CN115939461B - A method for judging the rationality of water content in fuel cells - Google Patents

Abstract

The invention provides a method for judging the rationality of the water content of a fuel cell. The method includes the following steps: measuring the stack voltage U ₀ of the fuel cell operating under normal rated working conditions, then increasing the coolant inlet and outlet temperatures, and judging Whether it is running stably, and measure the stack voltage U ₁ at this time to determine the water content of the stack; then reduce the coolant inlet and outlet temperatures to determine whether it is running stably, and measure the stack voltage U ₂ at this time to determine the water content of the stack; Then increase the temperature gradient operation at a lower temperature to determine whether the operation is stable, and measure the stack voltage U ₃ at this time to determine the water content in the coolant inlet area; then increase the temperature gradient operation at a higher temperature to determine whether it is stable. Run, and measure the stack voltage U ₄ at this time to determine the water content in the coolant outlet area. The method of the present invention only needs to adjust the temperature of the cooling liquid inlet and outlet to determine whether the water content is reasonable, which is simple and accurate.

Description

A method for judging the rationality of water content in fuel cells

Technical field

The invention belongs to the technical field of fuel cells and relates to a method for judging the rationality of water content in fuel cells.

Background technique

Fuel cells are widely used due to their high power density, light weight and abundant resources. During the operation of the fuel cell, excessive water content inside the battery will cause flooding failure, which will affect the mass transfer and diffusion of gases, thereby hindering the transmission of gas reactants to the reaction site, and the activation loss and concentration loss of the fuel cell will be significant. Increase; if the water content is insufficient, it will lead to membrane dryness failure. Membrane dryness failure will cause the resistivity to increase, causing the fuel cell to increase heat production during operation, further leading to a reduction in energy conversion efficiency and more serious membrane dryness failure, and even causing local Hot spots can cause permanent damage, which can affect fuel cell performance and durability in severe cases.

At the same time, as the power specifications of the fuel cell stack further increase, the demand for output current specifications increases, the active area of the single cell increases, the temperature difference and water content difference within the active area increase, and there are temperature and moisture differences everywhere in the active area. The water content deviates from the optimal state. Therefore, it is necessary to optimize the temperature in different areas according to differences in working conditions and control the water content in the fuel cell.

For example, the fuel cell water content control method, fuel cell system and fuel cell vehicle disclosed in CN 114583220A is based on the hydrogen circulation pump current, supplemented by the minimum voltage of the single cell and the consistency of the single cell voltage to determine the water content of the fuel cell. Is it within the normal range? If the water content is found to be too high or too low, first control and change the stack reaction temperature to try to adjust the fuel cell water content without wasting energy. After changing the stack reaction temperature, the effect will be Under unfavorable conditions, change the air compressor speed and hydrogen discharge frequency to speed up/reduce the drainage of water, improve the response speed to control instructions that change the water content of the fuel cell, and enable the fuel cell stack to work in a suitable environment. There is no need to add valves or pipelines, but the method of judging the water content is more complicated, the judgment results will be affected by differences in working conditions, and the rationality of the regional temperature cannot be judged based on the water content.

Based on the above research, it is necessary to provide a method for judging the rationality of the water content of the fuel cell. The method is simple and easy to implement, can accurately judge whether the water content is reasonable, and can reduce or increase the drainage volume of the stack based on the judgment results.

Contents of the invention

The object of the present invention is to provide a method for judging the rationality of the water content of a fuel cell. The method can judge whether the water content of the stack is reasonable by simply adjusting the temperatures of the coolant inlet and outlet, which is simple and highly accurate. , able to optimize the temperature in different areas according to differences in working conditions.

In order to achieve the purpose of this invention, the present invention adopts the following technical solutions:

The invention provides a method for judging the rationality of the water content of a fuel cell. The method includes the following steps: (1) The fuel cell is operated under normal rated working conditions, and the stack voltage U ₀ is measured at this time;

(2) Step (1) After measuring the stack voltage U ₀ , increase the coolant inlet temperature and coolant outlet temperature at the same time. If the fuel cell cannot operate stably, the water content of the stack is too low;

If the fuel cell can operate stably, measure the stack voltage U ₁ at this time. If U ₁ ≥ _{U 0} + △U, the water content of the stack is too high;

(3) After measuring the stack voltage U ₀ in step (1), or after the judgment in step (2) is completed, reduce the coolant inlet temperature and coolant outlet temperature at the same time. If the fuel cell cannot operate stably, the water content of the stack is too high. ;

