A fuel cell system with an air circulation humidification loop and a humidification method

Abstract

The present application relates to a kind of fuel cell system and humidification method with air circulation humidification loop, system includes fuel cell stack and air system with air circulation humidification loop, air system is equipped with air compressor and intercooler, the outlet of the air compressor and the inlet of the intercooler are communicated, the air pipeline that the intercooler and the air inlet of the fuel cell stack are communicated is equipped with stop valve, the air compressor is used to the air of the air system input is compressed, the inlet end of the air circulation humidification loop and the air exhaust of the fuel cell stack are communicated, the tail exhaust air of the outlet end of the air circulation humidification loop and the high-temperature compressed air exported from the outlet of the air compressor are mixed and input to the inlet of the intercooler.By setting air circulation humidification loop, make use of liquid water and water vapor in tail exhaust air to the cathode inlet air of stack effectively humidification, it is beneficial to fuel cell system in optimum state operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fuel cell technology, in particular to a fuel cell system with air circulation humidification circuit and a humidification method. BACKGROUND

[0002] Fuel cells can be divided into alkaline fuel cells, solid oxide fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells and proton exchange membrane fuel cells according to different fuels and electrolytes. Proton exchange membrane fuel cells have been rapidly developed in various application scenarios due to their high power density, low temperature, small volume and weight, short start-up time, safe and reliable operation, simple structure, easy operation and other advantages. The fuel cell mentioned in the technical solution below refers to a proton exchange membrane fuel cell.

[0003] A fuel cell system generally includes a stack, an air system, a hydrogen system, a cooling system and an electronic control system. The stack is the place of fuel cell electrochemical reaction. The air system is used to provide air that meets the given pressure, flow rate and temperature and humidity requirements. The hydrogen system is used to provide hydrogen that meets the given pressure, flow rate and temperature and humidity requirements. The cooling system achieves the heat dissipation requirement of the heat generated by the fuel cell reaction. The electronic control system completes the functions of power output, component control, monitoring and sampling of various operating parameters, etc.

[0004] In order to make the fuel cell achieve the best working state, the proton exchange membrane inside the stack needs appropriate humidity to maintain the proton conductivity, so the reaction gas (air and hydrogen) entering the stack needs to be humidified. It should be noted that both the reaction generated and the liquid water carried by the gas will affect the electrochemical reaction area of the proton exchange membrane and will cause the performance of the fuel cell to decrease. Therefore, the requirement for humidification is to increase the water vapor content and improve the relative humidity of the reaction gas. The current external humidification technology of the air circuit uses an independent humidifier to humidify the air entering the stack, which has the disadvantages of large volume, high cost and low system integration.

[0005] Therefore, it is necessary to provide a fuel cell system with an air circulation humidification circuit to solve the above technical problems, which has good air humidification effect and high integration degree. SUMMARY

[0006] In order to solve the above technical problems, the present application provides a fuel cell system with an air circulation humidification circuit. The technical problems of the prior art, which uses an independent humidifier to humidify the air entering the stack, have the disadvantages of large volume, high cost and low system integration.

[0007] The technical effects of the present application are achieved as follows:

[0008] The fuel cell system with air circulation humidification circuit comprises a fuel cell stack and an air system with air circulation humidification circuit, the fuel cell stack is provided with an air inlet and an air outlet, the air system is communicated with the fuel cell stack through the air inlet and the air outlet, the air system is provided with an air compressor and an intercooler, the outlet of the air compressor is communicated with the inlet of the intercooler, a stop valve is arranged on the air pipeline communicated with the intercooler and the air inlet, the air compressor is used for compressing the air input into the air system, the inlet end of the air circulation humidification circuit is communicated with the air outlet of the fuel cell stack, the tail exhaust air output from the outlet end of the air circulation humidification circuit is mixed with the high-temperature compressed air output from the outlet of the air compressor and then input into the inlet of the intercooler to complete the circulation of the partial tail exhaust air. By arranging the air circulation humidification circuit, the circulation of the partial tail exhaust air is realized, the liquid water in the circulation tail exhaust air is heated by the high-temperature compressed air from the outlet of the air compressor to obtain more water vapor, so that the humidification amount and humidification effect of the air input into the fuel cell stack are effectively improved, and the humidification effect of the air input into the fuel cell stack is achieved without the external humidifier. The tail exhaust air discharged from the air circulation humidification circuit is mixed with the high-temperature compressed air from the outlet of the air compressor and then enters the fuel cell stack after passing through the intercooler, so that the liquid water in the circulation tail exhaust air which is not vaporized can be vaporized into water vapor in the air transmission process, meanwhile, the dry air and the wet air are mixed for a long distance and the mixing is more sufficient, and the humidification effect is further improved.

