A cold start system for a hydrogen circulation pump and its cold start method

Abstract

The present invention provides a cold start system for a hydrogen circulation pump using ice melting and a cold start method thereof, comprising: a hydrogen tank, a fuel cell, a hydrogen circulation pump, a spiral hydrogen pipeline, valve A, valve B and valve C; the fuel cell includes an anode and a cathode, the spiral hydrogen pipeline is spirally sleeved on the outer wall of the hydrogen circulation pump, one end of the spiral hydrogen pipeline is connected to one end of a first branch pipeline, the other end of the spiral hydrogen pipeline is connected to one end of a second branch pipeline, the hydrogen circulation pump is connected to one end of a third branch pipeline, the other ends of the second branch pipeline and the third branch pipeline are aggregated into a fourth branch pipeline, and the other end of the fourth branch pipeline and the other end of the first branch pipeline are aggregated into a main hydrogen pipeline and connected to the outlet of the anode; valve A is provided on the first branch pipeline, valve B is provided on the second branch pipeline, and valve C is provided on the fourth branch pipeline. The present invention can achieve cold start in a low-temperature environment and collect the unreacted hydrogen during the start-up process of the hydrogen circulation pump.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to a cold start system for a hydrogen circulation pump using ice melting and a cold start method therefor. Background Art

[0002] Nowadays, China's National Energy Administration has proposed to vigorously promote new energy and hydrogen fuel cell vehicles in the transportation field to comprehensively replace traditional energy vehicles and contribute to the achievement of the carbon neutrality goal. However, fuel cell vehicles have not been widely promoted and used due to some technical bottlenecks. One important factor is that when the hydrogen circulation pump, which is a core component of the fuel cell, is cold-started in a low-temperature environment, the pump head and the housing are frozen and jammed, resulting in the inability of the hydrogen circulation pump to be used normally and even posing a risk of damage. During this period, the hydrogen utilization rate of the hydrogen circulation pump decreases, leading to a further reduction in the economy of the fuel cell system. How to safely start the hydrogen circulation pump in a low-temperature environment and improve the hydrogen utilization rate is an urgent problem to be solved in this field.

[0003] The existing cold start technical solutions for hydrogen circulation pumps are roughly divided into the following three categories:

[0004] One category is the traditional self-cooling start-up solution for hydrogen circulation pumps. For example, when the ambient temperature in the fuel cell system has not risen, the hydrogen circulation pump is not used until the surrounding ambient temperature reaches the requirement, and then the hydrogen circulation pump is started to conduct hydrogen circulation. Currently, research shows that the temperature rise of the hydrogen circulation pump mostly comes from the heat dissipation of the fuel cell. Because when the fuel cell starts at -20°C and -30°C, the heat generated by the stack itself can reach 289.6 kJ and 245.2 kJ respectively. During the two cold start processes, the heat dissipated by the battery is 94.92 kJ and 149.80 kJ respectively, and the heat carried away by the reaction gas is 762.45 kJ and 1113.53 kJ respectively. Although this solution avoids damage to the hydrogen circulation pump caused by forced start-up, the unreacted hydrogen generated during the process is discharged to the outside. Therefore, this solution has the problems of low hydrogen utilization rate and hydrogen leakage polluting the environment.

[0005] The second category is the solution of adding an energy-consuming auxiliary device for preheating before starting the hydrogen circulation pump. That is, before the motor starts, hot water is first injected into the heating channel from the water inlet, circulates in the heating channel, and then is discharged from the water outlet. During this process, the temperature of the compression chamber inside the housing of the supercharger can be increased to melt the ice formed by water vapor on the male and female rotors. Although this solution can increase the heating speed inside the pump and greatly reduce the ice melting time, it requires additional power to meet the heating demand, increasing the power consumption and complexity of the fuel cell system, and also increasing the weight and cost of the system.

