Air-cooled fuel cell system

Abstract

To provide an air-cooling fuel cell system with which it is possible to improve the power generation performance of a fuel cell.SOLUTION: Provided is an air-cooling fuel cell system. The air-cooling fuel cell system comprises a fuel cell, an oxidant gas system, and a cooling gas system. The fuel cell includes a fuel cell stack in which a plurality of single cells are stacked one on another, the single cell including a cathode separator having a corrugated plate-like oxidant gas passage, a membrane electrode gas diffusion layer joint body, an anode separator having a corrugated plate-like fuel gas passage, and a cooling fan having a corrugated plate-like cooling gas passage. The oxidant gas passage and the cooling gas passage, at least partly, intersect each other in a top view, and the cooling gas system includes a cooling gas supply unit for supplying a cooling gas to the fuel cell, a cooling gas piping, and a pressure loss body upstream of the fuel cell in the cooling gas piping. The air-cooling fuel cell system has a distribution of cooling capability with respect to the oxidant gas flow direction of the oxidant gas passage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to air-cooled fuel cell systems. [Background technology]

[0002] Various technologies have been proposed for fuel cell systems. For example, Patent Document 1 discloses an air-cooled fuel cell in which cooling gas supply ports and exhaust ports are alternately provided along the stacking direction of the unit cells in a fuel cell stack formed by alternately stacking unit cells and separators. Patent document 2 discloses a fuel cell comprising a fuel cell power generating unit (1) and separators (3) provided on both sides of the fuel cell power generating unit (1), with fuel gas supply grooves (4) and oxidant gas supply grooves (5) provided on both sides of the separator (3), and with through holes (10) provided in the separator (3) for cooling the fuel cell power generating unit (1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 1986-185871 [Patent Document 2] Japanese Patent Application Laid-Open No. 1994-020708 Summary of the Invention [Problem to be solved by the invention]

[0004] In a two-passage air-cooled fuel cell, in which the oxidant gas passage and the cooling gas passage are formed in a corrugated shape and the oxidant gas passage and the cooling gas passage intersect, the oxygen concentration distribution and temperature distribution within the cell surface inevitably occur due to the structure, resulting in a biased power generation distribution within the cell surface and reduced fuel cell performance. Furthermore, Patent Document 1 raises concerns about an increase in the number of parts. Furthermore, Patent Document 1 has a high possibility of high pressure loss due to its structure, and the area utilization rate of the power generation section in power generation is low in horizontally elongated cells.

[0005] The present disclosure has been made in view of the above circumstances, and has as its main object to provide an air-cooled fuel cell system that can improve the power generation performance of the fuel cell. [Means for solving the problem]

[0006] In a first embodiment of the present disclosure, there is provided an air-cooled fuel cell system, the air-cooled fuel cell system includes a fuel cell, an oxidant gas system, and a cooling gas system; the fuel cell has a fuel cell stack in which a plurality of unit cells are stacked, the unit cell includes a cathode separator having a corrugated oxidant gas flow path, a membrane electrode gas diffusion layer assembly, an anode separator having a corrugated fuel gas flow path, and a cooling fin having a corrugated cooling gas flow path; the oxidant gas flow path and the cooling gas flow path at least partially intersect with each other in a top view; the cooling gas system includes a cooling gas supply unit that supplies a cooling gas to the fuel cell, a cooling gas pipe, and a pressure drop body located upstream of the fuel cell in the cooling gas pipe; The air-cooled fuel cell system is characterized in that the cooling capacity is distributed in the oxidant gas flow direction of the oxidant gas passage.

[0007] In a second embodiment of the present disclosure, the air-cooled fuel cell system may have a high cooling capacity on the inlet side of the oxidant gas flow path and a low cooling capacity on the outlet side of the oxidant gas flow path.

[0008] In a third embodiment of the present disclosure, the oxidant gas flow path and the cooling gas flow path may have a contact area distribution such that the contact area between the oxidant gas flow path inlet side and the cooling gas flow path is larger than the contact area between the oxidant gas flow path outlet side and the cooling gas flow path, and the contact area decreases from the oxidant gas flow path inlet side toward the oxidant gas flow path outlet side.

[0009] In a fourth embodiment of the present disclosure, the pressure loss element may have a pressure loss distribution such that the pressure loss is lower on the oxidant gas flow path inlet side than on the oxidant gas flow path outlet side with respect to the oxidant gas flow path flow direction, and the pressure loss increases from the oxidant gas flow path inlet side to the oxidant gas flow path outlet side.

[0010] In a fifth embodiment of the present disclosure, the cooling gas supply unit may be disposed closer to the oxidizing gas flow field inlet than the center of the oxidizing gas flow field.

[0011] In a sixth embodiment of the present disclosure, the cooling fins may have a fin pitch distribution such that the fin pitch of the cooling gas flow channel is narrower on the inlet side of the oxidant gas flow channel than on the outlet side of the oxidant gas flow channel with respect to the flow direction of the oxidant gas flow channel.

