Fuel cell with humidity real-time control system

Abstract

The utility model relates to the technical field of fuel cell systems, in particular to a fuel cell with a humidity real-time control system, which comprises a cathode air supply system and a measuring system, the cathode air supply system comprises an air compressor, a humidity regulating valve, a back pressure valve, a humidifier and an intercooler, the air outlet end of the air compressor is connected with one end of the intercooler, and the other end of the intercooler is connected with the measuring system. The other end of the intercooler is divided into two paths to be respectively connected with one end of a stop valve and one end of a humidity regulating valve, an inlet and an outlet of a cooling cavity of the intercooler are directly connected with the galvanic pile in parallel to form an independent intercooler-galvanic pile water cooling loop, the other end of the stop valve is connected with an air inlet of the humidifier, and the other end of the humidity regulating valve is connected with an air outlet of the humidifier and is communicated with the air inlet of the galvanic pile. Compared with the prior art, the method has the advantages that the target cathode air inlet humidity can be obtained by presetting the current for the cathode air supply system, when the deviation between the target cathode air inlet humidity and the target cathode air inlet humidity is larger than the set threshold value, the in-pile humidity adjustment is rapidly achieved by adjusting the flow of dry air entering the electric pile to change the dry-wet ratio of mixed gas, and the method can rapidly adapt to the dynamic working condition humidity.

Description

Technical Field

[0001] This utility model relates to the field of fuel cell system technology, specifically a fuel cell with a real-time humidity control system. Background Technology

[0002] Hydrogen energy, due to its cleanliness, renewability, high energy density, and flexibility, is often hailed as the ultimate energy source of the future. Currently, fuel cells are commonly used as a carrier for hydrogen energy and are widely used in various types of electric vehicles. However, the durability of fuel cells remains the biggest obstacle to commercialization. Cathode humidity, cathode flow rate, and pressure have a crucial impact on stack performance and durability. Fuel cell stacks operate under different conditions, and the external humidification requirements vary under these conditions, necessitating a device that can adjust the humidity entering the stack in real time. This is challenging because any change in the air compressor or back pressure valve within the fuel cell will cause variations in flow rate and pressure.

[0003] In current technologies, there are humidity control methods that use the same humidity level to cope with different operating conditions. The disadvantage of this method is that when the fuel cell is operating at low power, the humidity at the fuel cell stack may be too low; under high power operating conditions, the humidity at the fuel cell stack may be too high, which may lead to flooding and damage.

[0004] There are also methods that use traditional dual-PI or single-PI to control cathode flow and pressure. The disadvantage of this method is that when one of the variables, flow and pressure, reaches the set target value first, the other variable needs to continue to converge. The back pressure valve and air compressor will continue to take corresponding actions. Due to the coupling characteristics, the quantity that has entered a steady state will overshoot and thus generate oscillation.

[0005] Patent application CN202110239103.3 discloses a method that allows dry air to be directly bypassed to the battery cathode by setting two humidity control valves at the inlet and outlet of the fuel cell stack, respectively. The humidity is then adjusted by controlling the opening of the humidity control valves by interpolating the actual air humidity and the target air humidity. However, the problem is that the opening of the outlet humidity control method will have a significant impact on the flow resistance characteristics of the entire air system. At the same time, it is difficult to balance the control of the two humidity control valves, which can easily pose a risk to the pressure stability control of the air system.

[0006] In summary, existing technologies still have significant shortcomings in cathode control of fuel cells, and there is an urgent need for a new control scheme or strategy to solve the humidity problem of fuel cells. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, this utility model provides a fuel cell with a real-time humidity control system. It is equipped with a cathode air supply system. By adjusting the opening of the humidity control valve, the flow rate of dry air from the intercooler outlet directly into the fuel cell stack can be realized. Then, by controlling the flow rate of humidified air from the humidifier, humidity regulation can be achieved.