[0006] The last category is the solution of breaking ice by jittering or rotating the hydrogen circulation pump, that is, sending a jitter instruction and a start instruction to the hydrogen circulation pump to control the hydrogen circulation pump to jitter for ice breaking until the ice in the hydrogen circulation pump is eliminated and the hydrogen circulation pump starts; although this solution reduces the redundant auxiliary heating equipment, when the hydrogen circulation pump jitters or rotates for ice breaking, it will cause additional wear and tear, resulting in a reduced service life of the pump and unnecessary noise. Summary of the Invention

[0007] Aiming at the deficiencies in the prior art, the present invention provides a cold start system for melting ice of a hydrogen circulation pump, which can achieve cold start in a low-temperature environment and collect the hydrogen that has not reacted completely during the start-up process of the hydrogen circulation pump.

[0008] The present invention achieves the above technical objectives through the following technical means.

[0009] A cold start system for melting ice of a hydrogen circulation pump, comprising: a hydrogen tank, a fuel cell, a hydrogen circulation pump, a spiral hydrogen pipeline, valve A, valve B and valve C;

[0010] The fuel cell includes an anode and a cathode. The spiral hydrogen pipeline is spirally sleeved on the outer wall of the hydrogen circulation pump. One end of the spiral hydrogen pipeline is connected to one end of the first branch pipeline, and the other end of the spiral hydrogen pipeline is connected to one end of the second branch pipeline. One end of the hydrogen circulation pump is connected to one end of the third branch pipeline. The other end of the second branch pipeline and the other end of the third branch pipeline are aggregated into a fourth branch pipeline, and the other end of the fourth branch pipeline and the other end of the first branch pipeline are aggregated into a main hydrogen pipeline and connected to the outlet of the anode;

[0011] Valve A is provided on the first branch pipeline, valve B is provided on the second branch pipeline, and valve C is provided on the fourth branch pipeline.

[0012] Further, the axial length of the spiral hydrogen pipeline is L, and L = 1.1L PUMP , where L PUMP is the length of the hydrogen circulation pump.

[0013] Further, the diameter of the spiral hydrogen pipeline is D, where D PUMP is the width of the hydrogen circulation pump, and H PUMP is the height of the hydrogen circulation pump.

[0014] Further, it further includes a control unit, as well as a hydrogen circulation pump controller, a valve controller A, a valve controller B, and a valve controller C connected to the control unit. The hydrogen circulation pump controller is used to control the hydrogen circulation pump, the valve controller A is used to control the valve A, the valve controller B is used to control the valve B, and the valve controller C is used to control the valve C.

[0015] Further, it further includes a temperature sensor for monitoring the temperature inside and outside the hydrogen circulation pump. The temperature sensor is connected to the control unit, and the control unit controls the opening and closing of the hydrogen circulation pump, valve A, valve B, and valve C according to the signal transmitted by the temperature sensor.

[0016] Further, it further includes a clamp-on flow sensor. A drain pipe is provided on the hydrogen circulation pump, and the clamp-on flow sensor is arranged on the drain pipe of the hydrogen circulation pump. The clamp-on flow sensor is connected to the control unit, and the control unit controls the opening and closing of the hydrogen circulation pump, valve A, valve B, and valve C according to the signal transmitted by the clamp-on flow sensor.

[0017] Further, it further includes a pressure sensor for monitoring the air pressure inside the spiral hydrogen pipeline. The pressure sensor is connected to the control unit, and the control unit controls the opening and closing of the valve C and the valve B according to the signal transmitted by the pressure sensor.

[0018] Further, the hydrogen tank is connected to the inlet of the anode through the hydrogen pipeline, and the outlet of the cathode is connected to the first water pipeline.

[0019] Further, the drain pipe and the first water pipeline are aggregated into the main water pipeline.

