A fuel cell system air path control system and method

Abstract

The application provides a fuel cell system air path control system and method, which comprises an air compressor, a humidifier, a valve R1, a valve R2, a three-way valve T1 and a valve R3; the air compressor is connected with the valve R1 and the first inlet of the humidifier through pipelines; the first outlet of the humidifier and the air inlet of the fuel cell are provided with the valve R2; the air outlet of the fuel cell is connected with the three-way valve T1 and the valve R3 through pipelines in sequence; and the valve R3 and the valve R1 are jointly connected to an exhaust port. The application can monitor the parameters of the air entering the fuel cell in real time through relevant sensors, adjust the corresponding electric valves to achieve the effect of controlling the parameters of the air inlet of the fuel cell and realize more fuel cell system air path control strategies.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cell system, and particularly relates to a fuel cell system air path control system and method. BACKGROUND

[0002] In recent years, the development of fuel cells has attracted more and more attention, among which the application of proton exchange membrane fuel cells is the most extensive. The fuel cell is a device for generating water and electrons by reacting hydrogen and oxygen in air, however, the pressure, temperature, flow rate and humidity of the gas can directly affect the performance of the fuel cell. The generated water is mainly in the air path of the fuel cell, and at present, the water brought out by the air outlet is generally humidified by a humidifier and then enters the air of the fuel cell.

[0003] Generally, the fuel cell system air path only has a main path without a bypass to cooperate with the air flow guide, at this time, the air path is controlled by adjusting the speed of the air compressor, and the air path control strategy has fewer implementable methods. The air path operating parameters are difficult to control under different conditions, which is not conducive to the stable performance and longer service life of the fuel cell. SUMMARY

[0004] Therefore, the present application provides a fuel cell system air path control system and method, which can adjust the pressure, flow rate and humidity of the fuel cell system air path to adapt to the requirements of different power levels of different fuel cells.

[0005] The present application adopts the following technical solutions:

[0006] The present application provides a fuel cell system air path control system, which comprises an air compressor, a humidifier, a valve R1, a valve R2, a three-way valve T1 and a valve R3; the air compressor is connected with the first inlet of the humidifier and the valve R1 through a pipeline, the first outlet of the humidifier and the air inlet of the fuel cell are provided with the valve R2, the air outlet of the fuel cell is connected with the three-way valve T1 and the valve R3 in sequence through a pipeline, and the valve R3 and the valve R1 are connected to an exhaust port.

[0007] Preferably, the valve R1, the valve R2 and the valve R3 are all electric butterfly valves.

[0008] Preferably, the three-way valve T1 is an electric three-way valve.

[0009] Preferably, a flowmeter F2 is arranged at the outlet of the valve R1.

[0010] Preferably, a flowmeter F1 is arranged at the inlet of the air compressor.

[0011] Preferably, the three-way valve T1 is connected with the second inlet of the humidifier, and the second outlet of the humidifier is connected with the valve R3.

[0012] Preferably, the air outlet of the fuel cell is provided with a humidity sensor H2.

[0013] Preferably, the air inlet of the fuel cell is provided with a pressure sensor P and a humidity sensor H1.

[0014] A fuel cell system air path control method, comprising the following steps:

[0015] Step S1, after receiving the instruction of system start, the air compressor is operated, the valve R1 and the three-way valve T1 are closed, and the valve R2 and the valve R3 are fully opened;

[0016] Step S2, whether the air compressor is in surge is detected, if yes, the air compressor is stopped, the valve R1, the valve R3 and the three-way valve T1 are fully opened, the valve R2 is fully closed, after the stop, the valve R1, the valve R2 and the valve R3 are fully closed, and the three-way valve T1 is fully opened, if not, the fuel cell system is normally operated, and step S3 is executed;

[0017] Step S3, whether the air pressure P and the air flow F are normal is judged, if abnormal, step S4 is executed, if normal, step S5 is executed;

[0018] Step S4, when the air pressure P and the air flow F all reach the preset maximum value, the air compressor speed is reduced, when the air pressure P reaches the preset maximum value, and the air flow F reaches the preset minimum value, the opening degree of the valve R3 is increased, and the opening degree of the valve R1 is reduced, when the air pressure P reaches the preset minimum value, and the air flow F reaches the preset maximum value, the opening degree of the valve R3 is reduced, and the opening degree of the valve R1 is increased, when the air pressure P and the air flow F all reach the preset minimum value, the air compressor speed is increased.

