Gas path dry-wet switching and pressure stabilization system and method for fuel cell stack testing

Abstract

The present invention relates to a gas path dry-wet switching and pressure stabilization system and method for fuel cell stack testing. The system includes a gas pretreatment system, a flow controller, a parallel dry gas branch and a wet gas branch, a temperature control system, a stack inlet and outlet detection system, a tail exhaust cooling system, a back pressure valve system, a water-gas separation system, and a wet gas path pressure compensation system, which are connected in sequence. The dry gas branch and the wet gas branch are used to transport dry gas and wet gas, respectively. The back pressure valve system is used to control the overall system pressure. The water-gas separation system is used to separate the tail exhaust liquid water. The wet gas path pressure compensation system acts on the wet gas branch to compensate for the wet gas branch pressure. Compared with the existing technology, the present invention has the advantages of ensuring pressure stability during dry-wet switching and steady-state operation during the overall test, and can simultaneously and accurately control the flow, temperature, and humidity of the overall test.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell stack testing, and in particular to a gas path dry-wet switching and pressure stabilization system and method for fuel cell stack testing. Background Art

[0002] As a new green power source, fuel cell engines are becoming a key research and development focus for automotive engines due to their high efficiency and low emissions. Fuel cell engines operate on a load-dependent basis, offering excellent controllability for the vehicle. Furthermore, their energy output is electrical, simplifying the transmission and speed control structure of traditional vehicles. While fuel cell engines offer numerous advantages over internal combustion engines, they still face challenges before they can replace internal combustion engines and become the mainstream automotive engine.

[0003] Among them, dry gas and wet gas switching is often required during the fuel cell stack life test. However, when performing dry-wet switching tests using existing fuel cell stack testing equipment, it is easy for the humidification tank to be too large, resulting in excessive pressure fluctuations and air shortage when switching from dry gas to wet gas, making the test results inaccurate and easily causing damage to the fuel cell stack; and when a pure dry gas test is desired, the humidification path is not completely isolated from the dry gas path, resulting in the gas still having humidity, affecting the test results.

[0004] When conducting accelerated life tests, it is often necessary to switch between dry and wet and change the pressure after switching. The overall volume cavity of the dry gas branch is small. When switching from wet gas to dry gas, the pressure fluctuation is negligible and has little impact on the stack test. When switching from dry gas to wet gas, since the volume cavity of the humidification tank of the humidification system is large, if the pressure is adjusted during dry gas, the overall pressure fluctuation is large after switching, which may cause the single chip voltage to be too low or gas shortage. For example, when testing a 10kW stack, the hydrogen flow rate is about 240NLPM (4L / s). If the dry gas inlet pressure is 200kPa, the original pressure in the humidification tank is 100kPa, and the volume cavity is 40L, without considering the consumption and emissions in the stack, the overall pressure needs 10s to compensate from 100kPa to 200kPa, which can easily cause the single chip voltage of the stack to be low and shut down due to load reduction. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a gas path dry-wet switching and pressure stabilization system and method for fuel cell stack testing.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] According to one aspect of the present invention, a gas path dry-wet switching and pressure stabilization system for fuel cell stack testing is provided, which is used to stabilize the pressure during dry-wet switching during testing and steady-state operation. The gas path dry-wet switching and pressure stabilization system includes a gas pretreatment system, a flow controller, parallel dry gas branches and wet gas branches, a temperature control system, a fuel cell stack inlet and outlet detection system, a tail exhaust cooling system, a back pressure valve system, a water-gas separation system, and a wet gas path pressure compensation system connected in sequence;

[0008] The gas pretreatment system is used to filter gas impurities; the flow controller is used to control the gas flow; the dry gas branch and the wet gas branch are used to transport dry gas and wet gas respectively; the temperature control system is used to control the temperature of the gas entering the stack; the stack inlet and outlet detection system is used to detect the gas temperature and pressure at the inlet and outlet of the stack of the tested device; the tail exhaust cooling system is used to cool the tail exhaust gas; the back pressure valve system is used to control the overall system pressure; the water-gas separation system is used to separate the tail exhaust liquid water; the wet gas path pressure compensation system acts on the wet gas branch to compensate for the wet branch pressure.

[0009] As a preferred technical solution, the gas pretreatment system includes a hydrogen delivery pipe and a pressure reducing valve, a filter and a solenoid valve arranged on the hydrogen delivery pipe.