[0012] In a seventh embodiment of the present disclosure, the oxidant gas flow path and the cooling gas flow path may have a contact area between the oxidant gas flow path and the inlet side of the cooling gas flow path that is smaller than the contact area between the oxidant gas flow path and the outlet side of the cooling gas flow path.

[0013] In an eighth embodiment of the present disclosure, the cathode separator has a plurality of throttle portions in a part of the oxidant gas flow channel, In a portion where the cooling gas flow path and the oxidant gas flow path intersect and contact each other when viewed from above, the number of contact points between the constriction portion and the cooling gas flow path may increase from the oxidant gas flow path inlet side toward the oxidant gas flow path outlet side.

[0014] In a ninth embodiment of the present disclosure, the cathode separator has a plurality of throttle portions in a part of the oxidant gas flow channel, The throttle portion does not have to be provided at the portion where the cooling gas flow passage and the oxygen-containing gas flow passage intersect and contact each other when viewed from above. [Effects of the Invention]

[0015] The air-cooled fuel cell system of the present disclosure can improve the power generation performance of the fuel cell. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective schematic diagram showing an example of the configuration of an air-cooled fuel cell according to the present disclosure. [Figure 2] FIG. 2 is an exploded perspective view showing an example of a single cell of the air-cooled fuel cell of the present disclosure. [Figure 3] Figure 3 shows, from top to bottom, (1) a diagram showing the state in which the contact area between the cooling gas flow path and the oxidant gas flow path is distributed in an air-cooled fuel cell system according to the third embodiment of the present disclosure, (2) an AA cross-sectional view, (3) a BB cross-sectional view, and (4) a CC cross-sectional view. [Figure 4] FIG. 4 is a diagram showing a state in which a pressure loss distribution is provided to the pressure loss body and a distribution is provided to the cooling capacity in an air-cooled fuel cell system according to a fourth embodiment of the present disclosure. [Figure 5] FIG. 5 is a diagram showing a state in which the cooling capacity is distributed by the arrangement of the cooling gas supply units in an air-cooled fuel cell system according to the fifth embodiment of the present disclosure. [Figure 6] Figure 6 shows, from top to bottom, (1) a diagram showing how the cooling capacity is distributed by distributing the fin pitch in an air-cooled fuel cell system according to the sixth embodiment of the present disclosure, (2) an AA cross-sectional view, and (3) a BB cross-sectional view. [Figure 7] Figure 7 shows, from top to bottom, (1) a diagram showing a state in which the contact area between the cooling gas flow path and the oxidant gas flow path is distributed to improve the temperature distribution in the flow direction of the cooling gas flow path in an air-cooled fuel cell system of the seventh embodiment of the present disclosure, (2) an AA cross-sectional view, (3) a BB cross-sectional view, and (4) a CC cross-sectional view. [Figure 8] Figure 8 shows, from top to bottom, (1) a diagram showing a state in which, when a flow path with a throttling section is applied to the oxidant gas flow path in an air-cooled fuel cell system according to the eighth embodiment of the present disclosure, a temperature distribution is achieved by distributing the contact points between the ribs constituting the throttling section and the cooling gas flow path, (2) a partially enlarged view of the diagram, and (3) a cross-sectional view taken along the line AA. [Figure 9] Figure 9 shows, from top to bottom, (1) a diagram showing a structure in an air-cooled fuel cell system according to a ninth embodiment of the present disclosure, in which the constriction portion is positioned so that the cooling gas flow path does not come into contact with the constriction portion, thereby reducing the contact resistance between the oxidant gas flow path and the cooling gas flow path and preventing a decrease in the power generation performance of the cell, (2) an AA cross-sectional view, and (3) a BB cross-sectional view. [Figure 10] FIG. 10 is a diagram for explaining the mechanism by which temperature distribution occurs, which is a problem to be solved in the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] Embodiments of the present disclosure will be described below. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the present disclosure (for example, the general configuration and manufacturing process of a fuel cell system that do not characterize the present disclosure) can be understood as design matters for those skilled in the art based on prior art in the relevant field. The present disclosure can be implemented based on the contents disclosed in this specification and common general technical knowledge in the relevant field. Furthermore, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships. In this specification, the use of "to" to indicate a range of values ​​means that the values ​​before and after it are included as the lower and upper limits. Any combination of upper and lower limits in the numerical range can be adopted.

[0018] FIG. 10 is a diagram illustrating the temperature distribution generation mechanism, which is a problem to be solved in the present disclosure. As shown in FIG. 10, in a flow path structure in which the cooling gas in the cooling gas flow path flows in a direction intersecting the gas flow direction in the oxidant gas flow path, the oxygen concentration is higher near the inlet of the oxidant gas flow path than near the outlet of the oxidant gas flow path, causing the temperature inside the cell to rise. This increases the amount of power generation and the amount of water produced. As a result, the power generation performance of the cell decreases near the outlet of the oxidant gas flow path, the area utilization rate of the power generation section on the cell surface decreases, and the electrodes on the cell surface are not fully utilized. Furthermore, the temperature is lower near the outlet of the oxidant gas flow path, making condensation more likely to occur, resulting in flooding.