[0019] Step S5, whether the air humidity H1 is judged, when the air humidity H1 reaches the preset maximum value, the opening degree of the three-way valve T1 is increased, and the proportion of the air at the outlet of the fuel cell passing through the humidifier is reduced, when the air humidity H1 reaches the preset minimum value, the opening degree of the three-way valve T1 is reduced, and the proportion of the air at the outlet of the fuel cell passing through the humidifier is increased.

[0020] Preferably, step S6 is further included, when receiving the instruction of system stop, the fuel cell system is stopped and purged, the valve R1 is fully closed, the valve R2, the valve R3 and the three-way valve T1 are fully opened, after the stop, the valve R1, the valve R2 and the valve R3 are fully closed, and the three-way valve T1 is fully opened.

[0021] The beneficial effects of the present application are:

[0022] This invention monitors the parameters of air entering the fuel cell in real time using relevant sensors, and adjusts the corresponding electric valves to control the air inlet parameters of the fuel cell and realize more air path control strategies for the fuel cell system. By controlling the air path parameters of the fuel cell system, the required operating parameters of the fuel cell are ensured. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of an air circuit control system for a fuel cell system according to the present invention.

[0024] In the diagram: 1-Flow meter F1; 2-Air compressor; 3-Electric butterfly valve R1; 4-Flow meter F2; 5-Humidifier; 6-Electric butterfly valve R2; 7-Pressure sensor P; 8-Humidity sensor H1; 9-Fuel cell; 10-Humidity sensor H2; 11-Electric three-way valve T1; 12-Electric butterfly valve R3;

[0025] Figure 2 This is a flowchart of an air circuit control method for a fuel cell system according to the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] To make the above-mentioned objectives, features, and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Figure 1As shown, 1-flow meter F1; 2-air compressor; 3-electric butterfly valve R1; 4-flow meter F2; 5-humidifier; 6-electric butterfly valve R2; 7-pressure sensor P; 8-humidity sensor H1; 9-fuel cell; 10-humidity sensor H2; 11-electric three-way valve T1; 12-electric butterfly valve R3. This invention includes an air compressor, a humidifier, valves R1, R2, three-way valve T1, and valve R3. The air compressor is connected via pipeline to valve R1 and the first inlet of the humidifier. Valve R2 is installed between the first outlet of the humidifier and the air inlet of the fuel cell. The air outlet of the fuel cell is connected via pipeline to three-way valve T1 and valve R3 in sequence. Valve R3 and valve R1 are connected together to the exhaust port. Three-way valve T1 is connected to the second inlet of the humidifier, and the second outlet of the humidifier is connected to valve R3. A flow meter F2 is installed at the outlet of valve R1; a flow meter F1 is installed at the inlet of the air compressor; a humidity sensor H2 is installed at the air outlet of the fuel cell; and a pressure sensor P and a humidity sensor H1 are installed at the air inlet of the fuel cell.

[0028] In this embodiment, valves R1, R2, and R3 are all electrically operated butterfly valves; three-way valve T1 is an electrically operated three-way valve. The opening degree of the three electrically operated butterfly valves and one electrically operated three-way valve can be adjusted by PWM or other signals. The humidifier has four interfaces, corresponding to the inlet and outlet of dry air and the inlet and outlet of humid air, respectively. The first inlet (inlet 1) is the inlet of dry air, the first outlet (outlet 1) is the outlet of dry air, the second inlet (inlet 2) is the inlet of humid air, and the second outlet (outlet 2) is the outlet of humid air.

[0029] The inlet of electric butterfly valve R1 is connected to the air compressor outlet and humidifier inlet 1 via a three-way valve. The outlet of electric butterfly valve R1 is connected to the outlet of electric butterfly valve R3 and the atmosphere via a three-way valve. Electric butterfly valve R2 connects humidifier outlet 1 and fuel cell air inlet. The inlet of electric three-way valve T1 is connected to fuel cell air outlet. One outlet of electric three-way valve T1 is connected to humidifier inlet 2, and the other outlet of electric three-way valve T1 is connected to humidifier outlet 2 and the inlet of electric butterfly valve R3 via a three-way valve. Pressure sensor P and humidity sensor H1 are installed at the air inlet, and another humidity sensor H2 is installed at the air outlet. Flow sensor F1 is installed before the air compressor inlet, and flow sensor F2 is installed at the outlet of electric butterfly valve R1.

