A humidification system and humidification method for a low-power fuel cell test bench

Abstract

The present invention belongs to the field of fuel cells, and specifically relates to a humidification system and a humidification method for a low-power fuel cell test bench. The humidified reaction gas can reach a certain set dew point temperature, and the reaction gas is dispersed into small bubbles through a bubbler head, and fully contacts with the pure water in the humidification tank. The temperature of the deionized water in the humidification tank is controlled by an external water circulation, and the deionized water in the humidification tank is circulated to the humidifier through a magnetic pump through a heater and a cooler. In order to better ensure the temperature of the humidification tank, two heating belts are wound around the upper and lower parts of the humidification tank; the humidification tank adopts a "wine bottle" shape with a large diameter at the bottom and a small diameter at the top; the pipeline of the humidification tank entering the fuel cell adopts a special heating bellows to ensure that the reaction gas entering the stack does not condense, and the circulation pump adopts a magnetic pump, which has a small suction range and is safe and reliable.

Description

Technical Field

[0001] The invention belongs to the field of fuel cells, and in particular relates to a humidification system and a humidification method for a low-power fuel cell test bench. Background Art

[0002] Fuel cells are clean, efficient and long-life power generation devices. Compared with conventional power generation technologies, fuel cells have great advantages in efficiency, safety, reliability, flexibility, cleanliness, and operational performance, and have broad application prospects. As a type of fuel cell, proton exchange membrane fuel cells also have the advantages of low operating temperature, high specific energy, long service life, fast response speed and no electrolyte leakage, and have good application prospects in national defense, energy, transportation, environmental protection, communications and other aspects. During the operation of proton exchange membrane fuel cells, the humidity control of cathode air intake (air) is one of the most important links. On the one hand, if the air humidity is too low, the proton exchange membrane will be dehydrated or dry. The proton conductivity of the membrane is closely related to its water content (wetting state). When the membrane is in a good wetting state, it has a high proton conductivity. The drying of the membrane will lead to a decrease in proton conductivity, an increase in membrane resistance, an increase in ohmic loss, and a decrease in battery performance; at the same time, the mechanical strength is reduced, and in severe cases, the membrane will rupture, causing hydrogen and oxygen to mix and explode. On the other hand, if the air humidity is too high, it will cause excessive water accumulation inside the battery, resulting in the catalyst in the electrode being pickled by water, reducing the reaction activity, and forming gas-liquid two-phase flow in the flow channel and diffusion layer, causing local blockage, hindering the gas mass transfer process, insufficient supply of reaction gas, causing the output performance of the fuel cell to decline, and affecting the operation of the battery. Therefore, the humidity control of the fuel cell reaction gas, especially the air humidity control, is crucial in the operation of the proton exchange membrane fuel cell and is one of the important control links.

[0003] At present, the small humidification system is mainly bubbling humidification; the bubbler refers to a container filled with liquid water and glass beads at the bottom. The air intake is directly connected to the bottom of the container through a straight pipe, and contacts with the small balls that can increase the evaporation area. Finally, the nearly saturated gas is discharged through another pipe on the liquid surface. The advantages of this humidification method are simple equipment structure, simple process, and high humidity at low flow rate; the disadvantages are that temperature and humidity are difficult to control accurately. When the battery starts quickly or the load changes suddenly and drastically, the humidification cannot respond synchronously with it in time. In addition, at high flow rate, the gas brings out too much liquid water after bubbling through the water container, causing the accumulation of liquid water at the outlet of the water container; at low flow rate, the system dissipates heat quickly, the dew point temperature is difficult to control, and the back pressure response time is too long; when a centrifugal pump is used for external circulation, the mechanical seal is unreliable and easy to leak. The suction range of the centrifugal pump is large, and it is easy to suck the gas from the bubbler head into the external circulation, causing centrifugal pump cavitation, affecting the overall performance of the fuel cell. Summary of the invention

[0004] In view of the above shortcomings, the present invention provides a fuel cell humidification system and a humidification method thereof, and the humidified reaction gas can reach a certain set dew point temperature. The reaction gas is dispersed into small bubbles through the bubbler head and fully contacts with the pure water in the humidification tank. The temperature of the deionized water in the humidification tank is controlled by the external water circulation. The deionized water in the humidification tank is circulated to the humidifier through the heater and the cooler through the magnetic pump. In order to better ensure the temperature of the humidification tank, two heating belts are wound around the upper and lower parts of the humidification tank; the humidification tank adopts a "wine bottle" shape with a large diameter at the bottom and a small diameter at the top; the pipeline from the humidification tank to the fuel cell adopts a special heating bellows to ensure that the reaction gas entering the stack does not condense, and the circulation pump adopts a magnetic pump with a small suction range, which is safe and reliable.

