Fuel cell and its airtightness detection method

Abstract

The present application provides a fuel cell and a method for detecting its airtightness. The fuel cell includes: a raw material gas supply system for supplying raw material gas to the fuel cell, with a hydrogen supply pipeline and a nitrogen supply pipeline connected in series with a raw material gas main shut-off valve; an airtightness testing system including a first shut-off valve, an airtightness detector, and a second shut-off valve connected in sequence; and a fuel cell stack to be tested; wherein, the raw material gas supply system is connected in parallel with the airtightness testing system and communicates with the anode inlet of the fuel cell stack to be tested. The anode inlet of the fuel cell can communicate with the gas source of the airtightness detection gas, so as to ensure that the anode is in a non-oxidizing atmosphere environment at high temperature, avoid anode oxidation, avoid changes in the anode structure, avoid affecting the output performance of the stack, avoid causing the battery chips to rupture, so as to avoid internal leakage in the stack, and thus detect the airtightness of the fuel cell stack to be tested at high temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to a fuel cell and a method for detecting its airtightness. Background Art

[0002] High-temperature fuel cells refer to fuel cells that can operate under high-temperature conditions, such as solid oxide fuel cells (SOFCs) operating at 600 - 1000 °C. At high temperatures, the airtightness of the fuel cell stack not only differs from that at low temperatures but also has a great impact on the output performance of the stack.

[0003] However, it is very difficult to detect the airtightness of a fuel cell stack at high temperatures. First of all, it is necessary to ensure that the anode must be in a non-oxidizing atmosphere at high temperatures; otherwise, the anode will be oxidized, causing local thermal stress, leading to changes in the anode structure, affecting the output performance of the stack, and even causing the battery chips to rupture, resulting in internal leakage of the stack. Moreover, the stack is very sensitive to pressure and pressure difference at high temperatures. Therefore, a control strategy for anode gas and stack pressure needs to be formulated for the airtightness detection of the stack at high temperatures. According to the pressure-bearing performance of different stacks, generally, the pressure differences between the anode inlet and the cathode inlet, between the anode inlet and the anode outlet, and between the cathode inlet and the cathode outlet are required to be below a certain pressure value, such as 10 KPa. Excessive pressure or pressure difference will affect the battery chips and sealing materials, and may cause the battery chips to rupture, leading to internal or external leakage of the stack.

[0004] Existing fuel cells and methods for detecting their airtightness often do not state whether they can be used at high temperatures. Without an anode gas supply control strategy and a pressure difference control strategy suitable for high temperatures, they should not be applicable to high-temperature detection environments. In addition, although existing fuel cells and methods for detecting their airtightness can complete all airtightness detections through one installation without the need to disassemble and adjust the interfaces midway, and some can detect external leakage of each cavity and internal leakage between cavities. However, they cannot achieve online detection, that is, stop the operation of the fuel cell during its operation, conduct an airtightness test, and then continue the operation of the fuel cell without going through the processes of heating up and cooling down. Summary of the Invention

[0005] In view of the problems in the above-mentioned prior art, the present application proposes a fuel cell and a method for detecting its airtightness. The anode inlet of the fuel cell can be connected to the gas source of the airtightness detection gas, so as to ensure that the anode is in a non-oxidizing atmosphere environment at high temperature, avoid anode oxidation, local thermal stress, avoid changes in the anode structure, avoid affecting the output performance of the stack, avoid causing the battery sheet to rupture, so as to avoid internal leakage of the stack, and thus detect the airtightness of the fuel cell stack to be tested at high temperature. At the same time, the structure of the fuel cell is conducive to realizing the on-line detection of the fuel cell stack to be tested, that is, during the operation of the fuel cell, the operation of the fuel cell is stopped, the airtightness test is carried out, and then the operation of the fuel cell is continued, without going through the heating and cooling processes.

