Air-cooled fuel cell system

Abstract

Provided is a fuel cell system capable of suppressing the occurrence of an abnormal potential in a fuel cell. This air-cooled fuel cell system is characterized by being provided with a fuel cell, a hydrogen system for supplying hydrogen to the fuel cell, a reaction air system for supplying reaction air to the fuel cell, and a cooling air system for supplying cooling air to the fuel cell. The fuel cell has a reaction air flow path and a cooling air flow path each having a flow path structure in which reaction air and cooling air are independent from each other, the fuel cell system interrupts the cathode and anode of the fuel cell from the outside of the fuel cell system when the system is stopped, and the fuel cell system stops the supply of reaction air to the fuel cell when the system is started. The supply of hydrogen to the fuel cell and the supply of cooling air to the fuel cell are started, and the supply of reaction air to the fuel cell is started after a predetermined time has elapsed from the start-up of the system.

Description

Technical Field

[0001] The present disclosure relates to an air-cooled fuel cell system. Background Art

[0002] Various technologies have been proposed regarding fuel cells (FC) such as those disclosed in Patent Documents 1 to 3.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2005-216783

[0004] Patent Document 2: Japanese Patent Application Publication No. 2009-158203

[0005] Patent Document 3: Japanese Patent Application Publication No. 2022-185247

[0006] In the case of an open air-cooled fuel cell, the cathode is also in an open state during the period from the last system shutdown to the current system startup, so there is air in the cathode. During this period, an abnormal potential is generated in the fuel cell, causing degradation of the fuel cell. Summary of the invention

[0007] The present disclosure has been made in view of the above-mentioned actual situation, and a main object thereof is to provide an air-cooled fuel cell system capable of suppressing the generation of abnormal potential in a fuel cell.

[0008] In the first embodiment of the present disclosure, a fuel cell system is provided, which is an air-cooled fuel cell system, characterized in that the fuel cell system comprises a fuel cell, a hydrogen system for supplying hydrogen to the fuel cell, a reaction air system for supplying reaction air to the fuel cell, and a cooling air system for supplying cooling air to the fuel cell, the fuel cell having a reaction air flow path and a cooling air flow path with independent flow path structures for the reaction air and the cooling air, the fuel cell system cuts off the cathode and anode of the fuel cell from the outside of the fuel cell system when the system is stopped, the fuel cell system stops the supply of the reaction air to the fuel cell when the system is started, and starts the supply of the hydrogen and the cooling air to the fuel cell, and the fuel cell system starts the supply of the reaction air to the fuel cell after a specified time has passed since the start of the system.

[0009] In the second embodiment of the present disclosure, it can also be constructed as follows: on the basis of the first embodiment, the above-mentioned reaction air system has a reaction air supply mechanism, the above-mentioned cooling air system has a cooling air supply mechanism, and the hydrogen exhaust flow path of the above-mentioned hydrogen system merges with the cooling air exhaust flow path of the above-mentioned cooling air system.

[0010] In a third embodiment of the present disclosure, in addition to the first embodiment, the fuel cell system may include an electrical system, and the fuel cell system may connect the fuel cell to a power line of the electrical system when the system is started.

[0011] In a fourth embodiment of the present disclosure, in addition to the first embodiment, the hydrogen system may include a hydrogen pump.

[0012] The fuel cell system of the present disclosure can suppress the generation of abnormal potential of the fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is an exploded perspective schematic diagram showing an example of a single cell of a fuel cell included in the fuel cell system of the present disclosure.

[0014] Figure 2 It is a perspective schematic diagram showing an example of a fuel cell stack included in the fuel cell system of the present disclosure.

[0015] Figure 3 1 is a system configuration diagram showing an example of a fuel cell system of the present disclosure.

[0016] Figure 4 1 is a circuit diagram showing an example of an electrical system included in the fuel cell system of the present disclosure.

[0017] Figure 5 1 is a flowchart showing an example of control of the fuel cell system of the present disclosure.

[0018] Figure 6 : is a flowchart showing another example of control of the fuel cell system of the present disclosure.

