Cooling liquid control system and method for fuel cell test

Abstract

The invention discloses a cooling liquid control system and method for fuel cell testing, and relates to the field of hydrogen fuel cell testing, the system comprises a water pump, an in-pile pressure sensor, a flow amplifier, a pneumatic control regulating valve, an expansion water tank, a water inlet pipeline, a water outlet pipeline and a system control unit; a reactor inlet pressure sensor is arranged on the water inlet pipeline on the outlet side of the water pump; a first air inlet, a first air outlet, an exhaust port and a pilot pressure port are formed in the flow amplifier, a second air inlet and a second air outlet are formed in the pneumatic control valve, the second air outlet is connected with the pilot pressure port, and the first air outlet is connected with a pressure control port of the expansion water tank through a connecting pipeline; the water pump, the reactor inlet pressure sensor, the flow amplifier and the pneumatic control regulating valve are connected with a system control unit. The system has the advantages that pressurization and pressure relief of the system are controlled in a coupling mode, the dynamic pressure control precision is higher, the dynamic overshoot is lower, and the response speed is higher.

Description

Technical Field

[0001] The present invention relates to the field of hydrogen fuel cell testing, and particularly to a coolant control system and method for fuel cell testing. Background Art

[0002] A hydrogen fuel cell is a device that uses hydrogen and oxygen as raw fuels to convert chemical energy into electrical energy. Fuel cells have the advantages of high energy conversion efficiency and zero pollution, so they have broad application prospects. The fuel cell test system mainly provides a stable, safe and convenient test platform for fuel cells. In the initial stage of fuel cell startup, its temperature is relatively low and its performance is poor, and a cooling system is required to heat up and preheat the fuel cell. During the test process, a large amount of heat is generated while the fuel cell generates electricity, and these heats need to be dissipated by means of a coolant system; and during the test process, the heat generation power of the fuel cell itself increases as the power of the fuel cell increases. During the test process, it is necessary to consider the conductivity of the fuel cell water cooling circuit and detect and control the pressure and temperature at the inlet and outlet of the fuel cell.

[0003] At present, the test of the cooling circuit in the fuel cell test bench only focuses on testing its heat dissipation ability, but it is unable to dynamically control the pressure of the cooling circuit and accurately control the pressure balance of the three chambers. If the stack is a graphite plate, it is easy to cause damage to the plate due to excessive pressure difference, seriously affecting the normal operation of the fuel cell.

[0004] The patent document with publication number CN112098854A discloses a cooling test system and its control method suitable for fuel cell testing, including a cooling system and a test system. The cooling system and the test system are connected by pipelines. When detection is required, the test system can form a test loop for detection; when the cooling system reaches the set temperature, the test system can adjust the flow rate of the coolant; when the coolant provided by the cooling system exchanges heat with the outside, the test system can control the flow rate ratio of the high- and low-temperature coolants to adjust the system temperature. This cooling test system and its control method do not mention pressure control, and it is easy to cause damage to the plate due to excessive pressure difference in the three chambers of the fuel cell during the test, and in severe cases, it will cause damage to the fuel cell.

[0005] The patent document with publication number CN111653808A discloses a circulating water pressure control system for a fuel cell test platform and its usage method. The system includes: a liquid storage container, on which an air inlet is provided and is connected to auxiliary gas through a pressure control unit, and a pressure relief unit is connected to the liquid storage container; a pressure control unit, which is used to control the on-off of the air inlet channel and the exhaust channel of the liquid storage container according to the instructions issued by the control unit; a liquid circulation unit, one end of which is connected to the water outlet of the liquid storage container and the other end is connected to the water inlet of the fuel cell stack; a first pressure feedback unit, which is connected to the pipeline in front of the water inlet of the fuel cell stack and is used to feedback the pressure at the water inlet of the fuel cell stack; a control unit, which is connected to the pressure control unit, the liquid circulation unit and the first pressure feedback unit, and controls the operation of the pressure control unit according to the pressure value collected by the first pressure feedback unit. The pressurization and pressure relief of this system are separately controlled, the dynamic pressure control effect is poor, the dynamic overshoot is serious, the response speed is slow. If the pressure gets out of control, there is no reasonable safety protection logic, and it is impossible to quickly relieve pressure emergently and protect the tested component, which poses a safety hazard. Summary of the Invention

[0006] The technical problem to be solved by the present invention is how to improve the dynamic pressure control effect of the fuel cell water-cooled test loop.

