Fuel cell system utilizing liquid hydrogen cold energy and working method thereof

Abstract

The invention relates to a fuel cell system utilizing liquid hydrogen cold energy and a working method thereof. A hydrogen source of the fuel cell system is connected with a high-pressure assembly, the high-pressure assembly is connected with a T-shaped pipeline, one branch of the T-shaped pipeline is connected with a vaporization ejector, and the other branch of the T-shaped pipeline is sequentially connected with a starting battery valve and a heater; the vaporization ejector and the heater are jointly connected with the backflow ejector, the backflow ejector is connected with the radiator, the radiator is connected with a cooling path inlet of the galvanic pile, a cooling path outlet of the galvanic pile is connected with the T-shaped pipeline, one branch of the T-shaped pipeline is connected with the vaporization ejector, the other branch of the T-shaped pipeline is sequentially connected with the hydrogen pump and the gas-liquid separator, and the gas-liquid separator is connected with an anode inlet of the galvanic pile. And an anode outlet of the electric pile is connected with the backflow ejector. The thermal load of the fuel cell system is reduced by using liquid hydrogen cold energy so as to improve the system efficiency, and the liquid hydrogen is vaporized by using electric pile waste heat, so that the system cost and complexity are reduced; and hydrogen is used as a heat dissipation medium of the fuel cell stack, so that the volume power density and the mass power density of the system are increased.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell system utilizing liquid hydrogen cooling energy and an operating method thereof. Background Art

[0002] Fuel cells generate a large amount of heat during power generation, which needs to be removed through cooling to maintain the reaction temperature within the cell. Existing fuel cell water-cooling systems typically use liquid water or antifreeze as the cooling medium. This complex cooling system significantly increases system complexity and reduces both the volumetric and mass power densities. Using liquid water as the cooling system can easily freeze in winter, impacting the normal operation of the fuel cell stack. Using antifreeze is prohibitively expensive, significantly increasing the cost of the system.

[0003] In the existing technology, fuel cells can also be cooled by air and use air for heat dissipation, but the specific heat of air is too low and the heat dissipation capacity is limited. The temperature of the hydrogen entering the stack is usually much lower than the temperature of the fuel cell stack, resulting in uneven temperature distribution in the fuel cell stack, which in turn leads to uneven water distribution in the stack and reduced durability of the fuel cell stack.

[0004] In addition, since the anode of the hydrogen fuel cell requires high-pressure hydrogen bottles to provide liquid hydrogen, the temperature of the liquid hydrogen is too low, and a separate heat exchanger is usually required for heat exchange before entering the stack, which increases the system complexity and usage cost, and the cold energy of the liquid hydrogen is not effectively utilized.

[0005] Existing technologies usually use spray-assisted cooling as a conventional cooling method to enhance the heat dissipation capacity of the radiator. The atomized liquid water easily adheres to impurities such as dust in the air, adheres to the cooling fan and the radiator surface, forms mud, and shortens the life of the radiator.

[0006] Therefore, it is urgent to design a fuel cell system and a working method thereof that utilizes liquid hydrogen cooling energy to solve the problems existing in the above-mentioned prior art. Summary of the Invention

[0007] In view of this, in order to solve the problems of the prior art, the present invention adopts the following technical solutions:

[0008] A fuel cell system utilizing liquid hydrogen cooling energy comprises a hydrogen source, a high-pressure component, a vaporization ejector, a starting cell valve, a heater, a reflux ejector, a radiator, a fuel cell stack, a hydrogen pump and a gas-liquid separator; the hydrogen source is connected to the high-pressure component, the high-pressure component is connected to a T-shaped pipe, one branch of the T-shaped pipe is connected to the vaporization ejector, and the other branch is sequentially connected to the starting cell valve and the heater; the vaporization ejector and the heater are commonly connected to the reflux ejector, the reflux ejector is connected to the radiator, the radiator is connected to the cooling path inlet of the fuel cell stack, the cooling path outlet of the fuel cell stack is connected to the T-shaped pipe, one branch of the T-shaped pipe is connected to the vaporization ejector, and the other branch is sequentially connected to the hydrogen pump and the gas-liquid separator, the gas-liquid separator is connected to the anode inlet of the fuel cell stack, and the anode outlet of the fuel cell stack is connected to the reflux ejector.