[0006] In a first aspect, the present invention provides a fuel cell, which includes: a raw material gas supply system for supplying raw material gas to the fuel cell, which includes parallel raw material gas supply branches, and each raw material gas supply branch is connected in series with a raw material gas main stop valve; a branch stop valve is provided on the raw material gas supply branch; an airtightness test system, which includes a first stop valve, an airtightness detector, and a second stop valve connected in sequence, and the first stop valve is arranged adjacent to the gas source of the airtightness detection gas and is located downstream of the gas source of the airtightness detection gas; and a fuel cell stack to be tested, an anode outlet stop valve is provided at the anode outlet thereof; wherein, the raw material gas supply system is connected in parallel with the airtightness test system and is connected to the anode inlet of the fuel cell stack to be tested. By using this fuel cell, the anode inlet of the fuel cell can be connected to the gas source of the airtightness detection gas, so as to ensure that the anode is in a non-oxidizing atmosphere environment at high temperature, avoid anode oxidation, local thermal stress, avoid changes in the anode structure, avoid affecting the output performance of the stack, avoid causing the battery sheet to rupture, so as to avoid internal leakage of the stack, and thus detect the airtightness of the fuel cell stack to be tested at high temperature. At the same time, the structure of the fuel cell is conducive to realizing the on-line detection of the fuel cell stack to be tested, that is, during the operation of the fuel cell, the operation of the fuel cell is stopped, the airtightness test is carried out, and then the operation of the fuel cell is continued, without going through the heating and cooling processes.

[0007] In an embodiment of the first aspect, the raw material gas supply system includes a parallel hydrogen supply pipeline and a nitrogen supply pipeline, the hydrogen supply pipeline and the nitrogen supply pipeline are connected in series with a raw material gas main stop valve; a hydrogen stop valve is provided near the hydrogen source on the hydrogen supply pipeline; a nitrogen stop valve is provided near the nitrogen source on the nitrogen supply pipeline.

[0008] In an embodiment of the first aspect, an anode inlet pressure sensor and a cathode inlet pressure sensor are respectively arranged at the anode inlet and the cathode inlet of the fuel cell stack to be tested. Through this embodiment, the anode inlet pressure sensor and the cathode inlet pressure sensor are respectively arranged at the anode inlet and the cathode inlet of the fuel cell stack to be tested, so that the pressure difference between the anode inlet and the cathode inlet can be monitored in real time, which is beneficial to avoiding the influence of excessive pressure or pressure difference on the battery sheets and sealing materials, beneficial to avoiding the rupture of the battery sheets, and thus beneficial to avoiding internal leakage or external leakage of the stack.

[0009] In an embodiment of the first aspect, a pressure reducing valve, a pressure sensor and an expansion tank are arranged between the airtightness detector and the second stop valve. Through this embodiment, the expansion tank can supply airtightness detection gas to the anode in the fuel cell stack to be tested, ensure the positive pressure in the anode chamber, and protect the anode of the stack.

[0010] In an embodiment of the first aspect, a cathode inlet stop valve and a cathode outlet stop valve are respectively arranged at the cathode inlet and the cathode outlet of the fuel cell stack to be tested. Through this embodiment, by respectively arranging the cathode inlet stop valve and the cathode outlet stop valve at the cathode inlet and the cathode outlet of the fuel cell stack to be tested, the external leakage amount of the fuel cell stack to be tested can be successfully obtained, and the internal leakage amount of the fuel cell stack to be tested can be obtained by using the overall leakage amount and the external leakage amount of the fuel cell stack to be tested.

[0011] In an embodiment of the first aspect, a hydrogen pressure reducing valve and a hydrogen mass flowmeter are arranged downstream of the hydrogen stop valve, and pressure sensors are arranged on both sides of the hydrogen pressure reducing valve; a nitrogen pressure reducing valve and a nitrogen mass flowmeter are arranged downstream of the nitrogen stop valve, and pressure sensors are arranged on both sides of the nitrogen pressure reducing valve; a airtightness gas pressure reducing valve is arranged between the first stop valve and the airtightness detector, and pressure sensors are arranged on both sides of the airtightness gas pressure reducing valve. Through this embodiment, the supply amount of hydrogen, nitrogen or airtightness detection gas can be reduced when needed, and its supply amount can be accurately adjusted and controlled.

[0012] In an embodiment of the first aspect, the airtightness detection gas is composed of nitrogen and hydrogen, and the content of hydrogen is between 5% and 20%. Through this embodiment, it is ensured that the airtightness detection gas is a non-oxidizing gas.