[0020] The present invention also provides a cold start method for a cold start system of a hydrogen circulation pump, including:

[0021] Step 1: The control unit determines whether the measured value of the temperature sensor is less than or equal to 0°C. If so, go to Step 2; if not, go to Step 4;

[0022] Step 2: The control unit controls the hydrogen circulation pump to be in the closed state, closes the valve B and the valve C, and opens the valve A;

[0023] Step 3: After the fuel cell PEM operates for a certain period of time, when it is determined that the measured value of the temperature sensor is greater than 0°C, if so, go to Step 4; if not, return to Step 2;

[0024] Step 4: Determine whether the measured value of the clamp - type flow sensor is less than the set value. If so, turn on the hydrogen circulation pump and Valve B, and turn off Valve A, then proceed to Step 5. If not, return to Step 3;

[0025] Step 5: When the measured value of the pressure sensor is less than 0 Pa, control Valve C to open and Valve B to close.

[0026] Advantages of the present invention:

[0027] 1. The present invention only needs to transform part of the hydrogen pipeline structure or layout to achieve the safe start - up of the hydrogen circulation pump in a low - temperature environment without wearing the hydrogen circulation pump and without adding other power - consuming devices. This not only avoids wearing the hydrogen circulation pump due to jitter and rotation, extends the service life of the hydrogen circulation pump, but also weakens the noise problem of the hydrogen circulation pump at the source.

[0028] 2. The present invention utilizes the waste heat generated by the fuel cell and most of the heat energy carried out of the fuel cell by the gas. Due to the compact structure and relatively large heat transfer area of the spiral hydrogen pipeline, it can exchange heat with the hydrogen circulation pump well, quickly raise the temperature of the hydrogen circulation pump, realize the efficient utilization of energy, and play a role in energy conservation and environmental protection.

[0029] 3. The temperature sensor and clamp - type flow sensor of the present invention can monitor the temperature inside the hydrogen circulation pump in real time, and the control unit can judge the ice - melting situation in the pump body, improving the safety of starting the hydrogen circulation pump in a low - temperature environment. Description of the Drawings

[0030] Figure 1 is a schematic structural diagram of a cold - start system for a hydrogen circulation pump according to an embodiment of the present invention;

[0031] Figure 2 is a schematic structure of a spiral hydrogen pipeline according to an embodiment of the present invention Figure 1 ;

[0032] Figure 3 is a schematic structure of a spiral hydrogen pipeline according to an embodiment of the present invention Figure 2 ;

[0033] Figure 4 is a schematic structure of a spiral hydrogen pipeline according to an embodiment of the present invention Figure 3 ;

[0034] Figure 5 is a schematic structure of a spiral hydrogen pipeline according to an embodiment of the present invention Figure 4 ;

[0035] Figure 6 is a flowchart of the cold - start of a cold - start system for a hydrogen circulation pump according to an embodiment of the present invention.

[0036] Reference numerals:

[0037] 1. Hydrogen storage tank, 2. Hydrogen circulation pump controller, 3. Hydrogen circulation pump, 4. Temperature sensor, 5. Spiral hydrogen pipeline, 6. Valve C, 7. Valve controller C, 8. Hydrogen pipeline, 9. Anode, 10. Valve A, 11. Valve controller A, 12. Valve B, 13. Valve controller B, 14. Clamp type flow sensor, 15. First water pipeline, 16. Pressure sensor, 17. Cathode. Detailed implementation mode

[0038] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, in which the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention, but should not be construed as a limitation of the present invention.

[0039] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0040] In the present invention, unless otherwise clearly specified and defined, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] First, a cold start system for a hydrogen circulation pump according to an embodiment of the present invention will be specifically described below with reference to the drawings.

[0042] Please refer to Figures 1 to 5, A cold start system for a hydrogen circulation pump according to an embodiment of the present invention includes a hydrogen tank 1, a fuel cell, a hydrogen circulation pump 3, a spiral hydrogen pipeline 5, a valve A10, a valve B12, a valve C6, a control unit, and a hydrogen circulation pump controller 2, a valve controller A11, a valve controller B13, and a valve controller C7 connected to the control unit.

[0043] Specifically, the hydrogen tank 1 is connected to the inlet of the anode 9 through the hydrogen pipeline 8, the outlet of the cathode 17 is connected to the first water pipeline, a drainage pipeline is provided on the hydrogen circulation pump 3, the drainage pipeline and the first water pipeline 15 are aggregated into the main water pipeline, and the main water pipeline is the cooling water pipeline of the fuel cell system.

