Z-axis, which represent the directions in the fuel cell unit 10. The X-axis, Y-axis, and Z-axis are perpendicular to each other. In this disclosure, the Y-axis is sometimes referred to as the first axis, the Z-axis as the second axis, and the X-axis as the third axis.

[0023] The first fuel cell stack 100A and the second fuel cell stack 100B are housed in a box-shaped stack housing 200. The first fuel cell stack 100A and the second fuel cell stack 100B are arranged side by side along the Y-axis within the stack housing 200. The first fuel cell stack 100A and the second fuel cell stack 100B are fixed to the stack housing 200.

[0024] Each fuel cell stack 100 has a plurality of individual cells 110, a pair of current collectors 120, a pair of insulating plates 130, and a pair of end plates 140. The plurality of individual cells 110 are stacked along the Z-axis. The end plates 140, insulating plates 130, current collectors 120, the plurality of individual cells 110, current collectors 120, insulating plates 130, and end plates 140 are stacked along the Z-axis in this order and secured to each other by fasteners not shown. Furthermore, in the figures, for the components of the first fuel cell stack 100A, the symbol ends with the character "A," and for the components of the second fuel cell stack 100B, the symbol ends with the character "B."

[0025] Figure 2 This is an explanatory diagram showing the flow of coolant CL in fuel cell unit 10. Figure 3 This is a cross-sectional view of fuel cell unit 10. (As shown...) Figure 2 As shown, inside the fuel cell stack 100, a coolant supply path 151, multiple coolant channels 152, and a coolant discharge path 153 are provided. Each coolant channel 152 is disposed between individual cells 110. One end of each coolant channel 152 is connected to the coolant supply path 151, and the other end of each coolant channel 152 is connected to the coolant discharge path 153. In this embodiment, the coolant CL is water. However, the coolant CL can also be a liquid other than water.

[0026] like Figure 3As shown, each coolant passage 152 is configured to pass through the power generation section GA of the single cell 110. Each coolant passage 152 is arranged along the X-axis. In this disclosure, the arrangement of the coolant passage 152 along the X-axis means that the inlet and outlet of the coolant passage 152 are located at different positions on the X-axis. Thus, the coolant passage 152 can be arranged in a straight line along the X-axis or it can be arranged meanderingly along the X-axis.

[0027] like Figure 2 As shown, the coolant supply path 151 supplies coolant CL to each coolant channel 152. In this embodiment, the coolant supply path 151 is arranged along the Z-axis. The coolant supply path 151 is formed by through holes provided on the single cell 110, the current collector plate 120, the insulating plate 130, and the end plate 140. The opening of the coolant supply path 151 is provided on the end plate 140 arranged at the -Z side end.

[0028] Coolant CL is discharged from each coolant channel 152 to the coolant discharge path 153. In this embodiment, the coolant discharge path 153 is arranged along the Z-axis. The coolant discharge path 153 is formed by through holes provided on the single cell 110, the current collector plate 120, the insulating plate 130, and the end plate 140. The opening of the coolant discharge path 153 is provided on the end plate 140 arranged at the -Z side end.

[0029] The coolant CL supplied to the fuel cell stack 100 flows in the order of coolant supply path 151, coolant passage 152, and coolant discharge path 153. A pump and a radiator are connected to the opening of the coolant discharge path 153 via coolant piping (not shown). The radiator is connected to the opening of the coolant supply path 151 via coolant piping. The coolant CL discharged from the coolant discharge path 153 is supplied to the radiator by the pump, cooled by the radiator, and then supplied back to the coolant supply path 151.

[0030] In the first fuel cell stack 100A and the second fuel cell stack 100B, the coolant supply path 151 and the coolant discharge path 153 are arranged in opposite directions. In this embodiment, in the first fuel cell stack 100A, the coolant supply path 151A is located at the +X side end, and the coolant discharge path 153A is located at the -X side end. Conversely, in the second fuel cell stack 100B, the coolant supply path 151B is located at the -X side end, and the coolant discharge path 153B is located at the +X side end.

[0031] like Figure 3As shown, the fuel cell stack 100 is further provided with a hydrogen supply path 161 for supplying hydrogen to the single cell 110, a hydrogen discharge path 163 for discharging hydrogen from the single cell 110, an air supply path 171 for supplying oxygen-containing air to the single cell 110, and an air discharge path 173 for discharging air from the single cell 110.