[0009] Furthermore, the liquid outlet of the gas-liquid separator is connected to a T-shaped pipe, one branch of the T-shaped pipe is connected to a water pump and an atomizer in sequence, the atomizer is arranged on one side of the radiator, and the atomizer sprays atomized water droplets into the radiator through an atomizing nozzle. After the atomized water droplets enter the radiator with the air, they vaporize and absorb a large amount of heat, thereby achieving the purpose of rapid cooling of the fuel cell system and shortening the shutdown time; a drainage battery valve is provided on the other branch of the T-shaped pipe, which is used to discharge the liquid water in the gas-liquid separator out of the fuel cell system.

[0010] Furthermore, a temperature sensor is provided at the outlet of the cooling path of the fuel cell stack for measuring the temperature at the outlet of the cooling path of the fuel cell stack; a first pressure sensor is provided at the anode inlet of the fuel cell stack for measuring the pressure at the anode inlet of the fuel cell stack; a second pressure sensor is provided at the anode outlet of the fuel cell stack for measuring the pressure at the anode outlet of the fuel cell stack.

[0011] The present invention also provides a method for operating the fuel cell system based on the above-mentioned use of liquid hydrogen cooling energy, the method including a startup method, specifically as follows:

[0012] During the startup process, the startup solenoid valve is opened. The liquid hydrogen provided by the hydrogen source is depressurized by the high-voltage component and flows to the heater through the startup cell valve. The liquid hydrogen vaporizes in the heater and then enters the reflux ejector. The reflux ejector ejects the gas from the anode outlet of the fuel cell stack and then enters the cooling path inlet of the fuel cell stack through the radiator. At this time, the radiator is not working. During the startup process, the heat generated by the fuel cell stack is used to heat the system.

[0013] When the temperature at the cooling path outlet reaches the set temperature, the start solenoid valve is closed, and the liquid hydrogen provided by the hydrogen source is depressurized by the high-pressure component and flows to the vaporization ejector, completing the start-up process.

[0014] Furthermore, the working method also includes a stable operation method:

[0015] The liquid hydrogen provided by the hydrogen source is depressurized by the high-pressure component and then flows into the vaporization ejector. In the vaporization ejector, the low-temperature liquid hydrogen mixes with the high-temperature gas flowing out of the fuel cell stack cooling path outlet. After the low-temperature liquid hydrogen absorbs the heat of the high-temperature gas flowing out of the fuel cell stack cooling path outlet, the low-temperature liquid hydrogen vaporizes and forms a primary mixed gas in the vaporization ejector.

[0016] The primary mixed gas in the vaporization ejector enters the reflux ejector, where the gas from the anode outlet of the stack is ejected, that is, the unreacted hydrogen at the anode outlet of the stack is recovered, and the water produced in the stack is taken out of the anode of the stack to form a secondary mixed gas in the reflux ejector;

[0017] The secondary mixed gas in the reflux ejector is first cooled by the radiator to form condensed water and low-temperature hydrogen, which then enters the fuel cell stack from the cooling path inlet. In the fuel cell stack, the condensed water vaporizes and absorbs a large amount of heat. The low-temperature hydrogen also absorbs heat. The low-temperature hydrogen temperature rises to the same temperature as the stack, and is then discharged from the cooling path outlet of the fuel cell stack.

[0018] Part of the high-temperature and high-humidity gas discharged from the outlet of the fuel cell stack cooling path flows back into the vaporization ejector to provide vaporization heat for the low-temperature liquid hydrogen provided by the hydrogen source. The other part is pumped into the gas-liquid separator by the hydrogen pump. After the liquid water is separated in the gas-liquid separator, it enters the fuel cell through the anode inlet of the fuel cell stack to participate in the reaction.