If the fuel cell can operate stably, measure the stack voltage U ₂ at this time. If U ₂ ≥ _{U 0} + △U, the stack water content is too low;

(4) After the judgment in step (3) is completed, increase the difference between the coolant outlet temperature and the coolant inlet temperature. If the fuel cell cannot operate stably, the water content in the coolant inlet area is too high;

If the fuel cell can operate stably, measure the stack voltage U ₃ at this time. If U ₃ ≥ _{U 0} +△U, the water content in the coolant inlet area is too low;

(5) After the judgment in step (3) is completed, increase the difference between the coolant outlet temperature and the coolant inlet temperature, or after the judgment in step (4) is completed, increase the coolant inlet temperature and the coolant outlet temperature while ensuring cooling The difference between the liquid outlet temperature and the coolant inlet temperature is not less than the difference described in step (4). If the fuel cell cannot operate stably, the water content in the coolant outlet area is too low;

If the fuel cell can operate stably, measure the stack voltage U ₄ at this time. If U ₄ ≥ _{U 0} + △U, the water content in the coolant outlet area is too high;

The water content refers to the water content under normal rated working conditions, and the △U is the performance deviation threshold of the total output voltage of the stack that requires response processing.

The present invention can judge whether the water content of the stack is reasonable by adjusting the stack coolant inlet temperature and the coolant outlet temperature. When the stack temperature is raised during operation, the temperatures of the coolant inlet and outlet are simultaneously raised. By judging At this time, the voltage value of the stack can determine whether the water content of the stack is too high or too low. If the water content is too high, the drainage volume needs to be increased. If the water content is too low, the drainage volume needs to be reduced. At the same time, as another method of the present invention The parallel technical solution can be operated by lowering the stack temperature, and it can also be judged whether the water content of the stack is reasonable; as another parallel technical solution of the present invention, after the operation of increasing the stack temperature in step (2) is completed, the By lowering the temperature of the stack, the rationality of the water content of the stack can be judged again. Therefore, the present invention can determine whether the water content of the stack is reasonable by simultaneously raising or lowering the temperature of the coolant inlet or outlet.

The present invention can not only judge whether the water content of the stack is reasonable, but also judge whether the regional water content is reasonable by increasing the temperature gradient between the coolant inlet and outlet, thereby judging whether the regional temperature is reasonable, and successfully control the upstream and downstream areas of the coolant. The temperature decoupling of Moisture content to determine whether the coolant outlet temperature is reasonable.

The order of step (2) and step (3) of the present invention can be exchanged, and the order of step (4) and step (5) can be exchanged, but it is necessary to ensure that step (4) and step (5) are in step (2) and step (5). 3) Do it later, otherwise it will affect the accuracy of moisture content judgment.

The water content mentioned in the present invention is reasonable, too high or too low, which refers to the situation under normal rated working conditions, and does not refer to the water content of the fuel cell at the current moment.

Preferably, in step (2), if U ₁ <U ₀ + ΔU, the water content of the stack is reasonable.

Preferably, in step (3), if U ₂ <U ₀ +ΔU, the water content of the stack is reasonable.

Preferably, after the determination in step (2) is completed, the subsequent steps of reducing the coolant inlet temperature and the coolant outlet temperature in step (3) are performed.

Preferably, in the step (4), if U ₃ <U ₀ +ΔU, the water content of the stack is reasonable.

Preferably, in step (5), if U ₄ <U ₀ +ΔU, the water content of the stack is reasonable.

Preferably, after completing the judgment in step (4), the coolant inlet temperature and the coolant outlet temperature are raised to make subsequent judgments.

Preferably, after completing step (5), the fuel cell is restored to normal rated operating conditions.

Preferably, if the water content in the cooling liquid inlet area is too low, the cooling liquid inlet temperature will be too high;

Preferably, if the water content in the cooling liquid inlet area is too high, the cooling liquid inlet temperature will be too low.

The invention performs real-time adjustment according to the regional water content to ensure the normal operation of the fuel cell. If the water content in the coolant inlet area is too low, the coolant inlet temperature will be too high, and the coolant inlet temperature needs to be lowered. Since the local temperature in the active area of the fuel cell determines the saturated vapor pressure of this part, it also determines key factors that affect the operating performance of the fuel cell, such as drainage performance and water content.

