Fuel cell system

Abstract

The fuel cell system comprises a gas source, a heat exchange device and a galvanic pile, a hydrogen source is connected with the heat exchange device, hydrogen output by the hydrogen source flows through the heat exchange device, the heated hydrogen is input into the galvanic pile, air output by an air source is input into the galvanic pile, and the galvanic pile is connected with the heat exchange device. The hydrogen and the air are subjected to electrochemical reaction in the electric pile; the electric pile is connected with the heat exchange device, and tail gas of the electric pile flows through the heat exchange device. Before hydrogen and air are input into the galvanic pile according to the set volume ratio, the hydrogen flows through the heat exchange device to be preheated and then is input into the galvanic pile, the hydrogen and the air are subjected to an electrochemical reaction in the galvanic pile to generate tail exhaust fluid, and the tail exhaust fluid flows through the heat exchange device to be subjected to heat exchange and then is discharged. In the whole process, hydrogen and air are subjected to electrochemical reaction in the galvanic pile to generate tail exhaust fluid, and the tail exhaust fluid is used for preheating the hydrogen, so that the utilization of heat carried by the tail exhaust fluid is realized.

Description

Technical Field

[0001] This application relates to the technical field of heat recovery and utilization, and more particularly to a fuel cell system. Background Art

[0002] Proton exchange membrane fuel cell engines have become relatively important power devices in energy storage power stations because they are green and pollution-free and can be linked through hydrogen production and storage. Therefore, how to improve the comprehensive efficiency of fuel cells is an issue that needs to be focused on.

[0003] For example, Chinese Patent No. CN 219203206U discloses a waste heat utilization device for a fuel cell power generation system. This patent uses the heat of the thermal management system to provide hot water and heating externally.

[0004] For example, Chinese Patent No. CN 114439565 A discloses a fuel cell waste heat utilization system and method. This patent uses the heat of the thermal management system to be coupled with the vehicle system, thereby recovering the heat in the thermal management system.

[0005] It can be seen that the above-mentioned disclosed patents all focus on how to utilize the heat of the thermal management system. However, after the hydrogen in the fuel cell undergoes an electrochemical reaction in the stack, the tail exhaust fluid of the stack also carries a large amount of heat. The above patents cannot utilize the tail exhaust heat, resulting in waste of the heat of the tail exhaust fluid and thus reducing the comprehensive utilization efficiency of the fuel cell. Summary of the Invention

[0006] In view of this, the purpose of the embodiments of this application is to provide a fuel cell system to solve the technical problem that the tail exhaust heat cannot be utilized, resulting in waste of the heat of the tail exhaust fluid and thus reducing the comprehensive utilization efficiency of the fuel cell.

[0007] The technical solution of this application is as follows: A fuel cell system, which includes a gas source, a heat exchange device, and a stack. The gas source includes a hydrogen source and an air source. The hydrogen source is connected to the heat exchange device. The hydrogen gas output by the hydrogen source flows through the heat exchange device for heat exchange and temperature rise. The heated hydrogen gas is input into the stack. The air source is connected to the stack. The air output by the air source is input into the stack, and the hydrogen gas and the air undergo an electrochemical reaction in the stack. The stack is connected to the heat exchange device, and the tail gas of the stack flows through the heat exchange device and exchanges heat with the hydrogen gas flowing through the heat exchange device to cool down.

[0008] The above fuel cell system further includes a hydrogen injector, a mixing chamber, and a hydrogen pump. The heat exchange device is connected to the hydrogen injector to convey the heat-exchanged hydrogen. The hydrogen injector is connected to the mixing chamber, the mixing chamber is connected to the fuel cell stack, and the hydrogen pump is connected to the fuel cell stack to extract the hydrogen after the reaction in the fuel cell stack. The hydrogen pump is also connected to the mixing chamber. After the hydrogen pump extracts the hydrogen, it is mixed with the hydrogen conveyed by the hydrogen injector and then enters the mixing chamber together. The mixed hydrogen in the mixing chamber is input into the fuel cell stack.