[0032] In this embodiment, single cells 110 of the same shape are used in both the first fuel cell stack 100A and the second fuel cell stack 100B. The single cells 110B of the second fuel cell stack 100B are arranged such that the single cells 110A of the first fuel cell stack 100A are rotated 180 degrees about the Z-axis. Alternatively, the single cells 110B of the second fuel cell stack 100B can also be arranged such that the single cells 110A of the first fuel cell stack 100A are rotated 180 degrees about the Y-axis. The shapes of the single cells 110 in the first fuel cell stack 100A and the second fuel cell stack 100B can also be different.

[0033] like Figure 2 As shown, in this embodiment, the flow directions of the coolant CL are opposite in the first fuel cell stack 100A and the second fuel cell stack 100B. Specifically, in the first fuel cell stack 100A, the coolant CL flows from the -Z side end to the +Z side end in the coolant supply path 151A located at the +X side end, flows from the +X side end to the -X side end in the coolant channel 152A, and flows from the +Z side end to the -Z side end in the coolant discharge path 153A located at the -X side end. In contrast, in the second fuel cell stack 100B, the coolant CL flows from the -Z side end to the +Z side end in the coolant supply path 151B located at the -X side end, flows from the -X side end to the +X side end in the coolant channel 152B, and flows from the +Z side end to the -Z side end in the coolant discharge path 153B located at the +X side end.

[0034] Here, the coolant CL flowing within the fuel cell stack 100 absorbs the heat generated by the power generation of the fuel cell stack 100. Therefore, the temperature of the coolant CL flowing within the fuel cell stack 100 increases as it approaches the coolant discharge path 153 from the upstream coolant supply path 151. When the flow direction of the coolant CL is the same in the first fuel cell stack 100A and the second fuel cell stack 100B, the high-temperature section of the first fuel cell stack 100A is adjacent to the high-temperature section of the second fuel cell stack 100B, and the low-temperature section of the first fuel cell stack 100A is adjacent to the low-temperature section of the second fuel cell stack 100B. Therefore, the temperature gradient between the high-temperature and low-temperature sections in each fuel cell stack 100A and 100B becomes larger. As a result, flooding is prone to occur in the low-temperature sections of each fuel cell stack 100A and 100B, and drying is prone to occur in the high-temperature sections of each fuel cell stack 100A and 100B. Flooding refers to water generated by the power generation of the fuel cell stack 100 remaining within the individual cells 110. When flooding occurs, the flow of reactant gases within the single cell 110 is impeded, reducing the power generation performance of the fuel cell stack 100. Drying refers to the electrolyte membrane within the single cell 110 drying out. When drying occurs, the proton conductivity of the electrolyte membrane decreases, further reducing the power generation performance of the fuel cell stack 100.

[0035] In contrast, in this embodiment, the flow directions of the coolant CL in the first fuel cell stack 100A and the second fuel cell stack 100B are opposite. The high-temperature portion of the first fuel cell stack 100A is adjacent to the low-temperature portion of the second fuel cell stack 100B, and vice versa. Therefore, heat is conducted from the high-temperature portion of the first fuel cell stack 100A to the low-temperature portion of the second fuel cell stack 100B, and vice versa. As a result, the temperature gradient between the high-temperature and low-temperature portions in the first fuel cell stack 100A and the second fuel cell stack 100B decreases. Consequently, the temperature gradient between the high-temperature and low-temperature portions in both the first and second fuel cell stacks 100A and 100B decreases. Therefore, it is easy to maintain each portion of each fuel cell stack 100A and 100B at an appropriate temperature, and flooding or drying out in each fuel cell stack 100A and 100B can be suppressed.

[0036] In this embodiment, a gap is provided between the first fuel cell stack 100A and the second fuel cell stack 100B. In other words, the first fuel cell stack 100A and the second fuel cell stack 100B are electrically insulated from each other by air. Since the individual cells 110A of the first fuel cell stack 100A and the individual cells 110B of the second fuel cell stack 100B have different potentials, a necessary insulation distance is ensured so that the conductive parts of each individual cell 110A, 110B will not come into contact with each other and short-circuit. However, the wider the gap, the more difficult the heat conduction becomes. Therefore, from the viewpoint of ease of heat conduction, a narrow gap is preferred. Thus, the width of the gap between the first fuel cell stack 100A and the second fuel cell stack 100B is preferably a width that can balance heat transfer and electrical insulation.

[0037] According to the fuel cell unit 10 of this embodiment described above, since the first fuel cell stack 100A and the second fuel cell stack 100B are arranged such that their high-temperature and low-temperature portions are adjacent to each other, heat is conducted from the high-temperature portion of the first fuel cell stack 100A to the low-temperature portion of the second fuel cell stack 100B, and vice versa. Therefore, the temperature gradient within each fuel cell stack 100A and 100B can be reduced. Consequently, flooding or drying out within each fuel cell stack 100A and 100B can be suppressed, and the reduction in power generation performance of each fuel cell stack 100A and 100B can be prevented.