[0019] The present disclosure relates to improving the performance of air-cooled fuel cells (FC), and is particularly effective in suppressing the distribution of power generation within the cell surface and the distribution of contact resistance within the cell surface. The researchers considered the filter, which is not present in water-cooled FC structures, to be a pressure loss body in air-cooled fuel cells, and discovered that by creating a pressure loss distribution, it is possible to raise the temperature in areas with low power generation. Furthermore, they discovered that in air-cooled fuel cells, further temperature distribution can be achieved by changing the position of the cooling gas supply unit, such as the fan, and by changing the shape of the flow path in the in-plane direction. According to the present disclosure, the power generation performance of an air-cooled fuel cell can be improved by increasing the temperature at the outlet side of the oxidant gas flow path, where the oxygen concentration decreases, power generation performance decreases, the temperature drops, and the generated water is likely to condense.This reduces the number of parts in an air-cooled fuel cell system and increases the area utilization rate of the power generation section in power generation, even if the cell has a horizontally elongated shape.

[0020] First embodiment In a first embodiment of the present disclosure, there is provided an air-cooled fuel cell system, the air-cooled fuel cell system includes a fuel cell, an oxidant gas system, and a cooling gas system; the fuel cell has a fuel cell stack in which a plurality of unit cells are stacked, the unit cell includes a cathode separator having a corrugated oxidant gas flow path, a membrane electrode gas diffusion layer assembly, an anode separator having a corrugated fuel gas flow path, and a cooling fin having a corrugated cooling gas flow path; the oxidant gas flow path and the cooling gas flow path at least partially intersect with each other in a top view; the cooling gas system includes a cooling gas supply unit that supplies a cooling gas to the fuel cell, a cooling gas pipe, and a pressure drop body located upstream of the fuel cell in the cooling gas pipe; The air-cooled fuel cell system is characterized in that the cooling capacity is distributed in the oxidant gas flow direction of the oxidant gas passage.

[0021] FIG. 1 is a perspective schematic diagram showing an example of the configuration of an air-cooled fuel cell according to the present disclosure. The air-cooled fuel cell shown in Fig. 1 has a fuel cell stack (sometimes simply referred to as a stack), with current collector plates and pressure plates arranged in that order at both ends of the stack. An oxidant gas flow path indicated by a reaction air inlet and a reaction air outlet and a fuel gas flow path indicated by a reaction H2 inlet and a reaction H2 outlet are arranged so as to form counterflows, and a cooling gas flow path through which cooling air passes is arranged so as to intersect with the oxidant gas flow path and the fuel gas flow path.

[0022] FIG. 2 is an exploded perspective view showing an example of a single cell of the air-cooled fuel cell of the present disclosure. The single cell (sometimes simply referred to as a cell) of the air-cooled fuel cell shown in FIG. 2 has, in this order, a cooling fin, a first separator, a resin frame that houses the MEGA in its opening, and a second separator. The cooling fins are arranged on the surface of the first separator in an area opposite to the MEGA. The first separator, the resin frame, and the second separator are provided with an oxidant gas supply manifold (reaction air in) and an oxidant gas discharge manifold (reaction air out) through which reactant air, which is an oxidant gas, can flow, as shown by the arrows, and a fuel gas supply manifold (reaction H2 in) and a fuel gas discharge manifold (reaction H2 out) through which hydrogen, which is a fuel gas, can flow. Note that, for convenience in this disclosure, the oxidant gas supply manifold, oxidant gas discharge manifold, fuel gas supply manifold, and fuel gas discharge manifold are collectively referred to as reaction gas manifolds. The first separator (cathode separator) is provided with a corrugated oxidant gas flow path through which reaction air, which serves as an oxidant, can flow, as shown by the arrows. The second separator (anode separator) is provided with a corrugated fuel gas flow path through which hydrogen, which is a fuel gas, can flow, as shown by the arrows. The cooling fins are provided with cooling gas flow paths in the shape of corrugated plates, as shown by the arrows, through which cooling air (cooling gas) serving as a refrigerant can flow. The air-cooled fuel cell may have a structure in which a coolant flows along the side surface.

[0023] In the present disclosure, the cooling gas flow passage is configured to intersect the flow of air as an oxidant gas for power generation and the flow of hydrogen as a fuel gas, resulting in a characteristic structure in which the corrugated flow passages cross each other. According to the present disclosure, the temperature distribution as shown in Figure 10, which occurs when the cooling gas in the cooling gas flow channel flows in a direction that intersects with the gas flow direction in the oxidant gas flow channel, can be improved, thereby improving the power generation performance of the cell. In the first embodiment of the present disclosure, the power generation performance of the fuel cell can be improved by distributing the cooling capacity in the flow direction of the oxidizing gas flow channel.

