CN114914475B - Electric pile heat management method for proton film fuel cell - Google Patents

Abstract

A pile thermal management method of proton membrane fuel cell includes filling liquid-gas phase change working medium in pile thermal management system and making filling quantity reach optimum filling quantity; when the electric pile thermal management system works, after the heater is controlled and the pressure of the liquid-gas phase change working medium in the electric pile thermal management system reaches 0.4 MPa-0.405 MPa, the temperature values of the first temperature-pressure sensor and the second temperature-pressure sensor are kept at 70-71 ℃ through the heater, the mechanical pump and the electromagnetic flow valve, and the flow value of the flowmeter is kept at 20-30% of the output flow value of the mechanical pump. The temperature of the liquid-gas phase change working medium in the electric pile phase change cold plates is the same, and the surface temperature of all cold plates is high, so that the working temperature of an exchange membrane in the proton exchange membrane fuel cell is kept between 70 and 90 ℃.

Description

A stack thermal management method for proton membrane fuel cells

Technical field

The invention relates to a proton membrane fuel cell, and in particular to a stack thermal management method for a proton membrane fuel cell.

Background technique

Proton exchange membrane fuel cell is a fuel cell stack. As a truly green and environmentally friendly energy, its theoretical specific energy is extremely high (for hydrogen-air system, its theoretical specific energy is as high as 32940WhP kg, which is much larger than (any other existing chemical power source) is considered to be one of the most important energy sources for future transportation, distributed power stations and various electronic products. The stack of a proton exchange membrane fuel cell has high requirements on temperature and water content. The operating temperature of the exchange membrane is 70 to 90°C. If the temperature exceeds this temperature, the water content will drop sharply and the conductivity will drop rapidly.

Contents of the invention

In view of the problems in the prior art, the present invention provides a stack thermal management method for a proton membrane fuel cell, aiming to maintain the operating temperature of the exchange membrane in the proton exchange membrane fuel cell at 70 to 90°C.

A stack thermal management method for a proton membrane fuel cell, including a stack thermal management system. The stack thermal management system includes a stack phase change cold plate disposed in the stack, and the stack phase change cold plate is Several independent flow channels are provided, an electromagnetic flow valve is provided on the liquid inlet of each flow channel, and a first temperature and pressure sensor is provided on the liquid outlet of each flow channel. The liquid outlets of the channels are all connected to the gas-liquid separator, and the liquid outlets at the lower part of the gas-liquid separator are connected to each of the electromagnetic flow valves through the flow meter, filter, mechanical pump, and second temperature and pressure sensor. are all connected, an expansion tank is provided on the pipeline between the mechanical pump and the filter, a heater is provided on the pipeline and the expansion tank, and the gas outlet of the gas-liquid separator passes through the condenser and is connected to the The liquid inlets of the above filters are connected;

The stack thermal management method includes filling the stack thermal management system with a liquid-gas phase change working fluid and making the filling amount reach an optimal filling amount; when the stack thermal management system is working, the heater is controlled and After the pressure of the liquid-vapor phase change working fluid in the stack thermal management system reaches 0.4 MPa ~ 0.405 MPa, the temperature values of the first temperature and pressure sensor and the second temperature and pressure sensor are maintained through the heater, mechanical pump and electromagnetic flow valve. At 70℃~71℃, keep the flow value of the flow meter at 20%~30% of the output flow value of the mechanical pump.

Further: the optimal filling amount is to make the phase change cold plate of the stack in a working environment of 55°C, fill the liquid gas phase change working medium in the stack thermal management system, and make the initial amount of liquid gas phase change The working fluid circulates in the stack thermal management system, and after the temperature difference between the first temperature and pressure sensors is stabilized, the liquid-vapor phase change working fluid is added into the stack thermal management system until the first temperature and pressure sensor When the temperature difference between them is less than A, stop filling the liquid gas phase change working fluid into the stack thermal management system. The value of A is between 0.1°C and 1°C.