[0044] The fuel cell includes an anode 9 and a cathode 17. The spiral hydrogen pipeline 5 is spirally sleeved on the outer wall of the hydrogen circulation pump 3, and by increasing the heat exchange area, a large amount of heat carried by the unreacted hydrogen is fully utilized to heat the hydrogen circulation pump 3, realizing the recycling of thermal energy.

[0045] One end of the spiral hydrogen pipeline 5 is connected to one end of the first branch pipeline, the other end of the spiral hydrogen pipeline 5 is connected to one end of the second branch pipeline, the hydrogen circulation pump 3 is connected to one end of the third branch pipeline, the other end of the second branch pipeline and the other end of the third branch pipeline are aggregated into the fourth branch pipeline, and the other end of the fourth branch pipeline and the other end of the first branch pipeline are aggregated into the main hydrogen pipeline and connected to the outlet of the anode 9.

[0046] A valve A10 is provided on the first branch pipeline, a valve B12 is provided on the second branch pipeline, a valve C6 is provided on the fourth branch pipeline, the hydrogen circulation pump controller 2 is used to control the hydrogen circulation pump 3, the valve controller A11 is used to control the valve A10, the valve controller B13 is used to control the valve B12, and the valve controller C7 is used to control the valve C6.

[0047] The axial length of the spiral hydrogen pipeline 5 is L, and L = 1.1L PUMP , where L PUMP is the length of the hydrogen circulation pump 3. The diameter of the spiral hydrogen pipeline 5 is D, where D PUMP is the width of the hydrogen circulation pump 3, and H PUMP is the height of the hydrogen circulation pump 3.

[0048] The temperature sensor 4 is a thermistor temperature sensor, which is arranged on the outer wall surface of the hydrogen circulation pump 3 and is used to monitor the temperature inside and outside the hydrogen circulation pump 3. The temperature sensor 4 is connected to the control unit, and the control unit controls the opening and closing of the hydrogen circulation pump 3, the valve A10, the valve B12, and the valve C6 according to the signal transmitted by the temperature sensor 4.

[0049] The clamp-type flow sensor 14 is arranged on the drainage pipeline of the hydrogen circulation pump 3 for monitoring the internal ice melting condition of the hydrogen circulation pump 3. The clamp-type flow sensor 14 is connected to the control unit, and the control unit controls the opening and closing of the hydrogen circulation pump 3, valve A 10, valve B 12 and valve C 6 according to the signal transmitted by the clamp-type flow sensor 14.

[0050] The pressure sensor 16 is used for monitoring the air pressure inside the spiral hydrogen pipeline 5, and judging whether the hydrogen stored in the spiral hydrogen pipeline 5 has been completely transported back to the circulation loop by the hydrogen circulation pump 3 according to the magnitude. The pressure sensor 16 is connected to the control unit, and the control unit controls the opening and closing of valve C 6 and valve B 12 according to the signal transmitted by the pressure sensor 16.

[0051] The working principle of a cold start system for ice melting of a hydrogen circulation pump according to an embodiment of the present invention is as follows:

[0052] The warm-up ice melting self-cold start scheme of the hydrogen circulation pump 3 includes:

[0053] When the fuel cell vehicle starts in a cold environment, the fuel cell PEM starts accordingly, but the hydrogen circulation pump 3 is suspended. Since the fuel cell PEM provides kinetic energy and heat energy for the entire fuel cell system, the heat dissipation generated by its cold start can increase the temperature of the fuel cell system, raise the ambient temperature around the hydrogen circulation pump 3, and then melt the ice inside the hydrogen circulation pump 3. In addition, the unreacted hydrogen in the fuel cell anode 9 carries a large amount of heat and enters the subsequent spiral hydrogen pipeline 5 from the fuel cell anode 9 to heat and melt the ice of the hydrogen circulation pump 3.