[0024] Second embodiment In a second embodiment of the present disclosure, the air-cooled fuel cell system may have a high cooling capacity on the inlet side of the oxidant gas flow path and a low cooling capacity on the outlet side of the oxidant gas flow path.

[0025] In the second embodiment of the present disclosure, the oxygen concentration in the oxidant gas flow path decreases, the power generation performance of the cell decreases, and the temperature inside the cell decreases, so the temperature on the outlet side of the oxidant gas flow path, where the generated water is likely to condense, can be increased, thereby improving the power generation performance of the fuel cell. In the present disclosure, the oxidant gas flow path inlet may be, in a single cell, a through-hole in the cathode separator, which may be an oxidant gas supply hole that can supply oxidant gas to the oxidant gas flow path on the surface of the cathode separator where the oxidant gas flow path is formed, or, in a fuel cell stack, may be an oxidant gas supply manifold to which the oxidant gas supply holes are connected. In addition, in the present disclosure, the oxidant gas flow path outlet may be, in a single cell, a through-hole in the cathode separator, which may be an oxidant gas discharge hole that can discharge the oxidant gas from the oxidant gas flow path on the surface of the cathode separator where the oxidant gas flow path is formed, or, in a fuel cell stack, may be an oxidant gas discharge manifold to which the oxidant gas discharge holes are connected. Furthermore, in the present disclosure, the oxidant gas flow path inlet side may be an upstream region in the oxidant gas flow direction within the cell surface of the fuel cell, or may be an upstream half region within the cell surface of the fuel cell when the fuel cell is divided into two equal parts along the oxidant gas flow direction. Furthermore, in the present disclosure, the oxidant gas flow path outlet side may be a region on the downstream side of the oxidant gas flow direction within the cell surface of the fuel cell, or may be a region on the downstream half of the cell surface of the fuel cell when the fuel cell is divided into two equal parts along the oxidant gas flow direction.

[0026] Third embodiment In a third embodiment of the present disclosure, the oxidant gas flow path and the cooling gas flow path may have a contact area distribution such that the contact area between the oxidant gas flow path inlet side and the cooling gas flow path is larger than the contact area between the oxidant gas flow path outlet side and the cooling gas flow path, and the contact area decreases from the oxidant gas flow path inlet side toward the oxidant gas flow path outlet side.

[0027] 3 shows, from top to bottom, (1) a diagram illustrating a state in which the contact area between the cooling gas flow channel and the oxidant gas flow channel is distributed in an air-cooled fuel cell system according to a third embodiment of the present disclosure, (2) an AA cross-sectional view, (3) a BB cross-sectional view, and (4) a CC cross-sectional view. Taking advantage of the correlation between the contact area between the cooling gas flow channel and the cathode separator and heat dissipation, as shown in Fig. 3, in a structure in which corrugated plates contact each other, the oxidant gas flow channel shape (the shape of the side in contact with the cooling gas flow channel) is adjusted so that the contact area between the ribs constituting the oxidant gas flow channel of the cathode separator and the cooling gas flow channel is larger on the oxidant gas flow channel inlet side than on the oxidant gas flow channel outlet side. This distribution of the contact area between the ribs constituting the oxidant gas flow channel and the cooling gas flow channel is achieved within the plane (for example, by making the shape of the ribs constituting the oxidant gas flow channel outlet side more arc-like). This creates a difference in cooling capacity and increases the temperature on the oxidant gas flow channel outlet side.

[0028] Fourth embodiment In a fourth embodiment of the present disclosure, the pressure loss element may have a pressure loss distribution such that the pressure loss is lower on the oxidant gas flow path inlet side than on the oxidant gas flow path outlet side with respect to the oxidant gas flow path flow direction, and the pressure loss increases from the oxidant gas flow path inlet side to the oxidant gas flow path outlet side.

[0029] 4 is a diagram showing a state in which a pressure drop distribution is applied to a pressure drop element and a distribution of cooling capacity is applied in an air-cooled fuel cell system according to a fourth embodiment of the present disclosure. In the fourth embodiment, it is desirable to install a filter on the cooling gas inlet side of the air-cooled FC stack to prevent foreign matter from entering, and this filter is considered as a pressure drop element. By providing a pressure drop distribution in the oxidant gas flow direction for the pressure drop element such that the pressure drop is smaller on the oxidant gas flow path inlet side than on the oxidant gas flow path outlet side and the pressure drop increases from the oxidant gas flow path inlet side to the oxidant gas flow path outlet side, the temperature on the oxidant gas flow path outlet side is raised.

[0030] Fifth embodiment In a fifth embodiment of the present disclosure, the cooling gas supply unit may be disposed closer to the oxidizing gas flow field inlet than the center of the oxidizing gas flow field.