Preferably, if the water content in the cooling liquid outlet area is too high, the cooling liquid outlet temperature will be too low.

Preferably, if the water content in the cooling liquid outlet area is too low, the cooling liquid outlet temperature will be too high.

After the present invention passes the judgment in step (4), when ensuring that the coolant inlet and outlet have a large temperature gradient, the temperature of the coolant inlet and outlet is increased, so that the water content of the coolant outlet area can be judged, thereby judging the cooling Check whether the liquid outlet temperature is reasonable. If the water content in the coolant outlet area is too high, the coolant outlet temperature is too low and the coolant outlet temperature needs to be raised.

Preferably, the cooling liquid inlet temperature is 60-80°C, for example, it can be 60°C, 65°C, 70°C, 75°C or 80°C, but is not limited to the listed values. Other unlisted values within the numerical range are the same. Be applicable.

Preferably, the cooling liquid outlet temperature is 70-90°C, for example, it can be 70°C, 75°C, 80°C, 85°C or 90°C, but is not limited to the listed values, and other unlisted values within the numerical range are the same. Be applicable.

In order to ensure the normal operation of the stack and obtain accurate judgment results, it is preferred that the coolant inlet temperature changes within 60-80°C, and the coolant outlet temperature changes within 70-90°C.

The temperature changes of the coolant inlet and outlet of the present invention are realized according to the changes of the coolant pump flow rate and the cooling fan air flow rate.

Preferably, △U in steps (2) to (5) are independently not less than 2mV/cell, for example, it can be 2mV/cell, 5mV/cell, 10mV/cell, 15mV/cell, 20mV/single cell, 25mV/single cell, 30mV/single cell or 35mV/single cell, but not limited to the listed values, other unlisted values within the numerical range are also applicable, preferably 20mV/single cell.

Preferably, the stable operation time is 10s-30min, for example, it can be 10s, 30s, 1min, 5min, 10min, 15min, 20min, 25min or 30min, but is not limited to the listed values, and other values within the range are not listed. The same numerical value applies, preferably 30s-5min.

The stable operation time of the present invention starts from when the coolant inlet and outlet temperature reaches and maintains at the set value.

As a preferred technical solution of the present invention, the method includes the following steps:

(1) The fuel cell is operating under normal rated working conditions, and the stack voltage U ₀ is measured at this time;

(2) Step (1) After measuring the stack voltage U ₀ , increase the coolant inlet temperature and coolant outlet temperature at the same time. If the fuel cell cannot operate stably, the water content of the stack is too low;

If the fuel cell can run stably for 30s-5min, measure the stack voltage U ₁ at this time. If U ₁ <U ₀ +△U, then the water content of the stack is reasonable. If U ₁ ≥U ₀ +△U, the stack contains Water volume is too high;

(3) After the judgment in step (2) is completed, lower the coolant inlet temperature and coolant outlet temperature at the same time. If the fuel cell cannot operate stably, the water content of the stack is too high;

If the fuel cell can run stably for 30s-5min, measure the stack voltage U ₂ at this time. If U ₂ <U ₀ +△U, then the water content of the stack is reasonable. If U ₂ ≥U ₀ +△U, the stack contains Water volume is too low;

(4) After the judgment in step (3) is completed, increase the difference between the coolant outlet temperature and the coolant inlet temperature. If the fuel cell cannot operate stably, the water content in the coolant inlet area is too high and the coolant inlet temperature is too low;

If the fuel cell can run stably for 30s-5min, measure the stack voltage U ₃ at this time. If U ₃ <U ₀ +△U, then the water content of the stack is reasonable. If U ₃ ≥U ₀ +△U, the coolant The water content in the inlet area is too low and the coolant inlet temperature is too high;

(5) After the judgment in step (4) is completed, increase the coolant inlet temperature and coolant outlet temperature, while ensuring that the difference between the coolant outlet temperature and the coolant inlet temperature is not less than the difference stated in step (4). If the fuel If the battery cannot operate stably, the water content in the coolant outlet area is too low and the coolant outlet temperature is too high;

If the fuel cell can run stably for 30s-5min, measure the stack voltage U ₄ at this time. If U ₄ <U ₀ +△U, then the water content of the stack is reasonable. If U ₄ ≥U ₀ +△U, the coolant The water content in the outlet area is too high and the coolant outlet temperature is too low;

(6) After the judgment in step (5) is completed, return the fuel cell to normal rated operating conditions;

The water content refers to the water content under normal rated working conditions, and the △U is the error value of the stack voltage.