[0030] The working process of this invention is as follows: When the fuel cell system is running, the air is compressed by the air compressor and divided into two paths. One path flows to the electric butterfly valve R1; the other path flows to the humidifier inlet 1, enters the humidifier, and then flows out through the outlet 1. It then passes through the electric butterfly valve R2 and enters the fuel cell through the air inlet. Inside the fuel cell, oxygen and hydrogen in the air undergo an electrochemical reaction, producing water and electrons. At this time, the air that has not participated in the reaction, carrying most of the water produced by the reaction, flows out through the fuel cell air outlet and then through the electric three-way valve T1. Another path enters the humidifier through the humidifier inlet 2, humidifies the dry air entering through inlet 1 inside the humidifier, and then flows out through the outlet 2, merging with the other path of gas through the electric butterfly valve R3. Finally, it merges with the gas that has passed through the electric butterfly valve R1 and is discharged into the atmosphere.

[0031] In this embodiment, the pressure and flow rate of the fuel cell air inlet are controlled by adjusting the opening degrees of electric butterfly valves R1, R2, and R3 in conjunction with different speeds of the air compressor. The actual inlet pressure is collected by pressure sensor P. The actual inlet flow rate F = F1 - F2.

[0032] Under certain flow and pressure conditions, the proportion of air entering the humidifier is controlled by adjusting the opening of the electric three-way valve T1. When T1 is fully closed, all the air enters the humidifier. At this time, there is more moisture in the humidifier, and the air is fully humidified before entering the reactor, so the air inlet humidity H1 is the largest. When T1 is fully open, the air does not pass through the humidifier. At this time, there is less moisture in the humidifier, and the air is not fully humidified before entering the reactor, so the air inlet humidity H1 is the smallest.

[0033] This invention refines the control of air path parameters in a fuel cell system, ensuring the required operating parameters for the fuel cell. Air is compressed by an air compressor and split into two streams. One stream flows to an electric butterfly valve R1; the other flows to the humidifier inlet 1, enters the humidifier, and then exits through outlet 1. It then passes through an electric butterfly valve R2 and enters the fuel cell through the air inlet. Inside the fuel cell, oxygen and hydrogen in the air undergo an electrochemical reaction, producing water and electrons. Air that has not participated in the reaction, carrying most of the water produced, flows out of the fuel cell air outlet through an electric three-way valve T1. The airflow through the humidifier can be controlled by adjusting the opening of T1. The two gas streams then merge through an electric butterfly valve R3, and finally merge with the gas that passed through the electric butterfly valve R1 before being discharged into the atmosphere. This process allows for control of the airflow and pressure entering the fuel cell by adjusting the openings of R1 and R2, and the airflow into the humidifier by adjusting the opening of T1, thereby controlling the humidity of the air entering the fuel cell.

[0034] like Figure 2 As shown, an air path control method for a fuel cell system includes the following steps:

[0035] Step S1: After receiving the system start command, the air compressor runs, valves R1 and T1 are closed, and valves R2 and R3 are fully open;

[0036] Step S2: Check if the air compressor is experiencing surge. If so, the air compressor stops running, valves R1, R3, and three-way valve T1 are fully open, and valve R2 is fully closed. After shutdown, valves R1, R2, and R3 are fully closed, and three-way valve T1 is fully open. If not, the fuel cell system operates normally, and step S3 is executed.

[0037] Step S3: Determine if the air pressure P and air flow rate F are normal. If they are abnormal, proceed to step S4; if they are normal, proceed to step S5.

[0038] Step S4: When both air pressure P and air flow rate F reach their preset maximum values, reduce the air compressor speed; when air pressure P reaches its preset maximum value and air flow rate F reaches its preset minimum value, increase the opening of valve R3 and decrease the opening of valve R1; when air pressure P reaches its preset minimum value and air flow rate F reaches its preset maximum value, decrease the opening of valve R3 and increase the opening of valve R1; when both air pressure P and air flow rate F reach their preset minimum values, increase the air compressor speed.