[0009] The above fuel cell system further includes a water separator. The water separator is provided with a first inlet, a first outlet, and a second outlet. The first inlet is connected to the fuel cell stack, and the hydrogen after the reaction is input into the water separator to separate the hydrogen and water. The first outlet is connected to the hydrogen pump, and the separated hydrogen is input into the hydrogen pump. The second outlet is connected to the heat exchange device, and the separated water is input into the heat exchange device.

[0010] The above water separator further includes a water separator body. The first inlet, the first outlet, and the second outlet are respectively arranged on the water separator body. The first outlet is also arranged at the upper end of the water separator body, and the second outlet is also arranged at the lower end of the water separator body.

[0011] The above fuel cell system further includes a drain pipe. The inlet of the drain pipe is connected to the second outlet, the outlet of the drain pipe is connected to the heat exchange device, and the drain pipe is provided with an exhaust valve.

[0012] The above fuel cell system further includes an air compressor and an intercooler. The air compressor is connected to the air source to compress the input air. The air compressor is connected to the intercooler, and the intercooler is used to cool the compressed air. The intercooler is also connected to the fuel cell stack, and the cooled compressed air is input into the fuel cell stack.

[0013] Inside the fuel cell stack, there are an air flow channel and a hydrogen flow channel. The inlet end of the air flow channel is connected to the intercooler through a first air pipe. The intercooler is connected to the heat exchange device through a second air pipe. The outlet end of the air flow channel is connected to the second air pipe through a third air pipe.

[0014] The above fuel cell system, wherein a first valve body is provided on the first gas pipeline, a second valve body is provided on the second gas pipeline, the first valve body and the second valve body are arranged in parallel, a third valve body is provided on the third gas pipeline, and the third valve body is arranged in series with the first valve body; when the first valve body and the third valve body are in the open state, the second valve body is in the closed state, and when the first valve body and the third valve body are in the closed state, the second valve body is in the open state.

[0015] The above fuel cell system, wherein the heat exchange device is one or more of a plate heat exchanger, a shell-and-tube heat exchanger or an indirect heat exchanger; the indirect heat exchanger includes a heat exchange circuit, a heat exchange fluid flows inside the heat exchange circuit, one end of the heat exchange circuit is wound around the hydrogen pipeline of the hydrogen source to exchange heat with the hydrogen, and the other end of the heat exchange circuit is wound around the second gas pipeline to exchange heat with the tail gas.

[0016] The above fuel cell system, wherein a power pump and an expansion valve are provided on the heat exchange circuit to drive the heat exchange fluid to flow, and the heat exchange fluid is a gas and / or a liquid.

[0017] Beneficial effects

[0018] Before hydrogen and air are input into the fuel cell stack according to a set volume ratio, the hydrogen gas flows through the heat exchange device to be preheated and then input into the fuel cell stack. Hydrogen and air undergo an electrochemical reaction inside the fuel cell stack to generate a tail exhaust fluid (mainly including water and air). The tail exhaust fluid flows through the heat exchange device for heat exchange and then is discharged. During the whole process, hydrogen and air undergo an electrochemical reaction inside the fuel cell stack to generate a tail exhaust fluid. The hydrogen is preheated by the tail exhaust fluid, which not only realizes the utilization of the heat carried by the tail exhaust fluid, but also the hot hydrogen transported by the hydrogen pump and the cold hydrogen transported by the hydrogen pump are mixed in the mixing chamber. At the same time, it also avoids the mixing of the hot hydrogen pumped by the hydrogen pump and the un-preheated cold hydrogen, resulting in the condensed liquid water entering the fuel cell stack along with the air flow and blocking the flow channels of the fuel cell stack. After the hydrogen source is decoupled from the thermal management system, the hydrogen plate heat exchanger can be cancelled. Therefore, the thermal management system does not need to carry out a diversion design for this component, simplifying the system structure and saving costs.