Compared with the existing technology, the present invention has the following beneficial effects:

The present invention can determine whether the water content of the stack is reasonable by increasing the stack temperature and lowering the stack temperature, and then based on the stack operation conditions and voltage, so that the drainage volume of the stack can be reduced or increased based on the judgment results; at the same time, , the present invention also obtains the judgment result of the regional water content by changing the temperature gradient between the inlet temperature and the outlet temperature of the coolant, that is, by changing the difference between the outlet temperature and the inlet temperature. Specifically, it can judge the inlet temperature and outlet temperature of the coolant. Whether the temperature is reasonable, the temperature of the upstream and downstream areas of the coolant is decoupled, so that the water content of each area can be analyzed based on performance changes.

Description of the drawings

Figure 1 is a flow chart of the method according to Embodiment 1 of the present invention.

Detailed ways

The technical solution of the present invention will be further described below through specific implementations. Those skilled in the art should understand that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

Example 1

This embodiment provides a method for judging the rationality of the water content of a fuel cell. The flow chart of the method is shown in Figure 1. The method includes the following steps:

(1) The fuel cell operates under normal rated operating conditions, where the coolant inlet temperature is 70°C and the coolant outlet temperature is 80°C. Measure the stack voltage U ₀ at this time;

(2) Step (1) After measuring the stack voltage U ₀ , increase the stack temperature operation, increase the coolant inlet temperature to 80°C, and the coolant outlet temperature to 90°C. If the fuel cell cannot operate stably, the content of the stack The water volume is too low and the drainage volume needs to be reduced;

If the fuel cell can run stably for 5 minutes, measure the stack voltage U ₁ at this time. If U ₁ <U ₀ +△U, then the water content of the stack is reasonable and it will operate under normal rated working conditions. If U ₁ ≥U ₀ +△U, The water content of the stack is too high and the drainage volume needs to be increased;

(3) After the judgment in step (2) is completed, lower the stack temperature for operation, lower the coolant inlet temperature to 60°C, and the coolant outlet temperature to 70°C. If the fuel cell cannot operate stably, the water content of the stack is too high. Improve drainage;

If the fuel cell can run stably for 5 minutes, measure the stack voltage U ₂ at this time. If U ₂ <U ₀ +△U, then the stack water content is reasonable and it will operate under normal rated working conditions. If U ₂ ≥U ₀ +△U, The water content of the stack is too low and the drainage volume needs to be reduced;

(4) After the judgment in step (3) is completed, increase the temperature gradient operation and raise the coolant outlet temperature to 80°C. At this time, the low coolant inlet temperature is 60°C and the coolant outlet temperature is 80°C. If the fuel cell cannot To ensure stable operation, the water content in the coolant inlet area is too high and the coolant inlet temperature is too low. The coolant inlet temperature needs to be raised;

If the fuel cell can run stably for 5 minutes, measure the stack voltage U ₃ at this time. If U ₃ <U ₀ +△U, then the stack water content is reasonable and the stack operates under normal rated working conditions. If U ₃ ≥U ₀ +△U , then the water content in the coolant inlet area is too low and the coolant inlet temperature is too high, so the coolant inlet temperature needs to be lowered;

(5) After the judgment in step (4) is completed, increase the coolant inlet temperature to 70°C and the coolant outlet temperature to 90°C. If the fuel cell cannot operate stably, the water content in the coolant outlet area is too low and the coolant outlet temperature is too high. High, the coolant outlet temperature needs to be lowered;

If the fuel cell can run stably for 5 minutes, measure the stack voltage U ₄ at this time. If U ₄ ＜U ₀ +△U, then the stack water content is reasonable and the stack operates under normal rated working conditions. If U ₄ ≥U ₀ +△U , then the water content in the coolant outlet area is too high and the coolant outlet temperature is too low, so the coolant outlet temperature needs to be increased;

(6) After the judgment in step (5) is completed, return the fuel cell to normal rated operating conditions. At this time, the coolant inlet temperature is 70°C and the coolant outlet temperature is 80°C;

Wherein, the water content refers to the water content under normal rated working conditions, and the △U is 20mV/single cell.