[0013] In an embodiment of the first aspect, the fuel cell further includes a control system to realize the automatic control of the fuel cell. Through this embodiment, it is beneficial to realize the automatic control of the fuel cell and ensure the safety of the fuel cell stack to be tested.

[0014] Second aspect, the present invention also provides a method for detecting the airtightness of the fuel cell described in the first aspect and any of its embodiments. The airtightness detection method includes the following steps: Before airtightness detection, the fuel cell stack to be tested is in a working state. At this time, the raw material gas supply system supplies raw material gas to the anode inlet of the fuel cell stack to be tested, the branch cutoff valve and the total raw material gas cutoff valve are in an open state, and the anode outlet cutoff valve is in an open state; after the reaction, the gas is discharged from the anode outlet; air enters the fuel cell stack to be tested from the cathode inlet and is discharged from the cathode outlet; during airtightness testing, first, the fuel cell stack to be tested is in an open-circuit voltage state, the branch cutoff valve and the total raw material gas cutoff valve are closed, and at the same time, the first cutoff valve and the second cutoff valve are opened. At this time, the airtightness detector is in a pressure-holding mode to purge the anode of the fuel cell stack to be tested; after the purging is completed, the first cutoff valve and the anode outlet cutoff valve are closed for airtightness detection. At this time, the airtightness detector is in a detection mode to detect the leakage amount of the fuel cell stack to be tested; after the detection is completed, if the airtightness detection is qualified, the second cutoff valve is closed, and the branch cutoff valve, the total raw material gas cutoff valve, and the anode outlet cutoff valve are opened to return the fuel cell stack to be tested to the working state. Using this detection method, during detection, the anode inlet of the fuel cell can be connected to the airtightness detection gas source, so as to ensure that the anode is in a non-oxidizing atmosphere environment at high temperature, avoid anode oxidation, local thermal stress, avoid changes in the anode structure, avoid affecting the output performance of the stack, avoid causing the battery sheet to rupture, so as to avoid internal leakage in the stack, thereby detecting the airtightness of the fuel cell stack to be tested at high temperature. At the same time, the structure of the fuel cell is conducive to realizing the on-line detection of the fuel cell stack to be tested, that is, stopping the operation of the fuel cell during the operation of the fuel cell, performing airtightness testing, and then continuing the operation of the fuel cell, without going through the processes of heating up and cooling down.

[0015] In an embodiment of the second aspect, when the fuel cell stack to be tested is in a working state, both the cathode inlet cutoff valve and the cathode outlet cutoff valve are in an open state; when detecting the overall leakage amount of the fuel cell stack to be tested, after the purging is completed, the cathode inlet cutoff valve and the cathode outlet cutoff valve are in an open state. Through this embodiment, the overall leakage amount of the fuel cell stack to be tested can be successfully obtained.

[0016] In an embodiment of the second aspect, when detecting the external leakage amount of the fuel cell stack to be tested, after the purging is completed, the cathode inlet stop valve and the cathode outlet stop valve are closed; the internal leakage amount of the fuel cell stack to be tested is the difference between the overall leakage amount of the fuel cell stack to be tested and the external leakage amount of the fuel cell stack to be tested. Through this embodiment, the external leakage amount of the fuel cell stack to be tested can be successfully obtained, and the internal leakage amount of the fuel cell stack to be tested can be obtained by using the overall leakage amount and the external leakage amount of the fuel cell stack to be tested.

[0017] In an embodiment of the second aspect, when detecting the leakage amount of the fuel cell stack to be tested, the expansion tank supplies the airtightness detection gas to the anode of the fuel cell stack to be tested through the second stop valve; the volume of the expansion tank is larger than the volume of the anode chamber. Through this embodiment, the expansion tank can supplement the airtightness detection gas to the anode in the fuel cell stack to be tested, can ensure the positive pressure in the anode chamber, and protect the anode of the fuel cell stack.

[0018] In an embodiment of the second aspect, during the detection process, if it is found that the leakage amount exceeds the volume of the anode chamber, the detection is immediately stopped, the airtightness detector is switched to the pressure holding mode, and the first stop valve and the anode outlet stop valve are opened. Through this embodiment, after the leakage amount exceeds the volume of the anode chamber, the anode of the fuel cell stack to be tested is immediately purged to ensure that the anode is in a non-oxidizing atmosphere environment at high temperature, avoid anode oxidation, local thermal stress, avoid changes in the anode structure, avoid affecting the output performance of the fuel cell stack, and avoid causing the battery chips to rupture, so as to avoid internal leakage of the fuel cell stack, thereby detecting the airtightness of the fuel cell stack to be tested at high temperature.