[0019] Description of Reference Numerals

[0020] 1…battery cell; 2…cooling fin (cooling air flow path); 3…reaction air inlet; 4…reaction air outlet; 5…hydrogen inlet; 6…hydrogen outlet; 7…cooling air (cooling gas); 8…hydrogen; 9…reaction air; 10…fuel cell stack; 11…diaphragm; 12…MEA, resin frame; 13…collector plate; 14…pressurizing plate; 20…reaction air system; 21…reaction air intake port; 22…air blower; 23…inlet side sealing valve; 24…outlet side sealing valve; 30…cooling air system; 31…cooling fan; 40…hydrogen system; 41…hydrogen tank; 42…hydrogen inlet valve; 43…gas-liquid separator; 44…hydrogen purge valve; 45…hydrogen pump; 50…electrical system; 51…power line; 52…diode; 53…relay; 54…power consumption absorption mechanism; 55…auxiliary equipment; 56…power consumption equipment. DETAILED DESCRIPTION

[0021] The following describes the embodiments of the present disclosure. In addition, matters required for the implementation of the present disclosure other than matters specifically mentioned in this specification (for example, the general structure and manufacturing process of the fuel cell system that does not characterize the present disclosure) can be understood as design matters for those skilled in the art based on the prior art in the art. The present disclosure can be implemented based on the contents disclosed in this specification and the technical common sense in the art.

[0022] In addition, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships.

[0023] In the present disclosure, the gas supplied to the anode of the fuel cell is the fuel gas (anode gas), and the gas supplied to the cathode of the fuel cell is the oxidant gas (cathode gas). The fuel gas is a gas mainly containing hydrogen, and may also be hydrogen. The oxidant gas is a gas containing oxygen, and may also be oxygen, air, etc. In the present disclosure, the air serving as the oxidant gas is referred to as reaction air, and the air serving as the cooling gas is referred to as cooling air.

[0024] In the present disclosure, a fuel cell system is provided, which is an air-cooled fuel cell system, characterized in that the fuel cell system includes a fuel cell, a hydrogen system for supplying hydrogen to the fuel cell, a reaction air system for supplying reaction air to the fuel cell, and a cooling air system for supplying cooling air to the fuel cell, the fuel cell having a reaction air flow path and a cooling air flow path with independent flow path structures for the reaction air and the cooling air, the fuel cell system cuts off the cathode and anode of the fuel cell from the outside of the fuel cell system when the system is stopped, the fuel cell system stops the supply of the reaction air to the fuel cell when the system is started, and starts the supply of the hydrogen and the cooling air to the fuel cell, and the fuel cell system starts the supply of the reaction air to the fuel cell after a specified time has passed since the start of the system.

[0025] When air is added to the cathode and hydrogen is added to the anode without current flowing, the potential of the fuel cell becomes high (about 0.95 to 1.05 V). In this state, although it is stable, the degradation of the fuel cell is aggravated. In addition, an oxide film is generated on the Pt catalyst, causing the performance of the catalyst to decrease. To avoid this, the potential of the fuel cell can also be operated at a constant level below 0.85 V.

[0026] In a general open air-cooled fuel cell, the air system opening is large and it is difficult to seal the air system. When the system is started, oxygen exists at both electrodes, and a high potential state of the fuel cell cannot be avoided.

[0027] Even when the cathode is sealed, it is necessary to replace nitrogen, oxygen, water, etc. in the hydrogen system with hydrogen and dilute the exhaust hydrogen when the system is started. If the reaction air supply mechanism such as an air blower is turned on to add reaction air to the cathode before hydrogen is introduced for dilution, the above-mentioned high potential state and abnormal potential will occur.

[0028] The present disclosure relates to improving the performance of an air-cooled fuel cell, and proposes a structure and method for preventing the generation of abnormal potential of a fuel cell and the degradation of the fuel cell, and for smoothly starting the system. A fuel cell having a flow path structure with independent reaction air and cooling air is started in a prescribed order. When the system is started, the supply of reaction air can be stopped and nitrogen, oxygen, moisture, etc. of the hydrogen system can be quickly purified, and hydrogen replacement of the anode can be performed, thereby suppressing the generation of abnormal potential of the fuel cell.

