A system for controlling low-pressure output of PEM fuel cells using air ejectors

Abstract

The invention discloses a system for controlling the low-pressure output of a PEM fuel cell by using an air ejector, comprising a high-pressure nitrogen cylinder, a hydrogen cylinder, a solenoid valve, a hydrogen circulation pump, a hydrogen tail exhaust valve, a first mixing chamber, an air tail exhaust valve, a load resistor, an ejector gas regulating valve, an ejector and an ejected gas regulating valve, wherein a solenoid valve is installed on a pipeline at one end of the hydrogen cylinder, one end of the solenoid valve is connected to a hydrogen circulation pump and a hydrogen tail exhaust valve, one end of the hydrogen tail exhaust valve is connected to the first mixing chamber, and one end of the first mixing chamber is installed with an air tail exhaust valve, and one end of the air tail exhaust valve is provided with an ejector gas regulating valve. The system for controlling the low-pressure output of a PEM fuel cell by using an air ejector takes a proton exchange membrane fuel cell as an object, improves the air supply system of the fuel cell, uses an air ejector to control the open circuit voltage of the fuel cell, prevents damage to the electrode of the fuel cell, thereby saving costs and extending the service life.

Description

Technical Field

[0001] The invention relates to the technical field of fuel cells, and in particular to a system for controlling the low-pressure output of a PEM fuel cell by using an air ejector. Background Art

[0002] In recent years, fuel cell vehicles are developing rapidly. However, the promotion and application of fuel cell vehicles are facing many difficulties and challenges. The cost and life of fuel cells are an aspect that cannot be ignored. In actual operation, the proton exchange membrane fuel cell (PEMFC) needs to operate within an acceptable voltage range (the cell voltage does not exceed 0.8V), especially under some unfavorable conditions, such as fuel cell shutdown purge, idling or other times when the fuel cell output power is not required. If the voltage of the fuel cell often exceeds a certain limit, the fuel cell electrode will be damaged, thereby reducing the performance and service life of the fuel cell. For this reason, we propose a system that uses an air ejector to control the low-pressure output of the PEM fuel cell. Summary of the invention

[0003] The object of the present invention is to provide a system for controlling the low-pressure output of a PEM fuel cell using an air ejector, so as to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a system for controlling the low-pressure output of a PEM fuel cell using an air ejector, comprising a high-pressure nitrogen cylinder, a hydrogen cylinder, a solenoid valve, a hydrogen circulation pump, a hydrogen tail exhaust valve, a first mixing chamber, an air tail exhaust valve, a load resistor, an ejector gas regulating valve, an ejector and an ejected gas regulating valve, wherein a solenoid valve is installed on a pipeline at one end of the hydrogen cylinder, one end of the solenoid valve is connected to a hydrogen circulation pump and a hydrogen tail exhaust valve, one end of the hydrogen tail exhaust valve is connected to the first mixing chamber, and one end of the first mixing chamber is installed with an air tail exhaust valve, one end of the air tail exhaust valve is provided with an ejector gas regulating valve, and one end of the ejector gas regulating valve is connected to an ejector, an ejector gas regulating valve is installed on the ejector, and one end of the ejector is connected to a high-pressure nitrogen cylinder;

[0005] The ejection gas regulating valve is used to adjust the ejection gas flow rate, and the ejected gas regulating valve is used to adjust the ejected gas flow rate;

[0006] The ejector is composed of an ejector nozzle, a receiving chamber, a second mixing chamber and a diffusion chamber connected in sequence;

[0007] The solenoid valve and the hydrogen tail exhaust valve are connected to the inlet and outlet of the anode respectively, the ejector and the air tail exhaust valve are connected to the inlet and outlet of the cathode respectively, and the two ends of the hydrogen circulation pump are connected to the inlet and outlet of the anode respectively.

[0008] Preferably, the load resistor is used to draw a small current from the fuel cell during shutdown and purge.

[0009] Preferably, the high-pressure nitrogen cylinder forms a communication structure with the ejector through the ejected gas regulating valve.