[0054] Furthermore, the power for the unreacted hydrogen to enter the subsequent hydrogen pipeline comes from the air pressure difference inside and outside the outlet end of the fuel cell anode 9. Before the hydrogen circulation pump 3 is started, the amount of hydrogen supplied by the hydrogen storage tank 1 to the fuel cell is greater than the consumption of hydrogen. Although the unreacted hydrogen will stay in the anode 9 stack for a certain period of time, as the hydrogen storage tank 1 continuously supplies hydrogen to the fuel cell, the air pressure difference inside and outside the outlet end of the fuel cell anode 9 increases, thereby pushing the unreacted hydrogen to leave the fuel cell anode 9 and enter the subsequent hydrogen pipeline.

[0055] The hydrogen storage scheme during the self-cold start of ice melting of the hydrogen circulation pump includes:

[0056] The hydrogen storage principle of the spiral hydrogen pipeline 5 is to add or transform the hydrogen pipeline on the hydrogen pipeline section from the outlet of the fuel cell anode 9 to the inlet of the hydrogen circulation pump 3 to achieve the purpose of hydrogen storage and utilization. Among them, due to its special structure, compared with the horizontal straight pipeline, the spiral hydrogen pipeline 5 indirectly increases the pipeline length and cross-section, thereby increasing the hydrogen storage capacity and achieving the hydrogen storage effect.

[0057] A cold start method for a cold start system of a hydrogen circulation pump according to an embodiment of the present invention includes:

[0058] Step 1: The control unit determines whether the measured value of the temperature sensor 4 is less than or equal to 0°C. If so, proceed to Step 2; if not, proceed to Step 4.

[0059] Step 2: The control unit determines that it is a cold start environment, controls the hydrogen circulation pump 3 to be in a closed state, the fuel cell operates normally, closes the valve C6 and the valve B12, and opens the valve A10. Due to the pressure difference, hydrogen that has carried a large amount of heat and has not fully reacted enters the hydrogen pipeline 8 at the anode outlet and gradually fills the spiral hydrogen pipeline 15, realizing hydrogen storage and heat exchange with the hydrogen circulation pump 3, and proceeding to the next step.

[0060] Step 3: After the fuel cell PEM operates for a certain period of time, when it is determined that the measured value of the temperature sensor 4 is greater than 0°C, if so, it is determined that the ice inside the hydrogen circulation pump 3 may have all melted, and proceed to Step 4 to further determine the melting situation; if not, it is determined that the ice inside the hydrogen circulation pump has not melted, and return to Step 2.

[0061] Step 4: After the temperature signal of the temperature sensor 4 continuously exceeds the set temperature, determine whether the measured value of the clamp-type flow sensor 14 is less than the set value. If so, it is determined that the ice inside the hydrogen circulation pump has all melted, turn on the hydrogen circulation pump 3 and the valve B12, close the valve A10, and continue with Step 5; if not, it is determined that the ice inside the hydrogen circulation pump 3 has not all melted, and return to Step 3.

[0062] Step 5: After the hydrogen circulation pump 3 operates for a period of time, when the measured value of the pressure sensor 16 is less than 0 Pa, it is determined that the hydrogen in the spiral hydrogen pipeline 5 has all been transported back to the hydrogen circulation loop, and control the valve C6 to open and the valve B12 to close.

[0063] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0064] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A cold start system for a hydrogen circulation pump, characterized in that, Comprising: A hydrogen gas tank (1), a fuel cell, a hydrogen circulation pump (3), a spiral hydrogen pipeline (5), a valve A (10), a valve B (12), and a valve C (6); The fuel cell includes an anode (9) and a cathode (17). The spiral hydrogen pipeline (5) is spirally sleeved on the outer wall of the hydrogen circulation pump (3). One end of the spiral hydrogen pipeline (5) is connected to one end of a first branch pipeline, and the other end of the spiral hydrogen pipeline (5) is connected to one end of a second branch pipeline. One end of the hydrogen circulation pump (3) is connected to one end of a third branch pipeline. The other end of the second branch pipeline and the other end of the third branch pipeline converge into a fourth branch pipeline. The other end of the fourth branch pipeline and the other end of the first branch pipeline converge into a main hydrogen pipeline and are connected to the outlet of the anode (9); The valve A (10) is provided on the first branch pipeline, the valve B (12) is provided on the second branch pipeline, and the valve C (6) is provided on the fourth branch pipeline.

