Cathode closed type air-cooled fuel cell system

Abstract

The utility model provides a cathode closed type air-cooled fuel cell system which has high-efficiency starting capability and is particularly suitable for a low-temperature environment. The system includes a fuel cell, an oxidant gas supply unit, a fuel gas supply unit, a temperature management unit, and a control and conversion unit (FDC). And the oxidant gas supply unit has the functions of internal circulation and heating of reaction air, so that the fuel cell can be quickly preheated. The temperature management unit has cooling air internal circulation and heating functions, on the premise of internal circulation, an auxiliary heat circulation mode is formed when heating is started, a mixed circulation mode is formed when heating is started and the fuel cell generates power and generates heat, and a self-heating circulation mode is formed when the fuel cell generates power and generates heat. According to the system, the starting efficiency, the operation stability and the environmental adaptability of the fuel cell are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air-cooled fuel cell systems, in particular to a cathode-enclosed air-cooled fuel cell system. BACKGROUND

[0002] A fuel cell is an energy conversion device that directly converts chemical energy stored in fuel gas and oxidant gas (hereinafter may be referred to as "reaction gas") into electrical energy through an electrochemical reaction, has the advantages of high energy conversion efficiency and less environmental pollution, and has a wide application prospect.

[0003] Generally, a fuel cell has a stacked structure in which a plurality of single cells are stacked, which is collectively referred to in the industry as a fuel cell stack (hereinafter referred to as "fuel cell"). Each single cell has the following configuration: a membrane electrode assembly (MEA) and a bipolar plate (BP) with a flow field formed therebetween for supplying reaction gas along the surface of the membrane electrode. The reaction gas flows from the supply manifold provided on one side of the outer edge of the bipolar plate to the surface of the membrane electrode, and flows toward the discharge manifold provided on the other side of the outer edge of the bipolar plate. The fuel gas is supplied to the anode electrode surface of the MEA and the oxidant gas is supplied to the cathode electrode surface on the other side to generate an electrochemical reaction, thereby generating electricity, and the working principle is as follows:

[0004] Anode: H2→ 2H + + 2e -

[0005] Cathode: 1 / 2O2+H + + 2e - → H2O

[0006] Fuel cell reaction: H2+1 / 2O2→H2O

[0007] Fuel cells can be divided into air-cooled fuel cells (hereinafter may be referred to as "air-cooled fuel cells" or "fuel cells") and liquid-cooled fuel cells (hereinafter referred to as "liquid-cooled fuel cells") according to different cooling methods.

[0008] Patent document 1: Invention patent with application publication number CN115441011.

[0009] In patent document 1, a method is described for heating to a temperature suitable for fuel cell power generation by circulating cooling air using heat generated during power generation. The heat generated during fuel cell power generation is used to circulate and preheat the fuel cell itself, which requires a certain heat generation capacity. In a low temperature environment, when the air-cooled fuel cell does not have sufficient heat generation capacity, starting the air-cooled fuel cell will become very slow or even fail to start.

[0010] Since the heat capacity of air as a refrigerant is much lower than that of water as a refrigerant liquid, air-cooled fuel cells are more prone to thermal runaway, and the operating conditions of air-cooled fuel cells in low-temperature environments are more demanding. On the other hand, when stored in a low-temperature environment, air-cooled fuel cells do not need to be stored or insulated like liquid-cooled fuel cells. Therefore, it is necessary to design an efficient air-cooled fuel cell low-temperature starting system. SUMMARY

[0011] The present application is proposed to solve the above problems, and the purpose of the present application is to provide an air-cooled fuel cell system that can be started efficiently. It has the following beneficial features: the system can be started efficiently in a low-temperature environment, solving the problem of difficult low-temperature starting of traditional air-cooled fuel cells; by integrating the control and conversion unit (FDC), the system structure is simplified, and the control efficiency and energy conversion efficiency are improved; the temperature management unit ensures that the fuel cell operates at the optimal operating temperature, improving the stability and efficiency of the system; the system supports multi-mode control and can flexibly switch between auxiliary heat cycle mode, mixed heat cycle mode and self-heat cycle mode to adapt to different environmental temperatures and operating conditions; the design of the rapid preheating cycle air passage shortens the starting time; the application of the heater improves the preheating efficiency and temperature control ability of the system; the precise control of the thermostat valve improves the cooling efficiency and the flexibility of temperature control; the system design takes into account the adaptability to low-temperature environments, and does not require the storage or insulation of the coolant; the use of the filter ensures the quality of the air entering the system, improving the service life and performance of the system. These features work together to make the air-cooled fuel cell system have significant advantages in starting efficiency, operating stability, environmental adaptability and energy conversion efficiency.