[0019] To make the above objects, features, and advantages of the present application more obvious and understandable, the following specifically gives preferred embodiments and, in conjunction with the accompanying drawings, the detailed description is as follows. Description of the drawings

[0020] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 Shows the overall system diagram of the fuel cell system provided by the embodiments of the present application;

[0022] Figure 2 Shows the system diagram of the coupling of the thermal management system and the heat exchange plate in the fuel cell provided by the embodiments of the present application;

[0023] Figure 3 For Figure 1 Schematic diagram of the heat exchange device in

[0024] Reference numerals

[0025] 1. Heat exchange device; 2. Stack; 31. Hydrogen injector; 32. Hydrogen pump; 34. Mixing chamber; 4. Water separator; 5. Drainage pipeline; 51. Exhaust valve; 61. Air compressor; 62. Intercooler; 71. Heat exchange circuit; 72. Power pump; 73. Expansion valve; 81. First gas pipeline; 82. Second gas pipeline; 83. Third gas pipeline; 91. First valve body; 92. Second valve body; 93. Third valve body; 10. Thermal management system; 11. Heat exchange plate. Detailed implementation manners

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some, rather than all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application to be protected, but only represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0027] Considering that after hydrogen reacts inside the fuel cell, the resulting tail exhaust fluid (mainly including water and air) carries a large amount of heat, such as Figure 3As shown, before hydrogen is input into the stack 2, it needs to be preheated. By increasing the input temperature of hydrogen, it is beneficial to solve the problem of condensed liquid water caused by the mixing of hot hydrogen pumped by the hydrogen pump and un-preheated cold hydrogen. The applicant's previous approach was to couple the hydrogen source with the thermal management system 10 through the heat exchange plate 11 and preheat the gas output from the hydrogen source through the thermal management system 10. However, this hydrogen preheating method not only fails to utilize the heat of the tail gas flow, but also increases the complexity of the entire system. In view of this, as Figure 1 shown, the applicant decouples the hydrogen source from the thermal management system 10 and couples the hydrogen source with the pipeline of the tail gas flow through the heat exchange device 1, and uses the heat of the tail gas flow to heat the hydrogen output from the hydrogen source, thereby realizing the effective utilization of the heat carried by the tail gas flow and improving the comprehensive utilization efficiency of the fuel cell.

[0028] A fuel cell system according to an embodiment of the present application includes a gas source, a heat exchange device 1, and a stack 2. The gas source includes a hydrogen source and an air source. The hydrogen source is connected to the heat exchange device 1. The hydrogen gas output from the hydrogen source flows through the heat exchange device 1 for heat exchange and temperature increase, and the heated hydrogen is input into the stack 2. The air source is connected to the stack 2, and the air output from the air source is input into the stack 2. The hydrogen and the air undergo an electrochemical reaction in the stack 2. The stack 2 is connected to the heat exchange device 1, and the tail gas of the stack 2 flows through the heat exchange device 1 and exchanges heat with the hydrogen flowing through the heat exchange device 1 to cool down.

[0029] Combined with the above embodiments, the gas source is used to input the gases participating in the reaction into the stack 2, such as hydrogen and air. The volume ratio of hydrogen and air is preset according to different conditions, such as the rated power, peak power, and voltage efficiency of the stack 2. Generally speaking, the larger the rated power, peak power, or voltage efficiency of the stack 2, the larger the corresponding volume ratio of hydrogen and air. However, the ratio of hydrogen and air has a lower limit, that is, the volume ratio of air cannot be too small, otherwise it is not conducive to the reaction of hydrogen, and the hydrogen content needs to meet the minimum volume value for hydrogen to react. Before hydrogen and air are input into the stack 2 according to the set volume ratio, the hydrogen gas flows through the heat exchange device 1 to be preheated and then input into the stack 2. Hydrogen and air undergo an electrochemical reaction inside the stack 2 to generate tail gas flow. The tail gas flow flows through the heat exchange device 1 for heat exchange and then is discharged. During the whole process, hydrogen and air undergo an electrochemical reaction inside the stack 2 to generate tail gas flow. By preheating hydrogen with the tail gas flow, not only the utilization of the heat carried by the tail gas flow is realized, but also the problem of generating liquid water due to the mixing of hot and cold is solved.