[0039] Step S5: Determine the air humidity H1. When the air humidity H1 reaches the preset maximum value, increase the opening of the three-way valve T1 to reduce the proportion of vented gas passing through the humidifier; when the air humidity H1 reaches the preset minimum value, decrease the opening of the three-way valve T1 to increase the proportion of vented gas passing through the humidifier. Here, vented gas refers to the air at the air outlet of the fuel cell stack.

[0040] Step S6: Upon receiving the system shutdown command, the fuel cell system shuts down and is purged. Valve R1 is fully closed, and valves R2, R3, and three-way valve T1 are fully open. After shutdown, valves R1, R2, and R3 are fully closed, and three-way valve T1 is fully open.

[0041] When the fuel cell system receives a start command from standby, the air compressor starts, electric butterfly valve R1 is fully closed, electric butterfly valves R2 and R3 are fully open, and electric three-way valve T1 is fully closed. If surge is detected in the air compressor at this time, the air compressor is immediately stopped, and simultaneously electric butterfly valves R1 and R3 are fully open, electric butterfly valve R2 is fully closed, and electric three-way valve T1 is fully open. This ensures that overpressurized air cannot enter the fuel cell, but is instead depressurized through R1. Overpressurized air inside the stack can also be discharged into the atmosphere through T1 and R3, thus protecting the fuel cell. When the system completely stops, electric butterfly valves R1, R2, and R3 are all closed, and electric three-way valve T1 is fully open. At this time, the oxygen in the fuel cell air chamber has been consumed, forming a sealed oxygen-free space, effectively preventing hydrogen-oxygen mixing inside the fuel cell and ensuring the safe operation of the fuel cell.

[0042] When the air compressor does not surge and other operating conditions meet the requirements, the fuel cell system enters the operating state. At this time, it is necessary to first determine whether the air pressure P and air flow rate F meet the current operating requirements. When P is too high and F is too high, reduce the air compressor speed; when P is too high and F is too low, increase the opening of R3 while decreasing the opening of R1; when P is too low and F is too high, decrease the opening of R3 while increasing the opening of R1; when P is too low and F is too low, increase the air compressor speed; throughout the entire adjustment process, the electric butterfly valve R2 remains fully open.

[0043] When the air compressor experiences surge, electric butterfly valves R1 and R3 are fully open, and R2 is fully closed. This reduces the air pipeline pressure, and the pressure relief does not pass through the fuel cell, thus protecting it. When the fuel cell system receives a shutdown command, the air compressor adjusts to the specified speed, electric butterfly valve R1 is fully closed, R2 and R3 are fully open, and electric three-way valve T1 is fully open. The purpose of purging is to dry the internal chambers of the fuel cell. With T1 fully open, humid air from the air outlet does not enter the humidifier, significantly reducing the humidifier's ability to humidify the air entering the fuel cell, thus ensuring relatively dry air during purging and allowing for faster fuel cell purging. After purging, R1, R2, and R3 are closed; T1 is fully open. At this point, the air chamber of the fuel cell is in a sealed state. Hydrogen is added to the fuel cell to consume the excess oxygen in the air chamber. Finally, only oxygen-free air remains in the air chamber. The oxygen in the fuel cell air chamber has been completely consumed, forming a sealed oxygen-free space. After the fuel cell is shut down, there is no opportunity for hydrogen and oxygen to come into contact, effectively preventing the occurrence of hydrogen-oxygen mixing inside the fuel cell and ensuring the safety of the fuel cell.

[0044] Once the air pressure P and flow rate F of the fuel cell system meet the current requirements, the humidity H1 at the fuel cell air inlet is adjusted by regulating the electric three-way valve T1. When the electric three-way valve T1 is fully closed, all outgoing gas passes through the humidifier. If H1 is too high, the opening of T1 can be increased, reducing the flow rate of outgoing gas through the humidifier. As the moisture inside the humidifier decreases, its humidification capacity for dry air decreases, thus reducing the humidity H1 at the fuel cell air inlet. If H1 is too low, the opening of T1 can be decreased, increasing the flow rate of outgoing gas through the humidifier. As the moisture inside the humidifier increases, its humidification capacity for dry air increases, thus increasing the humidity H1 at the fuel cell air inlet.