[0010] As a preferred technical solution, the dry gas branch includes a dry gas branch control solenoid valve for controlling the test bench to switch to dry gas.

[0011] As a preferred technical solution, the wet gas branch includes a wet gas inlet solenoid valve, a humidification system, a humidification system outlet pressure sensor and a wet gas outlet solenoid valve connected in sequence;

[0012] The moisture inlet solenoid valve and the moisture outlet solenoid valve are used to control the moisture switch; the humidification system is used to humidify the gas; and the humidification system outlet pressure sensor is used to detect the humidification system outlet pressure.

[0013] As a preferred technical solution, the wet gas line pressure compensation system includes a wet gas line pressure compensation air supply solenoid valve and a wet gas line pressure compensation exhaust solenoid valve;

[0014] The gas pretreatment system is connected to the humidification system through the wet gas path pressure compensation air supply solenoid valve for supplying air to the humidification system; the humidification system is connected to the back pressure valve system through the wet gas path pressure compensation exhaust solenoid valve for exhausting the humidification system.

[0015] As an optimal technical solution, the wet gas path pressure compensation system also includes a wet gas path pressure compensation flow controller, which is installed between the gas pretreatment system and the wet gas path pressure compensation gas supply solenoid valve to control the gas pressure compensation of the humidification system.

[0016] As a preferred technical solution, the temperature control system includes a heater, a temperature sensor and a plate heat exchanger, which are used to heat the gas and precisely control the temperature.

[0017] As a preferred technical solution, the stack inlet and outlet detection system includes a test piece inlet pressure sensor, a test piece inlet temperature sensor, a test piece outlet temperature sensor and a test piece outlet pressure sensor;

[0018] The pressure sensor at the inlet of the device under test and the temperature sensor at the inlet of the device under test are connected in sequence at the inlet of the battery stack to detect the gas pressure and temperature at the inlet of the device under test; the pressure sensor at the inlet of the device under test and the temperature sensor at the inlet of the device under test are connected in sequence at the inlet of the battery stack to detect the gas pressure and temperature at the inlet of the device under test; the temperature sensor at the outlet of the device under test and the pressure sensor at the outlet of the device under test are connected in sequence at the outlet of the battery stack to detect the gas temperature and pressure at the inlet of the device under test.

[0019] As an optimal technical solution, the tail exhaust cooling system includes a plate heat exchanger, a ball valve and a temperature sensor; the back pressure valve system includes a back pressure valve, an electric proportional valve, a buffer tank and a pressure regulating valve; the water-gas separation system includes a water-gas separation tank, a liquid level sensor and a solenoid valve.

[0020] According to another aspect of the present invention, a method for using the above-described gas path dry-wet switching and pressure stabilization system for fuel cell stack testing is provided, the method comprising the following steps:

[0021] Step 1: First, based on the self-learning function of the control system, record the difference between the inlet pressure sensor of the tested device and the outlet pressure sensor of the humidification system at different flow rates;

[0022] Step 2: When the air pressure is higher than the wet gas pressure during use, the wet gas circuit pressure compensation air supply solenoid valve is opened and the wet gas circuit pressure compensation flow controller is controlled to supply air inward at a smaller flow rate. According to the difference recorded in step 1, the pressure sensor at the outlet of the humidification system reaches a pressure value higher than the dry gas pressure;

[0023] Step 3: When the dry gas pressure is much lower than the wet gas pressure, open the wet gas pressure compensation exhaust solenoid valve to exhaust the air outwards. According to the difference recorded in step 1, the pressure sensor at the outlet of the humidification system reaches a pressure value slightly higher than the dry gas pressure.

[0024] Step 4: Accurately correct the pressure value by opening and closing the wet gas line pressure compensation air supply solenoid valve and the wet gas line pressure compensation exhaust solenoid valve at high frequencies.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1. A gas path dry-wet switching and pressure stabilization system for fuel cell stack testing is proposed.

[0027] 2. Under the premise of ensuring pressure stability, the temperature is still guaranteed not to fluctuate when switching the circuit.

[0028] 3. In addition to pressure control, it also includes flow control, humidity control and temperature control functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the structure of the pressure stabilization system of the present invention.