[0030] Furthermore, the gas source includes a hydrogen source and an air source. The hydrogen source is used to supply hydrogen to the fuel cell stack 2, and the air source is used to supply air to the fuel cell stack 2. The supplied hydrogen and air need to have sufficient cleanliness and dryness, which is conducive to the full reaction of hydrogen and air inside the fuel cell stack 2, thereby improving the overall reaction efficiency of the fuel cell stack 2. The hydrogen source may include a hydrogen tank, and the interior of the hydrogen tank stores clean and dry hydrogen. The air source may include an air tank, and the interior of the air tank stores clean and dry air. The hydrogen source and the air source can be assembled together in an integrated manner. For example, by assembling the hydrogen tank and the air tank in the same installation space or installation position, and placing the components of the tank body in the same area, it is conducive to the sub-region management of the entire system. The hydrogen source and the air source can also be assembled separately. For example, the hydrogen tank and the air tank are installed in different positions. The hydrogen tank is installed at a position close to the heat exchange device, and the air tank is installed at a position close to the fuel cell stack 2, which is conducive to saving the pipelines for transporting hydrogen and air, thereby saving the material cost.

[0031] The fuel cell system of this embodiment further includes a hydrogen injector 31 and a hydrogen pump 32. The heat exchange device 1 is connected to the hydrogen injector 31 to convey the heat-exchanged hydrogen. The hydrogen injector 31 is used to supply the heated hydrogen (hot hydrogen) to the fuel cell stack 2. The hydrogen pump 32 is connected to the fuel cell stack 2 to extract the hydrogen reacted inside the fuel cell stack 2. The hydrogen pump 32 is also connected to the mixing chamber 34 to convey the reacted hydrogen (cold hydrogen). After the hydrogen pump 32 extracts the hydrogen, it is mixed with the hydrogen conveyed by the hydrogen injector 31 in the mixing chamber and then supplies the mixed hydrogen to the fuel cell stack 2.

[0032] Combined with the above embodiment, the hydrogen injector 31 is connected to the heat exchange device 1 through a pipeline, and the preheated hydrogen is input into the hydrogen injector 31. The hydrogen injector 31 is used to spray the hydrogen inside into the fuel cell stack 2. After the hydrogen enters the fuel cell stack 2 and reacts, some hydrogen remains. The hydrogen pump 32 is used to extract the unreacted hydrogen from the fuel cell stack 2 and convey it back into the fuel cell stack 2, thereby realizing the full utilization of hydrogen.

[0033] The fuel cell system of this embodiment further includes a water separator 4. The water separator 4 is provided with a first inlet, a first outlet, and a second outlet. The first inlet is connected to the fuel cell stack 2, and the reacted hydrogen is input into the water separator 4 to separate hydrogen and water. The first outlet is connected to the hydrogen pump 32, and the separated hydrogen is input into the hydrogen pump 32. The second outlet is connected to the heat exchange device 1, and the separated water is input into the heat exchange device 1. The water separator 4 further includes a water separator body. The first inlet, the first outlet, and the second outlet are respectively arranged on the water separator body. The first outlet is also arranged at the upper end of the water separator body, and the second outlet is also arranged at the lower end of the water separator body.

[0034] Combined with the above embodiments, after the hydrogen undergoes an electrochemical reaction inside the fuel cell stack 2, water is generated. When recycling the unreacted hydrogen, it is necessary to separate the hydrogen from the water. The water separator 4 includes a water separator main body. A first inlet is provided on one side of the water separator main body, and the first inlet is connected to the fuel cell stack. The unreacted hydrogen and the water obtained from the reaction are input into the water separator main body through the first inlet.