[0010] Preferably, the load resistor is electrically connected between the anode and the cathode.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: the system using an air ejector to control the low-pressure output of a PEM fuel cell takes a proton exchange membrane fuel cell as an object, improves the air supply system of the fuel cell, uses an air ejector to control the open circuit voltage of the fuel cell, prevents the electrode of the fuel cell from being damaged, thereby saving costs and extending the service life;

[0012] The ejected fluid of the ejector is the exhaust gas of the cathode, which is recirculated into the fuel cell through the ejector, reducing the available amount of oxygen in the cathode gas, thereby preventing the open circuit voltage of the fuel cell from being too high. At the same time, the wet exhaust gas of the cathode ensures the humidity requirement of the gas recirculated into the fuel cell; the mixed gas recirculated to the cathode only reduces the oxygen content without reducing the flow rate, which ensures the uniformity of the voltage of each cell of the fuel cell;

[0013] The working fluid nitrogen of the ejector can quickly reduce the oxygen content in the cathode inlet gas, thereby quickly reducing the fuel cell output voltage. In addition, the ejector has a simple structure, low cost, and does not require energy consumption, which greatly improves the efficiency of the system and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the principle structure of the air injection system of the present invention;

[0015] Figure 2 It is a schematic diagram of the ejector structure of the present invention.

[0016] In the figure: 1. High-pressure nitrogen cylinder; 2. Hydrogen cylinder; 3. Solenoid valve; 4. Hydrogen circulation pump; 5. Hydrogen tail exhaust valve; 6. First mixing chamber; 7. Air tail exhaust valve; 8. Load resistor; 9. Ejector gas regulating valve; 10. Ejector; 11. Ejected gas regulating valve; 12. Ejector nozzle; 13. Receiving chamber; 14. Second mixing chamber; 15. Diffusion chamber. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1-2 The present invention provides a technical solution: a system for controlling the low-pressure output of a PEM fuel cell using an air ejector, comprising a high-pressure nitrogen cylinder 1, a hydrogen cylinder 2, a solenoid valve 3, a hydrogen circulation pump 4, a hydrogen tail exhaust valve 5, a first mixing chamber 6, an air tail exhaust valve 7, a load resistor 8, an ejector gas regulating valve 9, an ejector 10 and an ejected gas regulating valve 11, wherein the solenoid valve 3 is installed on a pipeline at one end of the hydrogen cylinder 2, one end of the solenoid valve 3 is connected to the hydrogen circulation pump 4 and the hydrogen tail exhaust valve 5, one end of the hydrogen tail exhaust valve 5 is connected to the first mixing chamber 6, and one end of the first mixing chamber 6 is installed with the air tail exhaust valve 7, and the air tail exhaust valve 7 is installed on the first mixing chamber 6. An ejector gas regulating valve 9 is provided at one end of the valve 7, and an ejector 10 is connected to one end of the ejector gas regulating valve 9, an ejector gas regulating valve 11 is installed on the ejector 10, and a high-pressure nitrogen cylinder 1 is connected to one end of the ejector 10; the ejector gas regulating valve 9 is used to adjust the ejector gas flow rate, the ejector gas regulating valve 11 is used to adjust the ejector gas flow rate, the ejector 10 is composed of an ejector nozzle 12, a receiving chamber 13, a second mixing chamber 14 and a diffusion chamber 15 connected in sequence, the gas enters the receiving chamber 13 through the ejector nozzle 12, then passes through the second mixing chamber 14 for mixing, and finally diffuses and discharges through the diffusion chamber 15;

[0019] When the fuel cell is shut down for purging, in order to prevent the fuel cell monomer from being too high and damaging the electrode, the voltage of the fuel cell needs to be maintained below a limit value. The high-pressure nitrogen from the high-pressure nitrogen bottle 1 is used to pass through the ejected gas regulating valve 11 to reach the inlet of the ejector 10 to eject air with a low oxygen concentration from the cathode. The ejected gas regulating valve 9 and the ejected gas regulating valve 11 can be used to adjust the flow of the ejected gas and the ejected gas. The residual exhaust gas from the cathode is ejected by high-pressure nitrogen to reduce the oxygen content of the gas entering the cathode, thereby reducing the potential of the fuel cell and avoiding unnecessary damage to the stack due to excessive voltage.

