fuel cell system

Abstract

To provide a fuel cell system that can reduce the cost of a fuel cell system and improve the power generation efficiency of a fuel cell.SOLUTION: An air-cooled fuel cell system includes a fuel cell, a cooling fluid supply channel that supplies cooling fluid to the fuel cell, a cooling fluid discharge channel that discharges the cooling fluid to the outside, a cooling fluid drive unit, and a heating element, and the heating element is arranged in a predetermined area capable of heating the cooling fluid supplied to the fuel cell.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Fuel cell systems are being studied to improve the performance of fuel cells. For example, Patent Document 1 discloses a fuel cell in which a heater is provided at the end of the fuel cell stack to appropriately adjust the temperature of the cells placed at the end of the fuel cell stack. Patent Document 2 discloses a temperature control device layout structure for a fuel cell vehicle that enables heating of the water circulation system of the fuel cell without installing a dedicated heater. Patent Document 3 discloses a fuel cell system that reduces the wasted energy conventionally emitted from a computer 10 and increases the power generation efficiency of a fuel cell 27. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-126782 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-104354 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-362972 Summary of the Invention [Problem to be solved by the invention]

[0004] If a heater is provided at the end of the fuel cell, extra power will be consumed by the heater, reducing the energy efficiency of the entire fuel cell system and reducing the power that can be extracted as the fuel cell output. Furthermore, the structure of the fuel cell system becomes complicated, making it difficult to install in a vehicle or the like, and also increasing costs.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and its main object is to provide a fuel cell system that can reduce the cost of the fuel cell system and improve the power generation efficiency of the fuel cell. [Means for solving the problem]

[0006] The fuel cell system of the present disclosure is an air-cooled fuel cell system, The fuel cell system includes a fuel cell, a cooling fluid supply flow path that supplies a cooling fluid to the fuel cell, a cooling fluid discharge flow path that discharges the cooling fluid to the outside, a cooling fluid drive unit, and a heating element, The heating element is disposed in a predetermined area where it can heat the cooling fluid supplied to the fuel cell. [Effects of the Invention]

[0007] According to the fuel cell system of the present disclosure, the cost of the fuel cell system can be reduced and the power generation efficiency of the fuel cell can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an example of the arrangement of heating elements in a fuel cell system according to the present disclosure. [Figure 2] FIG. 2 is a schematic diagram showing another example of the arrangement of heating elements in the fuel cell system of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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.

[0010] The fuel cell system of the present disclosure is an air-cooled fuel cell system, The fuel cell system includes a fuel cell, a cooling fluid supply flow path that supplies a cooling fluid to the fuel cell, a cooling fluid discharge flow path that discharges the cooling fluid to the outside, a cooling fluid drive unit, and a heating element, The heating element is disposed in a predetermined area where it can heat the cooling fluid supplied to the fuel cell.

[0011] According to the fuel cell system of the present disclosure, a heating element is installed in a predetermined area capable of heating the cooling fluid (cooling air) supplied to the fuel cell. In the fuel cell system of the present disclosure, heat is transferred to the cooling fluid passing near the heat generating element, causing the temperature of the cooling fluid to rise. The cooling fluid flows into the end of the fuel cell where a drop in temperature is a concern, warming the end of the fuel cell. By adjusting the temperature of the fuel cell to an appropriate temperature, the power generation performance of the fuel cell can be improved. The fuel cell system of the present disclosure eliminates the need for heaters and other components of conventional technology, thereby reducing the cost of the fuel cell system. Furthermore, since there is no need to generate heat using a heater, unnecessary power consumption is eliminated, and the power generation efficiency of the fuel cell is improved.

[0012] The fuel cell system of the present disclosure is an air-cooled fuel cell system. Air-cooled fuel cell systems primarily use air as the cooling fluid (refrigerant). The cooling fluid is at least one gas selected from the group consisting of air, oxygen, and nitrogen. In this disclosure, air used as a cooling fluid may be referred to as “cooling air.” In this disclosure, air used as an oxidant gas may be referred to as “reaction air.”

[0013] 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 is a gas that contains oxygen and may be oxygen, air, dry air, or the like.