[0019] In an embodiment of the second aspect, in the purging state, the readings of the pressure sensor between the expansion tank and the airtightness detector and the anode inlet pressure sensor are both less than the preset pressure value, and the difference between the readings of the anode inlet pressure sensor and the cathode inlet pressure sensor is less than the preset pressure difference, and the outlet pressure of the airtightness detector in the pressure holding state is the preset pressure value; after the purging is completed, when the readings of the pressure sensor between the expansion tank and the airtightness detector and the anode inlet pressure sensor are stable at the preset pressure value, the airtightness detector is switched from the pressure holding mode to the detection mode. Through this embodiment, by monitoring various pressures and pressure differences in real time, it is beneficial to avoid the influence of excessive pressure or pressure difference on the battery chips and sealing materials, beneficial to avoid the rupture of the battery chips, and thus beneficial to avoid internal leakage or external leakage of the fuel cell stack.

[0020] In an embodiment of the second aspect, the preset pressure value and the preset pressure difference are set according to the pressure-bearing characteristics of different fuel cell stacks to be tested; both the preset pressure value and the preset pressure difference are not higher than 10 KPa. Through this embodiment, it is beneficial to avoid the influence of excessive pressure or pressure difference on the battery sheets and sealing materials, and beneficial to avoid the rupture of the battery sheets, thereby avoiding internal leakage or external leakage of the stack.

[0021] In an embodiment of the second aspect, both the preset pressure value and the preset pressure difference are between 3 - 5 KPa. Through this embodiment, it is beneficial to further avoid the influence of excessive pressure or pressure difference on the battery sheets and sealing materials, and beneficial to avoid the rupture of the battery sheets, thereby avoiding internal leakage or external leakage of the stack.

[0022] In an embodiment of the second aspect, the control system is communicatively connected to the hydrogen cut-off valve, nitrogen cut-off valve, raw gas main cut-off valve, anode outlet cut-off valve, first cut-off valve, second cut-off valve, cathode inlet cut-off valve, cathode outlet cut-off valve, pressure reducing valve, pressure sensor, hydrogen mass flowmeter, nitrogen mass flowmeter, and airtightness detector, so as to realize the automatic control of the fuel cell. Through this embodiment, it is beneficial to realize the automatic control of the fuel cell and ensure the safety of the fuel cell stack to be tested.

[0023] In an embodiment of the second aspect, when the pressure is higher than the preset pressure value or when the pressure difference is higher than the preset pressure difference, the control system gives an alarm to ensure the safety of the fuel cell stack to be tested. Through this embodiment, it is beneficial to further ensure the safety of the fuel cell stack to be tested.

[0024] The fuel cell and its airtightness detection method provided by this application have the following beneficial effects compared with the prior art.

[0025] 1. By using this fuel cell, the anode inlet of the fuel cell can be connected to the gas source of the airtightness detection gas, so as to ensure that the anode is in a non-oxidizing atmosphere environment at high temperature, avoid anode oxidation, local thermal stress, avoid changes in the anode structure, avoid affecting the output performance of the stack, avoid causing the rupture of the battery sheets, and avoid internal leakage of the stack, thereby detecting the airtightness of the fuel cell stack to be tested at high temperature. At the same time, the structure of this fuel cell is beneficial to realizing the on-line detection of the fuel cell stack to be tested, that is, during the operation of the fuel cell, stop the operation of the fuel cell, conduct an airtightness test, and then continue the operation of the fuel cell without going through the heating and cooling processes.

[0026] 2. Monitor various pressures and pressure differences in real time to avoid the impact of excessive pressure or pressure difference on the battery cells and sealing materials, which is beneficial to avoid the rupture of battery cells and thus beneficial to avoid internal or external leakage of the stack. At the same time, if necessary, it can reduce the supply of hydrogen, nitrogen or airtightness detection gas and accurately adjust and control its supply volume.

