Fuel cell stack purging system and method

Abstract

The present invention relates to the technical field of fuel cell purging. Disclosed are a fuel cell stack purging system and method. The purging system comprises a purging device and a control unit, the purging device is separately connected to inlets and outlets of a hydrogen cavity, a water cavity and an air cavity in a fuel cell stack, the control unit is connected to the purging device, and is configured to control the purging device to purge the hydrogen cavity, the water cavity and the air cavity according to a first mode until the humidity of the fuel cell stack is not greater than a preset threshold, and then control the purging device to purge the hydrogen cavity, the water cavity and the air cavity according to a second mode until the humidity of the fuel cell stack is zero. In embodiment of the present invention, the control unit controls the purging device to perform purging according to two modes, so that gas can reach the interior of the fuel cell stack to purge liquid water accumulated at the bottom of the fuel cell stack, improving the purging efficiency.

Description

Fuel cell stack purging system and method TECHNICAL FIELD

[0001] The present application relates to the field of fuel cell purging technology, and in particular to a fuel cell stack purging system and method. BACKGROUND

[0002] A hydrogen fuel cell is a power generation device that converts the chemical energy of hydrogen and an oxidant into electrical energy through an electrochemical reaction. In use, water and heat are generated. The hydrogen fuel cell has the advantages of high energy conversion efficiency, high reliability, and no pollution emissions. In actual application, water is generated inside the fuel cell. After shutdown, the internal water vapor is usually purged to avoid internal icing in low-temperature extreme cold conditions. Ice particles formed by water vapor freezing at low temperatures can pierce the membrane electrode inside the stack, causing hydrogen-air intermixing failure of the stack. If the water channel of the bipolar plate is iced, it can also cause local deformation of the bipolar plate, damage the gas flow channel on the surface of the bipolar plate, and affect the flow resistance of hydrogen and air, thereby affecting the power generation performance of the stack.

[0003] In the prior art, the fuel cell stack is purged in real time, that is, the fuel cell stack is filled with gas from the three-cavity inlet and the gas is discharged from the outlet. However, the gas pressure of this purging method is constant, and the fixed inlet and outlet make the movement trajectory of the gas inside the fuel cell stack unchanged, resulting in less purging gas reaching the inside of the stack, making it difficult to purge the liquid water deposited at the bottom of the fuel cell stack, and low purging efficiency. SUMMARY

[0004] The embodiments of the present application provide a fuel cell stack purging system and method to solve the technical problem of the prior art that the air pressure of the existing purging method is constant, and the fixed inlet and outlet make the movement trajectory of the air inside the fuel cell stack unchanged, resulting in less purging gas reaching the inside of the stack, making it difficult to purge the liquid water deposited at the bottom of the fuel cell stack, and low purging efficiency.

[0005] In a first aspect, a fuel cell stack purging system is provided, comprising:

[0006] a purging device, connected to the inlets and outlets of a hydrogen cavity, a water cavity, and an air cavity in the fuel cell stack, respectively;

[0007] a control unit connected to the purging device and configured to:

[0008] control the purging device to purge the hydrogen cavity, the water cavity, and the air cavity in a first mode until the humidity of the fuel cell stack is not greater than a preset threshold value;

[0009] Then, the purging device is controlled to purge the hydrogen chamber, the water chamber, and the air chamber in the second mode until the humidity of the fuel cell stack is zero.

[0010] In some embodiments, controlling the purging device to purge the hydrogen chamber, the water chamber, and the air chamber in a first mode until the humidity of the fuel cell stack is not greater than a preset threshold includes:

[0011] Obtain the humidity of the fuel cell stack;

[0012] The corresponding charging pressure value is determined based on the humidity of the fuel cell stack.

[0013] The purging device is controlled to fill the hydrogen chamber, the water chamber, and the air chamber with air until the corresponding filling pressure value is reached, and then the purging device is controlled to discharge the air from the hydrogen chamber, the water chamber, and the air chamber.

[0014] In some embodiments, the purging device includes:

[0015] The first control valve, the second control valve, and the sixth control valve are sequentially connected to the hydrogen chamber inlet; the first control valve, the second control valve, and the seventh control valve are sequentially connected to the water chamber inlet; the first control valve, the second control valve, and the eighth control valve are sequentially connected to the air chamber inlet; the first control valve, the second control valve, and the ninth control valve are sequentially connected to the hydrogen chamber outlet; the first control valve, the second control valve, and the tenth control valve are sequentially connected to the water chamber outlet; the first control valve, the second control valve, and the eleventh control valve are sequentially connected to the air chamber outlet; one end of the third control valve is connected to the air outlet, and the other end is connected to the second control valve.