[0014] The fuel cell system of the present disclosure comprises a fuel cell, a cooling fluid supply flow path that supplies a cooling fluid to the fuel cell, a cooling fluid discharge flow path that discharges the cooling fluid to the outside, a cooling fluid drive unit, and a heating element. The fuel cell system of the present disclosure may be mounted on a moving body such as a vehicle. The vehicle may be a fuel cell vehicle, etc. Examples of moving bodies other than vehicles include trains, ships, and aircraft. The fuel cell system of the present disclosure may also be mounted on a mobile object such as a vehicle that can run on power from a secondary battery. A mobile object may be equipped with the fuel cell system of the present disclosure.

[0015] The fuel cell system of the present disclosure includes a fuel cell. The fuel cell may have only one unit cell, or may be a fuel cell stack, which is a stack of a plurality of unit cells. The number of stacked unit cells is not particularly limited, and may be, for example, from 2 to several hundred. In the present disclosure, both a single cell and a fuel cell stack formed by stacking single cells may be referred to as a fuel cell.

[0016] A single cell of a fuel cell typically comprises a membrane electrode gas diffusion layer assembly (MEGA). The membrane electrode gas diffusion layer assembly has, 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.

[0017] 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. The catalyst layer may include, for example, a catalytic metal that promotes an electrochemical reaction, an electrolyte having proton conductivity, and a carrier having electron conductivity. As the catalytic metal, for example, platinum (Pt) and alloys of Pt with other metals (for example, Pt alloys mixed with cobalt and nickel, etc.) can be used. The electrolyte may be a fluorine-based resin, etc. As the fluorine-based resin, for example, a Nafion solution may be used. The catalytic metal is supported on a carrier, and in each catalyst layer, the carrier supporting the catalytic metal (catalyst-supported carrier) and the electrolyte may be mixed together. Examples of the carrier for supporting the catalytic metal include carbon materials such as carbon, which are generally available commercially.

[0018] The cathode side gas diffusion layer and the anode side gas diffusion layer are collectively referred to as gas 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.

[0019] 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).

[0020] The single cell may optionally include two separators sandwiching both sides of the membrane electrode gas diffusion layer assembly. One of the two separators is an anode-side separator, and the other is a cathode-side separator. In the present disclosure, the anode-side separator and the cathode-side separator are collectively referred to as separators. The separator may have holes such as supply holes and discharge holes for allowing fluids such as reaction gases and cooling fluids to flow in the stacking direction of the unit cells. Examples of the supply holes include a fuel gas supply hole, an oxidant gas supply hole, and a cooling fluid supply hole. Examples of the exhaust holes include a fuel gas exhaust hole, an oxidant gas exhaust hole, and a cooling fluid exhaust hole. The separator may have a reactant gas flow path on the surface in contact with the gas diffusion layer, and may have a cooling fluid 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 be a gas-impermeable conductive material. Examples of the conductive material include resin materials such as thermosetting resin, thermoplastic resin, and resin fiber; dense carbon made by compressing carbon materials such as carbon powder and carbon fiber to make it gas-impermeable; and press-molded metal (e.g., iron, aluminum, stainless steel, etc.) plates. 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.

[0021] The fuel cell stack may have manifolds such as an inlet manifold to which each of the supply holes communicates, and an outlet manifold to which each of the discharge holes communicates. The inlet manifolds include an anode inlet manifold, a cathode inlet manifold, and a cooling fluid inlet manifold. Examples of the outlet manifold include an anode outlet manifold, a cathode outlet manifold, and a cooling fluid outlet manifold. In this disclosure, the cathode inlet manifold and the cathode outlet manifold are collectively referred to as the cathode manifold. In this disclosure, the cooling fluid inlet manifold and the cooling fluid outlet manifold are collectively referred to as the cooling fluid manifold. The fuel cell may have a structure in which the cathode manifold and the cooling fluid manifold are independent.

[0022] The fuel cell may have gaskets between adjacent unit cells, which are used as seals to prevent leakage of reactant gases from each reactant gas system. The gasket may be made of ethylene propylene diene rubber (EPDM) rubber, silicone rubber, thermoplastic elastomer resin, or the like.