It can be seen from Embodiment 1 that steps (2) and (3) can determine whether the water content of the stack is too high or too low. Through the judgment results, the drainage volume can be adaptively increased or reduced, thereby ensuring the normal operation of the fuel cell; step ( 4) and step (5) can determine whether the water content in the area near the coolant inlet and outlet is too high or too low by increasing the temperature gradient and ensuring that the temperature gradient is large. As a result, the temperatures at the coolant inlet and outlet are adjusted, achieving temperature decoupling between the upstream and downstream areas of the coolant.

At the same time, the judgment method of the present invention only involves changing the temperature at the cooling inlet and outlet and measuring the stack voltage, which is short in time and easy to operate.

Example 2

This embodiment provides a method for judging the rationality of the water content of a fuel cell. Except for increasing the coolant inlet temperature to 85°C and the coolant outlet temperature to 95°C as described in step (2), the method is the same as in the embodiment. 1 is the same.

Example 3

This embodiment provides a method for judging the rationality of the water content of a fuel cell. The method is the same as Embodiment 1 except that the coolant inlet temperature in step (4) is 50°C.

It can be seen from Examples 1-3 that the coolant inlet temperature preferably changes within 60-80°C, and the outlet temperature preferably changes within 70-90°C, which can further improve the accuracy of judgment and ensure the operation of the fuel cell.

To sum up, the present invention provides a method for judging the rationality of the water content of a fuel cell. The method only needs to adjust the temperature of the coolant inlet and outlet to judge whether the water content of the stack is reasonable. At the same time, it can Determine the rationality of the water content in the internal area, thereby determining the rationality of the coolant inlet temperature and coolant outlet temperature, which is simple, highly accurate, easy to implement, and can be optimized according to differences in working conditions.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the technical field should understand that any person skilled in the technical field, within the technical scope disclosed in the present invention, Changes or substitutions that can be easily imagined fall within the protection scope and disclosure scope of the present invention.

Claims (10)

1. A method of determining the water content rationality of a fuel cell, said method comprising the steps of:

(1) The fuel cell operates under normal rated condition, and the stack voltage U is measured ₀ ；

(2) Step (1) measuring the pile voltage U ₀ Then, the temperature of the cooling liquid inlet and the temperature of the cooling liquid outlet are increased at the same time, and if the fuel cell cannot stably operate, the water content of the electric pile is too low;

if the fuel cell can stably operate, the stack voltage U at the moment is measured ₁ If U ₁ ＜U ₀ If delta U is not shown, the water content of the electric pile is reasonable, the electric pile operates under normal rated working conditions, if U is not shown ₁ ≥U ₀ If delta U is in the range, the water content of the electric pile is too high;

(3) Step (1) measuring the pile voltage U ₀ Then, or after the step (2) is judged to be finished, simultaneously reducing the temperature of the cooling liquid inlet and the temperature of the cooling liquid outlet, and if the fuel cell cannot stably run, the water content of the electric pile is too high;

if the fuel cell can stably operate, the stack voltage U at the moment is measured ₂ If U ₂ ≥U ₀ If delta U is in the range, the water content of the electric pile is too low;

(4) After the step (3) is finished, increasing the difference value between the temperature of the cooling liquid outlet and the temperature of the cooling liquid inlet, and if the fuel cell cannot stably run, the water content of the cooling liquid inlet area is too high;

if the fuel cell can stably operate, the stack voltage U at the moment is measured ₃ If U ₃ ≥U ₀ If delta U is exceeded, the water content of the coolant inlet region is too low;

(5) After the step (3) is finished, increasing the difference value between the cooling liquid outlet temperature and the cooling liquid inlet temperature, and simultaneously ensuring that the difference value between the cooling liquid outlet temperature and the cooling liquid inlet temperature is not smaller than the difference value in the step (4), or after the step (4) is finished, increasing the cooling liquid inlet temperature and the cooling liquid outlet temperature, and simultaneously ensuring that the difference value between the cooling liquid outlet temperature and the cooling liquid inlet temperature is not smaller than the difference value in the step (4), and if the fuel cell cannot stably operate, the water content of a cooling liquid outlet area is too low;

if the fuel cell can stably operate, the stack voltage U at the moment is measured ₄ If U ₄ ≥U ₀ If delta U is exceeded, the water content of the cooling liquid outlet area is too high;

the water content refers to the water content under the normal rated working condition, and the DeltaU is a performance deviation threshold value of the total output voltage of the electric pile, which needs to be responded and processed.