[0012] In particular, the air-cooled fuel cell system of the present application is characterized in that the air-cooled fuel cell system comprises: a fuel cell, which is a membrane power generation device that performs an electrochemical reaction using fuel gas and oxidant gas; an oxidant gas supply unit that supplies reaction air to the fuel cell; a fuel gas supply unit that supplies reaction hydrogen to the fuel cell; a temperature management unit that provides the fuel cell with an optimal operating temperature; and a control and conversion unit (hereinafter referred to as "FDC") that integrates a fuel cell controller and a direct current converter for controlling the fuel cell and controlling the load output.

[0013] The oxidant gas supply unit comprises: a reaction air supply passage, a reaction air discharge passage, and a reaction air circulation passage.

[0014] Specifically, the reaction air supply path includes: a first filter, which purifies the reaction air entering the oxidant gas supply unit; an oxidant driver, which provides driving force for the reaction air to enter, discharge and circulate in the fuel cell; a first valve, which controls the opening degree of the reaction air inlet of the fuel cell; and a first temperature sensor, which collects the temperature of the reaction air at the inlet of the fuel cell.

[0015] Specifically, the reaction air discharge path includes a second valve, which controls the opening degree of the reaction air outlet of the fuel cell.

[0016] Specifically, the reaction air circulation path includes a third valve, which controls the opening degree of the reaction air circulation path; and a first heater, which heats the reaction air entering the reaction air circulation path.

[0017] The front end of the reaction air supply path is connected to the atmosphere and the temperature management unit, respectively, and the rear end of the reaction air supply path is connected to the reaction air inlet of the fuel cell. The front end of the reaction air discharge path is connected to the reaction air outlet of the fuel cell, and the rear end of the reaction air discharge path is connected to the atmosphere. The front end of the reaction air circulation path is connected to the reaction air outlet of the fuel cell, and the rear end of the reaction air circulation path is connected to the front end of the oxidant driver. The reaction air supply path and the reaction air discharge path together form the reaction air discharge path during power generation of the fuel cell. The reaction air supply path and the reaction air circulation path together form the circulation air path for rapid preheating of the fuel cell. The FDC controls the opening and closing of the first heater based on the temperature collected by the first temperature sensor.

[0018] The temperature management unit has a cooling air supply path, a cooling air discharge path, a cooling air circulation path and a cooling air bypass.

[0019] Specifically, the cooling air supply path includes: a second filter, which purifies the cooling air entering the temperature management unit; a fourth valve, which controls the opening degree of the cooling air inlet of the fuel cell; and a second temperature sensor, which collects the temperature of the cooling air at the inlet of the fuel cell.

[0020] Specifically, the cooling air discharge path includes a third temperature sensor, which collects the temperature of the fuel cell; a coolant driver, which provides driving force for the cooling air to enter, discharge and circulate in the fuel cell; and a thermostat valve, which controls the opening degree ratio of the cooling air outlet of the fuel cell towards two different paths, which are respectively connected to the atmosphere and the front end of the cooling air circulation path.

[0021] Specifically, the cooling air circulation path includes a second heater, which heats the cooling air entering the cooling air circulation path.

[0022] Specifically, the cooling air bypass includes a fifth valve that controls the opening degree of the connection between the fuel cell cooling air exhaust port and the front end of the reaction air supply passage.

[0023] The front end of the cooling air supply passage is connected to an atmospheric port, and the rear end of the cooling air supply passage is connected to the fuel cell cooling air intake port. The front end of the cooling air exhaust passage is connected to the fuel cell cooling air exhaust port, and the rear end of the cooling air exhaust passage is connected to the atmospheric port and the front end of the cooling air circulation passage. The front end of the cooling air circulation passage is connected to the rear end of the cooling air exhaust passage, and the rear end of the cooling air circulation passage is connected to the fuel cell cooling air intake port. The front end of the cooling air bypass is connected to the rear end of the coolant driver, and the rear end of the cooling air bypass is connected to the front end of the reaction air supply passage.