[0005] The above object of the present invention is achieved through the following technical solutions:

[0006] A humidification system for a low-power fuel cell test bench, wherein a humidification tank is connected to a reaction gas port and a deionized water supply port through pipelines, a water supply solenoid valve is provided on the pipeline between the humidification tank and the deionized water supply port, a bubbler head is provided inside the humidification tank, the top of the humidification tank is connected to the fuel cell through a pipeline, and a pressure sensor and a fuel cell are provided on a common pipeline close to the fuel cell; a heating short tube is provided in the pipeline close to the humidification tank, the heating short tube is integrated with a heating belt, and the heating short tube is provided with a heating tube inner thermometer and a heating tube wall thermometer respectively;

[0007] The bottom of the humidifier tank is connected to the magnetic pump, cooler and heater through a pipe to form a closed loop. The bottom of the pipe is connected to the discharge valve. One end of the cooler is connected to the cooling water inlet and the other end is connected to the cooling water return. A needle valve is provided on the cooling water return pipe.

[0008] Furthermore, the humidification tank is in the shape of a "wine bottle", with a thin upper part and a thick lower part.

[0009] Furthermore, the upper and lower parts of the humidification tank are respectively provided with a humidification tank top heating belt and a tank bottom heating belt to heat and keep the tank body warm.

[0010] Furthermore, the humidification tank is provided with a liquid level meter A, a liquid level meter B, a liquid level meter C and a humidification tank water temperature thermometer.

[0011] A humidification method for a low-power fuel cell test bench, wherein a reaction gas enters a humidification tank through a bubbling head, and deionized water in the humidification tank is circulated back to the humidification tank through a magnetic pump, a cooler, and a heater. The temperature of a gas phase thermometer of the humidification tank is controlled by the cooler and the heater to ensure temperature stability; the humidification tank uses a heating belt on the top of the humidification tank and a heating belt on the bottom of the tank to heat and insulate the tank body, and the liquid level of the humidification tank is controlled by a liquid level switch A, a liquid level switch B, and a liquid level switch C to control the switch of a water replenishment solenoid valve to ensure that the liquid level of the humidification tank is normal, and the gas phase of the humidification tank enters the fuel cell through a heating short tube, and the heating short tube is integrated with the heating belt. The temperature in the heating tube is controlled by a thermometer in the heating tube, and the temperature of the tube wall is detected by a thermometer on the heating tube wall. The liquid in the humidification tank is discharged through a discharge valve, and the flow of cooling water inlet and cooling water return is adjusted by a needle valve, and the pressure sensor is used to monitor the stack pressure to prevent overpressure, and the humidity of the stack is confirmed by a hygrometer.

[0012] The beneficial effects of the present invention compared with the prior art are:

[0013] 1) The present invention adopts a "wine bottle" shaped humidification tank, which is thin at the top and thick at the bottom; there is a chassis heater at the bottom, the tube wall is wrapped with insulation, the upper part is wrapped with a heating belt, the tube wall is wrapped with thicker insulation, and the final outer part is cylindrical, which ensures that the system is in an insulated state. Accurate control of the water temperature can ensure accurate control of the dew point, and the humidification tank makes the volume of the entire system reasonable. At a small flow rate, the response time of the back pressure is improved, thereby increasing the performance of the fuel cell.

[0014] 2) The reflux port of the present invention is ensured to be below the liquid surface, which can increase the stirring effect and make the gas-liquid exchange more complete on the one hand, and prevent liquid water from being carried into the fuel cell stack at a large flow rate on the other hand.

[0015] 3) Small humidification systems require small flow and small range circulation pumps. The mechanical seals of domestic small centrifugal pumps are unreliable and prone to leakage. The prior art generally uses centrifugal pumps with mechanical seals imported from abroad, which are expensive and have a long construction period. The present invention selects a magnetic pump with a small suction range to prevent the reaction gas from being sucked into the circulation pump, resulting in a lack of reaction gas entering the battery under small flow conditions, affecting battery performance.

[0016] 4) The present invention saves materials and has good economic benefits.