[0029] Hydrogen exhausted to the outside of the fuel cell system at the time of startup of the system can be diluted with cooling air.

[0030] The fuel cell system includes a fuel cell that generates electricity by reacting hydrogen with air, a hydrogen system that supplies hydrogen required for power generation to the fuel cell, a reaction air system that supplies reaction air to the fuel cell, and a cooling air system that supplies cooling air to the fuel cell to cool the heat generated by power generation.

[0031] The fuel cell may be a single cell (battery cell) having only one fuel cell, or may be a fuel cell stack (battery stack) which is a stacked body in which a plurality of cells are stacked.

[0032] In the present disclosure, there are cases where both a battery cell and a fuel cell stack are referred to as a fuel cell.

[0033] The number of stacked cells in the fuel cell stack is not particularly limited, and may be, for example, 2 to several hundred.

[0034] The fuel cell stack may include corrugated cooling fins serving as cooling air flow paths in each cell.

[0035] The fuel cell stack may have a current collecting plate, a pressure plate, etc. at the end portions in the stacking direction.

[0036] The fuel cell has a reaction air flow path (oxidant gas flow path) and a cooling air flow path (cooling gas flow path) with independent flow paths for reaction air and cooling air, and may further have a hydrogen flow path (fuel gas flow path).

[0037] The independent flow path structure of reaction air and cooling air means that the air does not communicate between the flow paths from the supply of air to the fuel cell to the exhaust of air from the fuel cell. In addition, the flow paths for exhausting the air exhausted from the fuel cell to the outside of the fuel cell system may be independent or not.

[0038] The cell may also include a flow path structure that allows the reaction air and the cooling air to flow so that the flow of the cooling air intersects with the flow of the reaction air in a plan view. The flow of the cooling air and the flow of the reaction air may intersect or be orthogonal.

[0039] The battery cell may have a power generation unit.

[0040] The shape of the power generation unit may be a rectangle in a plan view.

[0041] The power generation unit may be a membrane electrode assembly (MEA) including an electrolyte membrane and two electrodes.

[0042] The electrolyte membrane may also be a solid polymer electrolyte membrane. As the solid polymer electrolyte membrane, for example, a fluorine electrolyte membrane such as a film of perfluorosulfonic acid containing water, and a hydrocarbon electrolyte membrane may be cited. As the electrolyte membrane, for example, a Nafion membrane (manufactured by DuPont) may also be used.

[0043] The two electrodes are the anode (fuel or hydrogen) and the cathode (oxygen or air).

[0044] The electrode includes a catalyst layer and may include a gas diffusion layer as required, and the power generation unit may be a membrane electrode gas diffusion layer assembly (MEGA).

[0045] The catalyst layer may include a catalyst including a catalyst metal that promotes an electrochemical reaction, an electrolyte having proton conductivity, and a carrier having electron conductivity.

[0046] As the catalyst metal, for example, platinum (Pt) and alloys composed of Pt and other metals (for example, Pt alloys mixed with cobalt, nickel, etc.) can be used. The catalyst metal used as the cathode catalyst and the catalyst metal used as the anode catalyst may be the same or different.

[0047] The electrolyte may be a fluorine-based resin or the like. For example, a Nafion solution or the like may be used as the fluorine-based resin.

[0048] The above-mentioned catalyst metal is supported on a carrier, and in each catalyst layer, the carrier supporting the catalyst metal (catalyst-supporting carrier) and the electrolyte may be present in a mixed state.

[0049] Examples of the carrier for supporting the catalyst metal include carbon materials such as carbon generally available on the market.

[0050] The gas diffusion layer may be a conductive member having pores or the like.

[0051] Examples of the conductive member include carbon porous bodies such as carbon cloth and carbon paper, and metal porous members such as metal mesh and foamed metal.

[0052] The fuel cell may also include a membrane.

[0053] The diaphragm collects the current generated by power generation and functions as a partition. In the battery cell of a fuel cell, the diaphragm is usually arranged on both sides of the stacking direction of the power generation part in a way that a pair of diaphragms sandwich the power generation part. One side of the pair of diaphragms is the anode diaphragm and the other side is the cathode diaphragm.