[0024] The cooling air supply passage and the cooling air exhaust passage together form a cooling air exhaust passage during power generation of the fuel cell. The cooling air supply passage, the cooling air exhaust passage, and the cooling air circulation passage together form a circulating air passage for rapid preheating of the fuel cell. The FDC controls the fuel cell system to switch among the auxiliary heat cycle mode, the mixed heat cycle mode, and the self-heat cycle mode based on the temperature sensed by the third temperature sensor. The FDC controls the various actuators to switch among the different modes. BRIEF DESCRIPTION OF DRAWINGS

[0025] FIG. 1 is a schematic diagram of a cooling air bypass of a fuel cell system according to the present application; Figure 1 FIG. 1 is a schematic diagram of a cooling air bypass of a fuel cell system according to the present application;

[0026] FIG. 1 is a schematic diagram of a cooling air bypass of a fuel cell system according to the present application; Figure 2 FIG. 1 is a schematic diagram of a cooling air bypass of a fuel cell system according to the present application;

[0027] FIG. 1 is a schematic diagram of a cooling air bypass of a fuel cell system according to the present application; Figure 3 FIG. 1 is a schematic diagram of a cooling air bypass of a fuel cell system according to the present application;

[0028] The reference signs are as follows:

[0029] 10 - fuel cell; 100 - oxidant gas supply unit; 101 - first filter; 102 - oxidant driver; 103 - first valve; 104 - first temperature sensor; 105 - second valve; 106 - third valve; 107 - first heater; 200 - fuel gas supply unit; 201 - hydrogen source; 202 - pressure regulating valve; 203 - heat exchanger; 204 - safety valve; 205 - ejector; 206 - fourth temperature sensor; 207 - moisture trap; 208 - electromagnetic valve; 209 - check valve; 300 - temperature management unit; 301 - second filter; 302 - fourth valve; 303 - second temperature sensor; 304 - third temperature sensor; 305 - coolant driver; 306 - thermostat valve; 307 - second heater; 308 - fifth valve; 90 - FDC. DETAILED DESCRIPTION

[0030] The application will be further described in detail below with reference to the accompanying drawings.

[0031] Figure 1 A brief structure diagram of the air-cooled fuel cell system described in the application. The air-cooled fuel cell system of the application is characterized in that the air-cooled fuel cell system comprises: a fuel cell 10, which is a membrane power generation device using fuel gas and oxidant gas for electrochemical reaction; an oxidant gas supply unit 100, which provides reaction air to the fuel cell; a fuel gas supply unit 200, which provides reaction hydrogen to the fuel cell; a temperature management unit 300, which provides an optimal working temperature for the fuel cell; and an FDC 90, which integrates a fuel cell controller and a direct current converter for control of the fuel cell and control of load output.

[0032] The oxidant gas supply unit 100 comprises: a reaction air supply passage, a reaction air discharge passage, and a reaction air circulation passage.

[0033] Specifically, the reaction air supply passage comprises: a first filter 101, which purifies reaction air entering the oxidant gas supply unit; an oxidant driver 102, which provides driving force for reaction air entering, discharging and circulating in the fuel cell; a first valve 103, which controls opening degree of a reaction air inlet of the fuel cell; and a first temperature sensor 104, which collects reaction air temperature at the inlet of the fuel cell.

[0034] Specifically, the reaction air discharge passage comprises: a second valve 105, which controls opening degree of a reaction air outlet of the fuel cell.

[0035] Specifically, the reaction air circulation passage comprises: a third valve 106, which controls opening degree of the reaction air circulation passage; and a first heater 107, which warms reaction gas entering the reaction air circulation passage.

[0036] The front end of the reaction air supply passage is connected to the atmosphere and the temperature management unit, respectively, and the rear end of the reaction air supply passage is connected to the reaction air inlet of the fuel cell. The front end of the reaction air discharge passage is connected to the reaction air outlet of the fuel cell 10, and the rear end of the reaction air discharge passage is connected to the atmosphere. The front end of the reaction air circulation passage is connected to the reaction air outlet of the fuel cell 10, and the rear end of the reaction air circulation passage is connected to the front end of the oxidant driver 102. The reaction air supply passage and the reaction air discharge passage together form the reaction air discharge passage during power generation of the fuel cell 10. The reaction air supply passage and the reaction air circulation passage together form the circulation air passage during rapid preheating of the fuel cell 10. The FDC 90 controls the opening and closing of the first heater 107 based on the temperature value Tl collected by the first temperature sensor 104.