[0019] Furthermore, the hydrogen flow rate pumped into the fuel cell stack by the hydrogen pump is equal to the required hydrogen flow rate. The required hydrogen flow rate is determined by the operating current of the fuel cell stack. The required hydrogen flow rate m is calculated as follows:

[0020] m=I*n / 96485*β (1);

[0021] Where I is the stack operating current, n is the number of cells in the stack, and β is the hydrogen stoichiometric ratio.

[0022] Furthermore, the working method also includes a shutdown method:

[0023] During the shutdown process, the hydrogen source stops supplying liquid hydrogen and the high-voltage components are turned off. At this time, the hydrogen pump and radiator operate at high speed. The hydrogen in the fuel cell system passes through the hydrogen pump, gas-liquid separator, stack anode inlet, stack anode outlet, reflux ejector, radiator, stack cooling path inlet, stack cooling path outlet, and then returns to the hydrogen pump, repeating the cycle. At this time, the reflux ejector is only used as a pipeline.

[0024] The radiator operates at high speed, and the high-humidity hydrogen and condensed water in the stack circulate in the system under the action of the hydrogen pump. The gas-liquid separation is completed in the gas-liquid separator at the rear end of the hydrogen pump. The separated liquid water is discharged from the fuel cell system through the drain solenoid valve, realizing the shutdown and drainage of the fuel cell system.

[0025] During the shutdown and drainage process, when the outlet temperature of the stack cooling path reaches the ambient temperature and the pressure drop at the inlet and outlet of the stack anode remains stable, it is determined that the liquid water purge of the fuel cell system is completed, and all valves and components are closed to complete the shutdown process.

[0026] Furthermore, the cooling path outlet temperature is measured by a temperature sensor arranged at the outlet of the cooling path of the fuel cell stack; the fuel cell stack anode inlet and outlet pressure drop is calculated by the pressure at the fuel cell stack anode inlet and the pressure at the fuel cell stack anode outlet; the pressure at the fuel cell stack anode inlet is measured by a first pressure sensor arranged at the anode inlet of the fuel cell stack; the pressure at the fuel cell stack anode outlet is measured by a second pressure sensor arranged at the anode outlet of the fuel cell stack.

[0027] Furthermore, during the shutdown process, the drain solenoid valve is closed, and the liquid water separated in the gas-liquid separator is pumped out by a water pump to provide liquid water for the atomizer, and the atomizer sprays the atomized water droplets into the radiator through the atomizing nozzle.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) Liquid hydrogen cooling can reduce the thermal load of the fuel cell system and thus improve the system efficiency, and the waste heat of the fuel cell stack is used to vaporize the liquid hydrogen, reducing the system cost and complexity; hydrogen is used as the heat dissipation electrolyte of the fuel cell stack to increase the system volume power density and mass power density, and the condensed water in the radiator also enters the fuel cell stack, absorbing heat during phase change in the stack, further improving the cooling effect. At the same time, the heat exchange scheme in the stack makes the hydrogen temperature equal to the stack temperature, and the heated hydrogen enters from the anode inlet of the stack, so that the hydrogen entering the stack does not affect the temperature distribution inside the stack, thereby improving the service life of the stack.

[0030] (2) Using atomizer spray-assisted heat dissipation as a shutdown auxiliary heat dissipation method greatly shortens the shutdown time and energy consumption. At the same time, the shutdown only accounts for a very small part of the entire system operation period. The impurities attached during this process are limited, and this part of the impact can be eliminated during the next operation due to the self-purification ability of the radiator airflow; since the water source of the atomizer spray is provided by the gas-liquid separator, the water produced by the fuel cell stack is effectively utilized, thereby improving energy utilization.

[0031] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 A schematic structural diagram of a fuel cell system utilizing liquid hydrogen cooling energy according to an embodiment of the present invention is shown.