[0016] The step of controlling the purging device to fill the hydrogen chamber, the water chamber, and the air chamber with air until the corresponding filling pressure value is reached, and then controlling the purging device to discharge the air from the hydrogen chamber, the water chamber, and the air chamber, includes:

[0017] Open the first control valve, the second control valve, the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve, and the eleventh control valve to fill the hydrogen chamber, the water chamber, and the air chamber with gas until the corresponding filling pressure value is reached;

[0018] Then close the first control valve and the second control valve, and open the third control valve to discharge the air in the hydrogen chamber, the water chamber and the air chamber.

[0019] In some embodiments, determining the corresponding charging pressure value based on the humidity of the fuel cell stack includes:

[0020] The humidity of the fuel cell stack is positively correlated with the corresponding air charging pressure value.

[0021] In some embodiments, the control of the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until the corresponding air charging pressure value is reached, and then control the purging device to discharge air in the hydrogen cavity, the water cavity and the air cavity, further comprises:

[0022] Obtaining the pressure drop rate of the air discharged from the hydrogen cavity, the water cavity and the air cavity, and controlling the opening of the third control valve according to the pressure drop rate; wherein the opening of the third control valve is negatively correlated with the pressure drop rate of the fuel cell stack.

[0023] In some embodiments, the re-control of the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the second mode until the humidity of the fuel cell stack is zero, comprises:

[0024] Obtaining the humidity of the fuel cell stack;

[0025] Determining the corresponding air supply pressure value according to the humidity of the fuel cell stack;

[0026] Controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity at the corresponding air supply pressure value.

[0027] In some embodiments, the purging device further comprises:

[0028] A fourth control valve connected with the hydrogen cavity inlet, a second end of the fourth control valve being connected with the second end of the first control valve;

[0029] A fifth control valve connected with the air cavity outlet, a second end of the fifth control valve being connected with the second end of the first control valve;

[0030] A twelfth control valve, a first end of the twelfth control valve being connected with the water cavity inlet, and a second end of the twelfth control valve being connected with the hydrogen cavity outlet;

[0031] The control of the purging device to purge the hydrogen cavity, the water cavity and the air cavity at the corresponding air supply pressure value, comprises:

[0032] Opening the first control valve, the fourth control valve, the twelfth control valve, the tenth control valve and the third control valve, air entering the hydrogen cavity through the first control valve and the fourth control valve, entering the water cavity through the twelfth control valve, and then being discharged through the tenth control valve and the third control valve;

[0033] The fifth control valve and the eighth control valve are also opened, and air enters the air cavity through the first control valve and the fifth control valve, and is discharged through the eighth control valve and the third control valve.

[0034] In some embodiments, the control of the purging device to purge the hydrogen cavity, the water cavity and the air cavity at corresponding air supply pressure values further comprises:

[0035] The pressure in the hydrogen cavity and the air cavity is obtained, and the opening degrees of the fourth control valve and the fifth control valve are controlled according to the pressure difference between the hydrogen cavity and the air cavity.

[0036] In some embodiments, the purging device further comprises:

[0037] A humidity sensor, a first end of the humidity sensor being connected with a second end of the second control valve, a second end of the humidity sensor being connected with the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve and the eleventh control valve, the humidity sensor further being connected with the control unit and being configured to obtain the humidity of the fuel cell stack and transmit to the control unit.

[0038] In some embodiments, the purging device further comprises:

[0039] A first pressure sensor, a first end of the first pressure sensor being connected with the second end of the humidity sensor, a second end of the first pressure sensor being connected with the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve and the eleventh control valve, the first pressure sensor further being connected with the control unit and being configured to obtain the air charging pressure value of the fuel cell stack and transmit to the control unit.

[0040] In some embodiments, the purging device further comprises:

[0041] A second pressure sensor, a first end of the second pressure sensor being connected with the eighth control valve, a second end of the second pressure sensor being connected with the air cavity inlet, the second pressure sensor further being connected with the control unit and being configured to obtain the pressure value in the air cavity and transmit to the control unit.

[0042] In some embodiments, the purging device further comprises:

[0043] A third pressure sensor, a first end of the third pressure sensor being connected with the ninth control valve, a second end of the third pressure sensor being connected with the hydrogen cavity outlet, the third pressure sensor further being connected with the control unit and being configured to obtain the pressure value in the hydrogen cavity and transmit to the control unit.

[0044] In some embodiments, the purging device further comprises:

[0045] a flow splitting baffle arranged at the water cavity inlet and configured to increase the rolling flow disturbance of air in the water cavity.

[0046] In a second aspect, a fuel cell stack purging method is provided, using the fuel cell stack purging system as described above, comprising:

[0047] controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity in a first mode until the humidity of the fuel cell stack is not greater than a preset threshold value;

[0048] controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity in a second mode until the humidity of the fuel cell stack is zero.

[0049] In some embodiments, the controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity in a first mode until the humidity of the fuel cell stack is not greater than a preset threshold value comprises:

[0050] obtaining the humidity of the fuel cell stack;

[0051] determining a corresponding air charging pressure value according to the humidity of the fuel cell stack;

[0052] controlling the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until the corresponding air charging pressure value is reached, and then controlling the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity.