2. The ice melting cold start system of the hydrogen circulation pump according to claim 1, characterized in that, The axial length of the spiral hydrogen pipeline (5) is L, and L = 1.1L PUMP , where L PUMP is the length of the hydrogen circulation pump (3).

3. The ice melting cold start system of the hydrogen circulation pump according to claim 1, characterized in that, The diameter of the spiral hydrogen pipeline (5) is D, where D PUMP is the width of the hydrogen circulation pump (3), and H PUMP is the height of the hydrogen circulation pump (3).

4. The ice melting cold start system of the hydrogen circulation pump according to claim 1, characterized in that, It further includes a control unit, and a hydrogen circulation pump controller (2), a valve controller A (11), a valve controller B (13), and a valve controller C (7) connected to the control unit. The hydrogen circulation pump controller (2) is used to control the hydrogen circulation pump (3), the valve controller A (11) is used to control the valve A (10), the valve controller B (13) is used to control the valve B (12), and the valve controller C (7) is used to control the valve C (6).

5. The ice melting cold start system of the hydrogen circulation pump according to claim 4, characterized in that, It further includes a temperature sensor (4) for monitoring the temperature inside and outside the hydrogen circulation pump (3). The temperature sensor (4) is connected to the control unit, and the control unit controls the opening and closing of the hydrogen circulation pump (3), the valve A (10), the valve B (12), and the valve C (6) according to the signal transmitted by the temperature sensor (4).

6. The cold start system of the hydrogen circulation pump according to claim 5, characterized in that It further includes a clamp-on flow sensor (14). A drain pipeline is provided on the hydrogen circulation pump (3), and the clamp-on flow sensor (14) is arranged on the drain pipeline of the hydrogen circulation pump (3). The clamp-on flow sensor (14) is connected to the control unit, and the control unit controls the opening and closing of the hydrogen circulation pump (3), the valve A (10), the valve B (12), and the valve C (6) according to the signal transmitted by the clamp-on flow sensor (14).

7. The cold start system of the hydrogen circulation pump according to claim 6, characterized in that, It further includes a pressure sensor (16). The pressure sensor (16) is used to monitor the air pressure inside the spiral hydrogen pipeline (5). The pressure sensor (16) is connected to the control unit, and the control unit controls the opening and closing of the valve C (6) and the valve B (12) according to the signal transmitted by the pressure sensor (16).

8. The ice melting cold start system of the hydrogen circulation pump according to claim 1, characterized in that, The hydrogen gas tank (1) is connected to the inlet of the anode (9) through the hydrogen pipeline (8), and the outlet of the cathode (17) is connected to a first water pipeline (15).

9. The ice melting cold start system of the hydrogen circulation pump according to claim 6, characterized in that, The drain pipeline and the first water pipeline (15) converge into a main water pipeline.

10. The cold start method of the cold start system of the hydrogen circulation pump according to claim 7, characterized in that, Comprising: Step 1: The control unit determines whether the measured value of the temperature sensor (4) is less than or equal to 0 °C. If so, proceed to Step 2; if not, proceed to Step 4. Step 2: The control unit controls the hydrogen circulation pump (3) to be in the closed state, closes valve C (6) and valve B (12), and opens valve A (10). Step 3: After the fuel cell PEM operates for a certain period of time, determine whether the measured value of the temperature sensor (4) is greater than 0 °C. If so, proceed to Step 4; if not, return to Step 2. Step 4: Determine whether the measured value of the clamp-type flow sensor (14) is less than the set value. If so, turn on the hydrogen circulation pump (3) and valve B (12), close valve A (10), and continue with Step 5; if not, return to Step 3. Step 5: When the measured value of the pressure sensor (16) is less than 0 Pa, control valve C (6) to open and valve B (12) to close.

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