2. The method of claim 1, wherein in step (2), if U ₁ ＜U ₀ If delta U is in the range, the water content of the galvanic pile is reasonable;

in the step (3), if U ₂ ＜U ₀ If delta U is in the range, the water content of the galvanic pile is reasonable;

and (3) after the step (2) is judged to be finished, carrying out the subsequent steps of reducing the temperature of the cooling liquid inlet and the temperature of the cooling liquid outlet in the step (3).

3. The method of claim 1, wherein in step (4), if U ₃ ＜U ₀ If delta U is in the range, the water content of the galvanic pile is reasonable;

in the step (5), if U ₄ ＜U ₀ If delta U is in the range, the water content of the galvanic pile is reasonable;

and (3) after the judgment in the step (4) is completed, raising the temperature of the cooling liquid inlet and the temperature of the cooling liquid outlet, and carrying out subsequent judgment.

4. The method of claim 1, wherein after step (5) is completed, the fuel cell is returned to normal nominal operating conditions.

5. The method of claim 1, wherein the coolant inlet zone has a moisture content that is too low and the coolant inlet temperature is too high;

the coolant inlet temperature is too low if the coolant inlet region has too high a moisture content.

6. The method of claim 1, wherein the coolant outlet temperature is too low if the coolant outlet zone moisture content is too high.

7. The method of claim 1, wherein the coolant outlet zone has a water content that is too low and the coolant outlet temperature is too high.

8. The method of claim 1, wherein the coolant inlet temperature is 60-80 ℃;

the temperature of the cooling liquid outlet is 70-90 ℃;

and (3) step (2) to step (5) wherein DeltaU is not less than 2 mV/single cell independently.

9. The method of claim 1, wherein the steady operation time is 10s to 30min.

10. The method according to claim 1, characterized in that it comprises the steps of:

(1) Fuel electricityThe cell operates under normal rated working condition, and the pile voltage U is measured ₀ ；

(2) Step (1) measuring the pile voltage U ₀ Then, the temperature of the cooling liquid inlet and the temperature of the cooling liquid outlet are increased at the same time, and if the fuel cell cannot stably operate, the water content of the electric pile is too low;

if the fuel cell can stably run for 30s-5min, the stack voltage U is measured ₁ If U ₁ ＜U ₀ If delta U is not shown, the water content of the pile is reasonable, if U ₁ ≥U ₀ If delta U is in the range, the water content of the electric pile is too high;

(3) After the step (2) is finished, the temperature of the cooling liquid inlet and the temperature of the cooling liquid outlet are reduced, and if the fuel cell cannot stably run, the water content of the electric pile is too high;

if the fuel cell can stably run for 30s-5min, the stack voltage U is measured ₂ If U ₂ ＜U ₀ If delta U is not shown, the water content of the pile is reasonable, if U ₂ ≥U ₀ If delta U is in the range, the water content of the electric pile is too low;

(4) After the step (3) is finished, increasing the difference value between the temperature of the cooling liquid outlet and the temperature of the cooling liquid inlet, and if the fuel cell cannot stably run, the water content of the cooling liquid inlet area is too high, and the temperature of the cooling liquid inlet is too low;

if the fuel cell can stably run for 30s-5min, measuring the stack voltage U at the moment ₃ If U ₃ ＜U ₀ If delta U is not shown, the water content of the pile is reasonable, if U ₃ ≥U ₀ If delta U is exceeded, the water content of the cooling liquid inlet area is too low, and the cooling liquid inlet temperature is too high;

(5) After the step (4) is finished, the temperature of the cooling liquid inlet and the temperature of the cooling liquid outlet are raised, meanwhile, the difference value between the temperature of the cooling liquid outlet and the temperature of the cooling liquid inlet is not smaller than the difference value in the step (4), if the fuel cell cannot stably run, the water content of the cooling liquid outlet area is too low, and the temperature of the cooling liquid outlet is too high;

if the fuel cell can stably run for 30s-5min, measuring the stack voltage U at the moment ₄ If U ₄ ＜U ₀ If delta U is in the range of +, the water content of the pile is reasonableIf U ₄ ≥U ₀ If delta U is exceeded, the water content of the cooling liquid outlet area is too high, and the cooling liquid outlet temperature is too low;

(6) After the step (5) is judged to be completed, the fuel cell is restored to normal rated working condition operation;

the water content refers to the water content under the normal rated working condition, and the DeltaU is a performance deviation threshold value of the total output voltage of the electric pile, which needs to be responded and processed.