[0053] In some embodiments, the controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity in a second mode until the humidity of the fuel cell stack is zero comprises:

[0054] obtaining the humidity of the fuel cell stack;

[0055] determining a corresponding air supply pressure value according to the humidity of the fuel cell stack;

[0056] controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity at the corresponding air supply pressure value.

[0057] The technical solutions provided by the present application have the following beneficial effects:

[0058] The embodiment of the present application provides a fuel cell stack purging system and method, comprising: a purging device and a control unit, the purging device is connected with the inlet and outlet of a hydrogen cavity, a water cavity and an air cavity in a fuel cell stack respectively, the control unit is connected with the purging device and is configured to: control the purging device to purge the hydrogen cavity, the water cavity and the air cavity in a first mode until the humidity of the fuel cell stack is not greater than a preset threshold, and then control the purging device to purge the hydrogen cavity, the water cavity and the air cavity in a second mode until the humidity of the fuel cell stack is zero. The fuel cell stack purging system of the embodiment of the present application controls the purging device to purge in two modes respectively through the control unit, adjusts the gas charging pressure and the movement track of the gas in the fuel cell stack according to the humidity of the fuel cell stack, so that the gas can reach the inside of the stack, the liquid water deposited at the bottom of the fuel cell stack is purged, and the purging efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0060] Fig. 1 is a structural schematic diagram of a fuel cell stack purging system provided by the embodiment of the present application;

[0061] Fig. 2 is a flow chart of a fuel cell stack purging method provided by the embodiment of the present application;

[0062] Fig. 3 is a flow chart of the first mode purging provided by the embodiment of the present application;

[0063] Fig. 4 is a flow chart of the second mode purging provided by the embodiment of the present application;

[0064] Fig. 5 is a schematic diagram of water vapor evaporation in the inside of the stack in the first mode provided by the embodiment of the present application;

[0065] Fig. 6 is a schematic diagram of water vapor evaporation in the inside of the stack in the second mode provided by the embodiment of the present application;

[0066] Fig. 7 is a structural schematic diagram of a shunt baffle provided by the embodiment of the present application;

[0067] Fig. 8 is a schematic diagram of gas flow in the inside of the stack after the shunt baffle is provided according to the embodiment of the present application. DETAILED DESCRIPTION

[0068] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0069] The embodiments of the present application provide a fuel cell stack purging system and method, which can solve the technical problem that the air pressure of the existing purging method is constant, the fixed inlet and outlet make the movement track of the air in the fuel cell stack unchanged, the purging gas reaching the inside of the fuel cell stack is less, it is difficult to purge the liquid water deposited at the bottom of the fuel cell stack, and the purging efficiency is low.

[0070] Fig. 1 is a fuel cell stack purging system provided by the embodiments of the present application, which comprises:

[0071] The purging device is connected with the inlets and outlets of the hydrogen cavity, the water cavity and the air cavity in the fuel cell stack respectively, and the control unit is connected with the purging device and configured to control the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the first mode until the humidity of the fuel cell stack is not greater than a preset threshold, and then control the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the second mode until the humidity of the fuel cell stack is zero.

[0072] The fuel cell stack purging system of the embodiment of the present application is provided with a purging device and a control unit, the purging device is connected with the hydrogen cavity, water cavity and air cavity in the fuel cell stack respectively, the control unit is connected with the purging device and is configured to control the purging device to purge the hydrogen cavity, water cavity and air cavity in the first mode until the humidity of the fuel cell stack is not greater than a preset threshold, and then control the purging device to purge the hydrogen cavity, water cavity and air cavity in the second mode until the humidity of the fuel cell stack is zero. The preset threshold is 20% of relative humidity, the control unit first acquires the humidity of the fuel cell stack, if the humidity of the fuel cell stack is not less than 20% of relative humidity, the control device controls the purging device to purge the hydrogen cavity, water cavity and air cavity in the first mode until the humidity of the fuel cell stack is not greater than 20% of relative humidity, and then controls the purging device to purge the hydrogen cavity, water cavity and air cavity in the second mode until the humidity of the fuel cell stack is zero; if the humidity of the fuel cell stack is less than 20% of relative humidity, the control device controls the purging device to directly purge the hydrogen cavity, water cavity and air cavity in the second mode until the humidity of the fuel cell stack is zero. The gas filling pressure and gas flow trajectory of the first mode and the second mode are different, by adjusting the gas pressure and the movement trajectory of the gas in the fuel cell stack, the gas can reach the inside of the stack, purge the liquid water deposited at the bottom of the fuel cell stack, and improve the purging efficiency.