In order to prevent the leakage of the liquid-gas phase change working fluid from causing a short circuit in the proton membrane fuel cell, further: the liquid-gas phase change working fluid is an insulating material.

Further: the liquid-gas phase change working fluid is R134a, or R113, or R11, or R407c, or R410A.

Since the liquid working medium will contain metal impurities after circulation, in order to prevent these impurities from affecting the life of the mechanical pump, further: the filtration accuracy of the filter is less than 60um.

In order to prevent the mechanical pump from being damaged due to high hydraulic pressure at the liquid inlet of the mechanical pump, further: a safety valve is installed between the liquid inlet and the liquid outlet of the mechanical pump.

In order to improve the heat exchange efficiency of the condenser, further: a capillary structure is provided in the heat exchange flat tube of the condenser. In actual work, the liquid working medium flows in the capillary structure, and the gas working medium flows in a large area in the heat exchange flat tube. Spatial flow and two-phase flow liquid realize gas-liquid separation under working conditions, avoiding mutual interference between gas and liquid when exchanging heat with the outside world, and significantly improving heat exchange efficiency.

In order to improve the heat exchange efficiency of the stack phase change cold plate, further: the flow channel has a capillary structure.

Further: the capillary structure is formed by micro-channels, sintered mesh or sintered core.

The invention has beneficial effects: the temperature of the liquid-gas phase change working fluid inside the phase change cold plate of the stack is the same, and the surface temperature of all cold plates is uniformly high, so that the working temperature of the exchange membrane in the proton exchange membrane fuel cell is maintained at 70-90°C, thereby making The battery is kept working under ideal temperature conditions; the liquid-gas phase change working fluid is combined with the stack phase change cold plate with a capillary structure to ensure the temperature uniformity of the stack during operation and improve the stack performance of the proton exchange membrane fuel cell. The cooling effect improves the stack heat capacity and service life of proton exchange membrane fuel cells.

Description of drawings

Figure 1 is a system structure diagram of the present invention.

In the figure, 1. Mechanical pump; 2. Safety valve; 3. Second temperature and pressure sensor; 4. Electromagnetic flow valve; 5. Stack phase change cold plate; 6. First temperature and pressure sensor; 7. Controller; 8 , gas-liquid separator; 10. condenser; 11. filter; 12. liquid injection valve; 13. expansion tank; 14. heater; 15. flow meter.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings. Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present invention and cannot be construed as limiting the present invention. The terms left, center, right, up, and down in the examples of the present invention are only relative concepts or refer to the normal use state of the product, and should not be considered restrictive.

A stack thermal management method for a proton membrane fuel cell, including a stack thermal management system. The stack thermal management system includes a stack phase change cold plate 5 disposed in the stack. The stack phase change cold plate 5 is provided with several independent flow channels. The flow channels have a capillary structure. An electromagnetic flow valve 4 is provided on the liquid inlet of each of the flow channels. An electromagnetic flow valve 4 is provided on the liquid outlet of each of the flow channels. A first temperature and pressure sensor 6 is provided, and the liquid outlets of the flow channels are all connected to the gas-liquid separator 8. The liquid outlets at the lower part of the gas-liquid separator 8 pass through the flow meter 15, the filter 11, and the mechanical The pump 1 and the second temperature and pressure sensor 3 are connected to each of the electromagnetic flow valves 4. An expansion tank 13 is provided on the pipeline between the mechanical pump 1 and the filter 11. Inside the expansion tank 13 It is filled with a saturated liquid-gas phase change working fluid, and a heater 14 is provided on the pipeline and the expansion tank 13. The gas outlet of the gas-liquid separator 8 passes through the condenser 10 and is connected with the filter 11. The liquid inlets are connected. The expansion tank 13 contains gaseous and liquid working fluids in a saturated state. The expansion tank 13 is used to control and regulate the working temperature and pressure of the liquid-gas phase change working fluid in the stack thermal management system, and to heat the gaseous and liquid working fluids in the expansion tank 13 , after the liquid-gas phase change working fluid is heated, the saturation temperature and pressure of the liquid-gas phase change working fluid in the stack thermal management system increase, that is, the liquid working fluid changes into a gaseous state, the gaseous working fluid pressure rises, and the liquid working fluid pressure also rises. High; wherein, the filtration accuracy of the filter 11 is less than 60um. A safety valve 2 is installed between the liquid inlet and the liquid outlet of the mechanical pump 1 . A capillary structure is provided in the heat exchange flat tube of the condenser 10, and the capillary structure is formed by micro-channels or sintered wire mesh or sintered core;