[0054] The anode separator may have grooves serving as hydrogen flow paths on the surface on the power generation portion side, and may have grooves serving as cooling air flow paths on the surface on the opposite side to the power generation portion.

[0055] The cathode separator may have grooves serving as reaction air flow paths on the surface facing the power generation portion, and may have grooves serving as cooling air flow paths on the surface facing the opposite side to the power generation portion.

[0056] The separator may have holes constituting manifolds such as supply holes and discharge holes for allowing the fluid to flow in the stacking direction of the battery cells.

[0057] The separator may be, for example, dense carbon obtained by compressing carbon to be airtight, or press-formed metal (for example, iron, titanium, stainless steel, etc.).

[0058] The battery cell may also be provided with an insulating resin frame disposed on the outside (periphery) of the surface direction of the membrane electrode assembly between the anode separator and the cathode separator. The resin frame is formed into a plate-like and frame-like shape using a thermoplastic resin, and the anode separator and the cathode separator are sealed while the membrane electrode assembly is maintained in its central area. As the resin frame, for example, resins such as PE, PP, PET, and PEN can be used. The resin frame may also be a three-layer sheet body consisting of three layers in which an adhesive layer is disposed on the surface layer.

[0059] The fuel cell system may also include a control device, which controls the reaction air system, the hydrogen system, the cooling air system, etc., and may also control the entire fuel cell system.

[0060] The control device physically has, for example, a processing unit such as a CPU (central processing unit), a ROM (read-only memory) for storing control programs and control data processed by the CPU, a storage device such as a RAM (random access memory) mainly used as various work areas for control processing, and an input / output interface. It can also be an ECU (electronic control unit), etc.

[0061] The reaction air system supplies reaction air as an oxidant gas to the fuel cell and adjusts the flow rate of the reaction air.

[0062] The hydrogen system supplies hydrogen as fuel gas to the fuel cell and adjusts the flow rate of the hydrogen. The hydrogen system may also include a hydrogen tank, a hydrogen inlet valve, an ejector, a gas-liquid separator, a hydrogen purge valve, an ejector for hydrogen circulation, a hydrogen pump for hydrogen circulation, and hydrogen piping.

[0063] The cooling air system supplies cooling air as cooling gas to the fuel cell and adjusts the flow rate of the cooling air.

[0064] The reaction air system has an inlet-side sealing valve at the reaction air inlet of the fuel cell and an outlet-side sealing valve at the reaction air outlet of the fuel cell.

[0065] In the present disclosure, the fuel cell has an independent flow path structure for reaction air and cooling air, and in the reaction air system, valves (inlet side sealing valve and outlet side sealing valve) are set at the inlet and outlet of the reaction air of the fuel cell, thereby enabling the fuel cell to seal the cathode of the fuel cell with a smaller volume than the case of having a flow path structure shared by the reaction air and the cooling air.

[0066] The reaction air system may include a reaction air supply mechanism, the cooling air system may include a cooling air supply mechanism, and the hydrogen exhaust flow path of the hydrogen system may merge with the cooling air exhaust flow path of the cooling air system.

[0067] Furthermore, the hydrogen exhaust flow path of the hydrogen system may further include a merging portion capable of merging with the reaction air exhaust flow path of the reaction air system.

[0068] The reaction air system and the cooling air system have independent air supply mechanisms, and the hydrogen exhaust flow path merges with the cooling air exhaust flow path. Therefore, when the hydrogen system is replaced with hydrogen at system startup, the fuel cell system stops the reaction air supply mechanism and drives the cooling air supply mechanism, thereby being able to dilute the exhaust hydrogen with cooling air and discharge it to the outside of the fuel cell system.

[0069] The reaction air supply mechanism and the cooling air supply mechanism may also be an air compressor, an air pump, an air blower, an air fan, etc. respectively.

[0070] The reaction air system may include a reaction air intake port for taking in reaction air from outside the fuel cell system, and a pressure loss body such as an air filter may be provided at the reaction air intake port.