[0073] As an optional implementation, in one of the embodiments of the application, referring to FIG. 2, the control of the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the first mode until the humidity of the fuel cell stack is not greater than a preset threshold value comprises: obtaining the humidity of the fuel cell stack, determining a corresponding air charging pressure value according to the humidity of the fuel cell stack, controlling the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until the corresponding air charging pressure value is reached, and then controlling the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity. If the relative humidity of the fuel cell stack is 100%, the corresponding air charging pressure value is 200 Kpa, the control device controls the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until 200 Kpa is reached, and then controls the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity. If the relative humidity of the fuel cell stack is 90%, the corresponding air charging pressure value is 190 Kpa, the control device controls the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until 190 Kpa is reached, and then controls the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity. Different air charging pressure values are determined according to different humidity values of the fuel cell stack to purge the fuel cell stack, which can avoid the fuel cell stack being in a high-pressure purging state for a long time and protect the internal membrane electrode of the fuel cell stack.

[0074] As an optional implementation, in one of the embodiments of the application, referring to FIG. 1 and FIG. 3, the purging device comprises: a first control valve, a second control valve, a sixth control valve and the hydrogen cavity inlet connected in sequence, a first control valve, a second control valve, a seventh control valve and the water cavity inlet connected in sequence, a first control valve, a second control valve, an eighth control valve and the air cavity inlet connected in sequence, a first control valve, a second control valve, a ninth control valve and the hydrogen cavity outlet connected in sequence, a first control valve, a second control valve, a tenth control valve and the water cavity outlet connected in sequence, a first control valve, a second control valve, an eleventh control valve and the air cavity outlet connected in sequence, a third control valve connected to the air outlet at one end and connected to the second control valve at the other end. The control of the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until the corresponding air charging pressure value is reached, and then control the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity comprises: opening the first control valve, the second control valve, the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve, the eleventh control valve to charge air into the hydrogen cavity, the water cavity and the air cavity until the corresponding air charging pressure value is reached, then closing the first control valve and the second control valve, and opening the third control valve to discharge the air in the hydrogen cavity, the water cavity and the air cavity.

[0075] Specifically, referring to FIG. 1 and FIG. 5, the first control valve and the second control valve are connected with the air inlet, compressed air flows through the first control valve, the second control valve, the sixth control valve from the hydrogen cavity inlet into the hydrogen cavity, compressed air flows through the first control valve, the second control valve, the seventh control valve from the water cavity inlet into the water cavity, compressed air flows through the first control valve, the second control valve, the eighth control valve from the air cavity inlet into the air cavity, compressed air flows through the first control valve, the second control valve, the ninth control valve from the hydrogen cavity outlet into the hydrogen cavity, compressed air flows through the first control valve, the second control valve, the tenth control valve from the water cavity outlet into the water cavity, compressed air flows through the first control valve, the second control valve, the eleventh control valve from the air cavity outlet into the air cavity, until the pressure in the hydrogen cavity, the water cavity and the air cavity reaches the corresponding inflation pressure value, then the first control valve and the second control valve are closed, the third control valve is opened, the third control valve is connected with the air outlet, the air in the hydrogen cavity, the water cavity and the air cavity is discharged from the third control valve through the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve and the eleventh control valve at the same time, at the same time, the high-pressure gas in the fuel cell stack is quickly discharged to form a siphon effect, and the water vapor in the fuel cell stack is carried out, in this process, the six branches of the purge device are all discharging air, the air discharge distance is short, which is beneficial to the evaporation of water vapor in the central part of the fuel cell stack, and the evaporation path of the water vapor in the fuel cell stack is as shown in FIG. 5, and the water vapor content carried out by this kind of purge mode is relatively high, thereby improving the purge efficiency and quality.

[0076] As an optional embodiment, in one embodiment of the application, referring to FIG. 1, the corresponding inflation pressure value is determined according to the humidity of the fuel cell stack, which includes that the humidity of the fuel cell stack and the corresponding inflation pressure value are in a positive correlation, that is, when the humidity of the fuel cell stack increases or decreases, the corresponding inflation pressure value also increases or decreases. When the relative humidity of the fuel cell stack is 100%, the corresponding inflation pressure value is 200 Kpa; when the relative humidity of the fuel cell stack is 90%, the corresponding inflation pressure value is 190 Kpa.

[0077] As an optional implementation, in one of the embodiments, referring to FIG. 1, the control of the purging device to fill the hydrogen cavity, the water cavity and the air cavity with gas until the corresponding filling pressure value is reached, and then control the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity, further comprises: obtaining the pressure drop rate of the air discharged from the hydrogen cavity, the water cavity and the air cavity, and controlling the opening of the third control valve according to the pressure drop rate; wherein the opening of the third control valve is negatively correlated with the pressure drop rate of the fuel cell stack, and the pressure drop rate Vs is set to operate at 10 Kpa / s to keep the pressure drop rate of the fuel cell stack constant. When the pressure drop rate Vs is less than 10 Kpa / s, the opening of the third control valve is increased to speed up the air discharge rate in the hydrogen cavity, the water cavity and the air cavity; when the pressure drop rate Vs is greater than 10 Kpa / s, the opening of the third control valve is reduced to reduce the air discharge rate in the hydrogen cavity, the water cavity and the air cavity. Keeping the pressure drop rate constant can protect the fuel cell stack so that the internal membrane electrode will not be damaged due to excessive instantaneous pressure change during the purging process.