[0030] Among them, 1 is the gas pretreatment system, 2 is the flow controller, 3 is the dry gas branch, 4 is the wet gas branch, 5 is the temperature control system, 6 is the stack inlet and outlet detection system, 7 is the tail exhaust cooling system, 8 is the back pressure valve system, 9 is the water-gas separation system, 10 is the wet gas path pressure compensation system, 31 is the dry gas branch control solenoid valve, 41 is the wet gas inlet solenoid valve, 42 is the humidification system, 43 is the humidification system outlet pressure sensor, 44 is the wet gas outlet solenoid valve, 1001 is the wet gas path pressure compensation air supply solenoid valve, 1002 is the wet gas path pressure compensation exhaust solenoid valve, 1003 is the wet gas path pressure compensation flow controller, 61 is the inlet pressure sensor of the device under test, 62 is the inlet temperature sensor of the device under test, 63 is the outlet temperature sensor of the device under test, and 64 is the outlet pressure sensor of the device under test. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0032] The system of the present invention is composed of a gas pretreatment system, a flow controller, a dry gas branch, a wet gas branch, a temperature control system, a stack inlet and outlet detection system, a tail exhaust cooling system, a back pressure valve system, a water-gas separation system, and a wet gas circuit pressure compensation system; Figure 1As shown, a gas path dry-wet switching and pressure stabilization system for fuel cell stack testing is used to stabilize the pressure during dry-wet switching and steady-state operation during testing. The gas path dry-wet switching and pressure stabilization system includes a gas pretreatment system 1, a flow controller 2, a parallel dry gas branch 3 and a wet gas branch 4, a temperature control system 5, a fuel cell inlet and outlet detection system 6, a tail exhaust cooling system 7, a back pressure valve system 8 and a water-gas separation system 9 and a wet gas path pressure compensation system 10 connected in sequence. The wet gas path pressure compensation system 10 acts on the wet branch 4 to compensate the pressure of the wet branch 4. compensation; the gas pretreatment system is used to filter gas impurities; the flow controller is used to control the gas flow; the dry gas branch 3 and the wet gas branch 4 are used to transport dry gas and wet gas respectively; the temperature control system 5 is used to control the temperature of the gas entering the stack; the stack inlet and outlet detection system 6 is used to detect the gas temperature and pressure at the inlet and outlet of the stack of the tested device; the tail exhaust cooling system 7 is used to cool the tail exhaust gas; the back pressure valve system 8 is used to control the overall system pressure; the water-gas separation system 9 is used to separate the tail exhaust liquid water.

[0033] The gas pretreatment system 1 includes a hydrogen delivery pipe and a pressure reducing valve, a filter, and a solenoid valve provided on the hydrogen delivery pipe. The dry gas branch 3 includes a dry gas branch control solenoid valve 31, which is used to control the test bench to switch to dry gas.

[0034] The moisture branch 4 includes a moisture inlet solenoid valve 41, a humidification system 42, a humidification system outlet pressure sensor 43 and a moisture outlet solenoid valve 44 connected in sequence. The moisture inlet solenoid valve 41 and the moisture outlet solenoid valve 44 are used to control the moisture switch; the humidification system 42 is used to humidify the gas; the humidification system outlet pressure sensor 43 is used to detect the humidification system outlet pressure.

[0035] The wet gas path pressure compensation system 10 includes a wet gas path pressure compensation air supply solenoid valve 1001 and a wet gas path pressure compensation exhaust solenoid valve 1002. The gas pretreatment system 1 is connected to the humidification system 42 through the wet gas path pressure compensation air supply solenoid valve 1001, which is used to supply air to the humidification system 42; the humidification system 42 is connected to the back pressure valve system 8 through the wet gas path pressure compensation exhaust solenoid valve 1002, which is used to exhaust the humidification system 42.

[0036] The wet gas line pressure compensation system 10 also includes a wet gas line pressure compensation flow controller 1003, which is installed between the gas pretreatment system 1 and the wet gas line pressure compensation gas supply solenoid valve 1001 and is used to control the gas pressure compensation in the humidification system. The wet gas line pressure compensation flow controller 1003 can also be removed to save costs.

[0037] The temperature control system 5 includes a heater, a temperature sensor and a plate heat exchanger, which are used to heat the gas and precisely control the temperature.