[0009] Further, the air system is further provided with a second adjusting valve, the second adjusting valve is communicated with the inlet end of the air circulation humidification circuit, and the air system is arranged to discharge the tail exhaust air which is not input into the air circulation humidification circuit from the tail exhaust air outlet by adjusting the second adjusting valve.

[0010] Further, the air circulation humidification circuit is provided with an ejector, the ejector is provided with a first air inlet, a second air inlet and a first air outlet, the first air inlet is communicated with the outlet of the air compressor, the second air inlet is communicated with the air outlet, the first air outlet is communicated with the inlet of the intercooler, and a first adjusting valve is arranged on the air pipeline communicated with the second air inlet and the air outlet. By adjusting the second adjusting valve for air tail exhaust and the first adjusting valve on the air circulation humidification circuit, the flow of the tail exhaust air input into the air circulation humidification circuit can be controlled, so that the air meeting the air flow and humidity of the fuel cell stack is obtained by mixing the compressed air with a certain flow output from the air compressor, meanwhile, the air flow requirement of the air compressor is also reduced to a certain extent, so that the power consumption of the air compressor is reduced and the efficiency of the fuel cell system is improved.

[0011] Furthermore, a one-way valve is provided on the air pipeline connecting the second air inlet and the first regulating valve.

[0012] Furthermore, a circulation pump is provided on the air circulation and humidification circuit, and the circulation pump is provided with a third air inlet and a second exhaust port. The third air inlet is connected to the air exhaust port, and the second exhaust port is connected to the outlet of the air compressor. A first regulating valve is provided on the air pipeline connecting the third air inlet and the air exhaust port.

[0013] Furthermore, a one-way valve is provided on the air pipeline connected to the second exhaust port at a position for completing the mixing of the tail exhaust air and the high-temperature compressed air.

[0014] In addition, an air circulation humidification method for a fuel cell system is also provided. The method is implemented based on the above-mentioned fuel cell system with an air circulation humidification circuit, and includes:

[0015] Control the shut-off valve to open so that the air entering the air system is compressed by the air compressor to obtain high-temperature compressed air, which is then cooled by the intercooler and enters the fuel cell stack from the air inlet;

[0016] Controlling the second regulating valve to open so as to discharge tail exhaust air after chemical reaction inside the fuel cell stack from the second regulating valve;

[0017] Control the opening of the first regulating valve and adjust the flow of the first regulating valve, and at the same time adjust the flow of the second regulating valve, so as to mix the tail exhaust air based on the target reflux flow with the high-temperature compressed gas at the outlet of the air compressor through the ejector to complete the circulation reflux of the tail exhaust air.

[0018] Furthermore, controlling the first regulating valve to open and adjusting the flow of the first regulating valve previously includes:

[0019] Obtain the required air flow of the fuel cell stack and the flow of high-temperature compressed gas at the outlet of the air compressor;

[0020] The target reflux flow rate is obtained according to the required air flow rate and the flow rate of the high-temperature compressed gas.

[0021] In addition, an air circulation humidification method for a fuel cell system is also provided. The method is implemented based on the above-mentioned fuel cell system with an air circulation humidification circuit, and includes:

[0022] Control the shut-off valve to open so that the air entering the air system is compressed by the air compressor to obtain high-temperature compressed air, which is then cooled by the intercooler and enters the fuel cell stack from the air inlet;

[0023] controlling the second regulating valve to open to discharge the tail exhaust air after chemical reaction inside the fuel cell stack from the second regulating valve;

[0024] controlling the first regulating valve to open and regulating the flow of the first regulating valve, and regulating the flow of the second regulating valve to mix the tail exhaust air based on the target backflow flow and the high-temperature compressed gas at the outlet of the air compressor by the circulating pump to complete the circulating backflow of the tail exhaust air.

[0025] Further, the controlling the first regulating valve to open and regulating the flow of the first regulating valve, comprises:

[0026] obtaining the air demand flow of the fuel cell stack and the flow of the high-temperature compressed gas at the outlet of the air compressor;

[0027] obtaining the target backflow flow according to the air demand flow and the flow of the high-temperature compressed gas.

