Fuel cell system with active humidification function

Abstract

The utility model discloses a fuel cell system with an active humidifying function, which comprises a fuel cell stack and a hydrogen supply system for supplying hydrogen to the fuel cell stack, the hydrogen supply system comprises an ejector, a hydrogen path gas-water separator and a hydrogen circulating pump, the hydrogen circulating pump is connected with the ejector and the hydrogen path gas-water separator, and the ejector is connected with the hydrogen path gas-water separator. The ejector is connected with the mixing chamber, the water ejector is arranged on the mixing chamber, and the mixing chamber is connected with the fuel cell stack. The fuel cell system disclosed by the utility model can effectively realize accurate control of humidity and meet the requirements of vehicle products on active accurate control of key elements influencing the service life and the performance.

Description

Technical Field

[0001] The utility model belongs to the technical field of fuel cells, and specifically relates to a fuel cell system with an active humidification function. Background Art

[0002] At present, finding a sustainable alternative fuel that can also reduce greenhouse gas emissions such as CO2 has become a very promising and valuable research direction. Fuel cells, as an efficient power generation device that is not limited by the Carnot cycle and can convert hydrogen into electricity, have attracted more and more attention.

[0003] Proton exchange membrane fuel cells are power generation devices that convert chemical energy into electrical energy. The main product of fuel cells is water. During each startup, operation, and end of operation, a large amount of water will be generated at the cathode. Due to the existence of a water concentration gradient, water will be conducted from the cathode to the anode flow channel. On the one hand, when the cathode water output is high, the water content inside the stack will be high, which will easily block the flow channel and cause the stack performance to decline. On the other hand, when the cathode water output is insufficient, the water conducted from the cathode side to the anode side will also be insufficient, causing the overall water content inside the fuel cell stack to decrease, and the stack to dry out, resulting in a decline in stack performance.

[0004] Therefore, if the fuel cell is to be operated continuously and stably, it is necessary to maintain the water balance in the battery. Humidification is a very effective measure to maintain water balance. In order to achieve the purpose of humidification, a humidification system is now mostly set up, but this setting will make the battery complicated, and the cost of the battery will also increase significantly. Some people have proposed battery self-humidification technology, the purpose of which is to effectively transfer the water generated by the oxygen electrode to the hydrogen electrode to achieve humidity control. At present, self-humidification technology is divided into three categories: one is to try to speed up the diffusion rate of water generated by the oxygen electrode to the hydrogen electrode, which requires the formation of a high concentration gradient of water or a large diffusion coefficient, which has the defect of great technical difficulty; the second is to generate water through chemical reaction in the proton exchange membrane through catalytic reaction. The disadvantage of this technology is that the internal resistance is large, the water shortage and the water replenishment cannot match, and the humidity cannot be accurately controlled; the third is to achieve the purpose of self-humidification by improving the battery structure. So far, no better structure has been found to achieve this self-humidification purpose, and how to effectively achieve self-humidification is a technical problem that needs to be solved at present.

[0005] The Chinese patent application number 202311522932.8 discloses a humidity generating device (10) for generating a humidity-rich air flow or gas flow, the humidity generating device comprising a housing (H), the housing having an outflow area (3), wherein a gas flow or air flow can be generated at least in sections, and the housing has a lateral inlet area (EB), and the housing has a mixing area (MB), the mixing area extending inside the housing (H); the humidity generating device comprises a water injector (WI), the water injector is arranged in the lateral inlet area (EB), and by means of the water injector, atomized water can be injected into the water in a certain manner. into the mixing region (MB) at an angle of , wherein the gas or the air can be mixed with the atomized water in the mixing region (MB); the humidity generating device comprises a humidifying grid (BG), which is arranged in the mixing region (MB), and the water jet (WI) is aimed at the humidifying grid, and the humidity generating device comprises a flow generator (SZ), which is arranged in the housing (H) between the mixing region (MB) and the outflow region (3), and by means of which an air flow or a gas flow with atomized water can be conveyed to the outflow region (3) and generated.

[0006] The present application provides an improved fuel cell system, and in particular, provides a fuel cell system for effectively achieving precise humidity control. Utility Model Content

[0007] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model provides a fuel cell system with an active humidification function, the purpose of which is to effectively achieve accurate control of humidity.

[0008] In order to solve the above technical problems, the technical solution adopted by the utility model is: a fuel cell system with active humidification function, including a fuel cell stack and a hydrogen supply system for providing hydrogen to the fuel cell stack, the hydrogen supply system including an ejector, a hydrogen path gas-water separator and a hydrogen circulation pump, the hydrogen circulation pump is connected to the ejector and the hydrogen path gas-water separator, the ejector is connected to a mixing chamber, a water injector is arranged on the mixing chamber, and the mixing chamber is connected to the fuel cell stack.

[0009] The water ejector is connected to a high-pressure vortex pump, and the high-pressure vortex pump is connected to a water tank.