[0031] Fig. 5 is a diagram showing how the cooling capacity is distributed by the arrangement of a cooling gas supply unit in an air-cooled fuel cell system according to a fifth embodiment of the present disclosure. In the fifth embodiment, as shown in Fig. 5, a device (fan or the like) that sends cooling gas to the air-cooled FC stack as a cooling gas supply unit is installed closer to the oxidant gas flow path inlet than to the center of the FC stack or the center of the oxidant gas flow path, thereby distributing the cooling gas flow rate in the flow direction so that the cooling gas flow rate is higher at the oxidant gas flow path inlet than at the oxidant gas flow path outlet, thereby raising the temperature at the oxidant gas flow path outlet.

[0032] Sixth embodiment In a sixth embodiment of the present disclosure, the cooling fins may have a fin pitch distribution such that the fin pitch of the cooling gas flow channel is narrower on the inlet side of the oxidant gas flow channel than on the outlet side of the oxidant gas flow channel with respect to the flow direction of the oxidant gas flow channel.

[0033] 6 shows, from top to bottom, (1) a diagram showing a state in which cooling capacity is distributed by distributing the fin pitch in an air-cooled fuel cell system according to a sixth embodiment of the present disclosure, (2) an AA cross-sectional view, and (3) a BB cross-sectional view. The narrower the fin pitch in the cooling gas flow channel, the larger the heat dissipation area and the higher the cooling capacity. In the sixth embodiment, the fin pitch is narrower on the oxidant gas flow channel inlet side than on the oxidant gas flow channel outlet side, and wider (coarser) on the oxidant gas flow channel outlet side than on the oxidant gas flow channel inlet side, thereby increasing the temperature on the oxidant gas flow channel outlet side.

[0034] Seventh embodiment In a seventh embodiment of the present disclosure, the oxidant gas flow path and the cooling gas flow path may have a contact area between the oxidant gas flow path and the inlet side of the cooling gas flow path that is smaller than the contact area between the oxidant gas flow path and the outlet side of the cooling gas flow path.

[0035] Figure 7 shows, from top to bottom, (1) a diagram showing a state in which the contact area between the cooling gas flow path and the oxidant gas flow path is distributed to improve the temperature distribution in the flow direction of the cooling gas flow path in an air-cooled fuel cell system of the seventh embodiment of the present disclosure, (2) an AA cross-sectional view, (3) a BB cross-sectional view, and (4) a CC cross-sectional view. 7, by making the contact area between the cooling gas channel and the oxidant gas channel smaller on the inlet side of the cooling gas channel than on the outlet side of the cooling gas channel, the heat dissipation on the inlet side of the cooling gas channel is reduced and the heat dissipation on the outlet side of the cooling gas channel is increased. This reduces the temperature difference between the inlet side and the outlet side of the cooling gas channel, and suppresses the occurrence of differences in power generation performance between the cells on the inlet side and the outlet side of the cooling gas channel. In the present disclosure, the inlet side of the cooling gas flow path may be the upstream region of the cell surface of the fuel cell in the flow direction of the cooling gas, or may be the upstream half of the cell surface of the fuel cell when the fuel cell is divided into two equal parts along the flow direction of the cooling gas. Furthermore, in the present disclosure, the outlet side of the cooling gas flow path may be a region on the downstream side of the flow direction of the cooling gas within the cell surface of the fuel cell, or may be a region on the downstream half of the cell surface of the fuel cell when the fuel cell is divided into two equal parts along the flow direction of the cooling gas.

[0036] Eighth embodiment In an eighth embodiment of the present disclosure, the cathode separator has a plurality of throttle portions in a part of the oxidant gas flow channel, In a portion where the cooling gas flow path and the oxidant gas flow path intersect and contact each other when viewed from above, the number of contact points between the constriction portion and the cooling gas flow path may increase from the oxidant gas flow path inlet side toward the oxidant gas flow path outlet side.

[0037] FIG. 8 shows, from top to bottom, (1) a diagram illustrating a state in which a temperature distribution is achieved by distributing the contact points between the ribs constituting the throttling portion and the cooling gas flow path when a flow path with a throttling portion is applied to an air-cooled fuel cell system according to an eighth embodiment of the present disclosure; (2) a partial enlarged view of the diagram; and (3) an AA cross-sectional view. In the eighth embodiment, a throttling portion is provided in the oxidant gas flow path to improve the diffusion of the oxidant gas (air used for power generation) within the cell surface. The throttling portion reduces the contact area between the ribs constituting the oxidant gas flow path and the cooling gas flow path, thereby reducing the cooling function. Taking advantage of this, the contact points between the throttling portion and the cooling gas flow path are varied to achieve a distribution of heat dissipation within the cell surface. The contact points between the throttling portion and the cooling gas flow path are increased from the oxidant gas flow path inlet side to the oxidant gas flow path outlet side, so that the contact points between the throttling portion and the cooling gas flow path are fewer at the oxidant gas flow path inlet side than at the oxidant gas flow path outlet side. This increases the temperature at the oxidant gas flow path outlet side.

[0038] Ninth embodiment In a ninth embodiment of the present disclosure, the cathode separator has a plurality of throttle portions in a part of the oxidant gas flow channel, The throttle portion does not have to be provided at the portion where the cooling gas flow passage and the oxygen-containing gas flow passage intersect and contact each other when viewed from above.