[0028] As described above, the present application has the following beneficial effects:

[0029] 1) By setting the air circulating humidification loop, the circulating backflow of the partial tail exhaust air is realized, so that the liquid water in the circulating backflow of the tail exhaust air is heated by the high-temperature compressed air at the outlet of the air compressor to obtain more water vapor, thereby effectively improving the humidification amount and humidification effect of the inlet air of the fuel cell stack, so that the humidification effect of the inlet air of the fuel cell stack is achieved without the need for an external humidifier.

[0030] 2) The tail exhaust air discharged by the air circulating humidification loop is mixed with the high-temperature compressed gas at the outlet of the air compressor and then enters the fuel cell stack after passing through the intercooler, so that the liquid water in the circulating backflow of the tail exhaust air that has not been vaporized can be vaporized into water vapor during air transmission, and at the same time, the dry and wet air is mixed for a long distance and the mixing is more sufficient, and the humidification effect is further improved.

[0031] 3) By adjusting the second regulating valve for air tail exhaust and the first regulating valve on the air circulating humidification loop, the flow of the tail exhaust air entering the air circulating humidification loop can be controlled, so that the air satisfying the inlet flow and humidity of the fuel cell stack is obtained after being mixed with the compressed air with a certain flow output by the air compressor, and at the same time, the air flow requirement of the air compressor is also reduced to a certain extent, thereby reducing the power consumption of the air compressor and being beneficial to the improvement of the efficiency of the fuel cell system. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0033] Figure 1 A structural schematic diagram of a fuel cell system with an air circulation humidification circuit according to an embodiment of the present application is provided.

[0034] Figure 2 A structural schematic diagram of a fuel cell system with an air circulation humidification circuit provided with an ejector according to an embodiment of the present application is provided.

[0035] Figure 3 A structural schematic diagram of a fuel cell system with an air circulation humidification circuit provided with a circulation pump according to an embodiment of the present application is provided.

[0036] Figure 4 A flow chart of an air circulation humidification method applied to a fuel cell system according to an embodiment of the present application is provided.

[0037] In the drawings, the corresponding reference signs are as follows:

[0038] Fuel cell stack 1, air system 2, air circulation humidification circuit 3, air compressor 4, intercooler 5, stop valve 6, ejector 7, circulation pump 8, first regulating valve 9, one-way valve 10, second regulating valve 11, hydrogen system 12, cooling system 13. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0040] It should be noted that the terms "first", "second", and the like in the description and in the claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0041] Embodiment 1:

[0042] As Figure 1 shown, the embodiment of the present application provides a fuel cell system with an air circulation humidification circuit, comprising a fuel cell stack 1, an air system 2 with an air circulation humidification circuit 3, a hydrogen system 12, a cooling system 13, the fuel cell stack 1 is provided with an air inlet, an air outlet, a hydrogen inlet, a hydrogen outlet, a cooling liquid inlet and a cooling liquid outlet, the air system 2 communicates with the fuel cell stack 1 through the air inlet and the air outlet, the hydrogen system 12 communicates with the fuel cell stack 1 through the hydrogen inlet and the hydrogen outlet, the cooling system 13 communicates with the fuel cell stack 1 through the cooling liquid inlet and the cooling liquid outlet, the air system 2 is provided with an air compressor 4 and an intercooler 5, the outlet of the air compressor 4 and the inlet of the intercooler 5 communicate, a stop valve 6 is arranged on the air pipeline communicating the intercooler 5 and the air inlet, the air compressor 4 is used for compressing the air input into the air system 2, the inlet end of the air circulation humidification circuit 3 and the air outlet of the fuel cell stack 1 communicate, the tail exhaust air output from the outlet end of the air circulation humidification circuit 3 and the high-temperature compressed air output from the outlet of the air compressor 4 are mixed and input into the inlet of the intercooler 5 to complete the circulation backflow of part of the tail exhaust air.

[0043] It should be noted that the tail exhaust air includes air, liquid water and water vapor, by arranging the air circulation humidification circuit 3, the circulation backflow of part of the tail exhaust air is realized, so that the liquid water in the circulation backflow of the tail exhaust air is heated by the high-temperature compressed air at the outlet of the air compressor 4 to obtain more water vapor, thereby effectively improving the humidification amount and humidification effect of the air input into the fuel cell stack 1, so that the humidification effect of the air input into the fuel cell stack 1 is achieved without the need for an external humidifier.

