Air cooling type fuel cell system

Abstract

To provide an air cooling type fuel cell system capable of efficiently performing drainage and capable of reducing a moisture content in an exhaust gas.SOLUTION: Disclosed is an air cooling type fuel cell system. The fuel cell system comprises a case and a fuel cell stack. In the fuel cell system, the fuel cell stack is accommodated in the case, and the fuel cell stack is a laminate in which a plurality of single cells are laminated. The plurality of single cells are laminated while being tilted at 10° to 80° with respect to a horizontal direction. The fuel cell stack includes a reaction air inlet manifold, a reaction air outlet manifold, a hydrogen inlet manifold and a hydrogen outlet manifold. The hydrogen inlet manifold is positioned higher in a gravity direction with respect to the hydrogen outlet manifold, and the reaction air inlet manifold is positioned higher in the gravity direction with respect to the reaction air outlet manifold.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Various technologies have been proposed for fuel cells (FCs), such as that disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-046852 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses that an air-cooled fuel cell is mounted on a motorcycle at an angle. An open-type air-cooled fuel cell is being considered for mounting on vehicles such as motorcycles. In the case of an open-type fuel cell, water is sprayed around the fuel cell when drained.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and its main object is to provide an air-cooled fuel cell system that can efficiently drain water and reduce the amount of water in the exhaust gas. [Means for solving the problem]

[0006] That is, the present disclosure includes the following aspects. <1> An air-cooled fuel cell system, the fuel cell system includes a case and a fuel cell stack; the case accommodates the fuel cell stack; the fuel cell stack is a stack of a plurality of unit cells, The plurality of unit cells are stacked at an angle of 10° to 80° with respect to the horizontal direction, the fuel cell stack has a reactant air inlet manifold, a reactant air outlet manifold, a hydrogen inlet manifold, and a hydrogen outlet manifold; the hydrogen inlet manifold is located above the hydrogen outlet manifold in the direction of gravity, A fuel cell system, characterized in that the reactant air inlet manifold is located above the reactant air outlet manifold in the direction of gravity.

[0007] <2> The single cell has a reaction air flow path, a hydrogen flow path, and a cooling air flow path, In a plan view of the unit cell, the cooling air flow path intersects the reaction air flow path and the hydrogen flow path; an outlet side of the cooling air flow path is located above an inlet side of the cooling air flow path in a direction of gravity, In a plan view of the fuel cell stack, the hydrogen outlet manifold and the reactant air outlet manifold are located on an inlet side of the cooling air flow path, In a plan view of the fuel cell stack, the hydrogen inlet manifold and the reactant air inlet manifold are located on the outlet side of the cooling air flow path. <1> The fuel cell system according to claim 1.

[0008] <3> the fuel cell system includes an exhaust port; a gas-liquid separator is provided between the hydrogen outlet manifold and the exhaust port and between the reaction air outlet manifold and the exhaust port; <1> or <2> The fuel cell system according to claim 1. [Effects of the Invention]

[0009] The fuel cell system of the present disclosure can efficiently discharge water and reduce the amount of water in the exhaust gas. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 1 is an exploded perspective view showing an example of a single fuel cell included in a fuel cell system according to the present disclosure. [Figure 2] FIG. 2 is a schematic diagram showing an example of the arrangement of a fuel cell stack provided in the fuel cell system of the present disclosure. [Figure 3] FIG. 3 is a plan view schematically illustrating an example of a hydrogen flow path and a cooling air flow path of a single cell included in the fuel cell system of the present disclosure. [Figure 4] FIG. 4 is a plan view schematically illustrating an example of a reaction air flow path and a cooling air flow path of a single cell included in the fuel cell system of the present disclosure. [Figure 5] FIG. 5 is a system configuration diagram showing an example of a fuel cell system according to the present disclosure. [Figure 6] FIG. 6 is a system configuration diagram showing another example of a fuel cell system according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] 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 figures do not reflect the actual dimensional relationships. Figures 1 to 4 also show the directions of a three-dimensional Cartesian coordinate system. Here, the xy plane is the horizontal plane, the z-axis direction is the vertical direction, and the larger dimension in the z-axis direction is the top. In this disclosure, the gas supplied to the anode of the fuel cell is a fuel gas (anode gas), and the gas supplied to the cathode of the fuel cell is an oxidant gas (cathode 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, or the like. In this disclosure, air used as an oxidant gas is referred to as reaction air, and air used as a cooling gas is referred to as cooling air.