[0017] 5) The humidifier tank of the present invention has a liquid level switch. When the liquid level is low, the water replenishment pump is started, the water replenishment solenoid valve is opened, and water is replenished automatically. When the liquid level is high, the water replenishment pump is automatically stopped and the water replenishment solenoid valve is closed, thereby realizing fully automatic water replenishment and reducing operations.

[0018] 6) The inlet temperature of the present invention can be reliably controlled.

[0019] 7) The humidity of the pile entering the present invention is more reasonable.

[0020] 8) The stack heating pipe of the present invention adopts integrated control of the bellows and the heating belt, and the temperature inside the pipe can be controlled by proportional differential integral control PID. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0022] Figure 1 This is a diagram of a humidification system for a low-power fuel cell test bench according to the present invention.

[0023] In the figure: 1. reaction gas port, 2. deionized water supply port, 3. water supply solenoid valve, 4. bubbler, 5. humidification tank, 6. liquid level gauge A, 7. heating belt on the top of humidification tank, 8. gas phase thermometer, 9. heating belt on the bottom of tank, 10. water temperature thermometer of humidification tank, 11. magnetic pump, 12. discharge valve, 13. cooling water inlet, 14. cooling water return, 15. cooler, 16. heater, 17. heating short pipe, 18. pressure sensor, 19. fuel cell, 20. hygrometer, 21. needle valve, 22. heating tube internal thermometer, 23. heating tube wall thermometer, 24. heating belt, 25. liquid level gauge B, 26. liquid level gauge C. DETAILED DESCRIPTION

[0024] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0025] The humidification tank 5 of the present invention adopts a "wine bottle" shape, which reduces the volume of the equipment on the one hand, and increases the response time of the back pressure under a small gas volume on the other hand, thereby improving the battery performance. At the same time, the gas phase space needs better insulation, and the wine bottle shape with a thin top and a thick bottom can ensure that the upper part can have more insulation than the lower part, so that the system is in an adiabatic state.

[0026] The magnetic pump is used in the circulating heating system. The magnetic pump of this system has a small flow rate and a small suction range, which can ensure the stable reaction of the reaction gas under a small gas volume and avoid being sucked into the circulation.

[0027] The heating short pipe 17 is integrated with the heating tape 24. In the prior art, the stack inlet pipeline generally adopts a method of winding the heating tape with a hose. If the heating tape is wound unevenly in this method, the heating effect will be affected. The constant temperature heating pipe adopted in the present invention can ensure that the heating temperature of the entire pipeline is stable and uniform.

[0028] Example 1

[0029] The humidification tank 5 is connected to the reaction gas port 1 and the deionized water supply port 2 through pipelines, respectively. A water supply solenoid valve 3 is provided on the pipeline between the humidification tank 5 and the deionized water supply port 2. A bubbling head 4 is provided inside the humidification tank 5. The top of the humidification tank 5 is connected to the fuel cell 19 through a pipeline. A pressure sensor 18 and a fuel cell 19 are provided on a common pipeline close to the fuel cell 19. A heating short tube 17 is provided in the pipeline close to the humidification tank 5. The heating short tube 17 is integrated with a heating belt 24. The heating short tube 17 is provided with a heating tube inner thermometer 22 and a heating tube wall thermometer 23.

[0030] The bottom of the humidification tank 5 is connected to the magnetic pump 11, the cooler 15, and the heater 16 through a pipeline to form a closed loop. The bottom of the pipeline is connected to the discharge valve 12. One end of the cooler 15 is connected to the cooling water inlet 13, and the other end is connected to the cooling water return 14. A needle valve 21 is provided on the pipeline of the cooling water return 14.

[0031] Furthermore, the humidification tank 5 is in the shape of a "wine bottle", with a thin upper part and a thick lower part. The upper part and the lower part are respectively provided with a humidification tank top heating belt 7 and a tank bottom heating belt 9 to heat and keep the tank body warm. The humidification tank 5 is provided with a liquid level gauge A6, a liquid level gauge B25, a liquid level gauge C26 and a humidification tank water temperature thermometer 10.