[0007] The present invention solves the above technical problem by the following technical means: a coolant control system for fuel cell testing, including a water pump, an in-stack pressure sensor, a flow amplifier, a pneumatic control valve, an expansion tank, an inlet pipeline, an outlet pipeline and a system control unit; the water outlet of the expansion tank is connected to the water inlet of the hydrogen fuel cell stack through the inlet pipeline, the water outlet of the hydrogen fuel cell stack is connected to the water return port of the expansion tank through the outlet pipeline, a water pump is arranged on the inlet pipeline, and an in-stack pressure sensor is arranged on the inlet pipeline on the outlet side of the water pump; the flow amplifier is provided with a first air inlet, a first air outlet, an exhaust port and a pilot pressure port, the pneumatic control valve is provided with a second air inlet and a second air outlet, the second air outlet is connected to the pilot pressure port, and the first air outlet is connected to the pressure control port of the expansion tank through a connecting pipeline; the water pump, the in-stack pressure sensor, the flow amplifier and the pneumatic control valve are all connected to the system control unit. The pressurization and pressure relief of this system are coupled control, the dynamic pressure control accuracy is higher, the dynamic overshoot is lower, the response speed is faster, the structure is simple, and the control is convenient.

[0008] As an optimized technical solution, a pressure regulating hand valve is arranged on the connecting pipeline. The pressure regulating rate can be adjusted through the pressure regulating hand valve, and the steady-state fluctuation of the water-cooled pressure can be adjusted, which is beneficial to ensuring the high-precision control of the water-cooled pressure.

[0009] As an optimized technical solution, an outlet pressure sensor is provided on the outlet water pipeline, and the outlet pressure sensor is connected to the system control unit.

[0010] As an optimized technical solution, a flow meter is further provided on the inlet water pipeline on the outlet side of the water pump, and the flow meter is connected to the system control unit.

[0011] As an optimized technical solution, an inlet gas control valve is further provided on the inlet water pipeline on the outlet side of the water pump, an outlet gas control valve is provided on the outlet water pipeline, a quick pressure relief solenoid valve is provided at the top of the expansion tank, and the inlet gas control valve, the outlet gas control valve and the quick pressure relief solenoid valve are all connected to the system control unit. When the pressure sensor detects abnormal pressure and the system control unit receives the abnormal pressure signal, it immediately issues a protection instruction to promptly close the water pump, the inlet gas control valve and the outlet gas control valve, and open the quick pressure relief solenoid valve, which can quickly reduce the pressure of the water cooling circuit and protect the coolant control system and the hydrogen fuel cell stack, having a high safety protection mechanism.

[0012] As an optimized technical solution, an inlet temperature sensor is further provided on the inlet water pipeline on the outlet side of the water pump, an outlet temperature sensor and a water cooling temperature control module are provided on the outlet water pipeline, and the inlet temperature sensor, the outlet temperature sensor and the water cooling temperature control module are all connected to the system control unit. The water cooling temperature control module can control the coolant temperature according to the coolant inlet temperature and outlet temperature measured by the inlet temperature sensor and the outlet temperature sensor.

[0013] As an optimized technical solution, a conductivity sensor is provided on the expansion tank, and the conductivity sensor is connected to the system control unit. When there is a deviation between the conductivity and the set value and the system control unit receives the abnormal signal, it immediately issues an instruction to reduce the conductivity, unloads and shuts down the machine to protect the hydrogen fuel cell stack.

[0014] As an optimized technical solution, a first liquid level sensor, a second liquid level sensor and a third liquid level sensor are sequentially arranged from top to bottom on the expansion tank, the expansion tank is connected to a water replenishing mechanism, and the first liquid level sensor, the second liquid level sensor and the third liquid level sensor are all connected to the system control unit. When the liquid level in the expansion tank is at a low level, the system control unit receives the low liquid level signal and issues a water replenishing instruction to replenish water through the water replenishing mechanism. When the liquid level in the expansion tank is at a high level, the system control unit receives the high liquid level signal and issues a stop water replenishing instruction, and the water replenishing mechanism stops replenishing water.

[0015] As an optimized technical solution, a filter is provided on the inlet water pipeline on the inlet side of the water pump.

[0016] A coolant control method for fuel cell testing, using the coolant control system for fuel cell testing, includes the following steps: When the system control unit receives the pressure set value of the water cooling circuit, the system control unit sends the target pressure value instruction to the pneumatic control pressure regulating valve, and the pneumatic control pressure regulating valve outputs the target pressure to the flow amplifier. At this time, the flow amplifier inputs gas into the expansion tank; When the in-stack pressure sensor detects that the pressure reaches the set value, the in-stack pressure sensor gives a feedback signal to the pneumatic control pressure regulating valve, the pneumatic control pressure regulating valve stops pressurizing, and the flow amplifier stops gas input. At this time, the water cooling circuit pressure reaches the pressure target value; When the water cooling circuit heats up, the coolant expands due to heat, and the water cooling circuit pressure increases. When the in-stack pressure sensor detects that the pressure increases and deviates from the target value, the output pressure of the pneumatic control pressure regulating valve remains unchanged, and the exhaust port of the flow amplifier opens to release pressure outward; When the in-stack pressure sensor detects that the pressure reaches the target value, the pressure release stops, so that the water cooling circuit always maintains the target pressure.