[0012] The present disclosure provides an air-cooled fuel cell system, the fuel cell system includes a case and a fuel cell stack; the case accommodates the fuel cell stack; the fuel cell stack is a stack of a plurality of unit cells, The plurality of unit cells are stacked at an angle of 10° to 80° with respect to the horizontal direction, the fuel cell stack has a reactant air inlet manifold, a reactant air outlet manifold, a hydrogen inlet manifold, and a hydrogen outlet manifold; the hydrogen inlet manifold is located above the hydrogen outlet manifold in the direction of gravity, The fuel cell system is characterized in that the reactant air inlet manifold is positioned above the reactant air outlet manifold in the direction of gravity.

[0013] If the drainage from the fuel cell is not smooth, water will accumulate in the single cells, manifolds, and piping, causing blockages due to freezing, which will cause malfunctions of the fuel cell. If the exhaust gas contains a large amount of water, it will scatter water outside the fuel cell system, causing the walls and floors around the fuel cell system to become damp and condensation to occur, worsening the environment around the fuel cell system. In the present disclosure, tilted mounting of the air-cooled fuel cell improves water management and prevents malfunction of the fuel cell's power generation function and water splashing outside the fuel cell system.

[0014] The fuel cell system includes a case and a fuel cell stack. The fuel cell system may include a hydrogen system, a reaction air system, and a cooling air system.

[0015] The case houses the fuel cell stack. The case may have an intake and an exhaust port for a cooling air system.

[0016] A fuel cell stack (stack) is a stack of a plurality of unit cells (cells). In this disclosure, both a single cell and a fuel cell stack may be referred to as a fuel cell. Fuel cells generate electricity by reacting hydrogen with air. The number of cells stacked in the fuel cell stack is not particularly limited, and may be, for example, from 2 to several hundred. The fuel cell stack may have current collector plates, pressure plates, etc. at the ends in the stacking direction.

[0017] Within the case, the multiple unit cells are stacked at an inclination of 10° to 80° with respect to the horizontal. This allows gravity to promote drainage within the manifold. The lower limit of the inclination angle of the multiple unit cells with respect to the horizontal may be 10° or more, and may be 20° or more. The upper limit of the inclination angle of the multiple unit cells with respect to the horizontal may be 80° or less, and may be 70° or less. If the inclination angle is less than 10° or more than 80°, water is likely to accumulate within the manifold, and the manifold may be clogged due to freezing of the water. Furthermore, in order to drain the water, the gas flow rate needs to be increased, which reduces the power generation efficiency of the fuel cell.

[0018] The fuel cell stack has a reactant air inlet manifold, a reactant air outlet manifold, a hydrogen inlet manifold, and a hydrogen outlet manifold. The hydrogen inlet manifold is positioned above the hydrogen outlet manifold in the direction of gravity, which allows drainage in the hydrogen manifold along the force of gravity. The reaction air inlet manifold is located above the reaction air outlet manifold in the direction of gravity, thereby allowing drainage along the force of gravity in the reaction air manifold.