The stack thermal management method includes filling the stack thermal management system with a liquid-gas phase change working fluid to an optimal filling amount, and injecting liquid gas into the stack thermal management system through the liquid injection valve 12 of the expansion tank 13 Fill the liquid gas phase change working fluid; when the stack thermal management system is working, control the heater and make the pressure of the liquid gas phase change working fluid in the stack thermal management system reach 0.4MPa ~ 0.405MPa, through the heater 14. Mechanical The pump 1 and the electromagnetic flow valve 4 keep the temperature values of the first temperature and pressure sensor 6 and the second temperature and pressure sensor 3 at 70°C~71°C, and keep the flow value of the flow meter 15 at the output flow value of the mechanical pump 1 20%~30%. If the flow rate is too large, it means that the system margin is too large and uneconomical; if the flow rate is too small, it will bring certain heat dissipation risks. In extreme cases, the stack temperature may be too high; liquid working fluid enters The stack phase change cold plate 5 absorbs the heat generated during the operation of the stack, and about 70 to 80% of the liquid-gas phase change working medium absorbs heat and changes into a gas-liquid mixture, thereby ensuring that the stack of the proton membrane fuel cell is in operation. At an operating temperature of 70 to 90°C, it ensures the temperature uniformity of the stack of proton membrane fuel cells during operation, improves the cooling effect of the stack of proton membrane fuel cells, and improves the stack heat capacity and service life of proton membrane fuel cells. . The condenser and heater are used to ensure the stability of the operating temperature and pressure of the stack thermal management system.

Summary: When the phase change pressure changes synchronously with the accompanying temperature, and when the phase change pressure exceeds a certain range and the pressure is high, the operating temperature of the stack will be high and the stability will be poor. When the pressure is low, the operating temperature of the stack is better, but the cost is high and the feasibility is poor.

The optimal filling amount is to keep the phase change cold plate of the stack in a working environment of 55°C, fill the stack thermal management system with a liquid-gas phase change working fluid, and make the initial amount of liquid-gas phase change working fluid After the temperature difference between the first temperature and pressure sensors 6 is stabilized, the liquid-vapor phase change fluid is added to the stack thermal management system until the temperature difference between the first temperature and pressure sensors 6 is stabilized. When the temperature difference between them is less than A, stop filling the liquid gas phase change working fluid into the stack thermal management system. The value of A is between 0.1°C and 1°C. The internal working fluid temperature of the stack phase change cold plate 5 is the same, and the surface temperature of the stack phase change cold plate 5 is almost the same, ensuring that the battery operates under ideal temperature conditions, and the charging amount at this time is the optimal charging amount. When working at 55°C, the temperature difference of the working fluid can be kept within a very small range, so there will be no waste caused by overcharging, and there will be no high operating temperature of the stack caused by undercharging. Ensure safe and stable operation of the system. The liquid-gas phase change working fluid is an insulating material, and the liquid-gas phase change working fluid is R134a, or R113, or R11, or R407c, or R410A. The mechanical pump 1 provides driving force for the liquid-gas phase change working fluid, The liquid-gas phase change working fluid is allowed to flow in other components in the stack thermal management system. The liquid-vapor phase change working fluid absorbs heat through the stack phase change cold plate 5 and then changes into a two-phase gas-liquid mixed working fluid. The two-phase gas-liquid working fluid is The mixed working fluid enters the gas-liquid separator 8, and the liquid working fluid is separated and enters the filter 11. The gaseous working fluid enters the condenser 10 and is cooled by the ambient atmosphere into a liquid working fluid and then enters the filter 11. The liquid produced after passing through the condenser 10 The working fluid and the liquid working fluid separated by the gas-liquid separator 8 merge and then enter the filter 11 for filtration, so that the fluid cleanliness is higher than 60 μm, and then return to the mechanical pump 1, thus completing a cycle.