[0044] Preferably, the air system 2 is further provided with a second regulating valve 11, which is in communication with the inlet end of the air circulation humidification circuit 3, and the air system 2 is arranged to discharge the tail exhaust air that is not input into the air circulation humidification circuit 3 from the tail exhaust air outlet by adjusting the second regulating valve 11.

[0045] Specifically, by adjusting the second regulating valve 11 for air tail exhaust and the first regulating valve 9 on the air circulation humidification circuit 3 for tail exhaust air recirculation, the flow rate of the part of the tail exhaust air that enters the air circulation humidification circuit 3 can be controlled, so that after mixing with the compressed air with a certain flow rate output by the air compressor 4, air that satisfies the fuel cell stack 1 air inlet flow rate and humidity is obtained, and at the same time, the air flow rate requirement of the air compressor 4 is also reduced to a certain extent, so that the power consumption of the air compressor 4 is reduced, which is beneficial to the improvement of the fuel cell system efficiency.

[0046] As shown in FIG. 1, Figure 2 In the first embodiment, the air circulation humidification circuit 3 is provided with an ejector 7, the ejector 7 is provided with a first air inlet, a second air inlet and a first air outlet, the first air inlet is in communication with the outlet of the air compressor 4, the second air inlet is in communication with the air exhaust outlet, and the first air outlet is in communication with the inlet of the intercooler 5. The air pipeline that connects the second air inlet and the air exhaust outlet is provided with a first regulating valve 9.

[0047] Specifically, the air pipeline that connects the second air inlet and the first regulating valve 9 is provided with a one-way valve 10 to ensure the single flow direction of the recirculated tail exhaust air in the air circulation humidification circuit 3.

[0048] As shown in FIG. 2, Figure 3 In the second embodiment, the air circulation humidification circuit 3 is provided with a circulation pump 8, the circulation pump 8 is provided with a third air inlet and a second air outlet, the third air inlet is in communication with the air exhaust outlet, and the second air outlet is in communication with the outlet of the air compressor 4. The air pipeline that connects the third air inlet and the air exhaust outlet is provided with a first regulating valve 9.

[0049] Specifically, the air pipeline that connects the second air outlet and the position for mixing the tail exhaust air and the high-temperature compressed air is provided with a one-way valve 10 to ensure the single flow direction of the recirculated tail exhaust air in the air circulation humidification circuit 3.

[0050] It should be noted that if part of the high-humidity tail exhaust air is sent back to the air inlet of the fuel cell stack 1 for mixing and humidification, dry and wet air mixing, due to the relatively low air temperature of the air inlet of the fuel cell stack 1, the low amount of saturated water vapor, and the short distance of dry and wet gas mixing, the recirculation humidification effect of this way is limited to a certain extent.

[0051] Since the high-temperature compressed air at the outlet of the air compressor 4 has a high water vapor saturation degree, it can absorb and contain more water vapor. Therefore, the air circulation humidification circuit 3 is arranged in a backflow mode of the ejector 7 or the circulating pump 8 to return part of the tail exhaust air to the outlet of the air compressor 3 to mix with the high-temperature compressed air at the outlet of the air compressor 3, so that the high-temperature gas with a high water vapor saturation degree is used to achieve a better humidification effect.

[0052] Meanwhile, the tail exhaust air discharged from the air circulation humidification circuit 3 is mixed with the high-temperature compressed air at the outlet of the air compressor 4, and then enters the fuel cell stack 1 after passing through the intercooler 5, so that the mixing distance of dry air and wet air is longer, and the mixing is more sufficient, so that the liquid water that is not vaporized in the circulating backflow tail exhaust air can be vaporized into water vapor in the air transmission process, and the humidification effect is further improved.