[0038] The stack inlet and outlet detection system 6 includes a test piece inlet pressure sensor 61, a test piece inlet temperature sensor 62, a test piece outlet temperature sensor 63 and a test piece outlet pressure sensor 64. The test piece inlet pressure sensor 61 and the test piece inlet temperature sensor 62 are connected in sequence at the stack inlet to detect the gas pressure and temperature at the stack inlet of the test piece; the test piece inlet pressure sensor 61 and the test piece inlet temperature sensor 62 are connected in sequence at the stack inlet to detect the gas pressure and temperature at the stack inlet of the test piece; the test piece outlet temperature sensor 63 and the test piece outlet pressure sensor 64 are connected in sequence at the stack outlet to detect the gas temperature and pressure at the stack inlet of the test piece.

[0039] The exhaust cooling system 7 includes a plate heat exchanger, a ball valve, and a temperature sensor. The back pressure valve system 8 includes a back pressure valve, an electric proportional valve, a buffer tank, and a pressure regulating valve. The water vapor separation system 9 includes a water vapor separation tank, a liquid level sensor, and a solenoid valve.

[0040] The present invention adopts the method of the gas path dry-wet switching and pressure stabilization system for fuel cell stack testing, which includes the following steps:

[0041] Step 1: First, using the control system's self-learning function, record the difference between the pressure sensor 61 at the inlet of the device under test and the pressure sensor 43 at the outlet of the humidification system at different flow rates (due to different pressure losses at different flow rates, the pressure sensor 61 at the inlet of the device under test is generally slightly lower than the pressure sensor 43 at the outlet of the humidification system);

[0042] Step 2: In actual use, when the dry gas pressure is higher than the wet gas pressure, the wet gas circuit pressure compensation air supply solenoid valve 1001 is opened and the wet gas circuit pressure compensation flow controller 1003 is controlled to supply air at a smaller flow rate. Based on the difference recorded in step 1, the humidification system outlet pressure sensor 43 reaches a pressure value slightly higher than the dry gas pressure.

[0043] Step 3: In actual use, when the dry gas pressure is much lower than the wet gas pressure, the wet gas circuit pressure compensation exhaust solenoid valve 1002 is opened to exhaust the gas outward. According to the difference recorded in step 1, the humidification system outlet pressure sensor 43 reaches a pressure value slightly higher than the dry gas pressure;

[0044] Step 4: The pressure value can be accurately corrected by high-frequency opening and closing of the wet gas line pressure compensation air supply solenoid valve 1001 and the wet gas line pressure compensation exhaust solenoid valve 1002.

[0045] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A gas path dry-wet switching and pressure stabilization system for fuel cell stack testing, used to stabilize the pressure during dry-wet switching and steady-state operation during testing, characterized by: The gas path dry-wet switching and pressure stabilization system comprises a gas pretreatment system (1), a flow controller (2), a parallel dry gas branch (3) and a wet gas branch (4), a temperature control system (5), a stack inlet and outlet detection system (6), a tail exhaust cooling system (7), a back pressure valve system (8), a water-gas separation system (9), and a wet gas path pressure compensation system (10) connected in sequence; The gas pretreatment system (1) is used to filter gas impurities; the flow controller (2) is used to control the gas flow; the dry gas branch (3) and the wet gas branch (4) are used to transport dry gas and wet gas respectively; the temperature control system (5) is used to control the temperature of the gas entering the stack; the stack inlet and outlet detection system (6) is used to detect the gas temperature and pressure at the inlet and outlet of the stack of the tested device; the tail exhaust cooling system (7) is used to cool the tail exhaust gas; the back pressure valve system (8) is used to control the overall system pressure; the water-gas separation system (9) is used to separate the tail exhaust liquid water; and the wet gas path pressure compensation system (10) acts on the wet gas branch (4) to compensate for the pressure of the wet gas branch (4).

2. A gas path dry-wet switching and pressure stabilization system for fuel cell stack testing according to claim 1, characterized in that: The gas pretreatment system (1) comprises a hydrogen delivery pipe and a pressure reducing valve, a filter and a solenoid valve arranged on the hydrogen delivery pipe.

3. The gas path dry-wet switching and pressure stabilization system for fuel cell stack testing according to claim 1, characterized in that: The dry gas branch (3) comprises a dry gas branch control solenoid valve (31) for controlling the test bench to switch to dry gas.