[0078] As an optional implementation, in one of the embodiments, referring to FIG. 4, the re-control of the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the second mode until the humidity of the fuel cell stack is zero, comprises: obtaining the humidity of the fuel cell stack, determining the corresponding gas supply pressure value according to the humidity of the fuel cell stack, and controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity at the corresponding gas supply pressure value. If the relative humidity of the fuel cell stack is 20%, the humidity of the fuel cell stack determines the corresponding gas supply pressure value as 120 Kpa, and the purging device is controlled to purge the hydrogen cavity, the water cavity and the air cavity at a gas supply pressure value of 120 Kpa; if the humidity of the fuel cell stack is 10%, the humidity of the fuel cell stack determines the corresponding gas supply pressure value as 110 Kpa, and the purging device is controlled to purge the hydrogen cavity, the water cavity and the air cavity at a gas supply pressure value of 110 Kpa.

[0079] As an optional embodiment, in one of the embodiments of the application, referring to Figure 1, the purging device further comprises: a fourth control valve connected with the hydrogen cavity inlet, the second end of the fourth control valve being connected with the second end of the first control valve; a fifth control valve connected with the air cavity outlet, the second end of the fifth control valve being connected with the second end of the first control valve; a twelfth control valve, the first end of the twelfth control valve being connected with the water cavity inlet, and the second end of the twelfth control valve being connected with the hydrogen cavity outlet; and the control of the purging device to purge the hydrogen cavity, the water cavity and the air cavity at corresponding gas supply pressure values comprises: opening the first control valve, the fourth control valve, the twelfth control valve, the tenth control valve and the third control valve, air entering the hydrogen cavity through the first control valve and the fourth control valve, entering the water cavity through the twelfth control valve, and being discharged through the tenth control valve and the third control valve, and further opening the fifth control valve and the eighth control valve, air entering the air cavity through the first control valve and the fifth control valve, and being discharged through the eighth control valve and the third control valve.

[0080] Specifically, referring to Figures 1 and 6, compressed air enters the hydrogen cavity from the hydrogen cavity inlet through the first control valve and the fourth control valve, then enters the water cavity from the water cavity inlet through the twelfth control valve, and is discharged from the water cavity outlet through the tenth control valve and the third control valve, in the process, the gas at the hydrogen cavity outlet is recycled, because the hydrogen cavity has the least water vapor content among the three cavities, the gas at the hydrogen cavity outlet is introduced into the water cavity for secondary purging, that is, the hydrogen cavity and the water cavity are simultaneously purged, and the purging path of the hydrogen cavity is downward inlet and upward outlet; at the same time, the fifth control valve and the eighth control valve are opened, then compressed air enters the air cavity from the air cavity outlet through the first control valve and the fifth control valve, and is discharged from the air cavity inlet through the eighth control valve and the third control valve, and the purging path of the air cavity is upward inlet and downward outlet; because the hydrogen cavity and the air cavity are separated by a proton exchange membrane, the two cavities are in a close contact state, and the hydrogen cavity and the air cavity are simultaneously purged, then the different purging paths form a countercurrent purging, which can improve the relative flow rate on the surface of the proton exchange membrane, and the evaporation path of water vapor in the fuel cell stack is as shown in Figure 6, which accelerates the evaporation of water, thereby improving the purging efficiency and quality.

[0081] As an optional implementation, in one of the embodiments, referring to FIG. 1, the control of the purging device to purge the hydrogen cavity, the water cavity and the air cavity at corresponding air supply pressure values further comprises: acquiring the pressures in the hydrogen cavity and the air cavity, and controlling the opening degrees of the fourth control valve and the fifth control valve according to the pressure difference between the hydrogen cavity and the air cavity, the pressure difference between the hydrogen cavity and the air cavity being set as three groups of positive and negative pressure difference target values, the first group being +10Kpa~-10Kpa, the second group being +20Kpa~-20Kpa, and the third group being +30Kpa~-30Kpa, so that the purging device is purged according to the above three groups of pressure difference target values, that is, when the pressure difference between the hydrogen cavity and the air cavity is greater than +10Kpa, the opening degree of the fourth control valve is increased and the opening degree of the fifth control valve is decreased, and when the pressure difference between the hydrogen cavity and the air cavity is less than -10Kpa, the opening degree of the fourth control valve is decreased and the opening degree of the fifth control valve is increased; when the pressure difference between the hydrogen cavity and the air cavity is greater than +20Kpa, the opening degree of the fourth control valve is increased and the opening degree of the fifth control valve is decreased, and when the pressure difference between the hydrogen cavity and the air cavity is less than -20Kpa, the opening degree of the fourth control valve is decreased and the opening degree of the fifth control valve is increased; when the pressure difference between the hydrogen cavity and the air cavity is greater than +30Kpa, the opening degree of the fourth control valve is increased and the opening degree of the fifth control valve is decreased, and when the pressure difference between the hydrogen cavity and the air cavity is less than -30Kpa, the opening degree of the fourth control valve is decreased and the opening degree of the fifth control valve is increased, and one cycle of purging according to the above three groups of pressure difference target values is a period, and the purging is performed in the cycle to make the membrane electrode between the hydrogen cavity and the air cavity produce relative movement under different pressure differences, which is beneficial to the discharge of water vapor attached to the surface and improves the purging efficiency and quality.