[0017] The advantages of the present invention are as follows:

[0018] 1. The pressurization and pressure relief of this system are coupled controls, with higher dynamic control accuracy of pressure, lower dynamic overshoot, faster response speed, simple design structure, low manufacturing cost, small volume, simple control logic, good stability, and convenient installation and later maintenance.

[0019] 2. The pressure control rate can be adjusted through the pressure regulating hand valve, and the steady-state fluctuation of the water cooling pressure can be adjusted, which is beneficial to ensuring the high-precision control of the water cooling pressure.

[0020] 3. When the pressure sensor detects abnormal pressure, the system control unit receives the pressure abnormal signal, then immediately sends a protection instruction, closes the water pump, the in-stack pneumatic control valve and the out-stack pneumatic control valve in time, and opens the fast pressure relief solenoid valve, which can quickly reduce the water cooling circuit pressure and protect the coolant control system and the hydrogen fuel cell stack, having a high safety protection mechanism. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of the coolant control system for fuel cell testing in an embodiment of the present invention.

[0022] Figure 2 It is a schematic structural diagram of the flow amplifier and the pneumatic control regulating valve in an embodiment of the present invention. Detailed Embodiments

[0023] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] As Figure 1 shown, an embodiment of the present invention discloses a coolant control system for fuel cell testing, which is used for controlling the coolant for the hydrogen fuel cell stack 6 testing. The system includes a water pump 1, a flow meter 2, an inlet stack air control valve 3, an inlet stack pressure sensor 4, an inlet stack temperature sensor 5, an outlet stack temperature sensor 7, an outlet stack pressure sensor 8, an outlet stack air control valve 9, a water-cooling temperature control module 10, a conductivity sensor 11, a quick pressure relief solenoid valve 12, a pressure regulating hand valve 13, a flow amplifier 14, an air control regulating valve 15, a first liquid level sensor 16, a second liquid level sensor 17, a third liquid level sensor 18, an expansion tank 19, a filter 20, an inlet water pipe 21, an outlet water pipe 22 and a system control unit.

[0025] The outlet of the expansion tank 19 is connected to the inlet of the hydrogen fuel cell stack 6 through the inlet water pipe 21, and the outlet of the hydrogen fuel cell stack 6 is connected to the return port of the expansion tank 19 through the outlet water pipe 22. A water pump 1 is provided on the inlet water pipe 21, and a filter 20 is provided on the inlet water pipe 21 on the inlet side of the water pump 1.

[0026] On the inlet water pipe 21, a flow meter 2, an inlet stack air control valve 3, an inlet stack pressure sensor 4 and an inlet stack temperature sensor 5 are sequentially arranged from the outlet of the water pump 1 to the inlet of the hydrogen fuel cell stack 6. On the outlet water pipe 22, an outlet stack temperature sensor 7, an outlet stack pressure sensor 8, an outlet stack air control valve 9 and a water-cooling temperature control module 10 are sequentially arranged from the outlet of the hydrogen fuel cell stack 6 to the return port of the expansion tank 19. A quick pressure relief solenoid valve 12 is provided on the top of the expansion tank 19. The inlet stack pressure sensor 4, the inlet stack temperature sensor 5, the outlet stack temperature sensor 7 and the outlet stack pressure sensor 8 are all screwed to the pipeline.

[0027] The coolant flow rate is detected by the flow meter 2, and the coolant inlet stack pressure and the outlet stack pressure are respectively detected by the inlet stack pressure sensor 4 and the outlet stack pressure sensor 8, so that the pressure loss of the hydrogen fuel cell stack 6 under different inlet stack pressures and different flow rates can be obtained.

[0028] When the pressure sensor detects abnormal pressure, the system control unit receives the pressure abnormal signal, then immediately issues a protection instruction, closes the water pump 1, the inlet stack air control valve 3 and the outlet stack air control valve 9 in time, and opens the quick pressure relief solenoid valve 12, so as to quickly reduce the pressure of the water-cooling circuit and protect the coolant control system and the hydrogen fuel cell stack 6.

[0029] The water-cooling temperature control module 10 can control the coolant temperature according to the coolant inlet temperature and outlet temperature measured by the in-pile temperature sensor 5 and the out-pile temperature sensor 7.