[0008] To achieve the above objectives, a fuel cell with a real-time humidity control system is designed, including a fuel cell stack, a cathode gas supply system, and a measurement system. The cathode gas supply system includes an air compressor, a humidity regulating valve, a back pressure valve, a humidifier, and an intercooler. The air compressor's inlet is connected to external air, and its outlet is connected to one end of the intercooler. The other end of the intercooler is split into two paths, connected to one end of a shut-off valve and the other end of a humidity regulating valve. The inlet and outlet of the intercooler's cooling chamber are directly connected in parallel with the fuel cell stack, forming a separate intercooler-fuel cell stack water-cooling circuit. The other end of the shut-off valve is connected to the humidifier's inlet, and the other end of the humidity regulating valve is connected to the humidifier's outlet and also leads to the fuel cell stack's inlet. A DC-DC converter is installed inside the fuel cell stack, and the fuel cell stack's outlet is connected to the humidifier again. The gas is discharged after flowing through the back pressure valve.

[0009] The measurement system includes flow meter one, flow meter two, integrated temperature, humidity and pressure sensor, temperature sensor, and integrated temperature and pressure sensor.

[0010] The flow meter one is installed at the air compressor inlet, the flow meter two is installed between the humidity control valve and the fuel cell stack air inlet, the flow meter two is connected in parallel with the humid air circuit, the temperature, humidity and pressure integrated sensor is installed at the fuel cell stack inlet, the temperature sensor is installed between the fuel cell stack cooling chamber water outlet and the intercooler, and the temperature and pressure integrated sensor is installed between the fuel cell stack cooling chamber water inlet and the intercooler.

[0011] The humid air circuit includes an intercooler, a shut-off valve, a humidifier, a fuel cell stack, a water pump, an electronic three-way valve, and a radiator. The water pump is located between the outlet of the fuel cell stack's cooling chamber and the inlet of the intercooler's cooling chamber. The inlet of the electronic three-way valve is connected to the outlet of the water pump. One outlet of the electronic three-way valve is directly connected to the inlet of the fuel cell stack's cooling chamber, and the other outlet is connected to the inlet of the radiator. The outlet of the radiator is connected to the inlet of the fuel cell stack's cooling chamber.

[0012] The intercooler is also connected to a dry air circuit corresponding to the humid air circuit. The dry air circuit includes the intercooler, a humidity control valve, and an electric stack.

[0013] The intercooler can directly discharge gas through a bypass valve.

[0014] The DC-DC converter has an integrated impedance tester.

[0015] Compared with the prior art, this utility model can obtain the target humidity of the cathode air intake by presetting the current of the cathode air supply system. The humidity regulating valve can regulate the current humidity. When the deviation between them is greater than the set threshold, the humidity of the fuel cell can be quickly regulated according to the current fuel cell performance and by adjusting the flow rate of dry air entering the fuel cell to change the dry-wet ratio of the mixed gas. It can quickly adapt to dynamic operating humidity and there will be no large changes in the flow resistance characteristics of the air system. The pressure control of the air system is stable. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating the humidity regulation principle of this utility model.

[0017] See Figure 1 1 is flow meter one, 2 is air compressor, 3 is intercooler, 4 is bypass valve, 5 is humidity control valve, 6 is shut-off valve, 7 is flow meter two, 8 is back pressure valve, 9 is humidifier, 10 is temperature, humidity and pressure integrated sensor, 11 is fuel cell stack, 12 is DC-DC converter, 13 is impedance tester, 14 is temperature sensor, 15 is water pump, 16 is electronic three-way valve, 17 is radiator, and 18 is temperature and pressure integrated sensor. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings.