4. A gas path dry-wet switching and pressure stabilization system for fuel cell stack testing according to claim 1, characterized in that: The wet gas branch (4) comprises a wet gas inlet solenoid valve (41), a humidification system (42), a humidification system outlet pressure sensor (43) and a wet gas outlet solenoid valve (44) which are connected in sequence; The moisture inlet solenoid valve (41) and the moisture outlet solenoid valve (44) are used to control the moisture switch; the humidification system (42) is used to humidify the gas; and the humidification system outlet pressure sensor (43) is used to detect the humidification system outlet pressure.

5. A gas path dry-wet switching and pressure stabilization system for fuel cell stack testing according to claim 4, characterized in that: The wet gas line pressure compensation system (10) comprises a wet gas line pressure compensation air supply solenoid valve (1001) and a wet gas line pressure compensation exhaust solenoid valve (1002); The gas pretreatment system (1) is connected to the humidification system (42) via the wet gas path pressure compensation air supply solenoid valve (1001) for supplying air to the humidification system (42); the humidification system (42) is connected to the back pressure valve system (8) via the wet gas path pressure compensation exhaust solenoid valve (1002) for exhausting the humidification system (42).

6. A gas path dry-wet switching and pressure stabilization system for fuel cell stack testing according to claim 5, characterized in that: The wet gas line pressure compensation system (10) further comprises a wet gas line pressure compensation flow controller (1003), which is installed between the gas pretreatment system (1) and the wet gas line pressure compensation gas supply solenoid valve (1001) and is used to control the gas pressure compensation of the humidification system.

7. A gas path dry-wet switching and pressure stabilization system for fuel cell stack testing according to claim 1, characterized in that: The temperature control system (5) comprises a heater, a temperature sensor and a plate heat exchanger, and is used to heat the gas and perform precise temperature control.

8. The gas path dry-wet switching and pressure stabilization system for fuel cell stack testing according to claim 1, characterized in that: The stack inlet and outlet detection system (6) includes a test piece inlet pressure sensor (61), a test piece inlet temperature sensor (62), a test piece outlet temperature sensor (63), and a test piece outlet pressure sensor (64); The device under test inlet pressure sensor (61) and the device under test inlet temperature sensor (62) are sequentially connected to the inlet of the battery stack to detect the gas pressure and temperature at the inlet of the battery stack of the device under test; the device under test inlet pressure sensor (61) and the device under test inlet temperature sensor (62) are sequentially connected to the inlet of the battery stack to detect the gas pressure and temperature at the inlet of the battery stack of the device under test; the device under test outlet temperature sensor (63) and the device under test outlet pressure sensor (64) are sequentially connected to the outlet of the battery stack to detect the gas temperature and pressure at the inlet of the battery stack of the device under test.

9. The gas path dry-wet switching and pressure stabilization system for fuel cell stack testing according to claim 1, characterized in that: The tail exhaust cooling system (7) includes a plate heat exchanger, a ball valve and a temperature sensor; the back pressure valve system (8) includes a back pressure valve, an electric proportional valve, a buffer tank and a pressure regulating valve; and the water vapor separation system (9) includes a water vapor separation tank, a liquid level sensor and a solenoid valve.

10. A method for testing a fuel cell stack using the gas path dry-wet switching and pressure stabilization system according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: Step 1: First, according to the self-learning function of the control system, the difference between the inlet pressure sensor (61) of the tested component and the outlet pressure sensor (43) of the humidification system at different flow rates is recorded; Step 2: When the air pressure is higher than the wet gas pressure during use, the wet gas circuit pressure compensation air supply solenoid valve (1001) is opened and the wet gas circuit pressure compensation flow controller (1003) is controlled to supply air inward at a smaller flow rate. According to the difference value recorded in step 1, the pressure sensor (43) at the outlet of the humidification system reaches a pressure value slightly higher than the dry gas pressure. Step 3: When the air pressure is much lower than the wet gas pressure during use, the wet gas circuit pressure compensation exhaust solenoid valve (1002) is opened to exhaust the air outwards, and according to the difference recorded in step 1, the pressure sensor (43) at the outlet of the humidification system reaches a pressure value slightly higher than the dry gas pressure; Step 4: Accurately correct the pressure value by high-frequency opening and closing of the wet gas path pressure compensation air supply solenoid valve (1001) and the wet gas path pressure compensation exhaust solenoid valve (1002).

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