[0034] In the figure: 1. Hydrogen source; 2. High-pressure component; 3. Vaporization ejector; 4. Reflux ejector; 5. Radiator; 6. Atomizer; 7. Fuel cell; 8. Temperature sensor; 9. Hydrogen pump; 10. Gas-liquid separator; 11. First pressure sensor; 12. Water pump; 13. Drain cell valve; 14. Second pressure sensor; 15. Heater; 16. Start solenoid valve. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings 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 making creative efforts shall fall within the scope of protection of the present invention.

[0036] The embodiment of the present invention proposes a fuel cell system that utilizes liquid hydrogen cooling energy, as shown in the attached Figure 1 As shown, it includes a hydrogen source 1, a high-voltage component 2, a vaporization ejector 3, a starting cell valve 16, a heater 15, a reflux ejector 4, a radiator 5, a fuel cell stack 7, a hydrogen pump 9 and a gas-liquid separator 10; the hydrogen source 1 is connected to the high-voltage component 2, the high-voltage component is connected to a T-shaped pipe, one branch of the T-shaped pipe is connected to the vaporization ejector 3, and the other branch is connected to the starting cell valve 16 and the heater 15 in sequence; the vaporization ejector 3 and the heater 15 are commonly connected to the reflux ejector 4, the reflux ejector 4 is connected to the radiator 5, the radiator 5 is connected to the cooling path inlet of the fuel cell stack 7, the cooling path outlet of the fuel cell stack 7 is connected to the T-shaped pipe, one branch of the T-shaped pipe is connected to the vaporization ejector 3, and the other branch is connected to the hydrogen pump 9 and the gas-liquid separator 10 in sequence, the gas-liquid separator 10 is connected to the anode inlet of the fuel cell stack 7, and the anode outlet of the fuel cell stack 7 is connected to the reflux ejector 4.

[0037] The liquid outlet of the gas-liquid separator 10 is connected to a T-shaped pipe, one branch of the T-shaped pipe is connected to a water pump 12 and an atomizer 6 in sequence, and the atomizer 6 is arranged on one side of the radiator 5. The atomizer 6 sprays atomized water droplets into the radiator through an atomizing nozzle. After the atomized water droplets enter the radiator with the air, they vaporize and absorb a large amount of heat, thereby achieving the purpose of rapid cooling of the fuel cell system and shortening the shutdown time; a drainage battery valve 13 is provided on the other branch of the T-shaped pipe, which is used to discharge the liquid water in the gas-liquid separator 10 out of the fuel cell system.

[0038] A temperature sensor 8 is provided at the outlet of the cooling path of the fuel cell stack 7 for measuring the temperature at the outlet of the cooling path of the fuel cell stack; a first pressure sensor 11 is provided at the anode inlet of the fuel cell stack 7 for measuring the pressure at the anode inlet of the fuel cell stack; a second pressure sensor 14 is provided at the anode outlet of the fuel cell stack 7 for measuring the pressure at the anode outlet of the fuel cell stack.

[0039] The embodiment of the present invention further provides a method for operating the fuel cell system based on the above-mentioned utilization of liquid hydrogen cooling energy, the method including a startup method, specifically as follows:

[0040] During the startup process, the startup solenoid valve 16 is opened. At this time, since the flow resistance of the heater 15 is lower than the flow resistance of the vaporization ejector 3, the liquid hydrogen provided by the hydrogen source 1 is reduced in pressure by the high-pressure component 2 and flows to the heater 15 through the startup cell valve 16. The liquid hydrogen is vaporized in the heater 15 and then enters the reflux ejector 4. The gas from the anode outlet of the fuel cell stack 7 is ejected in the reflux ejector 4 and then enters the cooling path inlet of the fuel cell stack 7 through the radiator 5. At this time, the radiator 5 is not working. During the startup process, the heat generated by the fuel cell stack is used to heat the system.