[0023] The fuel cell may have cooling fins made of metal, such as Al, Ti, SUS, etc. The fuel cell may have cooling fins between adjacent single cells. The cooling fins may be corrugated plates having a number of recessed grooves that function as cooling fluid channels. The cooling fins may be made of, for example, a metal plate bent into a corrugated shape, etc. The surfaces of the cooling fins may be treated with a conductive material such as silver, nickel, or carbon. The grooves of the cooling fins may be formed by bending. The depth of the recessed groove may be, for example, 1.0 to 2.0 mm. The folding process may be performed to form recesses and protrusions at a pitch of, for example, a groove depth of 1.0 to 2.0 mm and a width of 1.0 to 2.0 mm. The cooling fins may be arranged in at least a part of the area between the adjacent unit cells in the planar direction, as long as they are arranged between the adjacent unit cells. The cooling fins may be arranged between adjacent unit cells in the planar direction, at least in the region facing the MEGA. The cooling fins may be arranged in an area other than the area where the gasket is arranged between adjacent unit cells in the planar direction. The shape of the cooling fins may be rectangular, horizontally elongated hexagonal, horizontally elongated octagonal, circular, oval, or the like.

[0024] The air-cooled fuel cell system may include an air introduction section as an air system. The air intake section takes in air from outside the air-cooled fuel cell system. The air introduction section may be, for example, an air intake port. The air introduction section may be provided with a pressure loss element, such as a filter.

[0025] The air introduction section may be equipped with an air distribution section. The air distribution section distributes the air taken in from the outside into reaction air and cooling air before introducing it into the fuel cell. Note that if the air introduction section includes a reaction air introduction section that takes in reaction air from the outside and a cooling air introduction section that takes in cooling air from the outside, the air distribution section is not necessarily required. The distribution ratio of the reaction air and the cooling air distributed by the air distribution section may be 1:20 to 1:50 in terms of flow rate ratio. The air distribution section may be a housing that can take air in. The material of the housing is not particularly limited, and may be metal, resin, carbon-based material, or the like.

[0026] The fuel cell system includes a cooling system for the fuel cell. The cooling system includes a cooling fluid supply channel, a cooling fluid discharge channel, a cooling fluid driver, and a heating element. The cooling fluid supply passage connects the air introduction section to a cooling fluid inlet of the fuel cell, and enables the supply of cooling fluid to the fuel cell. The cooling fluid inlet may be a cooling fluid supply hole, a cooling fluid inlet manifold, or the like. The cooling system may include a cooling fluid exhaust channel. The cooling fluid discharge flow path connects the cooling fluid outlet of the fuel cell to the outside, and enables the cooling fluid to be discharged to the outside. The cooling fluid outlet may be a cooling fluid discharge hole, a cooling fluid outlet manifold, etc. The cooling fluid driver may be disposed in the cooling fluid discharge channel. The cooling fluid driving unit is electrically connected to the control unit. The cooling fluid driving unit is driven in accordance with a control signal from the control unit. The control unit controls the flow rate of the cooling fluid supplied from the cooling fluid driving unit to the fuel cell. This may control the temperature of the fuel cell. Examples of the cooling fluid driving unit include an air pump, an air compressor, an air blower, and an air fan. By installing a cooling fluid drive unit on the cooling fluid outlet side of the cooling system, the pressure inside the cooling fluid manifold of the fuel cell can be made below atmospheric pressure. The cooling system has an open-to-air structure without valves, and the cooling fluid is kept at the same pressure as the outside air pressure (for example, -0.01 to -0.3 kPaG), thereby preventing differential pressure stress on the fuel cell structure and enabling the use of inexpensive, lightweight housing materials. The cooling fluid supply flow path and the cooling fluid discharge flow path may specifically be pipes.

[0027] The heating element may be disposed in a predetermined area where it can heat the cooling fluid supplied to the fuel cell. The heating element may be disposed at a predetermined position on the outer wall surface of the cooling fluid supply flow path, at a predetermined position on the inner wall surface, or at a predetermined position on the outer wall surface of the fuel cell. The heating element to be disposed may be selected and disposed with an appropriate thickness and height depending on the part of the fuel cell to be heated. For example, when the heating element is disposed at a predetermined position on the outer wall surface of the cooling fluid supply flow path, a thin heating element may be disposed in order to reduce the volume of the fuel cell system. The heating element may be a heater or an auxiliary component that constitutes a fuel cell system, but from the viewpoint of reducing costs, it may also be an auxiliary component that constitutes a fuel cell system. The auxiliary components may be a DC / DC converter, a battery, a control unit, an oxidant gas supply unit, or the like.

[0028] The fuel cell system includes an oxidant gas system. The oxidant gas system may include an oxidant gas supply unit, an oxidant gas supply channel, an oxidant gas discharge channel, an oxidant gas bypass channel, a bypass valve, etc. Specifically, the oxidant gas supply channel, the oxidant gas discharge channel, and the oxidant gas bypass channel may be pipes. The oxidizing gas supply unit supplies the oxidizing gas to the fuel cell, specifically, the oxidizing gas supply unit supplies the oxidizing gas to the cathode of the fuel cell. The enclosed volume of the oxidant gas system may be five times or less the enclosed volume of the fuel gas system.