[0039] 9 shows, from top to bottom, (1) a diagram illustrating a structure in an air-cooled fuel cell system according to a ninth embodiment of the present disclosure, in which a throttle portion is disposed at a position where the throttle portion does not contact the cooling gas flow path, thereby reducing contact resistance between the oxidant gas flow path and the cooling gas flow path and preventing a decrease in power generation performance of the cell, (2) an AA cross-sectional view, and (3) a BB cross-sectional view. As shown in Fig. 9, a throttle portion is provided in the oxidant gas flow path to improve the power generation performance of the cell, but by not providing a throttle portion at the contact portion with the cooling gas flow path, an increase in contact resistance between the oxidant gas flow path and the cooling gas flow path is suppressed, and the oxidant gas outlet temperature is increased by other means.

[0040] In this disclosure, the fuel gas and the oxidant gas are collectively referred to as reactant gases. The reactant gas supplied to the anode is the fuel gas, and the reactant gas supplied to the cathode is the oxidant gas. The fuel gas is a gas that mainly contains hydrogen and may be hydrogen. The oxidant gas may be oxygen, air, dry air, etc.

[0041] The air-cooled fuel cell system of the present disclosure includes a fuel cell, an oxidant gas system (reaction air system), and a cooling gas system, and typically also includes a fuel gas system.

[0042] The fuel cell in this disclosure is an air-cooled fuel cell. Air-cooled fuel cells primarily use air as a refrigerant, but other gases can also be used as long as they have a cooling function. In this disclosure, air as a refrigerant may be referred to as a cooling gas or cooling air. In this disclosure, air as an oxidant gas may be referred to as reaction air. The fuel cell has a fuel cell stack in which a plurality of unit cells are stacked. The number of stacked unit cells is not particularly limited, and may be from 2 to several hundred.

[0043] The single cell includes a cathode separator having a corrugated oxidant gas flow path, a membrane electrode gas diffusion layer assembly, an anode separator having a corrugated fuel gas flow path, and cooling fins having corrugated cooling gas flow paths.

[0044] The membrane electrode gas diffusion layer assembly (MEGA) comprises, in this order, an anode gas diffusion layer, an anode catalyst layer, an electrolyte membrane, a cathode catalyst layer, and a cathode gas diffusion layer. In the present disclosure, the power generation section mainly refers to a membrane electrode gas diffusion layer assembly.

[0045] The cathode (oxidant electrode) includes a cathode catalyst layer and a cathode-side gas diffusion layer. The anode (fuel electrode) includes an anode catalyst layer and an anode-side gas diffusion layer. The cathode catalyst layer and the anode catalyst layer are collectively referred to as catalyst layers.

[0046] The cathode side gas diffusion layer and the anode side gas diffusion layer are collectively referred to as gas diffusion layers or diffusion layers. The gas diffusion layer may be a gas-permeable conductive material or the like. Examples of the conductive member include porous carbon materials such as carbon cloth and carbon paper, and porous metal materials such as metal mesh and foam metal.

[0047] The single cell may have a microporous layer (MPL) between the catalyst layer and the gas diffusion layer, which may contain a mixture of a water-repellent resin such as PTFE and a conductive material such as carbon black.

[0048] The electrolyte membrane may be a solid polymer electrolyte membrane. Examples of the solid polymer electrolyte membrane include a fluorine-based electrolyte membrane such as a thin film of perfluorosulfonic acid containing water, and a hydrocarbon-based electrolyte membrane. The electrolyte membrane may be, for example, a Nafion membrane (manufactured by DuPont).

[0049] The anode separator and the cathode separator are collectively referred to as the separator. The membrane electrode gas diffusion layer assembly is sandwiched between an anode separator and a cathode separator. The separator may have a plurality of through-holes for allowing fluids such as reactant gases to flow in the stacking direction of the unit cells, such as an oxidant gas inlet, an oxidant gas outlet, a fuel gas inlet, and a fuel gas outlet. In the fuel cell, a reactant gas manifold may be formed by a plurality of through holes of the same type communicating with each other in the stacking direction. The separator may be a gas-impermeable conductive material. Examples of conductive materials include carbon composite materials formed by pressing a mixture containing a resin material such as a thermosetting resin, a thermoplastic resin, or a resin fiber, a carbon material such as a carbon powder or a carbon fiber, dense carbon formed by compressing carbon to make it gas-impermeable, and a press-formed metal (e.g., titanium, iron, aluminum, or SUS) plate. The separator may also have a current collecting function. The shape of the separator may be rectangular, horizontally elongated hexagonal, horizontally elongated octagonal, circular, oval, or the like.