[0041] When the temperature at the outlet of the cooling path reaches the set temperature, the start solenoid valve 16 is closed, and the liquid hydrogen provided by the hydrogen source 1 is depressurized by the high-pressure component 2 and flows to the vaporization ejector 3, completing the start-up process.

[0042] The working method also includes a stable operation method:

[0043] The liquid hydrogen provided by the hydrogen source 1 is depressurized by the high-pressure assembly 2 and flows into the vaporization ejector 3. In the vaporization ejector 3, the low-temperature liquid hydrogen mixes with the high-temperature gas flowing out of the cooling path outlet of the fuel cell stack 7. After the low-temperature liquid hydrogen absorbs the heat of the high-temperature gas flowing out of the cooling path outlet of the fuel cell stack 7, the low-temperature liquid hydrogen vaporizes and forms a primary mixed gas in the vaporization ejector 3.

[0044] The primary mixed gas in the vaporization ejector 3 enters the reflux ejector 4, where the gas from the anode outlet of the stack 7 is ejected, that is, the unreacted hydrogen at the anode outlet of the stack 7 is recovered, and the water produced in the stack is taken out of the anode of the stack, forming a secondary mixed gas in the reflux ejector 4;

[0045] The secondary mixed gas in the reflux ejector 4 is first cooled by the radiator 5 to form condensed water and low-temperature hydrogen, which then enters the fuel cell stack from the cooling path inlet of the fuel cell stack 7. In the fuel cell stack 7, the condensed water vaporizes and absorbs a large amount of heat. The low-temperature hydrogen also absorbs heat. The temperature of the low-temperature hydrogen rises to the same temperature as that inside the stack, and is then discharged from the cooling path outlet of the fuel cell stack 7.

[0046] Part of the high-temperature and high-humidity gas discharged from the cooling path outlet of the fuel cell stack 7 flows back into the vaporization ejector 3 to provide vaporization heat for the low-temperature liquid hydrogen provided by the hydrogen source, and the other part is pumped into the gas-liquid separator 10 by the hydrogen pump 9. After the liquid water is separated in the gas-liquid separator 10, it enters the fuel cell through the anode inlet of the fuel cell stack 7 to participate in the reaction.

[0047] Specifically, the hydrogen flow rate pumped into the fuel cell stack by the hydrogen pump 9 is equal to the required hydrogen flow rate. The required hydrogen flow rate is determined by the operating current of the fuel cell stack. The required hydrogen flow rate m is calculated as follows:

[0048] m=I*n / 96485*β (1);

[0049] Where I is the stack operating current, n is the number of cells in the stack, and β is the hydrogen stoichiometric ratio.

[0050] The flow rate of hydrogen pumped into the fuel cell stack by the hydrogen pump 9 is controlled by the speed of the hydrogen pump, and the relationship between the speed and the flow rate is obtained through calibration.

[0051] The working method also includes a shutdown method:

[0052] During the shutdown process, the hydrogen source 1 stops supplying liquid hydrogen and the high-voltage component 2 is turned off. At this time, the hydrogen pump 9 and the radiator 5 operate at high speed. The hydrogen in the fuel cell system passes through the hydrogen pump 9, the gas-liquid separator 10, the anode inlet of the fuel cell stack 7, the anode outlet of the fuel cell stack 7, the reflux ejector 4, the radiator 5, the cooling path inlet of the fuel cell stack 7, the cooling path outlet of the fuel cell stack 7, and then returns to the hydrogen pump 9, and the cycle repeats. At this time, the reflux ejector 4 is only used as a pipeline;

[0053] The high-speed operation of the radiator 5 causes the temperature inside the stack and the temperature of the hydrogen in the circulation route to drop rapidly to the ambient temperature, condensing a large amount of liquid water. The high-humidity hydrogen and condensed water in the stack circulate in the system under the action of the hydrogen pump 9, and the gas-liquid separation is completed in the gas-liquid separator 10 at the rear end of the hydrogen pump 9. The separated liquid water is discharged from the fuel cell system through the drain solenoid valve 13, realizing the shutdown and drainage of the fuel cell system;

[0054] During the shutdown and drainage process, when the outlet temperature of the cooling path of the stack 7 reaches the ambient temperature and the pressure drop at the inlet and outlet of the anode of the stack 7 remains stable, it is determined that the liquid water purge of the fuel cell system is completed, and all valves and components are closed to complete the shutdown process.