[0019] The single cell may have a reaction air flow path (oxidant gas flow path), a hydrogen flow path (fuel gas flow path), and a cooling air flow path (cooling gas flow path). In a plan view of the unit cell, the cooling air flow path may intersect with the reaction air flow path.In a plan view of the unit cell, the cooling air flow path may intersect with the hydrogen flow path. The outlet side of the cooling air flow path may be located above the inlet side of the cooling air flow path in the direction of gravity. In a plan view of the fuel cell stack, the hydrogen outlet manifold and the reactant air outlet manifold may be located on the inlet side of the cooling air flow path. In a plan view of the fuel cell stack, the hydrogen inlet manifold and the reactant air inlet manifold may be located on the outlet side of the cooling air flow path. The hydrogen outlet manifold and the reactant air outlet manifold are arranged on the inlet side, which is the low-temperature side of the cooling air flow path, and the hydrogen inlet manifold and the reactant air inlet manifold are arranged on the outlet side, which is the high-temperature side of the cooling air flow path. This positions the outlet side of the cooling air flow path of each unit cell higher than the inlet side, allowing heat to be dissipated from each unit cell by natural convection of the cooling air, thereby promoting cooling of each unit cell. By locating the hydrogen outlet manifold and the reactant air outlet manifold on the inlet side of the cooling air flow path, water vapor can be liquefied efficiently, reducing the amount of water contained in the exhaust gas and lowering the dew point of the exhaust gas. In each manifold arranged at an angle, liquid droplets are discharged out of the fuel cell by gravity.

[0020] The single cell may have a flow path structure for flowing the reaction air and the cooling air so that the flow of the cooling air and the flow of the reaction air intersect in a plan view. The flow of the cooling air and the flow of the reaction air may intersect or be perpendicular to each other. In a plan view of the single cell, the flow of hydrogen and the flow of the reaction air may intersect or be perpendicular to each other. The single cell may have a power generation section. The power generating section may have a rectangular shape in a plan view. The power generating section may be a membrane electrode assembly (MEA) including an electrolyte membrane and two electrodes. 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). The two electrodes are the anode (fuel electrode or hydrogen electrode) and the cathode (oxygen electrode or air electrode). The electrodes include a catalyst layer and may include a gas diffusion layer as needed, and the power generation section may be a membrane electrode gas diffusion layer assembly (MEGA). The catalyst layer includes a catalyst, and the catalyst may include a catalytic metal that promotes an electrochemical reaction, an electrolyte having proton conductivity, and a carrier having electron conductivity. Examples of catalyst metals that can be used include platinum (Pt) and alloys of Pt with other metals (e.g., Pt alloys mixed with cobalt and nickel, etc.) The catalyst metal used as the cathode catalyst and the catalyst metal used as the anode catalyst may be the same or different. 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 may be supported on a carrier, and in each catalyst layer, the carrier on which the catalytic metal is supported (catalyst-supported carrier) and the electrolyte may be mixed. Examples of the carrier for supporting the catalytic metal include carbon materials such as carbon, which are generally available commercially. The gas diffusion layer may be a conductive member having pores. Examples of the conductive member include porous carbon materials such as carbon cloth and carbon paper, and porous metal members such as metal mesh and foam metal. A single cell of the fuel cell may include a separator. The separators collect the current generated by power generation and function as partition walls. In a single fuel cell, the separators are usually arranged on both sides of the power generation section in the stacking direction so that the power generation section is sandwiched between a pair of separators. One of the pair of separators is an anode separator, and the other is a cathode separator. The anode separator may have grooves that serve as hydrogen gas flow paths on the surface facing the power generation section. The cathode separator may have grooves on the surface facing the power generation section to serve as reaction air channels. The separator may have holes that constitute manifolds such as supply holes and discharge holes for allowing fluid to flow in the stacking direction of the unit cells. The separator may be made of, for example, dense carbon made by compressing carbon to make it gas impermeable, or a press-molded metal (for example, iron, titanium, stainless steel, etc.). The single cell may include an insulating resin frame disposed on the outer periphery (periphery) of the membrane electrode assembly in the planar direction between the anode separator and the cathode separator. The resin frame is molded into a plate-like frame shape using a thermoplastic resin, and seals the gap between the anode separator and the cathode separator while holding the membrane electrode assembly in its central region. For example, resins such as PE, PP, PET, and PEN can be used for the resin frame. The resin frame may also be a three-layer sheet composed of three layers with adhesive layers disposed on the surface layers. The single cell may have wavy cooling fins that serve as cooling air channels.