[0038] B. Second implementation method:

[0039] Figure 4 This is a cross-sectional view of the fuel cell unit 10b in the second embodiment. In the second embodiment, unlike the first embodiment, a heat transfer component 300 is arranged between the first fuel cell stack 100A and the second fuel cell stack 100B. Otherwise, unless otherwise specified, it is the same as the first embodiment.

[0040] The fuel cell unit 10b is equipped with a first fuel cell stack 100A, a second fuel cell stack 100B, a stack housing 200, and a heat conduction component 300. The heat conduction component 300 is thermally conductive and electrically insulating. In this disclosure, being thermally conductive means having a thermal conductivity higher than that of air.

[0041] A heat-conducting component 300 is arranged to contact both the first fuel cell stack 100A and the second fuel cell stack 100B. The heat-conducting component 300 is arranged to fill the gap between the first fuel cell stack 100A and the second fuel cell stack 100B. The heat-conducting component 300 is arranged in part or all of the portions of the first fuel cell stack 100A and the second fuel cell stack 100B facing each other. The heat-conducting component 300 is preferably arranged such that heat can be easily conducted from the high-temperature portion of the first fuel cell stack 100A to the low-temperature portion of the second fuel cell stack 100B, and heat can also be easily conducted from the high-temperature portion of the second fuel cell stack 100B to the low-temperature portion of the first fuel cell stack 100A.

[0042] In addition to thermal conductivity and electrical insulation, the heat-conducting component 300 preferably possesses flexibility. Within the fuel cell stack 100, the positions of individual cells 110 may sometimes deviate. Therefore, unevenness may sometimes occur on the sides of the fuel cell stack 100. When unevenness occurs on the sides of the fuel cell stack 100, the spacing between the first fuel cell stack 100A and the second fuel cell stack 100B becomes uneven. If the heat-conducting component 300 is flexible, even if the spacing between the first fuel cell stack 100A and the second fuel cell stack 100B is uneven, the heat-conducting component 300 can be kept in close contact with the sides of the first fuel cell stack 100A and the second fuel cell stack 100B. For example, a composite material formed by filling silicone rubber with ceramic filler can be used for the heat-conducting component 300.

[0043] According to the fuel cell unit 10b in this embodiment described above, since a heat conduction component 300 is arranged between the first fuel cell stack 100A and the second fuel cell stack 100B, heat is easily conducted between the first fuel cell stack 100A and the second fuel cell stack 100B. Therefore, the temperature gradient within each fuel cell stack 100A and 100B can be reduced more effectively.

[0044] C. Third implementation method:

[0045] Figure 5 This is a cross-sectional view of the fuel cell unit 10c in the third embodiment. In the third embodiment, unlike the first embodiment, the three fuel cell stacks 100A to 100C are housed within the stack housing 200. Otherwise, unless otherwise specified, they are the same as in the first embodiment.

[0046] The fuel cell unit 10c includes a first fuel cell stack 100A, a second fuel cell stack 100B, a third fuel cell stack 100C, and a stack housing 200. Unless otherwise specified, the construction of the third fuel cell stack 100C is the same as that of the first fuel cell stack 100A and the second fuel cell stack 100B. Additionally, in Figure 5In the symbol, the components of the first fuel cell stack 100A are marked with the character "A", the components of the second fuel cell stack 100B are marked with the character "B", and the components of the third fuel cell stack 100C are marked with the character "C".

[0047] The first fuel cell stack 100A, the second fuel cell stack 100B, and the third fuel cell stack 100C are arranged side-by-side along the Y-axis within the stack housing 200. The second fuel cell stack 100B is arranged between the first fuel cell stack 100A and the third fuel cell stack 100C. In other words, the first fuel cell stack 100A and the second fuel cell stack 100B are arranged adjacent to each other, and the second fuel cell stack 100B and the third fuel cell stack 100C are arranged adjacent to each other.

[0048] In this embodiment, in the first fuel cell stack 100A and the third fuel cell stack 100C, coolant supply paths 151A and 151C are located at the +X side end, and coolant discharge paths 153A and 153C are located at the -X side end. In the second fuel cell stack 100B, coolant supply path 151B is located at the -X side end, and coolant discharge path 153B is located at the +X side end. That is, in this embodiment, in two adjacent fuel cell stacks 100, the coolant supply path 151 and the coolant discharge path 153 are arranged oppositely. Therefore, in two adjacent fuel cell stacks 100, the flow direction of the coolant CL flowing in the coolant channel 152 is opposite.