[0055] The outlet temperature of the cooling path is measured by a temperature sensor 8 provided at the outlet of the cooling path of the fuel cell stack 7; the pressure drop at the inlet and outlet of the anode of the fuel cell stack 7 is calculated by the pressure at the anode inlet of the fuel cell stack 7 and the pressure at the anode outlet of the fuel cell stack 7; the pressure at the anode inlet of the fuel cell stack 7 is measured by a first pressure sensor 11 provided at the anode inlet of the fuel cell stack 7; the pressure at the anode outlet of the fuel cell stack 7 is measured by a second pressure sensor 14 provided at the anode outlet of the fuel cell stack 7.

[0056] During the shutdown process, the drain solenoid valve 13 is closed, and the water pump 12 is used to pump out the liquid water separated in the gas-liquid separator 10 to provide liquid water for the atomizer 6. The atomizer 6 sprays the atomized water droplets into the radiator through the atomizing nozzle. After the atomized water droplets enter the radiator with the air, they vaporize and absorb a large amount of heat, thereby achieving the purpose of rapid cooling of the fuel cell system and shortening the shutdown time.

[0057] The calculation method for the reduction effect of the heat load of the fuel cell system and its operating method using liquid hydrogen cooling energy on the fuel cell stack is as follows:

[0058] α=P_H2 / P_the (2);

[0059] Where α is the rate at which liquid hydrogen cooling can reduce the thermal load of the stack, P_H2 is the amount of heat absorbed by liquid hydrogen vaporization, and P_the is the amount of heat generated by the battery.

[0060] P_the=P_che–P (3);

[0061] Where P_che is the total energy released per unit time by the fuel cell reaction; P is the power of the fuel cell system, which can be obtained by checking the polarization curve of the fuel cell system.

[0062] P_che=U_th*I*n (4);

[0063] Where U_th is the theoretical voltage of a single cell, which is 1.189V for a hydrogen / oxygen cell and 1.23V for a hydrogen / air cell; n is the number of cells in the stack, and I is the stack operating current.

[0064] P_H2=m_th*Q (5);

[0065] Where m_th is the mass flow rate of hydrogen consumed by the stack; Q is the vaporization enthalpy of liquid hydrogen, 4386.19 J / g.

[0066] m_th=I*n / 96485 (6);

[0067] Where I is the stack operating current, a known quantity, and n is the number of cells in the stack. Calculations show that liquid hydrogen cooling can reduce the system's thermal load by approximately 10%.

[0068] Liquid hydrogen cooling can reduce the thermal load of the fuel cell system and thus improve the system efficiency, and the waste heat of the stack is used to vaporize the liquid hydrogen, reducing the system cost and complexity; hydrogen is used as the heat dissipation electrolyte of the fuel cell stack to increase the system volume power density and mass power density, and the condensed water in the radiator also enters the stack, absorbing heat during phase change in the stack, further improving the cooling effect. At the same time, the heat exchange scheme in the stack makes the hydrogen temperature equal to the stack temperature, and the heated hydrogen enters from the anode inlet of the stack, so that the hydrogen entering the stack does not affect the temperature distribution inside the stack, thereby improving the service life of the stack.

[0069] Using atomizer spray-assisted heat dissipation as a shutdown auxiliary heat dissipation method greatly shortens the shutdown time and energy consumption. At the same time, the shutdown only accounts for a very small part of the entire system operation period. The impurities attached during this process are limited, and this part of the impact can be eliminated during the next operation due to the self-purification ability of the radiator airflow; since the water source of the atomizer spray is provided by the gas-liquid separator, the water produced by the fuel cell stack is effectively utilized, which improves energy utilization.