[0021] The fuel cell system may include a control device that controls the reaction air system, the hydrogen system, the cooling air system, etc., and may also control the entire fuel cell system. The control device physically has, for example, a processing unit such as a CPU (central processing unit), a ROM (read-only memory) that stores control programs and control data processed by the CPU, a storage device such as a RAM (random access memory) that is mainly used as various working areas for control processing, and an input / output interface, and may be an ECU (electronic control unit) or the like.

[0022] The hydrogen system supplies hydrogen to the fuel cell as a fuel gas and adjusts the flow rate of the hydrogen. The hydrogen system may have a circulation system that circulates the hydrogen supplied to the fuel cell. The hydrogen system includes a hydrogen tank, a hydrogen inlet valve, an injector, a hydrogen purge valve, hydrogen piping, etc., and may also include a gas-liquid separator, a hydrogen pump, an ejector, and hydrogen circulation piping as a circulation system. The hydrogen circulation piping connects the gas-liquid separator, hydrogen pump, and ejector in this order from the hydrogen outlet of the fuel cell to the hydrogen inlet of the fuel cell, enabling hydrogen circulation. The hydrogen system may include an exhaust port for exhausting hydrogen off-gas outside the fuel cell system.

[0023] The reaction air system supplies reaction air to the fuel cell as an oxidant gas and adjusts the flow rate of the reaction air. The reaction air system may have an inlet-side sealing valve at the inlet for the reaction air of the fuel cell, and an outlet-side sealing valve at the outlet for the reaction air of the fuel cell. The reaction air system may have a reaction air intake port and a reaction air blowing means. A pressure loss body (such as an air filter) may be installed at the reaction air intake port. The reaction air blowing means may be an air compressor, an air pump, an air blower, an air fan, or the like. The reaction air system may include an exhaust port for exhausting the reaction air off-gas to the outside of the fuel cell system.

[0024] The cooling air system supplies cooling air as a cooling gas to the fuel cell and adjusts the flow rate of the cooling air. The cooling air system may have a cooling air blowing means for generating a flow of cooling air. The cooling air system may have an air intake port for drawing air from the outside. A pressure loss body (such as an air filter) may be installed in the air intake port. The cooling air blowing means may be an air compressor, an air pump, an air blower, an air fan, or the like.

[0025] The fuel cell system may include an exhaust port for exhausting the gas outside the fuel cell system. The fuel cell system may include a gas-liquid separator between the hydrogen outlet manifold and the exhaust port, and between the reaction air outlet manifold and the exhaust port. The fuel cell system may have a gas-liquid separator downstream of the outlet-side sealing valve of the reaction air system and downstream of the hydrogen purge valve of the hydrogen system. The exhaust gas passes through a gas-liquid separator, which separates the liquid droplets and produces low-dew-point exhaust gas, preventing condensation and clogging downstream of the exhaust piping. In fuel cell systems equipped with a hydrogen circulation system, water clogging of the hydrogen circulation piping and single cells can be prevented. When the hydrogen outlet manifold is located on the inlet side, which is the low-temperature side of the cooling air flow path, the dew point of the circulating gas is low, and the hydrogen inlet manifold is located on the high-temperature side of the cooling air flow path, so condensation is less likely to occur. If gas with a high moisture content is discharged to the outside of the fuel cell system, it will wet the outside surroundings of the fuel cell system, but by using exhaust gas with a lower dew point, it is possible to prevent the outside surroundings of the fuel cell system from getting wet. The gas-liquid separation section may be any section that has a gas-liquid separation function. The gas-liquid separation unit may be a water storage tank that stores liquid water, or the upper space of the water storage tank may be used to separate the gas and liquid. The separated liquid water is collected in the water storage tank to prevent it from leaking out of the fuel cell system. The water storage tank may be provided with a drain valve. The gas-liquid separator may be a hose, and the water may be continuously discharged to a drain outlet via the hose. The gas-liquid separator may be a simple T-pipe.