[0029] 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 may be provided with an independent oxidant gas supply unit before the oxidant gas is introduced into the fuel cell. By providing the cooling system and the oxidant gas system with independent cooling fluid drive units and oxidant gas supply units, respectively, it is possible to independently control the flow rates of the cooling air as the cooling fluid and the reaction air as the oxidant gas, thereby enabling accurate control of drainage and humidity, and improving the power generation performance of the fuel cell. The oxidizing gas supply unit may be arranged upstream of the fuel cell in the oxidizing gas supply channel. The oxidant gas supply unit is electrically connected to the control unit. The oxidant gas supply unit is driven in accordance with a control signal from the control unit. The oxidant gas supply unit may be configured to control at least one of the flow rate and pressure of the oxidant gas supplied from the oxidant gas supply unit to the cathode by the control unit.

[0030] The oxidizing gas supply passage connects the oxidizing gas supply unit and the oxidizing gas inlet of the fuel cell. The oxidant gas supply channel allows the supply of oxidant gas from the oxidant gas supply unit to the cathode of the fuel cell. The oxidant gas inlet may be an oxidant gas supply hole, a cathode inlet manifold, etc. The oxidant gas supply channel may branch off from the air distribution unit. The oxidizing gas supply channel may be provided with a pressure drop element upstream of the oxidizing gas supply section. Examples of pressure loss bodies include filters. The pressure loss body provided in the oxidant gas supply channel may be a finer filter with a higher pressure loss than the pressure loss body provided in the air inlet section. Purifying the entire air inlet system increases the energy loss of the fuel cell, but purifying only the oxidant gas system can suppress the energy loss of the fuel cell. Furthermore, using a finer filter can reduce contamination of the cooling air used as a cooling fluid, improving the durability of the fuel cell.

[0031] The oxidant gas discharge passage connects the oxidant gas outlet of the fuel cell to the outside of the air-cooled fuel cell system. The oxidant gas discharge passage allows the oxidant gas discharged from the cathode of the fuel cell to be discharged to the outside of the air-cooled fuel cell system. The oxidant gas outlet may be an oxidant gas discharge hole, a cathode outlet manifold, or the like. The oxidant gas discharge passage may have an oxidant gas pressure regulating valve downstream of the oxidant gas outlet of the fuel cell. The oxidant gas pressure regulating valve is electrically connected to the control unit, and when the control unit opens the oxidant gas pressure regulating valve, the oxidant gas is discharged from the oxidant gas discharge channel to the outside. Also, the pressure of the oxidant gas supplied to the cathode (cathode pressure) may be adjusted by adjusting the opening degree of the oxidant gas pressure regulating valve.

[0032] The oxidant gas bypass channel branches off from the oxidant gas supply channel, bypasses the fuel cell, and connects the branched portion of the counter oxidant gas supply channel and the junction of the oxidant gas discharge channel. A bypass valve is disposed in the oxidant gas bypass passage. The bypass valve is electrically connected to the control unit, and when the bypass valve is opened by the control unit, the oxidant gas can be discharged to the outside from the oxidant gas discharge flow path, bypassing the fuel cell, when there is no need to supply oxidant gas to the fuel cell.