[0035] Further, a first outlet is provided at the upper end of the water separator main body, and the first outlet is connected to the hydrogen pump 32. The hydrogen inside the water separator main body automatically accumulates at the top of the water separator main body and enters the hydrogen pump 32 through the first outlet. In addition, a gas-liquid separation structure can be provided at the first outlet to reduce the liquid water content in the hydrogen recycled into the hydrogen pump 32. A second outlet is provided at the lower end of the water separator main body, and the second outlet is connected to the heat exchange device. The water separated by the water separator accumulates at the lower part of the separator main body and flows out of the separator through the second outlet. By providing the first outlet at the upper part of the water separator main body and the second outlet at the lower part of the water separator main body, the hydrogen automatically flows out of the water separator from the first outlet, and the water automatically flows out of the water separator from the second outlet.

[0036] The fuel cell system according to the embodiment of the present application is characterized in that it further includes a liquid discharge pipeline 5. The liquid inlet of the liquid discharge pipeline 5 is connected to the second outlet, the liquid outlet of the liquid discharge pipeline 5 is connected to the heat exchange device 1, and the liquid discharge pipeline 5 is provided with an exhaust valve 51.

[0037] Combined with the above embodiments, both ends of the liquid discharge pipeline 5 are respectively connected to the second outlet and the heat exchange device 1, and the water in the water separator 4 then flows through the heat exchange device 1 through the liquid discharge pipeline 5. An exhaust valve 51 is provided on the liquid discharge pipeline 5, and the exhaust valve 51 can be an electromagnetic valve, a hydraulic valve, etc. A pressure sensor can also be provided on the exhaust pipeline 5. The pressure sensor collects the pressure value inside the exhaust pipeline 5. When the pressure value inside the liquid discharge pipeline 5 exceeds the pressure threshold, since the pressure inside the liquid discharge pipeline 5 is too high, the water inside the water separator 4 cannot naturally flow into the liquid discharge pipeline 5. At this time, it is necessary to open the exhaust valve 51 to reduce the internal pressure of the liquid discharge pipeline 5, so that the water naturally flows from the water separator 4 into the liquid discharge pipeline 5.

[0038] The fuel cell system of this embodiment further includes an air compressor 61 and an intercooler 62. The air compressor 61 is connected to the air source to compress the input air. The air compressor 61 is connected to the intercooler 62. The intercooler 62 is used to cool the compressed air. The intercooler 62 is also connected to the fuel cell stack 2, and the cooled compressed air is input into the fuel cell stack 2.

[0039] Combined with the above embodiments, an air source is sequentially connected to an air compressor 61 and an intercooler 62. The intercooler 62 is connected to the fuel cell stack 2. The air source inputs air into the air compressor 61. The air compressor 61 is used to compress the input air, and the intercooler 62 is used to cool the compressed air to a suitable temperature, thereby realizing the input of air on the air side.

[0040] In the fuel cell system according to the embodiment of the present application, an air flow channel and a hydrogen flow channel are arranged inside the fuel cell stack 2. The intake end of the air flow channel is connected to the intercooler 62 through a first gas pipeline 81. The intercooler 62 is connected to the heat exchange device 1 through the second gas pipeline 82. The outlet end of the air flow channel is connected to the second gas pipeline 82 through a third gas pipeline 83.

[0041] Combined with the above embodiments, an air flow channel and a hydrogen flow channel are arranged inside the fuel cell stack 2. For example, an air pipeline and a hydrogen pipeline can be arranged inside the fuel cell stack 2. Air flows inside the air pipeline to form an air flow channel, and hydrogen flows inside the hydrogen pipeline to form a hydrogen flow channel. The intercooler 62 is connected to the intake end of the air pipeline through the first gas pipeline 81. The intercooler 62 is also connected to the heat exchange device 1 through the second gas pipeline 82. The outlet end of the air pipeline is connected to the end of the second gas pipeline 82 through the third gas pipeline 83, thereby forming a complete air supply path, which is convenient for adjusting the air input into the fuel cell stack 2.