[0070] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fuel cell system utilizing liquid hydrogen cooling energy, characterized in that: It includes a hydrogen source, a high-pressure component, a vaporization ejector, a starting cell valve, a heater, a reflux ejector, a radiator, a fuel cell stack, a hydrogen pump and a gas-liquid separator; the hydrogen source is connected to the high-pressure component, the high-pressure component is connected to a T-shaped pipe, one branch of the T-shaped pipe is connected to the vaporization ejector, and the other branch is connected to the starting cell valve and the heater in sequence; the vaporization ejector and the heater are connected to the reflux ejector together, the reflux ejector is connected to the radiator, the radiator is connected to the cooling path inlet of the fuel cell stack, the cooling path outlet of the fuel cell stack is connected to the T-shaped pipe, one branch of the T-shaped pipe is connected to the vaporization ejector, and the other branch is connected to the hydrogen pump and the gas-liquid separator in sequence, the gas-liquid separator is connected to the anode inlet of the fuel cell stack, and the anode outlet of the fuel cell stack is connected to the reflux ejector.

2. The fuel cell system using liquid hydrogen cooling energy as claimed in claim 1, characterized in that: The liquid outlet of the gas-liquid separator is connected to a T-shaped pipe, one branch of the T-shaped pipe is connected to a water pump and an atomizer in sequence, the atomizer is arranged on one side of the radiator, and the atomizer sprays atomized water droplets into the radiator through an atomizing nozzle. After the atomized water droplets enter the radiator along with the air, they vaporize and absorb a large amount of heat, thereby achieving the purpose of rapid cooling of the fuel cell system and shortening the shutdown time; a drainage battery valve is arranged on the other branch of the T-shaped pipe, which is used to discharge liquid water in the gas-liquid separator out of the fuel cell system.

3. The fuel cell system using liquid hydrogen cooling energy as claimed in claim 2, characterized in that: A temperature sensor is provided at the outlet of the cooling path of the fuel cell stack to measure the temperature at the outlet of the cooling path of the fuel cell stack; a first pressure sensor is provided at the anode inlet of the fuel cell stack to measure the pressure at the anode inlet of the fuel cell stack; a second pressure sensor is provided at the anode outlet of the fuel cell stack to measure the pressure at the anode outlet of the fuel cell stack.

4. A method for operating a fuel cell system using liquid hydrogen cooling energy according to any one of claims 1 to 3, characterized in that: The working method includes a starting method, which is as follows: During the startup process, the startup solenoid valve is opened, and the liquid hydrogen provided by the hydrogen source is depressurized by the high-pressure component and flows to the heater through the startup battery valve. The liquid hydrogen vaporizes in the heater and then enters the reflux ejector. The gas from the anode outlet of the stack is ejected in the reflux ejector and then enters the inlet of the stack cooling path through the radiator. At this time, the radiator does not work. During the startup process, the heat generated by the stack is used to heat the system. When the temperature at the cooling path outlet reaches the set temperature, the start solenoid valve is closed, and the liquid hydrogen provided by the hydrogen source is depressurized by the high-pressure component and flows to the vaporizing ejector, completing the start-up process.