[0010] A drain valve is arranged at the bottom of the water tank.

[0011] The fuel cell stack is connected to an air-path water separator, and the air-path water separator is connected to the water tank.

[0012] The air-path water separator is connected to the back-pressure valve, and the back-pressure valve is connected to the tail exhaust muffler.

[0013] The ejector is connected to a proportional valve, and the proportional valve is connected to a stop valve.

[0014] A first pressure sensor is arranged in the pipeline connecting the stop valve and the proportional valve.

[0015] A second pressure sensor and a first temperature sensor are arranged in a pipeline connecting the mixing chamber and the fuel cell stack.

[0016] A third pressure sensor and a second temperature sensor are arranged in the pipeline connecting the fuel cell stack and the hydrogen path gas-water separator.

[0017] The fuel cell system of the utility model has the following beneficial effects:

[0018] 1. It can effectively realize precise control of humidity and meet the requirements of vehicle products for active and precise control of key factors affecting life and performance;

[0019] 2. Replace the currently commonly used humidifier, which can significantly reduce costs. At the same time, the sub-components of the system are small in size and relatively flexible in layout. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the fuel cell system of the utility model;

[0021] The marks in the above figures are: 1. stop valve; 2. first pressure sensor; 3. proportional valve; 4. ejector; 5. water injector; 6. second pressure sensor; 7. first temperature sensor; 8. hydrogen circulation pump; 9. hydrogen path air-water separator; 10. third pressure sensor; 11. second temperature sensor; 12. high-pressure vortex pump; 13. water tank; 14. drain valve; 15. electrochemical impedance spectrometer; 16. fuel cell stack; 17. air path water separator; 18. back pressure valve; 19. tail exhaust silencer; 20. fuel cell control module. DETAILED DESCRIPTION

[0022] The specific implementation methods of the utility model are further explained in detail below with reference to the accompanying drawings through the description of embodiments, with the aim of helping technicians in the field to have a more complete, accurate and in-depth understanding of the concept and technical solution of the utility model and facilitating its implementation.

[0023] It should be noted that, in the following embodiments, the “first”, “second” and “third” mentioned do not represent an absolute distinction in structure and / or function, nor do they represent a sequence of execution, but are merely for the convenience of description.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly connected by technicians in the technical field to which the present invention belongs. The terminology used in the specification of the present invention is for the purpose of describing specific embodiments and is not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0025] like Figure 1 As shown, the utility model provides a fuel cell system with active humidification function, including a fuel cell stack 16 and a hydrogen supply system for providing hydrogen to the fuel cell stack 16, the hydrogen supply system includes an ejector 4, a hydrogen path gas-water separator 9 and a hydrogen circulation pump 8, the hydrogen circulation pump 8 is connected to the ejector 4 and the hydrogen path gas-water separator 9, the ejector 4 is connected to a mixing chamber, a water ejector 5 is arranged on the mixing chamber, and the mixing chamber is connected to the fuel cell stack 16.

[0026] Specifically, if Figure 1 As shown, the ejector 4 is connected to the proportional valve 3, and the proportional valve 3 is connected to the stop valve 1. When the fuel cell system is working, the stop valve 1 is opened, and the hydrogen inlet pressure of the fuel cell anode is controlled by the hydrogen circuit proportional valve 3. After being pressurized through the secondary flow inlet in the ejector 4, it is mixed with the circulating hydrogen at the hydrogen return port of the hydrogen circulation pump 8. By arranging a mixing chamber between the ejector 4 and the hydrogen circuit stack inlet, before the dry hydrogen enters the fuel cell stack 16, the water ejector 5 first sprays high-pressure atomized water, and the atomized water and hydrogen are fully mixed in the mixing chamber and evaporated to form water vapor, which enters the fuel cell stack 16 together.

[0027] like Figure 1 As shown, the water ejector 5 is connected to the high pressure vortex pump 12, and the high pressure vortex pump 12 is connected to the water tank 13. A drain valve 14 is provided at the bottom of the water tank 13. The fuel cell stack 16 is connected to the air-circuit water separator 17, and the air-circuit water separator 17 is connected to the water tank 13.

[0028] The water spraying amount of the water injector 5 is adjusted and controlled by the injection pulse width time, and the required water spraying amount is determined in different situations by the following two methods.

[0029] First, under dynamic conditions, according to the collected ambient temperature T env 、Environmental pressure P env and ambient relative humidity R Henv , calculate the water vapor mass flow rate m in the current air flow vap.env , and then according to the collected pile temperature T in , pile pressure P in And the designed target relative humidity R Hin , calculate the target required water vapor mass flow rate m vap.in, the difference between the two is m vap.in-mvap.env That is, the injection amount of the water injector 5. Using this open-loop control strategy under dynamic conditions can enable the system to reach the target humidity faster and improve the response speed. Under steady-state conditions, the impedance data collected by the electrochemical impedance spectrometer 15 is used to judge the humidity state of the membrane, which is used to accurately adjust the water injection amount and realize closed-loop control. In addition, the two control strategies can be supplemented when one of them fails or malfunctions to ensure that the system functions normally and runs smoothly.