[0027] 3. By respectively arranging a cathode inlet shut-off valve and a cathode outlet shut-off valve at the cathode inlet and cathode outlet of the fuel cell stack to be measured, the external leakage amount of the fuel cell stack to be measured can be successfully obtained, and the internal leakage amount of the fuel cell stack to be measured can be obtained by using the overall leakage amount and the external leakage amount of the fuel cell stack to be measured.

[0028] 4. The expansion tank can supplement the airtightness detection gas to the anode in the fuel cell stack to be measured, can ensure the positive pressure in the anode chamber, and protect the anode of the stack.

[0029] The above technical features can be combined in various suitable ways or replaced by equivalent technical features as long as the purpose of the present invention can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Hereinafter, the present invention will be described in more detail based on embodiments with reference to the drawings, wherein:

[0031] Figure 1 shows a schematic structural diagram of a fuel cell according to an embodiment of the present invention.

[0032] LIST OF REFERENCE NUMERALS:

[0033] 1 - Hydrogen shut-off valve; 2 - Pressure sensor; 3 - Pressure reducing valve; 5 - Hydrogen mass flowmeter; 6 - Nitrogen shut-off valve; 10 - Nitrogen mass flowmeter; 11 - Total raw gas shut-off valve; 12 - First shut-off valve; 16 - Airtightness detector; 19 - Expansion tank; 20 - Second shut-off valve; 21 - Anode inlet pressure sensor; 22 - Anode outlet shut-off valve; 23 - Stack; 24 - Cathode inlet shut-off valve; 25 - Cathode outlet shut-off valve; 26 - Cathode inlet pressure sensor.

[0034] In the drawings, the same components are denoted by the same reference numerals. The drawings are not drawn to actual scale. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The present invention will be further described below with reference to the drawings.

[0036] As Figure 1As shown in the figure, this embodiment provides a fuel cell, which includes: a raw material gas supply system for supplying raw material gas to the fuel cell, including a hydrogen supply pipeline and a nitrogen supply pipeline connected in parallel, and the hydrogen supply pipeline and the nitrogen supply pipeline are connected in series with a raw material gas main cut-off valve 11; a hydrogen cut-off valve 1 is provided near the hydrogen source of the hydrogen supply pipeline; a nitrogen cut-off valve 6 is provided near the nitrogen source of the nitrogen supply pipeline; an airtightness test system, which includes a first cut-off valve 12, an airtightness detector 16, and a second cut-off valve 20 connected in sequence, and the first cut-off valve 12 is provided adjacent to the gas source of the airtightness test gas and is located downstream of the gas source of the airtightness test gas; and a fuel cell stack 23 to be tested, with an anode outlet cut-off valve 22 provided at its anode outlet; wherein, the raw material gas supply system is connected in parallel with the airtightness test system and is connected to the anode inlet of the fuel cell stack 23 to be tested.

[0037] Figure 1 The middle heat zone refers to the high-temperature area of the fuel cell, and the fuel cell stack 23 is located in the heat zone.

[0038] In the prior art, it is very difficult to detect the airtightness of the fuel cell stack 23 at high temperatures. The existing airtightness detection methods cannot ensure that the anode environment is a non-oxidizing atmosphere at high temperatures. It cannot avoid the oxidation of the anode, resulting in local thermal stress, cannot avoid the change of the anode structure, affecting the output performance of the fuel cell stack 23, and even causing the battery chips to rupture, resulting in internal leakage of the fuel cell stack 23.

[0039] The fuel cell of this embodiment includes an airtightness test system, which can connect the anode inlet of the fuel cell to the gas source of the airtightness test gas, so as to ensure that the anode is in a non-oxidizing atmosphere environment at high temperatures, avoid anode oxidation, local thermal stress, avoid changes in the anode structure, avoid affecting the output performance of the fuel cell stack 23, avoid causing battery chips to rupture, so as to avoid internal leakage of the fuel cell stack 23, thereby detecting the airtightness of the fuel cell stack 23 to be tested at high temperatures; wherein, the airtightness test gas is a non-oxidizing gas.

[0040] At the same time, the existing fuel cells cannot achieve online detection, that is, during the operation of the fuel cell, stop the operation of the fuel cell, conduct an airtightness test, and then continue the operation of the fuel cell without going through the heating and cooling processes.