[0082] As an optional implementation, in one of the embodiments, referring to FIG. 1, the purging device further comprises a humidity sensor H, a first end of the humidity sensor H being connected with a second end of the second control valve, a second end of the humidity sensor H being connected with the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve and the eleventh control valve, the humidity sensor H further being connected with the control unit and being configured to acquire the humidity of the fuel cell stack and transmit the humidity to the control unit, the control unit controlling the purging device to purge according to the first mode and the second mode or directly according to the second mode according to the acquired humidity of the fuel cell stack, and the control unit determining corresponding air charging pressure values or air supply pressure values according to the acquired humidity of the fuel cell stack.

[0083] As an optional implementation, in one of the embodiments of the application, referring to FIG. 1, the purging device further comprises: a first pressure sensor P1, a first end of the first pressure sensor P1 is connected with a second end of the humidity sensor H, a second end of the first pressure sensor P1 is connected with the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve, the eleventh control valve, and the first pressure sensor P1 is further connected with the control unit and is configured to obtain the air charging pressure value of the fuel cell stack and transmit to the control unit, when the corresponding air charging pressure value is reached inside the fuel cell stack, the control unit closes the first control valve and the second control valve to stop air charging, and then opens the third control valve to discharge the air in the hydrogen cavity, the water cavity and the air cavity, at the same time, the first pressure sensor P1 is further configured to obtain the pressure drop rate of the fuel cell stack and transmit to the control unit, and the control unit controls the opening degree of the third control valve according to the pressure drop rate of the fuel cell stack.

[0084] As an optional implementation, in one of the embodiments of the application, referring to FIG. 1, the purging device further comprises: a second pressure sensor P2, a first end of the second pressure sensor P2 is connected with the eighth control valve, a second end of the second pressure sensor P2 is connected with the air cavity inlet, and the second pressure sensor P2 is further connected with the control unit and is configured to obtain the pressure value in the air cavity and transmit to the control unit, when the compressed air flows through the first control valve and the fifth control valve from the air cavity outlet into the air cavity, the second pressure sensor P2 can detect the air pressure value inside the air cavity and feed back to the control unit.

[0085] As an optional implementation, in one of the embodiments of the application, referring to FIG. 1, the purging device further comprises: a third pressure sensor P3, a first end of the third pressure sensor P3 is connected with the ninth control valve, a second end of the third pressure sensor P3 is connected with the hydrogen cavity outlet, and the third pressure sensor P3 is further connected with the control unit and is configured to obtain the air charging pressure value of the hydrogen cavity and transmit to the control unit, when the compressed air flows through the first control valve and the fourth control valve from the hydrogen cavity inlet into the hydrogen cavity, the third pressure sensor P3 can detect the air pressure value inside the hydrogen cavity and feed back to the control unit, and the control unit calculates the pressure difference between the air pressure value inside the air cavity and the air pressure value inside the hydrogen cavity according to the feedback, and controls the opening degree of the fourth control valve and the fifth control valve according to the pressure difference between the two.

[0086] As an optional embodiment, in one of the embodiments of the application, referring to FIG. 7 and FIG. 8, the purging device further comprises a flow dividing baffle arranged at the water cavity inlet for increasing the rolling flow disturbance of the air in the water cavity. The flow path of the gas in the fuel cell stack is shown in FIG. 8. In order to improve the purging effect, the flow dividing baffle is arranged at the water cavity inlet to increase the rolling flow disturbance of the gas in the water cavity, so as to increase the contact area of the gas and the liquid water, improve the water vapor carrying capacity of the gas, and achieve the purpose of enhancing the purging effect.

[0087] The embodiment of the application further provides a fuel cell stack purging method, comprising the following steps:

[0088] Step S10, controlling the purging device to purges the hydrogen cavity, the water cavity and the air cavity in the first mode until the humidity of the fuel cell stack is not greater than a preset threshold value.

[0089] Step S20, controlling the purging device to purges the hydrogen cavity, the water cavity and the air cavity in the second mode until the humidity of the fuel cell stack is zero.