[0053] Specifically, the working process of air circulation humidification is as follows:

[0054] 1) The air enters the air compressor 4 through the air filter, and high-temperature compressed air is obtained after being compressed by the air compressor 4;

[0055] 2) The high-temperature compressed air is discharged from the outlet of the air compressor 4, cooled by the intercooler 5, and then enters the fuel cell stack 1 through the opened stop valve 6;

[0056] 3) The air performs electrochemical reaction in the fuel cell stack 1, and the residual high-humidity air and the generated liquid water form tail exhaust air together and are discharged through the second adjusting valve 11;

[0057] 4) According to the operating state and requirements of the fuel cell system, the first adjusting valve 9 is opened, and the required flow of tail exhaust air is circulated back through the first adjusting valve 9 and the one-way valve 10 under the control of the ejector 7 or the circulating pump 8;

[0058] 5) The circulating backflow tail exhaust air is mixed with the high-temperature gas at the outlet of the air compressor 4, and the mixed air is fully mixed in the long-distance air pipeline between the mixing place and the air inlet of the fuel cell stack 1, so as to achieve the required air humidity requirement and realize the best performance of the fuel cell stack 1.

[0059] As shown in FIG. 1, Figure 4 The embodiment of the present specification provides an air circulation humidification method applied to a fuel cell system, which is realized based on the fuel cell system with the air circulation humidification circuit corresponding to the first embodiment of the first embodiment, and the method comprises the following steps:

[0060] S100: Control the stop valve 6 to be opened, so that the air entering the air system 2 is compressed by the air compressor to obtain high-temperature compressed air, which is cooled by the intercooler 5 and then enters the fuel cell stack 1 from the air inlet.

[0061] S200: controlling the second regulating valve 11 to open, so as to discharge the tail exhaust air after chemical reaction inside the fuel cell stack 1 from the second regulating valve 11;

[0062] S300: controlling the first regulating valve 9 to open and regulating the flow of the first regulating valve 9, while regulating the flow of the second regulating valve 11, so as to mix the tail exhaust air based on the target backflow flow with the high-temperature compressed gas at the outlet of the air compressor 4 through the ejector 7, to complete the mixed humidification of the cathode inlet air of the fuel cell stack 1.

[0063] In a specific embodiment, before controlling the first regulating valve 9 to open and regulating the flow of the first regulating valve 9, the method further comprises:

[0064] obtaining the air demand flow of the fuel cell stack 1 and the flow of the high-temperature compressed gas at the outlet of the air compressor 4;

[0065] obtaining the target backflow flow according to the air demand flow and the flow of the high-temperature compressed gas.

[0066] The embodiment of the present specification provides an air circulation humidification method applied to a fuel cell system, which is implemented based on the second embodiment of the fuel cell system with the air circulation humidification loop in the embodiment 1, and comprises:

[0067] controlling the stop valve 6 to open, so as to make the air entering the air system 2 enter the fuel cell stack 1 from the air inlet after being compressed into high-temperature compressed air by the air compressor and being cooled by the intercooler 5;

[0068] controlling the second regulating valve 11 to open, so as to discharge the tail exhaust air after chemical reaction inside the fuel cell stack 1 from the second regulating valve 11;

[0069] controlling the first regulating valve 9 to open and regulating the flow of the first regulating valve 9, while regulating the flow of the second regulating valve 11, so as to mix the tail exhaust air based on the target backflow flow with the high-temperature compressed gas at the outlet of the air compressor 4 through the circulation pump 8, to complete the mixed humidification of the cathode inlet air of the fuel cell stack 1.

[0070] In a specific embodiment, before controlling the first regulating valve 9 to open and regulating the flow of the first regulating valve 9, the method further comprises:

[0071] obtaining the air demand flow of the fuel cell stack 1 and the flow of the high-temperature compressed gas at the outlet of the air compressor 4;

[0072] obtaining the target backflow flow according to the air demand flow and the flow of the high-temperature compressed gas.

[0073] Although the present application has been described by way of preferred embodiments, it is not intended to limit the application to the embodiments described herein, but rather includes all variations and modifications without departing from the scope of the application.

[0074] The features of the above described embodiments and embodiments in the present document can be combined with each other, without conflict.

[0075] The above disclosure only describes a preferred embodiment of the present application, and of course cannot limit the scope of the present application, so the equivalent changes made according to the claims of the present application still fall within the scope of the present application.