[0019] like Figure 1As shown, the cathode air supply system includes an air compressor 2, a humidity control valve 5, a back pressure valve 8, a humidifier 9, and an intercooler 3. Air is introduced from the outside through the air compressor 2, which controls the initial airflow into the fuel cell. The air compressor 2's outlet is connected to one end of the intercooler 3. The intercooler 3 is responsible for timely cooling of the high-temperature air after compression by the air compressor, thus controlling the fuel cell temperature and eliminating humidity fluctuations caused by the large temperature difference between dry air and humid air at the humidifier outlet. The other end of the intercooler 3 is split into two paths, connected to one end of a shut-off valve 6 and the other end of a humidity control valve 5. Furthermore, the inlet and outlet of the intercooler 3's cooling chamber are directly connected in parallel with the fuel cell stack 11, forming a separate intercooler-fuel cell stack water-cooling loop. This allows for more precise control of air humidity. The other end of the stop valve 6 is connected to the air inlet of the humidifier 9, and the other end of the humidity regulating valve 5 is connected to the air outlet of the humidifier 9 and enters the air inlet of the fuel cell stack 11. The humidity regulating valve 5 is used to regulate the humidity of the air entering the stack. In this patent, it is mainly used to dry the air. The humidifier 9 can increase the humidity of the gas. The fuel cell stack 11 is equipped with a DC-DC converter 12. The DC-DC converter 12 integrates an impedance tester 13. The DC-DC converter 12 performs impedance testing on the fuel cell stack 11. Based on the current actual performance of the fuel cell stack, it is determined whether humidity regulation is required. The air outlet of the fuel cell stack 11 is connected to the back pressure valve 8. The gas flows through the back pressure valve 8 and is discharged. The back pressure valve 8 forms a certain pressure due to its own function. The air pressure entering the stack can be controlled by adjusting the pressure inside the valve.

[0020] The measurement system includes flow meter 1, flow meter 7, integrated temperature, humidity and pressure sensor 10, temperature sensor 14, and integrated temperature and pressure sensor 18. Flow meter 1 is installed at the inlet of air compressor 2, and records and measures the initial flow rate. Flow meter 7 is installed in parallel with the humid air circuit between humidity control valve 5 and air inlet of fuel cell stack 11. More precise humidity control can be achieved by monitoring the flow rate of flow meter 7. Integrated temperature, humidity and pressure sensor 10 is installed at the inlet of fuel cell stack 11, and can monitor the temperature, humidity and pressure of air inlet of fuel cell stack 11 in real time. Temperature sensor 14 is installed between the water outlet of cooling chamber of fuel cell stack 11 and intercooler 3. Integrated temperature and pressure sensor 18 is installed between the water inlet of cooling chamber of fuel cell stack 11 and intercooler 3. Temperature sensor 14 and integrated temperature and pressure sensor 18 are responsible for monitoring the temperature and pressure of water outlet of cooling chamber of fuel cell stack 11.

[0021] The humid air circuit includes an intercooler 3, a shut-off valve 6, a humidifier 9, a fuel cell stack 11, a water pump 15, an electronic three-way valve 16, and a radiator 17. The water pump 15 is located between the outlet of the cooling chamber of the fuel cell stack 11 and the inlet of the cooling chamber of the intercooler 3. The inlet of the electronic three-way valve 16 is connected to the outlet of the water pump 15. One outlet of the electronic three-way valve 16 is directly connected to the inlet of the cooling chamber of the fuel cell stack 11, and the other outlet is connected to the inlet of the radiator 17. The outlet of the radiator 17 is connected to the inlet of the cooling chamber of the fuel cell stack 11. The intercooler-fuel cell stack water cooling circuit plays a role in controlling the temperature.

[0022] The dry air circuit includes an intercooler 3, a humidity control valve 5, and an electric stack 11. The dry air circuit has the characteristic of fast response speed.

[0023] Intercooler 3 can directly discharge gas through bypass valve 4.

[0024] The DC-DC converter 12 integrates an impedance tester 13.

[0025] The specific adjustment process of this utility model is as follows: The fuel cell has two air circuits: a dry air circuit as the secondary circuit and a humid air circuit as the primary circuit. The gas entering the stack is typically a mixture of dry and humid air. A predetermined current is preset through an open-loop test to obtain the target humidity of the cathode intake air. A preset current is applied to the stack 11, and the air compressor 2 is started to intake air, controlling the air flow rate. The initial air flow rate is measured and recorded by flow meter 1. The air flow rate is adjusted by the speed of air compressor 2. The air temperature is controlled by the intercooler 3. The intercooler 3 also has a separate intercooler-stack circuit. Temperature sensor 14 and integrated temperature and pressure sensor 18 monitor the temperature and pressure at the outlet of the cooling chamber of the stack 11, further monitoring the humidity, temperature, and pressure inside the fuel cell. The dry air circuit... Flow meter 7 measures and records the air flow rate. The flow rate of flow meter 7 is used as the secondary loop of cascade control. Its output is the input of the PI controller of humidity control valve 5, which can realize fast and accurate humidity control. After the dry and wet air loops are integrated, they are fed into the fuel cell stack. The overall temperature, humidity and pressure of the mixed air are measured and recorded by temperature, humidity and pressure integrated sensor 10. The air pressure entering the stack is controlled by adjusting the opening of back pressure valve 8, thereby adjusting the air flow rate entering the stack. When DC-DC converter 12 performs impedance testing on fuel cell stack 11, and determines that humidity adjustment is required based on the current actual performance of the fuel cell stack, the opening of the humidity control valve is increased to allow more dry air to enter the fuel cell stack 11, adjusting the dry and wet air ratio entering the fuel cell stack to achieve the current intake air humidity adjustment. The reason for using dry air to interfere with wet air is that dry air has a faster response speed and can achieve the effect of real-time adjustment.