[0090] The fuel cell stack purging method provided by the embodiment of the application acquires the humidity of the fuel cell stack through the control unit. If the humidity of the fuel cell stack is not less than 20% relative humidity, the control device controls the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the first mode until the humidity of the fuel cell stack is not greater than 20% relative humidity, and then controls the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the second mode until the humidity of the fuel cell stack is zero. If the humidity of the fuel cell stack is less than 20% relative humidity, the control device controls the purging device to directly purge the hydrogen cavity, the water cavity and the air cavity in the second mode until the humidity of the fuel cell stack is zero. The gas filling pressure and the gas flow trajectory in the first mode and the second mode are different. By adjusting the gas pressure and the gas flow trajectory in the fuel cell stack, the gas can reach the inside of the stack to purge the liquid water deposited at the bottom of the fuel cell stack, and the purging efficiency is improved.

[0091] As an optional implementation, in one of the embodiments, the controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the first mode until the humidity of the fuel cell stack is not greater than a preset threshold value comprises: obtaining the humidity of the fuel cell stack, determining a corresponding air charging pressure value according to the humidity of the fuel cell stack, controlling the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until the corresponding air charging pressure value is reached, and then controlling the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity; if the relative humidity of the fuel cell stack is 100%, the corresponding air charging pressure value is 200 Kpa, the controlling device controls the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until 200 Kpa is reached, and then controls the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity. Different air charging pressure values are determined according to different humidity values of the fuel cell stack to purge the fuel cell stack, which can avoid the fuel cell stack being in a high-pressure purging state for a long time and protect the internal membrane electrode of the fuel cell stack.

[0092] As an optional implementation, in one of the embodiments, the re-controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the second mode until the humidity of the fuel cell stack is zero comprises: obtaining the humidity of the fuel cell stack, determining a corresponding air supply pressure value according to the humidity of the fuel cell stack, and controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity at the corresponding air supply pressure value; if the relative humidity of the fuel cell stack is 20%, the humidity of the fuel cell stack determines that the corresponding air supply pressure value is 120 Kpa, and the purging device is controlled to purge the hydrogen cavity, the water cavity and the air cavity at the air supply pressure value of 120 Kpa.

[0093] In the description of the present application, it should be noted that the positions or position relationships indicated by the terms "upper", "lower" and the like are based on the positions or position relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular position, be constructed and operated in a particular position, and therefore cannot be understood as a limitation on the present application. Unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be a fixed connection, or a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0094] It should be noted that, in the present application, the relational terms such as "first" and "second", and the like, are used solely to distinguish one from another entity or action, without necessarily requiring or implying any actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0095] The foregoing is considered as illustrative only of the principles of the application. Numerous modifications and changes will readily occur to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Accordingly, the scope of the application is intended to be defined only as set forth in the claims.

Claims

1. A fuel cell stack purging system, characterized by, The method comprises the following steps: a purging device connected with the hydrogen cavity, the water cavity and the air cavity in the fuel cell stack respectively; a control unit connected with the purging device and configured to: control the purging device to purge the hydrogen cavity, the water cavity and the air cavity in a first mode until the humidity of the fuel cell stack is not greater than a preset threshold value; control the purging device to purge the hydrogen cavity, the water cavity and the air cavity in a second mode until the humidity of the fuel cell stack is zero.

2. The fuel cell stack purge system of claim 1, wherein, The step of controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the first mode until the humidity of the fuel cell stack is not greater than a preset threshold value comprises the following steps: obtaining the humidity of the fuel cell stack; determining the corresponding air charging pressure value according to the humidity of the fuel cell stack; controlling the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until the corresponding air charging pressure value is reached, and then controlling the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity.

3. A fuel cell stack purge system according to claim 2, characterised in that, The purging device comprises: the first control valve, the second control valve and the sixth control valve are connected with the hydrogen cavity inlet in sequence, the first control valve, the second control valve and the seventh control valve are connected with the water cavity inlet in sequence, the first control valve, the second control valve and the eighth control valve are connected with the air cavity inlet in sequence, the first control valve, the second control valve and the ninth control valve are connected with the hydrogen cavity outlet in sequence, the first control valve, the second control valve and the tenth control valve are connected with the water cavity outlet in sequence, the first control valve, the second control valve and the eleventh control valve are connected with the air cavity outlet in sequence, one end of the third control valve is connected with the air outlet and the other end is connected with the second control valve. The step of controlling the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until the corresponding air charging pressure value is reached, and then controlling the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity comprises the following steps: opening the first control valve, the second control valve, the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve and the eleventh control valve to charge air into the hydrogen cavity, the water cavity and the air cavity until the corresponding air charging pressure value is reached; then closing the first control valve and the second control valve and opening the third control valve to discharge the air in the hydrogen cavity, the water cavity and the air cavity.

4. The fuel cell stack purge system of claim 2, wherein, The step of determining the corresponding air charging pressure value according to the humidity of the fuel cell stack comprises the following steps: the humidity of the fuel cell stack and the corresponding air charging pressure value are in a positive correlation.