[0032] Example 2

[0033] The reaction gas 1 enters the humidification tank 5 through the bubbling head 4, and the deionized water in the humidification tank 5 is circulated back to the humidification tank 5 through the magnetic pump 11, the cooler 15 and the heater 16. The temperature of the gas phase thermometer 8 of the humidification tank 5 is controlled by the cooler 15 and the heater 16 to ensure the temperature stability; the humidification tank 5 adopts a "wine bottle" shape, with a thin upper part and a thick lower part. The upper and lower parts have a humidification tank top heating belt 7 and a tank bottom heating belt 9 to heat and keep the tank body warm. The liquid level of the humidification tank 5 is controlled by the liquid level switch A6, the liquid level switch B25 and the liquid level switch C26. The water solenoid valve 3 is switched to ensure that the liquid level of the humidification tank 5 is normal. The gas phase of the humidification tank 5 enters the fuel cell 19 through the heating short tube 17. The heating short tube 17 is integrated with the heating belt 24. The temperature inside the tube 22 can be controlled by proportional differential integral PID control, and the tube wall temperature 23 can be detected at the same time. The liquid in the humidification tank 5 can be discharged through the discharge valve 12. The flow of the cooling water inlet 13 and the cooling water return 14 can be adjusted by the needle valve 21. The stack pressure can be monitored by the stack pressure sensor 18 to prevent overpressure, and the stack humidity can be confirmed by the hygrometer 20.

[0034] Example 3

[0035] The present invention has been put into practical application, and the specific data are as follows:

[0036] Air tank dew point <70℃: air flow 0.5-5SLPM, water temperature +1℃ and heating +4℃; dew point >70℃: water temperature +2℃ and heating +4℃.

[0037] The hydrogen flow rate of the hydrogen tank is <0.5SLPM, the water temperature is +4℃ and the heating is +6℃; the hydrogen flow rate is ≥0.5SLPM, the water is +2℃ and the heating is +4℃.

[0038] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A humidification system for a low-power fuel cell test bench, It is characterized in that The humidification tank (5) is connected to the reaction gas port (1) and the deionized water supply port (2) respectively through pipelines; a water supply solenoid valve (3) is provided in the pipeline between the humidification tank (5) and the deionized water supply port (2); a bubbler head (4) is provided inside the humidification tank (5); the top of the humidification tank (5) is connected to the fuel cell (19) through a pipeline; a common pipeline close to the fuel cell (19) is provided with a pressure sensor (18) and a fuel cell (19); a heating short tube (17) is provided in the pipeline close to the humidification tank (5); the heating short tube (17) is integrated with a heating belt (24); the heating short tube (17) is provided with a heating tube inner thermometer (22) and a heating tube wall thermometer (23); the bottom of the humidification tank (5) is provided with a heating tube inner thermometer (22) and a heating tube wall thermometer (23). The humidifying tank (5) is connected to the magnetic pump (11), the cooler (15) and the heater (16) through a pipeline to form a closed loop. The bottom of the pipeline is connected to the discharge valve (12). One end of the cooler (15) is connected to the cooling water inlet (13), and the other end is connected to the cooling water return (14). A needle valve (21) is provided on the cooling water return (14) pipeline. The humidifying tank (5) adopts a "wine bottle" shape, with a thin upper part and a thick lower part. The upper and lower parts of the humidifying tank (5) are respectively provided with a humidifying tank top heating belt (7) and a tank bottom heating belt (9) to heat and keep the tank body warm. The humidifying tank (5) is provided with a liquid level gauge A (6), a liquid level gauge B (25), a liquid level gauge C (26) and a humidifying tank water temperature thermometer (10).

2. A humidification method for a low-power fuel cell test bench, It is characterized in that The reaction gas (1) enters the humidification tank (5) through the bubbler (4), and the deionized water in the humidification tank (5) is circulated back to the humidification tank (5) through the magnetic pump (11) through the cooler (15) and the heater (16). The temperature of the gas phase thermometer (8) of the humidification tank (5) is controlled by the cooler (15) and the heater (16) to ensure temperature stability. The humidification tank (5) uses a heating belt (7) at the top of the humidification tank and a heating belt (9) at the bottom of the tank to heat and insulate the tank body. The liquid level of the humidification tank (5) is controlled by a liquid level switch A (6), a liquid level switch B (25) and a liquid level switch C (26) to control a water supply solenoid valve (3 ) switch to ensure that the liquid level of the humidification tank (5) is normal. The gas phase of the humidification tank (5) enters the fuel cell (19) through the heating short tube (17). The heating short tube (17) is integrated with the heating belt (24). The temperature inside the tube is controlled by the thermometer (22) inside the heating tube. The temperature of the tube wall is detected by the thermometer (23) on the heating tube wall. The liquid in the humidification tank (5) is discharged through the discharge valve (12). The flow of the cooling water inlet (13) and the cooling water return (14) is adjusted by the needle valve (21). The pressure sensor (18) monitors the stack pressure to prevent overpressure. The humidity of the stack is confirmed by the hygrometer (20).

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