[0026] FIG. 1 is an exploded perspective view showing an example of a single fuel cell included in a fuel cell system according to the present disclosure. The single cell 1 shown in Fig. 1 includes cooling fins (cooling air flow paths) 2 that serve as flow paths for cooling air (cooling gas) 7, a reactant air inlet manifold 3, a reactant air outlet manifold 4, a hydrogen inlet manifold 5, a hydrogen outlet manifold 6, two separators 11, and an MEA and resin frame 12 sandwiched between the two separators 11. As shown in Fig. 1, the single cell 1 of the fuel cell has a flow path structure in which the reactant air 9 and the cooling air 7 flow independently. Hydrogen 8 and the reactant air 9 flow in countercurrent directions.

[0027] FIG. 2 is a schematic diagram showing an example of the arrangement of a fuel cell stack provided in the fuel cell system of the present disclosure. The fuel cell system 100 shown in FIG. 2 has a case 50 and a cooling fan 31, and the case 50 houses the fuel cell stack 10. The fuel cell stack 10 is a stack of a plurality of unit cells 1 stacked one on top of the other. Within the case 50, the plurality of unit cells 1 (fuel cell stack 10) are arranged at an inclination of θ degrees relative to the horizontal direction. The fuel cell stack 10 has a reaction air inlet manifold 3 , a reaction air outlet manifold 4 , a hydrogen inlet manifold 5 , and a hydrogen outlet manifold 6 . The hydrogen inlet manifold 5 is located above the hydrogen outlet manifold 6 in the direction of gravity. The reaction air inlet manifold 3 is located above the reaction air outlet manifold 4 in the direction of gravity.

[0028] FIG. 3 is a plan view schematically illustrating an example of a hydrogen flow path and a cooling air flow path of a single cell included in the fuel cell system of the present disclosure. In the unit cell 1 shown in FIG. 3, the cooling air flow path 2 intersects with the hydrogen flow path 15 in plan view. The outlet side of the cooling air flow path 2 is located above the inlet side of the cooling air flow path 2 in the direction of gravity. In a plan view of the unit cell 1 (and the fuel cell stack 10), the hydrogen outlet manifold 6 is located on the inlet side of the cooling air flow path 2. In a plan view of the unit cell 1 (and the fuel cell stack 10), the hydrogen inlet manifold 5 is located on the outlet side of the cooling air flow path 2.

[0029] FIG. 4 is a plan view schematically illustrating an example of a reaction air flow path and a cooling air flow path of a single cell included in the fuel cell system of the present disclosure. In the unit cell 1 shown in FIG. 4, the cooling air flow path 2 intersects with the reaction air flow path 16 in plan view. The outlet side of the cooling air flow path 2 is located above the inlet side of the cooling air flow path 2 in the direction of gravity. In a plan view of the unit cell 1 (and the fuel cell stack 10), the reactant air outlet manifold 4 is located on the inlet side of the cooling air flow path 2. In a plan view of the unit cell 1 (and the fuel cell stack 10), the reactant air inlet manifold 3 is located on the outlet side of the cooling air flow path 2.