5. The fuel cell stack purge system of claim 2, wherein, The step of controlling the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until the corresponding air charging pressure value is reached, and then controlling the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity further comprises the following steps: The pressure drop rate of air in the hydrogen cavity, the water cavity and the air cavity is obtained, and the opening degree of the third control valve is controlled according to the pressure drop rate; wherein the opening degree of the third control valve is negatively correlated with the pressure drop rate of the fuel cell stack.

6. The fuel cell stack purge system of claim 3, wherein, The purging device is further controlled to purge the hydrogen cavity, the water cavity and the air cavity in the second mode until the humidity of the fuel cell stack is zero, comprising: obtaining the humidity of the fuel cell stack; determining the corresponding air supply pressure value according to the humidity of the fuel cell stack; controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity at the corresponding air supply pressure value.

7. A fuel cell stack purge system according to claim 6, characterised in that, The purging device further comprises: a fourth control valve connected with the hydrogen cavity inlet, a second end of the fourth control valve being connected with a second end of the first control valve; a fifth control valve connected with the air cavity outlet, a second end of the fifth control valve being connected with a second end of the first control valve; a twelfth control valve, a first end of the twelfth control valve being connected with the water cavity inlet, and a second end of the twelfth control valve being connected with the hydrogen cavity outlet; The control of the purging device to purge the hydrogen cavity, the water cavity and the air cavity at the corresponding air supply pressure value comprises: opening the first control valve, the fourth control valve, the twelfth control valve, the tenth control valve and the third control valve, and air enters the hydrogen cavity through the first control valve and the fourth control valve, enters the water cavity through the twelfth control valve, and is discharged through the tenth control valve and the third control valve; the fifth control valve and the eighth control valve are also opened, and air enters the air cavity through the first control valve and the fifth control valve, and is discharged through the eighth control valve and the third control valve.

8. The fuel cell stack purge system of claim 6, wherein, The control of the purging device to purge the hydrogen cavity, the water cavity and the air cavity at the corresponding air supply pressure value further comprises: obtaining the pressure in the hydrogen cavity and the air cavity, and controlling the opening degrees of the fourth control valve and the fifth control valve according to the pressure difference between the hydrogen cavity and the air cavity.

9. The fuel cell stack purge system of claim 7, wherein, The purging device further comprises: a humidity sensor, a first end of the humidity sensor being connected with a second end of the second control valve, a second end of the humidity sensor being connected with the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve and the eleventh control valve, and the humidity sensor being further connected with the control unit and being configured to obtain the humidity of the fuel cell stack and transmit the humidity to the control unit.

10. The fuel cell stack purge system of claim 9, wherein, The purging device further comprises: a first pressure sensor, a first end of the first pressure sensor being connected with a second end of the humidity sensor, a second end of the first pressure sensor being connected with the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve and the eleventh control valve, and the first pressure sensor being further connected with the control unit and being configured to obtain the air charging pressure value of the fuel cell stack and transmit the air charging pressure value to the control unit.

11. The fuel cell stack purge system of claim 10, wherein, The purging device further comprises: A second pressure sensor, a first end of the second pressure sensor being connected with the eighth control valve, a second end of the second pressure sensor being connected with the air cavity inlet, the second pressure sensor further being connected with the control unit and being configured to acquire a pressure value in the air cavity and transmit the pressure value to the control unit.

12. The fuel cell stack purge system of claim 11, wherein, The purging device further comprises: A third pressure sensor, a first end of the third pressure sensor being connected with the ninth control valve, a second end of the third pressure sensor being connected with the hydrogen cavity outlet, the third pressure sensor further being connected with the control unit and being configured to acquire a pressure value in the hydrogen cavity and transmit the pressure value to the control unit.

13. The fuel cell stack purge system of claim 12, wherein, The purging device further comprises: A flow splitting baffle, the flow splitting baffle being arranged at the water cavity inlet and being configured to increase the rolling flow disturbance of air in the water cavity.

14. A method of purging a fuel cell stack using the fuel cell stack purging system of claim 1, characterized by, The method comprises: Controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity in a first mode until the humidity of the fuel cell stack is not greater than a preset threshold value; Controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity in a second mode until the humidity of the fuel cell stack is zero.

15. The fuel cell stack purging method according to claim 14, characterized by, The controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the first mode until the humidity of the fuel cell stack is not greater than the preset threshold value comprises: Acquiring the humidity of the fuel cell stack; Determining a corresponding air charging pressure value according to the humidity of the fuel cell stack; Controlling the purging device to charge air into the hydrogen cavity, the water cavity and the air cavity until the corresponding air charging pressure value is reached, and then controlling the purging device to discharge the air in the hydrogen cavity, the water cavity and the air cavity.

16. The fuel cell stack purging method of claim 14, wherein, The controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity in the second mode until the humidity of the fuel cell stack is zero comprises: Acquiring the humidity of the fuel cell stack; Determining a corresponding air supply pressure value according to the humidity of the fuel cell stack; Controlling the purging device to purge the hydrogen cavity, the water cavity and the air cavity at the corresponding air supply pressure value.

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