[0049] According to the fuel cell unit 10c in this embodiment described above, since the high-temperature and low-temperature portions of the first fuel cell stack 100A and the second fuel cell stack 100B are arranged adjacent to each other, and the high-temperature and low-temperature portions of the second fuel cell stack 100B and the third fuel cell stack 100C are also arranged adjacent to each other, heat is conducted from the high-temperature portion of the adjacent fuel cell stacks 100 to the low-temperature portion. Therefore, the temperature gradient within each fuel cell stack 100A to 100C can be reduced.

[0050] In this embodiment, similar to the second embodiment, a heat transfer component 300 may also be arranged between the first fuel cell stack 100A and the second fuel cell stack 100B. A heat transfer component 300 may also be arranged between the second fuel cell stack 100B and the third fuel cell stack 100C. In this case, the temperature gradient within each fuel cell stack 100A~100C can be reduced more effectively.

[0051] D. Other implementation methods:

[0052] (D1) In the fuel cell unit 10c of the third embodiment described above, the flow direction of the coolant CL in the coolant channels 152 of all adjacent fuel cell stacks 100 is opposite. In contrast, in the fuel cell unit 10c, it is sufficient that the flow direction of the coolant CL in the coolant channels 152 of one set of adjacent fuel cell stacks 100 is opposite; the flow direction of the coolant CL in the coolant channels 152 of the remaining set of adjacent fuel cell stacks 100 can be the same. Even in this manner, compared to the method where the flow direction of the coolant CL in the coolant channels 152 of all adjacent fuel cell stacks 100 is the same, the temperature gradient within the fuel cell stack 100 can be reduced.

[0053] (D2) In the fuel cell units 10 to 10c of the above embodiments, four or more fuel cell stacks 100 may be arranged side by side along the Y-axis within the stack housing 200. In this case, it is sufficient that the flow direction of the coolant CL in the coolant passage 152 of at least one set of adjacent fuel cell stacks 100 is opposite.

[0054] (D3) In the fuel cell units 10-10c of the above embodiments, the openings of the coolant supply path 151 and the coolant discharge path 153 are provided on the end plate 140 at the -Z side end. Conversely, the openings of the coolant supply path 151 and the coolant discharge path 153 may also be provided on the end plate 140 at the +Z side end. Alternatively, one of the openings of the coolant supply path 151 and the coolant discharge path 153 may be provided on the end plate 140 at the +Z side end, and the other may be provided on the end plate 140 at the -Z side end.

[0055] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, in order to solve some or all of the above problems, or to achieve some or all of the above effects, the technical features in the embodiments corresponding to the technical features in the various methods described in the invention summary can be appropriately replaced or combined. In addition, if a technical feature is not described as an essential feature in this specification, it can be appropriately deleted.

[0056] Explanation of reference numerals in the attached figures

[0057] 10, 10b, 10c... Fuel cell unit, 100A... First fuel cell stack, 100B... Second fuel cell stack, 100C... Third fuel cell stack, 110... Single cell, 120... Current collector plate, 130... Insulation plate, 140... End plate, 151... Coolant supply path, 152... Coolant passage, 153... Coolant discharge path, 161... Hydrogen supply path, 163... Hydrogen discharge path, 171... Air supply path, 173... Air discharge path, 200... Stack shell, 300... Heat transfer components

Claims

1. A fuel cell unit, wherein, The system includes multiple fuel cell stacks arranged side-by-side along a first axis, and each fuel cell stack includes: multiple individual cells stacked along a second axis perpendicular to the first axis; a coolant channel arranged along a third axis perpendicular to both the first and second axes; a coolant supply path supplying coolant to the coolant channel; and a coolant discharge path from the coolant channel to the coolant discharge path. The plurality of fuel cell stacks include: A first fuel cell stack, wherein the first fuel cell stack has the coolant supply path at one end of the third shaft and the coolant discharge path at the other end of the third shaft; and A second fuel cell stack has a coolant discharge path at one end of the third shaft and a coolant supply path at the other end of the third shaft, and is adjacent to the first fuel cell stack.

2. The fuel cell unit as described in claim 1, wherein, Also includes: A heat conduction component is disposed between the first fuel cell stack and the second fuel cell stack, and is in contact with the first fuel cell stack and the second fuel cell stack, and has a heat conduction rate higher than that of air.

3. The fuel cell unit as described in claim 1, wherein, The plurality of fuel cell stacks further includes a third fuel cell stack, which has the coolant supply path at one end of the third shaft and the coolant discharge path at the other end of the third shaft. The second fuel cell stack is arranged between the first fuel cell stack and the third fuel cell stack.

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