[0045] Upon receiving a shutdown command, the fuel cell system initiates a shutdown purging process. The air compressor is adjusted to the specified speed, electric butterfly valve R1 is fully closed, and R2 and R3 are fully open, while electric three-way valve T1 is fully open. The purpose of purging is to dry the internal cavity of the fuel cell. With T1 fully open, humid air from the air outlet does not enter the humidifier, significantly reducing the humidifier's ability to humidify the inlet air of the fuel cell. This ensures that the purging air is relatively dry, allowing for faster purging of the fuel cell. After purging, electric butterfly valves R1, R2, and R3 are closed, electric three-way valve T1 is fully open, and hydrogen is continuously supplied to the fuel cell's hydrogen chamber to consume the oxygen within. Eventually, the oxygen in the sealed cavity is depleted, preventing hydrogen-oxygen mixing inside the fuel cell and ensuring its safety.

[0046] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and its equivalents, this invention also intends to include these modifications and variations.

Claims

1. A control method for an air circuit control system of a fuel cell system, characterized in that: The control system includes an air compressor, a humidifier, valves R1 and R2, a three-way valve T1, and valve R3. The air compressor is connected to valve R1 and the first inlet of the humidifier via pipelines. Valve R2 is installed between the first outlet of the humidifier and the air inlet of the fuel cell. The air outlet of the fuel cell is connected to the second inlet of the humidifier and valve R3 via pipelines and the three-way valve T1. Valve R3 and valve R1 are connected to the exhaust port. The control method includes the following steps: Step S1: After receiving the system start command, the air compressor runs, valves R1 and T1 are closed, and valves R2 and R3 are fully open; Step S2: Check if the air compressor is experiencing surge. If so, the air compressor stops running, valves R1, R3, and three-way valve T1 are fully open, and valve R2 is fully closed. After the fuel cell system stops, valves R1, R2, and R3 are fully closed, and three-way valve T1 is fully open. If not, the fuel cell system runs normally, and step S3 is executed. Step S3: Determine if the air pressure P and air flow rate F are normal. If they are abnormal, proceed to step S4; if they are normal, proceed to step S5. Step S4: When both air pressure P and air flow rate F reach their preset maximum values, reduce the air compressor speed; when air pressure P reaches its preset maximum value and air flow rate F reaches its preset minimum value, increase the opening of valve R3 and decrease the opening of valve R1; when air pressure P reaches its preset minimum value and air flow rate F reaches its preset maximum value, decrease the opening of valve R3 and increase the opening of valve R1; when both air pressure P and air flow rate F reach their preset minimum values, increase the air compressor speed. Step S5: Determine the air humidity H1. When the air humidity H1 reaches the preset maximum value, increase the opening of the three-way valve T1 to reduce the proportion of air passing through the humidifier at the fuel cell outlet. When the air humidity H1 reaches the preset minimum value, decrease the opening of the three-way valve T1 to increase the proportion of air passing through the humidifier at the fuel cell outlet.

2. The control method for an air circuit control system of a fuel cell system according to claim 1, characterized in that: Valve R1, valve R2 and valve R3 are all electric butterfly valves.

3. The control method for an air circuit control system of a fuel cell system according to claim 1, characterized in that: The three-way valve T1 is an electric three-way valve.

4. The control method for an air circuit control system of a fuel cell system according to claim 1, characterized in that: A flow meter F2 is installed at the outlet of the valve R1.

5. The control method for an air circuit control system of a fuel cell system according to claim 1, characterized in that: A flow meter F1 is installed at the inlet of the air compressor.

6. The control method for an air circuit control system of a fuel cell system according to claim 1, characterized in that: The three-way valve T1 is connected to the second inlet of the humidifier, and the second outlet of the humidifier is connected to the valve R3.

7. A control method for an air circuit control system of a fuel cell system according to any one of claims 1-6, characterized in that: The air outlet of the fuel cell is equipped with a humidity sensor H2.

8. The control method for an air circuit control system of a fuel cell system according to claim 7, characterized in that: The air inlet of the fuel cell is equipped with a pressure sensor P and a humidity sensor H1.

9. The control method for an air circuit control system of a fuel cell system according to claim 6, characterized in that: It also includes step S6, where, upon receiving a shutdown command for the fuel cell system, the fuel cell system is shut down and purged, valve R1 is fully closed, and valves R2, R3, and three-way valve T1 are fully open; after the fuel cell system is shut down, valves R1, R2, and R3 are fully closed, and three-way valve T1 is fully open.

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