[0071] The cooling air system may include a cooling air intake port for taking in cooling air from outside the fuel cell system, and a pressure loss body such as an air filter may be provided at the cooling air intake port.

[0072] The fuel cell system cuts off the cathode and anode of the fuel cell from the outside of the fuel cell system when the system is stopped. The fuel cell system stops the supply of reaction air to the fuel cell when the system is started, and starts the supply of hydrogen to the fuel cell and the supply of cooling air to the fuel cell. The fuel cell system starts the supply of reaction air to the fuel cell after a specified time has passed since the system was started. The cathode can also be cut off from the outside of the fuel cell system by closing the reaction air inlet side sealing valve and the reaction air outlet side sealing valve. The anode can also be cut off from the outside of the fuel cell system by closing the hydrogen inlet valve and the hydrogen purge valve.

[0073] By starting up the fuel cell system according to the following startup sequence, it is possible to prevent degradation of the fuel cell.

[0074] (1) Start sequence 1

[0075] The hydrogen replacement of the hydrogen system is started from the state where the fuel cell system is stopped, with the reaction air inlet side sealing valve, reaction air outlet side sealing valve, hydrogen inlet valve and hydrogen purge valve all closed and sealed, and the cathode and anode are cut off from the outside of the fuel cell system. It can also be configured such that when the hydrogen purge valve is opened and closed and the hydrogen purge of the hydrogen system is performed, the air supply mechanism of the reaction air system is stopped and the cathode is kept sealed, reaction air is not introduced into the fuel cell, only the cooling fan of the cooling air system is turned on, and cooling air is introduced into the fuel cell to dilute the hydrogen.

[0076] (2) Start sequence 2

[0077] After a predetermined time has passed since the system was started, the reaction air inlet side sealing valve and the reaction air outlet side sealing valve are opened, and the air blower of the reaction air system is turned on to introduce reaction air into the fuel cell, and the fuel cell starts power generation. The predetermined time can be set appropriately or in advance.

[0078] A fuel cell having a flow path structure with independent reaction air and cooling air is used, a reaction air inlet side sealing valve and a reaction air outlet side sealing valve are set in the reaction air system, and the cathode is made into a closed structure, thereby preventing oxygen from entering the fuel cell when the system is stopped. Unlike the previous air-cooled fuel cell, a state where there is no oxygen at the anode can be formed at startup. Starting from this state, before adding reaction air to the cathode in (1) startup sequence 1, hydrogen replacement of the anode is performed. In order to perform hydrogen purge of the hydrogen system, it is necessary to use air for dilution and exhaust. At this time, by setting an independent air supply mechanism in the cooling air system, the air supply mechanism of the reaction air system is not operated, and only the cooling fan of the cooling air system is operated, thereby safely exhausting hydrogen while keeping the cathode in a closed state. After the hydrogen replacement of the anode is completed, reaction air is introduced to the cathode in (2) startup sequence 2, thereby starting the fuel cell power generation without generating abnormal potential.

[0079] The fuel cell system may also include an electrical system.

[0080] The electrical system may include a diode on the power line to the fuel cell and a relay for the fuel cell. By including a diode, it is possible to avoid the generation of reverse current from the power line side to the fuel cell.

[0081] The fuel cell system may also connect the fuel cell to the power line of the electrical system when the system is started. A power consumption absorption mechanism such as a secondary battery (battery) or a capacitor is connected to the power line.

[0082] When a structure in which a diode and a relay are provided in the power line of the electrical system, the fuel cell is connected to the power line by a relay before the implementation of the above-mentioned (1) start sequence 1 or before the implementation of (2) start sequence 2. When hydrogen is introduced or when reaction air is introduced, it is possible to prevent the potential from becoming high and to achieve V1≤V2. If the fuel cell is not connected to the power line by a relay and reaction air is introduced into the fuel cell when the fuel cell is in an open circuit state, the cell voltage of the fuel cell becomes a high potential (exceeding 0.9V) of the open circuit voltage (OCV), and the degradation of the fuel cell is aggravated. Before introducing reaction air into the fuel cell, the power line is connected to the fuel cell via a diode, thereby avoiding the generation of reverse current and maintaining the potential of the fuel cell below V2. V2 can also be adjusted by a power consumption absorption mechanism such as a connected battery or capacitor so that the cell voltage becomes an operating range of less than 0.85V.