[0033] The fuel cell system may include a fuel gas system. The fuel gas system supplies fuel gas to the fuel cell. The fuel gas system may include a fuel gas supply unit, a fuel gas supply passage, a fuel off-gas discharge passage, a fuel gas circulation passage, and the like. The fuel gas supply unit supplies fuel gas to the anode of the fuel cell. The fuel gas supply unit may be, for example, a fuel tank, and more specifically, a liquid hydrogen tank, a compressed hydrogen tank, or the like. The fuel gas supply unit is electrically connected to the control unit. The fuel gas supply unit may control ON / OFF of the supply of fuel gas to the fuel cell by controlling the opening and closing of a main stop valve of the fuel gas supply unit in accordance with a control signal from the control unit. The fuel gas supply channel connects the fuel gas supply unit to the anode inlet of the fuel cell. The fuel gas supply channel allows for the supply of fuel gas containing hydrogen to the anode of the fuel cell. The anode inlet may be a fuel gas supply hole, an anode inlet manifold, or the like. The fuel off-gas discharge passage connects the anode outlet of the fuel cell to the outside of the fuel cell system. The fuel off-gas discharge passage may merge with the oxidant off-gas discharge passage in a predetermined region of the oxidant off-gas discharge passage. The anode outlet may be a fuel gas discharge hole, an anode outlet manifold, or the like. The fuel off-gas may contain fuel gas that has passed through the anode without reacting, water that has been produced at the cathode and has reached the anode, etc. The fuel off-gas may also contain corrosive substances produced in the catalyst layer, the electrolyte membrane, etc., and an oxidant gas that may be supplied to the anode during scavenging. The fuel gas circulation flow path branches off from the fuel off-gas discharge flow path at a branching point of the fuel off-gas discharge flow path and merges with the fuel gas supply flow path at a merging point of the fuel gas supply flow path, allowing the fuel off-gas to be circulated within the fuel gas system as a circulating gas. A discharge / circulation control three-way valve capable of controlling the discharge flow rate of the fuel off-gas to the outside and the circulation flow rate within the fuel gas system may be disposed at the branching point of the fuel off-gas discharge flow path. The discharge / circulation control three-way valve may be electrically connected to a control unit, and the control unit may control the opening / closing and aperture of the discharge / circulation control three-way valve, thereby controlling the discharge flow rate of the fuel off-gas to the outside and the circulation flow rate within the fuel gas system.

[0034] The fuel cell system may include a battery. The battery (secondary battery) may be any battery that can be charged and discharged, and examples thereof include conventionally known secondary batteries such as nickel-metal hydride secondary batteries and lithium-ion secondary batteries. The secondary battery may also include a storage element such as an electric double layer capacitor. The secondary battery may be configured with multiple batteries connected in series. The secondary battery supplies power to an air compressor or the like. The secondary battery may be rechargeable from an external power source of a mobile object such as a vehicle, for example, a household power source. The secondary battery may be charged by the output of a fuel cell. The charging and discharging of the secondary battery may be controlled by a control unit.

[0035] A fuel cell system typically includes a control unit that controls the ON / OFF operation of the cooling fluid drive unit, 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). The control unit may be electrically connected to an ignition switch that may be mounted on a moving object such as a vehicle, and the control unit may be operable by an external power source even when the ignition switch is turned off.

[0036] FIG. 1 is a schematic diagram showing an example of the arrangement of heating elements in a fuel cell system according to the present disclosure. In FIG. 1, the heating element 11 is disposed on the outer wall side of a cooling fluid supply flow path 20 capable of heating the cooling fluid CF supplied to the fuel cell 10. The power generation region of the fuel cell 10 tends to have low temperature areas at both ends and high temperature areas in the center, and by heating the cooling fluid CF passing through both ends, the temperature inside the fuel cell 10 can be kept uniform.

[0037] FIG. 2 is a schematic diagram showing another example of the arrangement of heating elements in the fuel cell system of the present disclosure. In FIG. 2, the heating element 11 is disposed inside a cooling fluid supply flow path 20 capable of heating the cooling fluid CF supplied to the fuel cell 10. In FIG. 2 as well, the temperature inside the fuel cell 10 can be kept uniform by heating the cooling fluid CF passing through the low-temperature portion. [Explanation of symbols]

[0038] 10 fuel cell 11 Heating element 20 Cooling fluid supply passage CF cooling fluid

Claims

1. An air-cooled fuel cell system, The fuel cell system includes a fuel cell, a cooling fluid supply flow path that supplies a cooling fluid to the fuel cell, a cooling fluid discharge flow path that discharges the cooling fluid to the outside, a cooling fluid drive unit, and a heating element, A fuel cell system, characterized in that the heating element is disposed at a position where it heats from the outside the cooling fluid passing through an end of the fuel cell.

2. A fuel cell system as described in claim 1, wherein the cooling fluid is at least one gas selected from the group consisting of air, oxygen, and nitrogen.

3. A fuel cell system as described in claim 1, wherein the heating element is an auxiliary component.

4. A fuel cell system as described in claim 3, wherein the auxiliary component is at least one selected from the group consisting of a DC / DC converter, a battery, a control unit, and an oxidizer gas supply unit.

5. A fuel cell system as described in claim 1, wherein the heating element is arranged on at least one of the outer wall side and inner wall side of the cooling fluid supply flow path.

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