[0020] At the same time, the moist air at the cathode can increase the humidity of the mixed gas entering the fuel cell stack, avoiding damage to the proton exchange membrane caused by excessive drying of the gas. At the anode, the high-pressure hydrogen in the hydrogen bottle 2 enters the anode inlet of the fuel cell stack after various levels of pressure reduction and its control solenoid valve 3. The unconsumed hydrogen is re-delivered to the anode inlet through the hydrogen circulation pump 4 to participate in the reaction again. The hydrogen tail exhaust valve 5 and the air tail exhaust valve 7 are the tail exhaust valves of the hydrogen path and the air path respectively. The residual exhaust gas from the anode and the cathode is diluted in the first mixing chamber 6 and then discharged into the atmosphere. The load resistor 8 is used to draw a small current from the fuel cell during shutdown and purge to allow the fuel cell stack to The voltage drops quickly; the system uses an air ejector to control the low-voltage output of a PEM fuel cell. Taking proton exchange membrane fuel cells as the object, the air supply system of the fuel cell is improved, and an air ejector is used to control the open-circuit voltage of the fuel cell to prevent damage to the fuel cell electrodes, thereby saving costs and extending service life. The working fluid nitrogen of the ejector can quickly reduce the oxygen content in the cathode inlet gas, thereby quickly reducing the output voltage of the fuel cell. In addition, the ejector has a simple structure, low cost, and does not require energy consumption, which greatly improves the efficiency of the system and reduces costs.

[0021] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for controlling the low-pressure output of a PEM fuel cell using an air ejector, comprising a high-pressure nitrogen cylinder (1), a hydrogen cylinder (2), a solenoid valve (3), a hydrogen circulation pump (4), a hydrogen tail exhaust valve (5), a first mixing chamber (6), an air tail exhaust valve (7), a load resistor (8), an ejector gas regulating valve (9), an ejector (10) and an ejected gas regulating valve (11), characterized in that: A solenoid valve (3) is installed on a pipeline at one end of the hydrogen cylinder (2), one end of the solenoid valve (3) is connected to a hydrogen circulation pump (4) and a hydrogen tail exhaust valve (5), one end of the hydrogen tail exhaust valve (5) is connected to a first mixing chamber (6), and one end of the first mixing chamber (6) is installed with an air tail exhaust valve (7), one end of the air tail exhaust valve (7) is provided with an ejection gas regulating valve (9), and one end of the ejection gas regulating valve (9) is connected to an ejector (10), an ejector (10) is installed with an ejected gas regulating valve (11), and one end of the ejector (10) is connected to a high-pressure nitrogen cylinder (1); The ejection gas regulating valve (9) is used to regulate the ejection gas flow rate, and the ejected gas regulating valve (11) is used to regulate the ejected gas flow rate; The ejector (10) is composed of an ejector nozzle (12), a receiving chamber (13), a second mixing chamber (14) and a diffusion chamber (15) which are connected in sequence; The solenoid valve (3) and the hydrogen tail exhaust valve (5) are respectively connected to the inlet and outlet of the anode, the ejector (10) and the air tail exhaust valve (7) are respectively connected to the inlet and outlet of the cathode, and both ends of the hydrogen circulation pump (4) are respectively connected to the inlet and outlet of the anode.

2. A system for controlling low-pressure output of a PEM fuel cell using an air ejector according to claim 1, characterized in that: The load resistor (8) is used to draw a small current from the fuel cell during shutdown and purge.

3. A system for controlling low-pressure output of a PEM fuel cell using an air ejector according to claim 1, characterized in that: The high-pressure nitrogen cylinder (1) forms a communication structure with the ejector (10) through the ejected gas regulating valve (11).

4. A system for controlling low-pressure output of a PEM fuel cell using an air ejector according to claim 1, characterized in that: The load resistor (8) is electrically connected between the anode and the cathode.

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