Claims

1. A fuel cell with a real-time humidity control system, comprising a fuel cell stack, a cathode gas supply system, and a measurement system, characterized in that: The cathode air supply system includes an air compressor (2), a humidity control valve (5), a back pressure valve (8), a humidifier (9), and an intercooler (3). The air compressor (2) is supplied with air from the outside, and the air compressor (2) is connected to one end of the intercooler (3). The other end of the intercooler (3) is split into two paths, one end of a shut-off valve (6) and the other end of a humidity control valve (5). The inlet and outlet of the cooling chamber of the intercooler (3) are directly connected in parallel with the fuel cell stack (11) to form a separate intercooler-fuel cell stack water-cooled circuit. The shut-off valve (6) is connected to the fuel cell stack (11). The other end is connected to the air inlet of the humidifier (9), and the other end of the humidity control valve (5) is connected to the air outlet of the humidifier (9) and enters the air inlet of the fuel cell stack (11). The fuel cell stack (11) is equipped with a DC-DC converter (12). The air outlet of the fuel cell stack (11) is connected to the humidifier (9) again. The gas flows through the back pressure valve (8) and is discharged. The measurement system includes flow meter one (1), flow meter two (7), temperature, humidity and pressure integrated sensor (10), temperature sensor (14), and temperature and pressure integrated sensor (18).

2. A fuel cell with a real-time humidity control system according to claim 1, characterized in that: The flow meter 1 (1) is installed at the inlet of the air compressor (2), the flow meter 2 (7) is installed between the humidity control valve (5) and the air inlet of the fuel cell stack (11), the flow meter 2 (7) is connected in parallel with the humid air circuit, the temperature, humidity and pressure integrated sensor (10) is installed at the inlet of the fuel cell stack (11), the temperature sensor (14) is installed between the water outlet of the cooling chamber of the fuel cell stack (11) and the intercooler (3), and the temperature and pressure integrated sensor (18) is installed between the water inlet of the cooling chamber of the fuel cell stack (11) and the intercooler (3).

3. A fuel cell with a real-time humidity control system according to claim 2, characterized in that: The humid air circuit includes an intercooler (3), a shut-off valve (6), a humidifier (9), a fuel cell stack (11), a water pump (15), an electronic three-way valve (16), and a radiator (17). The water pump (15) is located between the cooling chamber outlet of the fuel cell stack (11) and the cooling chamber inlet of the intercooler (3). The inlet of the electronic three-way valve (16) is connected to the outlet of the water pump (15). One outlet of the electronic three-way valve (16) is directly connected to the cooling chamber inlet of the fuel cell stack (11), and the other outlet is connected to the inlet of the radiator (17). The outlet of the radiator (17) is connected to the cooling chamber inlet of the fuel cell stack (11).

4. A fuel cell with a real-time humidity control system according to claim 1, characterized in that: The intercooler (3) is also connected to a dry air circuit corresponding to the humid air circuit. The dry air circuit includes the intercooler (3), the humidity control valve (5), and the fuel cell stack (11).

5. A fuel cell with a real-time humidity control system according to claim 1, characterized in that: The intercooler (3) can directly discharge gas through the bypass valve (4).

6. A fuel cell with a real-time humidity control system according to claim 1, characterized in that: The DC-DC converter (12) has an impedance tester (13) integrated inside.

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