[0083] The hydrogen system may also have a hydrogen pump for circulation. By having a hydrogen pump, hydrogen replacement and drainage can be efficiently performed with a small amount of hydrogen. The hydrogen concentration in the fuel cell can be quickly uniformized, thereby preventing degradation caused by local hydrogen deficiency.

[0084] It is also possible to homogenize the hydrogen concentration of the hydrogen system by circulating the hydrogen system through a hydrogen pump during the start-up sequence 2 .

[0085] Figure 1 It is an exploded perspective schematic diagram showing an example of a single cell of a fuel cell included in the fuel cell system of the present disclosure.

[0086] Figure 1 The cell 1 shown in the figure has cooling fins (cooling air flow path) 2 which serve as a flow path for cooling air (cooling gas) 7, a reaction air inlet 3, a reaction air outlet 4, a hydrogen inlet 5, a hydrogen outlet 6, two diaphragms 11, and an MEA and a resin frame 12 sandwiched between the two diaphragms 11. Figure 1 As shown, the cell 1 of the fuel cell has a flow path structure in which the reaction air 9 and the cooling air 7 are independent.

[0087] Figure 2 It is a perspective schematic diagram showing an example of a fuel cell stack included in the fuel cell system of the present disclosure.

[0088] Figure 2 The fuel cell stack shown is a stacked body in which a plurality of battery cells 1 are stacked, and includes current collector plates 13 and pressure plates 14 at both ends in the stacking direction.

[0089] Figure 3 1 is a system configuration diagram showing an example of a fuel cell system of the present disclosure.

[0090] Figure 3 The fuel cell system shown in the figure includes 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 cooling air system 30 includes a cooling fan 31. 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. Figure 3 The fuel cell system shown in the figure is provided with sealing valves 23 and 24 at the inlet and outlet of the reaction air system 20 , and is provided with independent air supply mechanisms 22 and 31 in the reaction air system 20 and the cooling air system 30 .

[0091] Figure 4 1 is a circuit diagram showing an example of an electrical system included in the fuel cell system of the present disclosure.

[0092] Figure 4 The illustrated electrical system 50 includes a power line 51 , a diode 52 , a relay 53 , a power consumption absorbing mechanism 54 such as a battery or a capacitor, auxiliary equipment 55 , and power consuming equipment 56 .

[0093] By providing the diode 52 on the power line 51 , the fuel cell stack 10 is connected to the power line 51 during the recovery control, thereby avoiding the generation of reverse current from the power line 51 to the fuel cell stack 10 and shortening the recovery control time.

[0094] Figure 5 1 is a flowchart showing an example of control of the fuel cell system of the present disclosure.

[0095] Figure 5 The start-up sequence is performed in the fuel cell system structure including the hydrogen pump, relays, and diodes.

[0096] After being left alone for a while, the fuel cell system is started from a state where the fuel cell voltage V1≈0V.

[0097] The relay of the fuel cell is connected (S101). The fuel cell voltage V1 < V2, and there is a diode, so the current does not flow.

[0098] Perform hydrogen replacement of the hydrogen system (S102). Open the hydrogen inlet valve and introduce hydrogen into the anode (S103). In order to produce a pulsed airflow, the hydrogen inlet valve may be opened and closed appropriately. When oxygen enters the cathode during a long-term stop, if the relay is not connected, the cell may become high potential (OCV≈1.0V) and the degradation of the fuel cell may be aggravated.

[0099] In order to dilute the exhaust hydrogen, the cooling fan of the cooling air system is turned on in advance (S104). In the case where the reaction air and the cooling air are independent flow path structures, and the reaction air system and the cooling air system do not have independent air supply mechanisms, the reaction air is passed through the cathode, and the cathode becomes a high potential or an abnormal potential. In order to avoid high potential and abnormal potential, it is necessary to add a three-way valve or other device for bypassing the cathode to allow air to flow. Hydrogen is diluted to the exhaust port position that contacts the outside of the fuel cell system, so the on-off timing of the cooling air fan can also be slightly advanced or slightly delayed relative to the opening and closing of the hydrogen purge valve.