[0042] In the fuel cell system according to the embodiment of the present application, a first valve body 91 is arranged on the first gas pipeline 81, a second valve body 92 is arranged on the second gas pipeline 82, the first valve body 91 and the second valve body 92 are arranged in parallel, a third valve body 93 is arranged on the third gas pipeline 83, and the third valve body 93 is arranged in series with the first valve body 91; when the first valve body 91 and the third valve body 93 are in the open state, the second valve body 92 is in the closed state, and when the first valve body 91 and the third valve body 93 are in the closed state, the second valve body 92 is in the open state.

[0043] Combined with the above embodiments, a first valve body 91 is provided on the first gas pipeline 81, a second valve body 92 is provided on the second gas pipeline 82, and a third valve body 93 is provided on the third gas pipeline 83. The first valve body 91, the second valve body 92, and the third valve body 93 can be solenoid valves, hydraulic valves, expansion valves, etc. The first valve body 91 and the third valve body 93 are respectively provided on the first gas pipeline 81 and the third gas pipeline 83, and the first gas pipeline 81 and the third gas pipeline 83 are connected in series. Therefore, the opening and closing states of the first valve body 91 and the third valve body 93 are the same. The first gas pipeline 81 and the second gas pipeline 82 are connected in parallel. Therefore, the opening and closing states of the first valve body 91 and the second valve body 92 are opposite. Since it is necessary to maintain a certain back pressure in the air inside the stack 2, although the opening and closing states of the first valve body 91 and the third valve body 93 are the same, the opening degree of the third valve body 93 when it is open needs to be smaller than that of the first valve body 91.

[0044] The working processes of the first valve body 91, the second valve body 92, and the third valve body 93 are as follows: When the first valve body 91 and the third valve body 93 are open, the second valve body 92 is closed, and air is sequentially input into the stack through the air compressor 61 and the intercooler 62. After the air participates in the reaction inside the stack 2, it flows out through the third gas pipeline 83. Since the opening degree of the third valve body 93 is smaller than that of the first valve body 91, the amount of air input into the stack 2 is always more than the amount of air output by the stack 2, so as to maintain a certain back pressure inside the stack 2; when the first valve body 91 and the third valve body 93 are closed, the second valve body 92 is open, and after the air flows through the air compressor 61 and the intercooler 62, it is discharged into the heat exchange device 1 through the second gas pipeline 82. At this time, the air does not participate in the electrochemical reaction inside the stack 2.

[0045] For the fuel cell system of the embodiment of the present application, the heat exchange device 1 is one or more of a plate heat exchanger, a shell-and-tube heat exchanger, or an indirect heat exchanger; the indirect heat exchanger includes a heat exchange circuit 71, and a heat exchange fluid flows inside the heat exchange circuit 71. One end of the heat exchange circuit 71 is wound around the hydrogen pipeline of the hydrogen source to exchange heat with the hydrogen, and the other end of the heat exchange circuit 71 is wound around the second gas pipeline 82 to exchange heat with the tail gas.

[0046] Combined with the above embodiments, as Figure 2 shown, the heat exchange device 1 can be one or more of a plate heat exchanger, a shell heat exchanger, and an indirect heat exchanger. When the heat exchange device 1 is an indirect heat exchanger, the indirect heat exchanger can include a heat exchange circuit 71, and a heat exchange fluid flows inside the heat exchange circuit 71. For example, a heat exchange fluid with a relatively large specific heat capacity can be selected, such as cooling water, liquid nitrogen, etc. A power pump 72 and an expansion valve 73 are provided on the heat exchange circuit 71. When the power pump 72 and the expansion valve 73 work, they drive the heat exchange fluid to flow, and heat exchange between the tail discharge fluid and the hydrogen is realized through the heat exchange fluid, and finally preheating of the hydrogen is realized.

[0047] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all embodiments. The components of the embodiments of the present application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

Claims

1. A fuel cell system, characterized in that, It includes a gas source, a heat exchange device and an electrolytic stack. The gas source includes a hydrogen source and an air source. The hydrogen source is connected to the heat exchange device. The hydrogen gas output by the hydrogen source flows through the heat exchange device to exchange heat and increase in temperature. The heated hydrogen gas is input into the electrolytic stack. The air source is connected to the electrolytic stack. The air output by the air source is input into the electrolytic stack. The hydrogen gas and the air undergo an electrochemical reaction in the electrolytic stack. The electrolytic stack is connected to the heat exchange device. The tail gas of the electrolytic stack flows through the heat exchange device and exchanges heat with the hydrogen gas flowing through the heat exchange device to decrease in temperature.