[0037] Specifically, when the temperature value T3 collected by the third temperature sensor 304 is less than the first temperature threshold, the reaction air in the atmosphere passes through the first filter 101, enters the oxidant driver 102 for pressurization, the first valve 103 and the third valve 106 are in the open state, and the second valve 105 is in the closed state. The reaction air enters the fuel cell 10 and is preheated by the first heater 107, returns to the oxidant driver 102 for pressurization, and repeatedly circulates in the above-mentioned passages, forming an auxiliary heating circulation mode to rapidly heat the fuel cell 10. When the temperature value T3 collected by the third temperature sensor 304 is greater than or equal to the first temperature threshold, the reaction air in the atmosphere passes through the first filter 101, enters the oxidant driver 102 for pressurization, the first valve 103 and the second valve 105 are in the open state, and the third valve 106 is in the closed state. The reaction air enters the fuel cell 10 and is discharged after passing through the second valve 105, thereby forming the reaction air discharge passage during power generation of the fuel cell 10.

[0038] Figure 2 The oxidant gas supply unit control flowchart of the air-cooled fuel cell system described in the present application.

[0039] The FDC 90 controls the opening degree of the first valve 103, the second valve 105, and the third valve 106 based on the temperature value Tl collected by the first temperature sensor 104.

[0040] Specifically, when the oxidant gas supply unit 100 is in the auxiliary heating circulation mode and the value Tl collected by the first temperature sensor 104 is less than the fourth temperature threshold, the first heater 107 is turned on to heat the circulating reaction air. When the value Tl collected by the first temperature sensor 104 is greater than or equal to the fourth temperature threshold, the first heater 107 is turned off to stop heating the circulating reaction air.

[0041] Specifically, when the oxidant gas supply unit 100 is in the auxiliary heating cycle mode, the reaction air is heated by the first heater 107, and since the reaction air enters the fuel cell 10 directly contacting the membrane electrode surface, the temperature is transmitted more directly, and the fuel cell 10 is preheated faster. In the auxiliary heating cycle mode, the fuel cell 10 does not undergo an electrochemical reaction, and the oxygen in the reaction air is not consumed.

[0042] The temperature management unit 300 described above is provided with: a cooling air supply passage, a cooling air discharge passage, a cooling air circulation passage, and a cooling air bypass.

[0043] Specifically, the cooling air supply passage includes: a second filter 301 that purifies the cooling air entering the temperature management unit 300; a fourth valve 302 that controls the opening degree of the cooling air inlet of the fuel cell 10; and a second temperature sensor 303 that acquires the temperature of the cooling air at the inlet of the fuel cell 10.

[0044] Specifically, the cooling air discharge passage includes: a third temperature sensor 304 that acquires the temperature of the fuel cell 10; a coolant driver 305 that provides driving force for the entry, discharge, and circulation of the cooling air in the fuel cell 10; and a thermostat valve 306 that controls the opening degree ratio of the cooling air outlet of the fuel cell 10 toward two different passages, the two passages being connected to the atmospheric end and the front end of the cooling air circulation passage, respectively.

[0045] Specifically, the cooling air circulation passage includes: a second heater 307 that heats the cooling air entering the cooling air circulation passage.

[0046] Specifically, the cooling air bypass includes: a fifth valve 308 that controls the opening degree of the connection of the cooling air outlet of the fuel cell to the front end of the reaction air supply passage.

[0047] The front end of the cooling air supply passage is connected to the atmospheric end, and the end of the cooling air supply passage is connected to the cooling air inlet of the fuel cell 10. The front end of the cooling air discharge passage is connected to the cooling air outlet of the fuel cell 10, and the end of the cooling air discharge passage is connected to the atmospheric end and the front end of the cooling air circulation passage, respectively. The front end of the cooling air circulation passage is connected to the end of the cooling air discharge passage, and the end of the cooling air circulation passage is connected to the cooling air inlet of the fuel cell 10. The front end of the cooling air bypass is connected to the rear end of the coolant driver 305, and the end of the cooling air bypass is connected to the front end of the reaction air supply passage.

[0048] The cooling air supply passage and the cooling air discharge passage together form a cooling air discharge passage for the fuel cell 10 during power generation.

[0049] The FDC 90 controls the flow direction and the opening degree of the thermostat valve 306 based on the temperature value T2 collected by the second temperature sensor 303. The flow direction of the thermostat valve 306 is the direction from the end of the cooling air discharge passage to the front end of the cooling air circulation passage, and the opening degree is 100%. The thermostat valve 306 can be a thermostat, a reversing valve, a louver, or the like.

[0050] Specifically, the cooling air in the atmosphere enters the fuel cell 10 through the second filter 301 and the fourth valve 302, is preheated by the second heater 307 after being pressurized by the coolant driver 305, and returns to the fuel cell 10. The cooling air repeatedly circulates in the above-mentioned passages to form a cooling air circulation passage.