Claims

1. A fuel cell system with an air circulation humidification loop, characterized by, The application relates to a fuel cell system with an air circulation humidification circuit, comprising a fuel cell stack (1) provided with an air inlet and an air outlet, and an air system (2) in communication with the fuel cell stack (1) through the air inlet and the air outlet, wherein the air system (2) is provided with an air compressor (4) and an intercooler (5), the outlet of the air compressor (4) is in communication with the inlet of the intercooler (5), a stop valve (6) is arranged on an air pipeline in communication with the intercooler (5) and the air inlet, the air compressor (4) is used for compressing air input into the air system (2), the air circulation humidification circuit (3) is in communication with the air outlet of the fuel cell stack (1), and tail exhaust air output from the outlet end of the air circulation humidification circuit (3) is mixed with high-temperature compressed air output from the outlet of the air compressor (4) and then input into the inlet of the intercooler (5) to complete the circulation of the partial tail exhaust air. The air circulation humidification circuit (3) is provided with an ejector (7) provided with a first air inlet, a second air inlet and a first air outlet, the first air inlet is in communication with the outlet of the air compressor (4), the second air inlet is in communication with the air outlet, the first air outlet is in communication with the inlet of the intercooler (5), and a first regulating valve (9) is arranged on an air pipeline in communication with the second air inlet and the air outlet. Or the air circulation humidification circuit (3) is provided with a circulation pump (8) provided with a third air inlet and a second air outlet, the third air inlet is in communication with the air outlet, the second air outlet is in communication with the outlet of the air compressor (4), and a first regulating valve (9) is arranged on an air pipeline in communication with the third air inlet and the air outlet.

2. The fuel cell system with an air-circulation humidification circuit according to claim 1, characterized by, The air system (2) is further provided with a second regulating valve (11) in communication with the inlet end of the air circulation humidification circuit (3), and the air system (2) is arranged to discharge tail exhaust air not input into the air circulation humidification circuit (3) from the air outlet by adjusting the second regulating valve (11).

3. The fuel cell system with air cycle humidification loop of claim 1, wherein, A one-way valve (10) is arranged on an air pipeline in communication with the second air inlet and the first regulating valve (9).

4. The fuel cell system with air cycle humidification loop of claim 1, wherein, A one-way valve (10) is arranged on an air pipeline in communication with the second air outlet.

5. An air circulation humidification method applied to a fuel cell system, characterized by, The method is realized based on the fuel cell system with the air circulation humidification circuit as claimed in claim 3, comprising the following steps: The stop valve (6) is controlled to be opened, so that high-temperature compressed air obtained by compressing air entering the air system (2) is cooled by the intercooler (5) and then enters the fuel cell stack (1) from the air inlet; The second regulating valve (11) is controlled to be opened, so that tail exhaust air after chemical reaction in the fuel cell stack (1) is discharged from the second regulating valve (11); controlling the first regulating valve (9) to open and regulating the flow of the first regulating valve (9), and regulating the flow of the second regulating valve (11) to mix the exhaust air based on the target recirculation flow with the high-temperature compressed gas at the outlet of the air compressor (4) through the ejector (7) to complete the recirculation of the exhaust air.

6. The air circulation humidifying method for a fuel cell system according to claim 5, characterized by, Before controlling the first regulating valve (9) to open and regulating the flow of the first regulating valve (9), the method comprises: obtaining the air demand flow of the fuel cell stack (1) and the flow of the high-temperature compressed gas at the outlet of the air compressor (4); obtaining the target recirculation flow according to the air demand flow and the flow of the high-temperature compressed gas.

7. An air circulation humidification method applied to a fuel cell system, characterized by, The method is implemented based on the fuel cell system with the air circulation humidification loop as claimed in claim 4, and comprises: controlling the shutoff valve (6) to open to make the air entering the air system (2) to enter the fuel cell stack (1) from the air inlet after the high-temperature compressed air obtained by compressing the air is cooled by the intercooler (5); controlling the second regulating valve (11) to open to discharge the exhaust air after chemical reaction inside the fuel cell stack (1) from the second regulating valve (11); controlling the first regulating valve (9) to open and regulating the flow of the first regulating valve (9), and regulating the flow of the second regulating valve (11) to mix the exhaust air based on the target recirculation flow with the high-temperature compressed gas at the outlet of the air compressor (4) through the circulation pump (8) to complete the recirculation of the exhaust air.

8. The air circulation humidifying method for a fuel cell system according to claim 7, characterized by, Before controlling the first regulating valve (9) to open and regulating the flow of the first regulating valve (9), the method comprises: obtaining the air demand flow of the fuel cell stack (1) and the flow of the high-temperature compressed gas at the outlet of the air compressor (4); obtaining the target recirculation flow according to the air demand flow and the flow of the high-temperature compressed gas.

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