2. The fuel cell system according to claim 1, characterized in that, It further includes a hydrogen injector, a mixing chamber and a hydrogen pump. The heat exchange device is connected to the hydrogen injector to convey the hydrogen gas after heat exchange. The hydrogen injector is connected to the mixing chamber. The mixing chamber is connected to the electrolytic stack. The hydrogen pump is connected to the electrolytic stack to extract the hydrogen gas after reaction in the electrolytic stack. The hydrogen pump is also connected to the mixing chamber. After the hydrogen pump extracts the hydrogen gas, it is mixed with the hydrogen gas conveyed by the hydrogen injector and then enters the mixing chamber together. The mixed hydrogen gas in the mixing chamber is input into the electrolytic stack.

3. The fuel cell system according to claim 2, wherein It further includes a water separator. The water separator is provided with a first inlet, a first outlet and a second outlet. The first inlet is connected to the electrolytic stack. The hydrogen gas after reaction is input into the water separator to separate hydrogen gas and water. The first outlet is connected to the hydrogen pump. The separated hydrogen gas is input into the hydrogen pump. The second outlet is connected to the heat exchange device. The separated water is input into the heat exchange device.

4. The fuel cell system according to claim 3, wherein The water separator further includes a water separator body. The first inlet, the first outlet and the second outlet are respectively arranged on the water separator body. The first outlet is also arranged at the upper end of the water separator body. The second outlet is also arranged at the lower end of the water separator body.

5. The fuel cell system according to claim 3 or 4, characterized in that, It further includes a liquid discharge pipeline. The liquid inlet of the liquid discharge pipeline is connected to the second outlet. The liquid outlet of the liquid discharge pipeline is connected to the heat exchange device. The liquid discharge pipeline is provided with an exhaust valve.

6. The fuel cell system according to claim 5, wherein It further includes an air compressor and an intercooler. The air compressor is connected to the air source to compress the input air. The air compressor is connected to the intercooler. The intercooler is used to cool the compressed air. The intercooler is also connected to the electrolytic stack. The cooled compressed air is input into the electrolytic stack.

7. The fuel cell system according to claim 6, characterized in that, An air flow channel and a hydrogen gas flow channel are arranged inside the electrolytic stack. The air inlet end of the air flow channel is connected to the intercooler through a first gas pipeline. The intercooler is connected to the heat exchange device through a second gas pipeline. The air outlet end of the air flow channel is connected to the second gas pipeline through a third gas pipeline.

8. The fuel cell system according to claim 7, characterized in that, A first valve body is arranged on the first gas pipeline. A second valve body is arranged on the second gas pipeline. The first valve body and the second valve body are arranged in parallel. A third valve body is arranged on the third gas pipeline. The third valve body is arranged in series with the first valve body. When the first valve body and the third valve body are in the open state, the second valve body is in the closed state. When the first valve body and the third valve body are in the closed state, the second valve body is in the open state.

9. The fuel cell system according to claim 7, characterized in that, The heat exchange device is one or more of a plate heat exchanger, a shell-and-tube heat exchanger, or an indirect heat exchanger; the indirect heat exchanger includes a heat exchange circuit, and a heat exchange fluid flows inside the heat exchange circuit. One end of the heat exchange circuit is wound around the hydrogen delivery pipeline of the hydrogen source to exchange heat with the hydrogen, and the other end of the heat exchange circuit is wound around the second gas pipeline to exchange heat with the tail gas.

10. The fuel cell system according to claim 9, wherein, A power pump and an expansion valve are provided on the heat exchange circuit to drive the flow of the heat exchange fluid, and the heat exchange fluid is a gas and / or a liquid.

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