[0030] The water source of the water injector 5 comes from the water discharged from the cathode side when the fuel cell system is working. The cathode discharges a saturated mixed gas with liquid water. The water vapor discharged from the battery cathode is separated by a water separator. The separated gas is discharged after passing through a back pressure valve 18 and a tail exhaust silencer 19. The separated liquid water is collected by a water tank 13.

[0031] When the water collected by the water tank 13 is more than the water consumed by the water ejector 5, the liquid level in the water tank 13 will gradually rise. When it reaches the set threshold, the drain valve 14 at the bottom of the water tank 13 can be opened to drain some of the water to prevent the water tank 13 from being filled with water and causing the water separator to be blocked.

[0032] The high-pressure vortex pump 12 draws water from the water tank 13 and compresses it, which serves as a pressure source for the water injector 5 to ensure a better atomization effect when the water is injected.

[0033] like Figure 1 As shown, the air-path water separator 17 is connected to the back-pressure valve 18 , and the back-pressure valve 18 is connected to the tail exhaust muffler 19 .

[0034] like Figure 1 As shown, a first pressure sensor 2 is arranged in the pipeline connecting the stop valve 1 and the proportional valve 3, and the first pressure sensor 2 detects the hydrogen pressure in the pipeline.

[0035] like Figure 1 As shown, a second pressure sensor 6 and a first temperature sensor 7 are provided in the pipeline connecting the mixing chamber and the fuel cell stack 16 , and the second pressure sensor 6 detects the hydrogen pressure in the pipeline, and the first temperature sensor 7 detects the temperature in the pipeline.

[0036] like Figure 1 As shown, a third pressure sensor 10 and a second temperature sensor 11 are provided in the pipeline connecting the fuel cell stack 16 and the hydrogen path gas-water separator 9. The third pressure sensor 10 detects the hydrogen pressure in the pipeline, and the second temperature sensor 11 detects the temperature in the pipeline.

[0037] The fuel cell system of the above structure adopts the method of anode self-humidification. When the anode humidity is insufficient, the wet gas discharged from the cathode outlet of the fuel cell stack 16 is used to accurately humidify the anode with water in the wet gas through an injector. By real-time online combination with the electrochemical impedance spectroscopy, accurate closed-loop control of the humidity is achieved.

[0038] Through real-time collection of ambient temperature, pressure, humidity, and stack temperature, pressure, and target humidity by sensors, stable operation can be achieved under specific conditions, realizing precise control of anode humidity of fuel cell systems of various powers under all-weather and all-operating conditions.

[0039] The utility model is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the utility model is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the utility model, or the concept and technical solution of the utility model are directly applied to other occasions without improvement, they are all within the protection scope of the utility model.

Claims

1. A fuel cell system with active humidification function, comprising a fuel cell stack and a hydrogen supply system, wherein the hydrogen supply system comprises an ejector, a hydrogen path gas-water separator and a hydrogen circulation pump, wherein the hydrogen circulation pump is connected to the ejector and the hydrogen path gas-water separator, and wherein: The ejector is connected to a mixing chamber, a water ejector is arranged on the mixing chamber, and the mixing chamber is connected to the fuel cell stack.

2. The fuel cell system with active humidification function according to claim 1, characterized in that: The water ejector is connected to a high-pressure vortex pump, and the high-pressure vortex pump is connected to a water tank.

3. The fuel cell system according to claim 2, characterized in that: A drain valve is arranged at the bottom of the water tank.

4. The fuel cell system with active humidification function according to claim 2, characterized in that: The fuel cell stack is connected to an air-path water separator, and the air-path water separator is connected to the water tank.

5. The fuel cell system with active humidification function according to claim 4, characterized in that: The air-path water separator is connected to the back-pressure valve, and the back-pressure valve is connected to the tail exhaust muffler.

6. The fuel cell system with active humidification function according to any one of claims 1 to 5, characterized in that: The ejector is connected to a proportional valve, and the proportional valve is connected to a stop valve.

7. The fuel cell system with active humidification function according to claim 6, characterized in that: A first pressure sensor is arranged in the pipeline connecting the stop valve and the proportional valve.

8. The fuel cell system with active humidification function according to any one of claims 1 to 5, characterized in that: A second pressure sensor and a first temperature sensor are arranged in a pipeline connecting the mixing chamber and the fuel cell stack.

9. The fuel cell system with active humidification function according to any one of claims 1 to 5, characterized in that: A third pressure sensor and a second temperature sensor are arranged in the pipeline connecting the fuel cell stack and the hydrogen path gas-water separator.

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