[0030] A conductivity sensor 11 is provided on one side of the expansion tank 19. When there is a deviation between the conductivity and the set value, the system control unit receives an abnormal signal, and immediately issues an instruction to reduce the conductivity, unloads and shuts down to protect the hydrogen fuel cell stack 6.

[0031] On the other side of the expansion tank 19, a first liquid level sensor 16, a second liquid level sensor 17, and a third liquid level sensor 18 corresponding to the high liquid level, medium liquid level, and low liquid level are arranged in sequence from top to bottom. The expansion tank 19 is connected to a water replenishing mechanism (not shown in the figure). When the liquid level in the expansion tank 19 is at the low liquid level, the system control unit receives a low liquid level signal and issues a water replenishing instruction to replenish water through the water replenishing mechanism. When the liquid level in the expansion tank 19 is at the high liquid level, the system control unit receives a high liquid level signal and issues a stop water replenishing instruction, and the water replenishing mechanism stops replenishing water.

[0032] Such as Figure 1 、 Figure 2 As shown, the flow amplifier 14 is provided with a first air inlet 141, a first air outlet 142, an exhaust port 143, and a pilot pressure port 144. The pneumatic control valve 15 is provided with a second air inlet 151 and a second air outlet 152. The second air outlet 152 is connected to the pilot pressure port 144 through a ferrule. The first air outlet 142 is connected to the pressure control port of the expansion tank 19 through a connecting pipe. A pressure regulating hand valve 13 is arranged on the connecting pipe; the pressure control rate can be adjusted through the pressure regulating hand valve 13, and the steady-state fluctuation of the water-cooling pressure can be adjusted, which is beneficial to ensuring the high-precision control of the water-cooling pressure; the flow amplifier 14 is an existing air source treatment element, and its function is to generate a high flow rate and an amplified pressure output with a pneumatic signal.

[0033] The water pump 1, the flow meter 2, the in-pile pneumatic control valve 3, the in-pile pressure sensor 4, the in-pile temperature sensor 5, the out-pile temperature sensor 7, the out-pile pressure sensor 8, the out-pile pneumatic control valve 9, the water-cooling temperature control module 10, the conductivity sensor 11, the quick pressure relief solenoid valve 12, the flow amplifier 14, the pneumatic control valve 15, the first liquid level sensor 16, the second liquid level sensor 17, and the third liquid level sensor 18 are all connected to the system control unit, and the system control unit is used to control the above components.

[0034] Working principle: When the hydrogen fuel cell stack 6 starts to work, pressure control is required for the anode, cathode, and water chamber of the hydrogen fuel cell stack 6. The system mainly adds a portable pressure control mechanism and a quick pressure relief device to the expansion tank 19, and adopts the combination of the flow amplifier 14 and the pneumatic pressure regulating valve 15 to solve the problem that most existing test benches cannot control the water-cooling pressure of the fuel cell stack. When testing the hydrogen fuel cell stack 6, it can control the water inlet pressure of the hydrogen fuel cell stack 6 water circuit, maintain the pressure balance of the three chambers, improve the versatility of the test bench, avoid damage to the electrode plates due to large pressure differences in the three chambers during the test of the hydrogen fuel cell stack 6, and effectively protect the hydrogen fuel cell stack 6. The pressurization speed can reach 6 Kpa / S, the pressure reduction speed can reach 8 Kpa / S, the dynamic pressure overshoot is within ±2 Kpa, the steady-state pressure control accuracy is within ±1 Kpa, the response speed is fast, the dynamic performance is good, the dynamic and steady-state control accuracy is high, the design structure is simple, the manufacturing cost is low, the volume is small, the control logic is simple, the stability is good, and it is convenient for installation and later maintenance.