[0050] The cathode separator has an oxidant gas flow path in the form of a corrugated plate. Specifically, the cathode separator has grooves and ribs that serve as oxidant gas flow paths, which are alternately arranged periodically at a predetermined groove pitch. The cathode separator may have a plurality of throttle portions in a portion of the oxidant gas flow channel. The width of the throttle portion may be narrower than the width of the oxidant gas flow path. The anode separator has a corrugated fuel gas flow path, specifically, grooves and ribs that serve as fuel gas flow paths, which are alternately arranged periodically at a predetermined groove pitch. The groove pitch means a repeating unit of the sum of the groove width and the rib width. The separator may have a reactant gas flow path on the surface in contact with the gas diffusion layer, and may have a coolant flow path on the surface opposite to the surface in contact with the gas diffusion layer to maintain a constant temperature of the fuel cell. The separator may have a gas distribution section. The gas distribution section is disposed in a region between the reactant gas manifold and the reactant gas flow channel, and is a section that widens or converges the gas flow from the reactant gas manifold to the power generation region. The gas distribution section has a structure that widens the gas flow on the reactant gas inlet side. The gas distribution section has a structure that converges the gas flow on the reactant gas outlet side.

[0051] The cooling fins have a corrugated cooling gas flow path. Specifically, the cooling fins have grooves and ribs that serve as cooling gas flow paths, arranged alternately at a predetermined fin pitch. The fin pitch is synonymous with the groove pitch. The cooling fins may be corrugated plates having a number of grooves that act as cooling gas channels. The cooling fins may be made of metal plates such as aluminum, titanium, and stainless steel that are bent into a corrugated shape. The surfaces of the cooling fins may be treated with conductive materials such as silver, nickel, and carbon. The shape of the cooling fins may be rectangular, horizontally elongated hexagonal, horizontally elongated octagonal, circular, oval, or the like. The oxidant gas flow channel of the cathode separator and the cooling gas flow channel of the cooling fin may intersect each other at least partially in a top view, and may intersect each other in at least a part of the region facing the MEGA, or may intersect each other over the entire region facing the MEGA. The oxidant gas flow channel of the cathode separator and the cooling gas flow channel of the cooling fin may be perpendicular to each other in a top view.

[0052] The single cell may have a resin frame. The resin frame may be disposed around the outer periphery of the membrane electrode gas diffusion layer assembly and between the cathode separator and the anode separator. The resin frame may have a skeleton, an opening, and a through-hole. The framework is the main part of the resin frame that connects to the membrane electrode gas diffusion layer assembly. The opening is a holding area for the membrane electrode-gas diffusion layer assembly, and is an area that penetrates a part of the skeleton to accommodate the membrane electrode-gas diffusion layer assembly. The opening may be located in the resin frame at a position where the skeleton is disposed around (the outer periphery of) the membrane electrode-gas diffusion layer assembly, or may be located in the center of the resin frame. The through holes of the resin frame allow a fluid such as a reactant gas to flow in the stacking direction of the unit cells, and may be aligned with the through holes of the separators so as to communicate with each other. The resin frame can be made of a conventionally known material.

[0053] The fuel cell may include a gasket that seals the reactant gas between two adjacent unit cells. The gasket may be made of ethylene propylene diene rubber (EPDM) rubber, silicone rubber, thermoplastic elastomer resin, or the like.

[0054] An air-cooled fuel cell system includes a cooling gas system. The cooling gas system includes a cooling gas supply unit that supplies cooling gas to the fuel cell, a cooling gas pipe, and a pressure drop element located upstream of the fuel cell in the cooling gas pipe. The cooling gas pipe has a pressure drop body upstream of the fuel cell. The pressure drop body may be a filter or the like. The cooling gas pipe connects the outside of the air-cooled fuel cell system to a cooling gas inlet of the fuel cell, and also connects the cooling gas outlet of the fuel cell to the outside of the air-cooled fuel cell system. The cooling gas supply unit may be disposed at any position on the cooling gas piping, and may be disposed downstream of the fuel cell on the cooling gas piping. Examples of the cooling gas supply unit include an air pump, an air compressor, an air blower, and an air fan. The cooling gas supply unit is electrically connected to the control unit. The cooling gas supply unit is driven in accordance with a control signal from the control unit. The control unit controls the flow rate of the cooling gas supplied from the cooling gas supply unit to the fuel cell. This may control the temperature of the fuel cell. The cooling gas system has an open-to-air structure without valves, and by making the cooling air equal to the outside air pressure (for example, -0.01 to -0.3 kPaG), differential pressure stress on the fuel cell structure can be prevented and inexpensive, lightweight housing materials can be used.

[0055] The air-cooled fuel cell system is equipped with an oxidant gas system (reaction air system). The oxidant gas system may include an oxidant gas supply unit, an oxidant gas pipe, an oxidant gas pressure regulating valve, and the like. The oxidant gas pipe connects the outside of the air-cooled fuel cell system to an oxidant gas inlet of the fuel cell, and also connects the oxidant gas outlet of the fuel cell to the outside of the air-cooled fuel cell system. The oxidant gas supply unit supplies an oxidant gas to the cathode of the fuel cell. The oxidizing gas supply unit may be disposed at any position in the oxidizing gas piping, and may be disposed upstream of the fuel cell in the oxidizing gas piping. Examples of the oxidant gas supply unit include an air pump, an air compressor, an air blower, and an air fan. The oxidant gas system is equipped with an independent oxidant gas supply unit before the oxidant gas is introduced into the fuel cell. By providing an independent cooling gas supply unit and an oxidant gas supply unit for each system, it is possible to independently control the flow rates of the cooling air and the reaction air (oxidant gas), which is the oxidant gas, and to accurately control drainage and humidity, thereby improving the power generation performance of the fuel cell. The oxidizing gas supply unit is electrically connected to the control unit and is driven in accordance with a control signal from the control unit.