[0100] The hydrogen purge valve is opened to discharge nitrogen, oxygen, moisture, etc. accumulated during the system shutdown (S105).

[0101] The hydrogen pump is turned on to make the hydrogen concentration in the anode uniform (S106). When liquid water accumulates during system shutdown, the hydrogen purge valve is opened and closed to perform exhaust and drainage while the hydrogen pump is turned on (S107).

[0102] When the exhaust and water discharge is completed and the anode is filled with high-concentration hydrogen, the hydrogen replacement is considered to be completed (S108).

[0103] The inlet and outlet sealing valves of the reaction air system are opened to introduce air to the cathode (S109). At this time, if the relay is not connected, there is a situation where the cell becomes high potential (OCV≈1.0V) and the degradation of the fuel cell is aggravated. Although the cell temporarily becomes high potential, the relay can also be connected after the reaction air is supplied.

[0104] The air blower of the reaction air system delivers a specified amount of reaction air required for power generation to the cathode, starting power generation in the fuel cell.

[0105] Figure 6 : is a flowchart showing another example of control of the fuel cell system of the present disclosure.

[0106] Figure 6 Hydrogen replacement is performed in a fuel cell system configuration that does not include a hydrogen pump.

[0107] After being left alone for a while, the fuel cell system is started from a state where the fuel cell voltage V1≈0V.

[0108] The hydrogen system is replaced with hydrogen. The hydrogen inlet valve is opened to introduce hydrogen into the anode (S201).

[0109] In order to dilute the exhaust hydrogen, a cooling fan of the cooling air system is turned on in advance (S202).

[0110] The hydrogen purge valve is opened and closed to discharge nitrogen, oxygen, moisture, etc. accumulated during the system shutdown (S203).

[0111] When the exhaust and water discharge is completed and the anode is filled with high-concentration hydrogen, the hydrogen replacement is considered to be completed (S204).

Claims

1. A fuel cell system, which is an air-cooled fuel cell system, characterized in that: The fuel cell system includes a fuel cell, a hydrogen system for supplying hydrogen to the fuel cell, a reaction air system for supplying reaction air to the fuel cell, and a cooling air system for supplying cooling air to the fuel cell. The fuel cell has a reaction air flow path and a cooling air flow path in a structure in which the reaction air and the cooling air have independent flow paths. When the fuel cell system is stopped, the cathode and anode of the fuel cell are disconnected from the outside of the fuel cell system. The fuel cell system stops supplying the reaction air to the fuel cell and starts supplying the hydrogen and the cooling air to the fuel cell when the system is started. The fuel cell system starts supplying the reaction air to the fuel cell after a predetermined time has elapsed from the start-up of the system.

2. The fuel cell system according to claim 1, characterized in that: The reaction air system has a reaction air supply mechanism. The cooling air system comprises a cooling air supply mechanism. The hydrogen exhaust flow path of the hydrogen system merges with the cooling air exhaust flow path of the cooling air system.

3. The fuel cell system according to claim 1, characterized in that: The fuel cell system comprises an electrical system, The fuel cell system connects the fuel cell to a power line of the electrical system when the system is started.

4. The fuel cell system according to claim 1, characterized in that: The hydrogen system has a hydrogen pump.

5. The fuel cell system according to claim 1, characterized in that: The fuel cell has at least one single cell, which has an anode diaphragm, a power generation unit, and a cathode diaphragm in sequence. The cathode diaphragm has the reaction air flow path on one side of the power generation unit and the cooling air flow path on the opposite side of the power generation unit.

6. The fuel cell system according to claim 5, characterized in that: The single cell has corrugated cooling fins as the cooling air flow path.

7. The fuel cell system according to claim 1, characterized in that: The fuel cell system stops supply of the reaction air to the fuel cell at system startup, starts supply of the hydrogen to the fuel cell and starts supply of the cooling air to the fuel cell, and then starts hydrogen purging of the hydrogen system.

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