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have other aspects. Various changes and modifications are possible, which fall within the scope of the claimed invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims (8)

1. A stack thermal management method for a proton membrane fuel cell, which is characterized in that: it includes a stack thermal management system, and the stack thermal management system includes a stack phase change cold plate arranged in the stack, and the stack thermal management system includes: Several independent flow channels are provided in the stack phase change cold plate. An electromagnetic flow valve is provided at the liquid inlet of each flow channel. A first temperature sensor is provided at the liquid outlet of each flow channel. pressure sensor, the liquid outlets of the flow channels are all connected with the gas-liquid separator, and the liquid outlets at the lower part of the gas-liquid separator pass through the flow meter, filter, mechanical pump, and the second temperature and pressure sensor in sequence and are connected to each The electromagnetic flow valves are all connected, an expansion tank is provided on the pipeline between the mechanical pump and the filter, a heater is provided on the pipeline and the expansion tank, and the gas outlet of the gas-liquid separator After passing through the condenser, it is connected to the liquid inlet of the filter; the stack thermal management method includes filling the liquid-gas phase change working fluid in the stack thermal management system and making the filling amount reach the optimal filling level. When the stack thermal management system is working, the heater is controlled to make the pressure of the liquid-vapor phase change working fluid in the stack thermal management system reach 0.4MPa~0.405MPa, and all the pressure is controlled through the heater, mechanical pump and electromagnetic flow valve. The temperature values of the first temperature and pressure sensor and the second temperature and pressure sensor are maintained at 70°C~71°C, and the flow value of the flow meter is maintained at 20%~30% of the output flow value of the mechanical pump; the optimal filling The amount is: make the phase change cold plate of the stack in a working environment of 55℃, fill the liquid gas phase change working fluid in the stack thermal management system, and make the initial amount of liquid gas phase change working fluid in the stack thermal management system Circular flow, and after the temperature difference between the first temperature and pressure sensors is stable, add liquid gas phase change refrigerant into the stack thermal management system until the temperature difference between the first temperature and pressure sensors is less than A. Stop Add a liquid-vapor phase change working fluid into the stack thermal management system, and the value of A is between 0.1°C and 1°C. 2. The stack thermal management method of a proton membrane fuel cell according to claim 1, characterized in that: the liquid-gas phase change working medium is an insulating material. 3. The stack thermal management method of a proton membrane fuel cell according to claim 1, characterized in that: the liquid-gas phase change working fluid is R134a, or R113, or R11, or R407c, or R410A. 4. The stack thermal management method of a proton membrane fuel cell according to claim 1, characterized in that: the filtration accuracy of the filter is less than 60 μm. 5. The stack thermal management method of a proton membrane fuel cell according to claim 1, characterized in that: a safety valve is installed between the liquid inlet and the liquid outlet of the mechanical pump. 6. The stack thermal management method of a proton membrane fuel cell according to claim 1, characterized in that: a capillary structure is provided in the heat exchange flat tube of the condenser. 7. The stack thermal management method of a proton membrane fuel cell according to claim 1, characterized in that: the flow channel has a capillary structure. 8. The stack thermal management method of a proton membrane fuel cell according to claim 6 or 7, characterized in that: the capillary structure is formed by micro-channels, sintered mesh or sintered core.