5. The operating method of a fuel cell system utilizing liquid hydrogen cooling energy as claimed in claim 4, characterized in that: The working method also includes a stable operation method: The liquid hydrogen provided by the hydrogen source is depressurized by the high-pressure component and then flows into the vaporizing ejector. In the vaporizing ejector, the low-temperature liquid hydrogen is mixed with the high-temperature gas flowing out of the outlet of the stack cooling path. After the low-temperature liquid hydrogen absorbs the heat of the high-temperature gas flowing out of the outlet of the stack cooling path, the low-temperature liquid hydrogen vaporizes to form a primary mixed gas in the vaporizing ejector. The primary mixed gas in the vaporization ejector enters the reflux ejector, and the gas from the anode outlet of the stack is ejected in the reflux ejector, that is, the unreacted hydrogen at the anode outlet of the stack is recovered, and the water produced in the stack is taken out of the anode of the stack to form a secondary mixed gas in the reflux ejector; The secondary mixed gas in the reflux ejector is first cooled by the radiator to form condensed water and low-temperature hydrogen, which then enters the fuel cell stack from the entrance of the fuel cell stack cooling path. In the fuel cell stack, the condensed water vaporizes and absorbs a large amount of heat, and the low-temperature hydrogen also absorbs heat. The temperature of the low-temperature hydrogen rises to the same temperature as that in the stack, and then is discharged from the outlet of the fuel cell stack cooling path. Part of the high-temperature and high-humidity gas discharged from the outlet of the fuel cell stack cooling path flows back into the vaporization ejector to provide vaporization heat for the low-temperature liquid hydrogen provided by the hydrogen source, and the other part is pumped into the gas-liquid separator by the hydrogen pump. After the liquid water is separated in the gas-liquid separator, it enters the fuel cell through the anode inlet of the fuel cell stack to participate in the reaction.

6. The operating method of a fuel cell system using liquid hydrogen cooling energy as claimed in claim 5, characterized in that: The hydrogen flow rate pumped into the fuel cell stack by the hydrogen pump is equal to the required hydrogen flow rate. The required hydrogen flow rate is determined by the operating current of the fuel cell stack. The calculation formula for the required hydrogen flow rate m is as follows: m = I*n / 96485*β (1); Where I is the working current of the stack, n is the number of cells in the stack, and β is the hydrogen stoichiometric ratio.

7. The operating method of a fuel cell system utilizing liquid hydrogen cooling energy as claimed in claim 4, characterized in that: The working method also includes a shutdown method: During the shutdown process, the hydrogen source stops supplying liquid hydrogen and the high-pressure components are turned off. At this time, the hydrogen pump and the radiator operate at high speed. The hydrogen in the fuel cell system passes through the hydrogen pump, the gas-liquid separator, the anode inlet of the stack, the anode outlet of the stack, the reflux ejector, the radiator, the inlet of the stack cooling path, the outlet of the stack cooling path, and then returns to the hydrogen pump, and the cycle repeats. At this time, the reflux ejector is only used as a pipeline. The radiator runs at high speed, and the high-humidity hydrogen and condensed water in the stack circulate in the system under the action of the hydrogen pump, and the gas-liquid separation is completed in the gas-liquid separator at the rear end of the hydrogen pump. The separated liquid water is discharged from the fuel cell system through the drainage solenoid valve, realizing the shutdown drainage of the fuel cell system; During the shutdown and drainage process, when the outlet temperature of the stack cooling path reaches the ambient temperature and the inlet and outlet pressure drop of the stack anode remains stable, it is determined that the liquid water purge of the fuel cell system is completed, and all valves and components are closed to complete the shutdown process.

8. The operating method of a fuel cell system using liquid hydrogen cooling energy as claimed in claim 7, characterized in that: The cooling path outlet temperature is measured by a temperature sensor arranged at the outlet of the cooling path of the fuel cell stack; the fuel cell stack anode inlet and outlet pressure drop is calculated by the pressure at the fuel cell stack anode inlet and the pressure at the fuel cell stack anode outlet; the pressure at the fuel cell stack anode inlet is measured by a first pressure sensor arranged at the anode inlet of the fuel cell stack; the pressure at the fuel cell stack anode outlet is measured by a second pressure sensor arranged at the anode outlet of the fuel cell stack.

9. The operating method of a fuel cell system using liquid hydrogen cooling energy as claimed in claim 7, characterized in that: During the shutdown process, the drain solenoid valve is closed, and the liquid water separated in the gas-liquid separator is pumped out by a water pump to provide liquid water for the atomizer, and the atomizer sprays the atomized water droplets into the radiator through the atomizing nozzle.

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