[0030] FIG. 5 is a system configuration diagram showing an example of a fuel cell system according to the present disclosure. The fuel cell system 100 shown in FIG. 5 includes a case 50, a fuel cell stack 10, a reaction air system 20, a cooling air system 30, and a hydrogen system 40. The reaction air system 20 includes a reaction air intake port 21, an air blower 22, an inlet-side sealing valve 23, and an outlet-side sealing valve 24. The reaction air intake port 21 may include an air filter. The cooling air system 30 includes a cooling fan 31 and an air intake 32. The air intake 32 may include an air filter. The hydrogen system 40 includes a hydrogen tank 41 , a hydrogen inlet valve 42 , a gas-liquid separator 43 , a hydrogen purge valve 44 , and a hydrogen pump 45 . The fuel cell system 100 includes independent blower means 22 and 31 for the reaction air system 20 and the cooling air system 30 . The fuel cell system 100 includes an exhaust port 80 for exhausting gas to the outside of the fuel cell system 100 . The fuel cell system 100 has a second gas-liquid separator (gas-liquid separation section) 70 downstream of the outlet-side sealing valve 24 of the reaction air system 20 and downstream of the hydrogen purge valve 44 of the hydrogen system 40, and has a water storage tank 71 downstream of the second gas-liquid separator 70 for storing separated liquid water.

[0031] FIG. 6 is a system configuration diagram showing another example of a fuel cell system according to the present disclosure. In FIG. 6, the same components as those in FIG. 5 are assigned the same reference numerals, and the description thereof will be omitted. 6 does not include the gas-liquid separator 43, the second gas-liquid separator (gas-liquid separation unit) 70, and the hydrogen pump 45, as compared to the fuel cell system 100. The water storage tank 71 has a drain valve 72 that drains the stored liquid water to the outside of the fuel cell system 200. A drain outlet may be provided downstream of the drain valve 72. [Explanation of symbols]

[0032] 1. Cell 2. Cooling fins (cooling air flow path) 3. Reactor air inlet manifold 4. Reactor air outlet manifold 5. Hydrogen inlet manifold 6. Hydrogen outlet manifold 7. Cooling air (cooling gas) 8. Hydrogen gas 9.Reaction air 10. Fuel cell stack 11. Separator 12.MEA, resin frame 15. Hydrogen flow path 16.Reaction air flow path 20.Reaction air system 21.Reaction air intake 22. Air Blower 23. Inlet side sealing valve 24.Outlet side sealing valve 30. Cooling air system 31. Cooling fan 32.Air intake 40. Hydrogen 41. Hydrogen Tank 42. Hydrogen inlet valve 43. Gas-liquid separator 44. Hydrogen purge valve 45. Hydrogen pump 50. Case 70.Second gas-liquid separator 71. Water Tank 72.Drain valve 80. Exhaust port 100. Fuel Cell System 200. Fuel Cell System

Claims

1. An air-cooled fuel cell system, the fuel cell system includes a case and a fuel cell stack; the case accommodates the fuel cell stack; the fuel cell stack is a stack of a plurality of unit cells, The plurality of unit cells are stacked at an angle of 10° to 80° with respect to the horizontal direction, the fuel cell stack has a reactant air inlet manifold, a reactant air outlet manifold, a hydrogen inlet manifold, and a hydrogen outlet manifold; the hydrogen inlet manifold is located above the hydrogen outlet manifold in the direction of gravity, A fuel cell system, characterized in that the reactant air inlet manifold is located above the reactant air outlet manifold in the direction of gravity.

2. The single cell has a reaction air flow path, a hydrogen flow path, and a cooling air flow path, In a plan view of the unit cell, the cooling air flow path intersects the reaction air flow path and the hydrogen flow path; an outlet side of the cooling air flow path is located above an inlet side of the cooling air flow path in a direction of gravity, In a plan view of the fuel cell stack, the hydrogen outlet manifold and the reactant air outlet manifold are located on an inlet side of the cooling air flow path, 2. The fuel cell system according to claim 1, wherein, in a plan view of the fuel cell stack, the hydrogen inlet manifold and the reactant air inlet manifold are located on the outlet side of the cooling air flow path.

3. the fuel cell system includes an exhaust port; 2. The fuel cell system according to claim 1, further comprising a gas-liquid separator between the hydrogen outlet manifold and the exhaust port and between the reactant air outlet manifold and the exhaust port.

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