[0056] An air-cooled fuel cell system typically includes a fuel gas system. The fuel gas system supplies fuel gas to the fuel cell. The fuel gas system may include a fuel gas tank for storing fuel gas, a fuel gas supply pipe connecting the fuel gas tank to the fuel gas inlet of the fuel cell, and a fuel gas exhaust pipe connecting the fuel gas outlet of the fuel cell to the outside of the air-cooled fuel cell system.

[0057] The air-cooled fuel cell system may include a controller. The control unit controls the ON / OFF and output of the cooling gas supply unit, the oxidant gas supply unit, and the like. The control unit physically includes, for example, a processing unit such as a CPU (Central Processing Unit), a storage device such as a ROM (Read Only Memory) that stores control programs and control data processed by the CPU, a RAM (Random Access Memory) that is used mainly as various work areas for control processing, and an input / output interface. The control unit may also be, for example, a control device such as an Electronic Control Unit (ECU).

Claims

1. 1. An air-cooled fuel cell system, comprising: the air-cooled fuel cell system includes a fuel cell, an oxidant gas system, and a cooling gas system; the fuel cell has a fuel cell stack in which a plurality of unit cells are stacked, the unit cell includes a cathode separator having a corrugated oxidant gas flow path, a membrane electrode gas diffusion layer assembly, an anode separator having a corrugated fuel gas flow path, and a cooling fin having a corrugated cooling gas flow path; the oxidant gas flow path and the cooling gas flow path at least partially intersect with each other in a top view; the cooling gas system includes a cooling gas supply unit that supplies a cooling gas to the fuel cell, a cooling gas pipe, and a pressure drop body located upstream of the fuel cell in the cooling gas pipe; The air-cooled fuel cell system is characterized in that the cooling capacity at the inlet side of the oxidant gas flow path is high relative to the oxidant gas flow direction of the oxidant gas flow path, and the cooling capacity at the outlet side of the oxidant gas flow path is lower than the cooling capacity at the inlet side of the oxidant gas flow path.

2. 2. The air-cooled fuel cell system according to claim 1, wherein the oxidant gas flow path and the cooling gas flow path have a contact area distribution such that the contact area between the oxidant gas flow path inlet side and the cooling gas flow path is larger than the contact area between the oxidant gas flow path outlet side and the cooling gas flow path, and the contact area decreases from the oxidant gas flow path inlet side toward the oxidant gas flow path outlet side.

3. The pressure loss body is a filter, 3. The air-cooled fuel cell system according to claim 1, wherein the pressure loss element has a pressure loss distribution such that the pressure loss is lower at the oxidant gas flow inlet side than at the oxidant gas flow outlet side with respect to the oxidant gas flow direction, and the pressure loss increases from the oxidant gas flow inlet side to the oxidant gas flow outlet side.

4. 4. The air-cooled fuel cell system according to claim 1, wherein the cooling gas supply unit is positioned closer to the oxidant gas flow path inlet than to the center of the oxidant gas flow path, and the flow rate of the cooling gas is distributed in the oxidant gas flow direction so that the flow rate of the cooling gas on the oxidant gas flow path inlet side is greater than the flow rate of the cooling gas on the oxidant gas flow path outlet side.

5. 5. The air-cooled fuel cell system according to claim 1, wherein the cooling fins have a fin pitch distribution such that the fin pitch of the cooling gas flow path is narrower on the inlet side of the oxidant gas flow path than on the outlet side of the oxidant gas flow path with respect to the oxidant gas flow direction.

6. 6. The air-cooled fuel cell system according to claim 1, wherein the contact area between the oxidant gas flow path and the cooling gas flow path on the inlet side is smaller than the contact area between the oxidant gas flow path and the cooling gas flow path on the outlet side.

7. the cathode separator has a plurality of throttle portions in a part of the oxidant gas flow channel, 7. The air-cooled fuel cell system according to claim 1, wherein, in a portion where the cooling gas flow passage and the oxidant gas flow passage intersect and contact each other in a top view, the number of contact points between the constriction portion and the cooling gas flow passage increases from the oxidant gas flow passage inlet side toward the oxidant gas flow passage outlet side.

8. the cathode separator has a plurality of throttle portions in a part of the oxidant gas flow channel, 7. The air-cooled fuel cell system according to claim 1, wherein the throttle portion is not provided at a portion where the cooling gas flow path and the oxidant gas flow path intersect and contact each other when viewed from above.

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