[0051] Specifically, the auxiliary heat circulation mode is configured to preheat the fuel cell 10 by preheating the circulating reaction air by the first heater 107 and preheating the circulating cooling air by the second heater 307. The mixed heat circulation mode is configured to preheat the fuel cell 10 by preheating the circulating cooling air by power generation of the fuel cell 10 and preheating the circulating cooling air by the second heater 307. The self-heat circulation mode is configured to preheat the fuel cell 10 by preheating the circulating cooling air by power generation of the fuel cell 10.

[0052] In addition, after a certain volume of cooling air enters the cooling air circulation passage, the fourth valve 302 and the fifth valve 308 are closed, which can reduce the unheated cooling air entering the cooling air circulation passage and improve the preheating efficiency of the fuel cell 10.

[0053] Figure 3 A start-up control flowchart of the air-cooled fuel cell system described in the present application.

[0054] The FDC 90 controls the fuel cell system to switch among the auxiliary heat circulation mode, the mixed heat circulation mode, and the self-heat circulation mode based on the temperature value T3 collected by the third temperature sensor 304.

[0055] When the temperature value T3 collected by the third temperature sensor 304 is less than the first temperature threshold, the FDC 90 executes the auxiliary heat circulation mode.

[0056] When the temperature value T3 collected by the third temperature sensor 304 is greater than or equal to the first temperature threshold and T3 is less than the second temperature threshold, the FDC 90 executes a mixed heat cycle mode.

[0057] When the temperature value T3 collected by the third temperature sensor 304 is greater than or equal to the second temperature threshold and T3 is less than the third temperature threshold, the FDC 90 executes a self-heat cycle mode.

[0058] When the temperature value T3 collected by the third temperature sensor 304 is greater than or equal to the third temperature threshold, the FDC 90 exits the cycle mode.

[0059] The first temperature threshold can be set to -25℃, -15℃, -5℃, etc., and is preferably set to -15℃.

[0060] The second temperature threshold can be set to 0℃, 5℃, 10℃, etc., and is preferably set to 5℃.

[0061] The third temperature threshold can be set to 50℃, 55℃, 60℃, etc., and is preferably set to 55℃.

[0062] The fourth temperature threshold can be set to 50℃, 60℃, 70℃, etc., and is preferably set to 60℃.

[0063] The first valve 103, the second valve 105, the third valve 106, and the fifth valve 308 can be a throttle valve, a solenoid valve, a shutter, etc., and the application preferably uses a throttle valve.

[0064] The fourth valve 302 and the thermostat valve 30 can be a throttle valve, a solenoid valve, a reversing valve, a shutter, etc., and the application preferably uses a shutter.

[0065] The first heater 107 and the second heater 307 can be a PTC module, a heating wire module, etc., and the application preferably uses a PTC module.

[0066] The above is only the preferred specific embodiment of the application, but the protection scope of the application is not limited thereto, and any person skilled in the art can easily think of changes or replacement methods within the technical scope disclosed by the application, which should be covered within the protection scope of the application.

Claims

1. A cathode-enclosed air-cooled fuel cell system, characterized by comprising: Comprise: Oxidant gas supply unit, with the function of circulating and heating the reaction air, to make the fuel cell preheat quickly; Temperature management unit, with the function of circulating and heating the cooling air; Control and conversion unit (FDC) for controlling the oxidant gas supply unit and temperature management unit.

2. The system of claim 1, wherein, The temperature management unit constitutes an auxiliary heating cycle mode when the heating is turned on under the premise of internal circulation, a mixed cycle mode when the heating and the fuel cell power generation heat are turned on, and a self-heating cycle mode when the fuel cell power generation heat is turned on.

3. The system of claim 1, wherein, The oxidant gas supply unit controls the reaction air circulation through the first valve, the second valve, the third valve and the reaction air driver.

4. The system of claim 1, wherein, The control and conversion unit (FDC) controls the first heater to turn on and off based on the first temperature sensor value and the fourth temperature threshold value, to control the circulating reaction air temperature not higher than the fourth temperature threshold value.

5. The system of claim 1, wherein, The temperature management unit controls the cooling air internal circulation through the temperature valve, the fourth valve, the fifth valve and the cooling air driver.

6. The system of claim 1, wherein, The control and conversion unit (FDC) controls the second heater and the fuel cell power generation based on the third temperature sensor value, the first temperature threshold value, the second temperature threshold value and the third temperature threshold value, to control the conversion of the auxiliary heating cycle mode, the mixed cycle mode and the self-heating cycle mode, and to ensure the efficient preheating of the fuel cell.

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