[0035] The embodiment of the present invention also discloses a coolant control method for fuel cell testing. Using the coolant control system for fuel cell testing, it includes the following steps: When the system control unit receives the water-cooling circuit pressure set value, the system control unit issues a target pressure value command to the pneumatic pressure regulating valve 15, and the pneumatic pressure regulating valve 15 outputs the target pressure to the flow amplifier 14. At this time, the flow amplifier 14 inputs gas into the expansion tank 19, and the input gas is nitrogen; when the inlet stack pressure sensor 4 detects that the pressure reaches the set value, the inlet stack pressure sensor 4 gives a feedback signal to the pneumatic pressure regulating valve 15, the pneumatic pressure regulating valve 15 stops pressurizing, and the flow amplifier 14 stops gas input. At this time, the water-cooling circuit pressure reaches the pressure target value; when the water-cooling circuit heats up, the coolant expands due to heat, and the water-cooling circuit pressure increases. When the inlet stack pressure sensor 4 detects that the pressure increases and deviates from the target value, the output pressure of the pneumatic pressure regulating valve 15 remains unchanged, and the exhaust port 143 of the flow amplifier 14 opens to release pressure; when the inlet stack pressure sensor 4 detects that the pressure reaches the target value, the pressure relief stops, so that the water-cooling circuit always maintains the target pressure.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fuel cell test coolant control system, characterized in that: It includes a water pump, a stack pressure sensor, a flow amplifier, a gas-controlled regulating valve, an expansion water tank, a water inlet pipeline, a water outlet pipeline and a system control unit; the water outlet of the expansion water tank is connected to the water inlet of the hydrogen fuel cell stack through the water inlet pipeline, the water outlet of the hydrogen fuel cell stack is connected to the water return port of the expansion water tank through the water outlet pipeline, a water pump is arranged on the water inlet pipeline, and a stack pressure sensor is arranged on the water inlet pipeline on the outlet side of the water pump; the flow amplifier is provided with a first air inlet, a first air outlet, an exhaust port and a pilot pressure port, the gas-controlled regulating valve is provided with a second air inlet and a second air outlet, the second air outlet is connected to the pilot pressure port, and the first air outlet is connected to the pressure control port of the expansion water tank through a connecting pipe; the water pump, the stack pressure sensor, the flow amplifier and the gas-controlled regulating valve are all connected to the system control unit.

2. The fuel cell test coolant control system according to claim 1, characterized in that: A pressure regulating hand valve is arranged on the connecting pipeline.

3. The fuel cell test coolant control system according to claim 1, characterized in that: The water outlet pipeline is provided with a stack pressure sensor, and the stack pressure sensor is connected to the system control unit.

4. The fuel cell test coolant control system according to claim 1, characterized in that: A flow meter is also provided on the water inlet pipeline at the outlet side of the water pump, and the flow meter is connected to the system control unit.

5. The fuel cell test coolant control system according to claim 1, characterized in that: An inlet gas control valve is also provided on the water inlet pipeline on the outlet side of the water pump, and an outlet gas control valve is also provided on the water outlet pipeline. A quick pressure relief solenoid valve is provided on the top of the expansion water tank, and the inlet gas control valve, outlet gas control valve and quick pressure relief solenoid valve are all connected to the system control unit.

6. The fuel cell test coolant control system according to claim 1, characterized in that: A stack inlet temperature sensor is also provided on the water inlet pipe at the outlet side of the water pump, and a stack outlet temperature sensor and a water cooling temperature control module are provided on the water outlet pipe. The stack inlet temperature sensor, stack outlet temperature sensor and water cooling temperature control module are all connected to the system control unit.

7. The fuel cell test coolant control system according to claim 1, characterized in that: The expansion water tank is provided with a conductivity sensor, and the conductivity sensor is connected to the system control unit.

8. The fuel cell test coolant control system according to claim 1, characterized in that: The expansion water tank is provided with a first liquid level sensor, a second liquid level sensor and a third liquid level sensor in sequence from top to bottom. The expansion water tank is connected to a water replenishment mechanism. The first liquid level sensor, the second liquid level sensor and the third liquid level sensor are all connected to the system control unit.

9. The fuel cell test coolant control system according to claim 1, characterized in that: A filter is arranged on the water inlet pipeline at the inlet side of the water pump.

10. A method for controlling a coolant for testing a fuel cell, using the coolant control system for testing a fuel cell according to any one of claims 1 to 9, characterized in that: The following steps are involved: When the system control unit receives the water cooling circuit pressure setting value, the system control unit sends the target pressure value instruction to the air-controlled pressure regulating valve, and the air-controlled pressure regulating valve outputs the target pressure to the flow amplifier. At this time, the flow amplifier inputs gas into the expansion water tank; when the stack pressure sensor detects that the pressure reaches the set value, the stack pressure sensor gives a feedback signal to the air-controlled pressure regulating valve, the air-controlled pressure regulating valve stops pressurizing, and the flow amplifier stops gas input. At this time, the water cooling circuit pressure reaches the pressure target value; when the water cooling circuit heats up, the coolant expands due to the heat, and the water cooling circuit pressure increases. When the stack pressure sensor detects that the pressure increases to deviate from the target value, the output pressure of the air-controlled pressure regulating valve remains unchanged, and the exhaust port of the flow amplifier opens to release pressure to the outside; when the stack pressure sensor detects that the pressure reaches the target value, it stops releasing pressure, so that the water cooling circuit always maintains the target pressure.

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