[0041] The raw material gas supply system of the fuel cell of this embodiment is connected in parallel with the airtightness test system and is connected to the anode inlet of the fuel cell stack 23 to be tested.

[0042] Before the airtightness detection, the fuel cell stack 23 to be tested is in a working state. At this time, the raw material gas supply system supplies hydrogen and nitrogen to the anode inlet of the fuel cell stack 23 to be tested. The hydrogen cut-off valve 1, the nitrogen cut-off valve 6, and the raw material gas main cut-off valve 11 are in the open state, and the anode outlet cut-off valve 22 is in the open state; after the reaction, the gas is discharged from the anode outlet; air enters the fuel cell stack 23 to be tested from the cathode inlet and is discharged from the cathode outlet.

[0043] During the airtightness test, first, the fuel cell stack 23 to be tested is in the open-circuit voltage state. The hydrogen cut-off valve 1, the nitrogen cut-off valve 6, and the raw material gas main cut-off valve 11 are closed. At the same time, the first cut-off valve 12 and the second cut-off valve 20 are opened to supply airtightness detection gas to the anode inlet of the fuel cell stack 23 to be tested. Among them, the airtightness detection gas is a non-oxidizing gas. At this time, the airtightness detector 16 is in the pressure-holding mode to purge the anode of the fuel cell stack 23 to be tested.

[0044] After the purging is completed, the first cut-off valve 12 and the anode outlet cut-off valve 22 are closed for airtightness detection. At this time, the airtightness detector 16 switches to the detection mode to detect the leakage amount of the fuel cell stack 23 to be tested.

[0045] After the detection is completed, if the airtightness detection is qualified, the second cut-off valve 20 is closed, and the hydrogen cut-off valve 1, the nitrogen cut-off valve 6, the raw material gas main cut-off valve 11, and the anode outlet cut-off valve 22 are opened to return the fuel cell stack 23 to be tested to the working state.

[0046] Obviously, the structure of this fuel cell is conducive to the on-line detection of the fuel cell stack 23 to be tested, that is, during the operation of the fuel cell, the operation of the fuel cell is stopped for airtightness testing, and then the operation of the fuel cell is continued without going through the heating and cooling processes.

[0047] Using this fuel cell, the anode inlet of this fuel cell can be connected to the gas source of the airtightness detection gas, so as to ensure that the anode is in a non-oxidizing atmosphere environment at high temperature, avoid anode oxidation, local thermal stress, avoid changes in the anode structure, avoid affecting the output performance of the stack 23, avoid causing the battery chips to rupture, so as to avoid internal leakage in the stack 23, and thus detect the airtightness of the fuel cell stack 23 to be tested at high temperature. At the same time, the structure of this fuel cell is conducive to the on-line detection of the fuel cell stack 23 to be tested, that is, during the operation of the fuel cell, the operation of the fuel cell is stopped for airtightness testing, and then the operation of the fuel cell is continued without going through the heating and cooling processes.

[0048] In one embodiment, as Figure 1 shown, an anode inlet pressure sensor 21 and a cathode inlet pressure sensor 26 are respectively arranged at the anode inlet and the cathode inlet of the fuel cell stack 23 to be tested.

[0049] At high temperatures, the fuel cell stack 23 is very sensitive to pressure and pressure difference. However, the prior art does not formulate a control strategy for the anode gas and the pressure of the fuel cell stack 23 at high temperatures. According to the pressure-bearing performance of different fuel cell stacks 23, generally, the pressure differences between the anode inlet and the cathode inlet, between the anode inlet and the anode outlet, and between the cathode inlet and the cathode outlet are required to be below a certain pressure value, such as 10 KPa. In the prior art, due to the lack of a pressure difference control strategy suitable for high temperatures, excessive pressure or pressure difference will affect the battery cells and sealing materials, and may cause the battery cells to rupture, resulting in internal leakage or external leakage of the fuel cell stack 23.

[0050] Through this embodiment, an anode inlet pressure sensor 21 and a cathode inlet pressure sensor 26 are respectively arranged at the anode inlet and the cathode inlet of the fuel cell stack 23 to be tested, which can monitor the pressure difference between the anode inlet and the cathode inlet in real time, is beneficial to avoiding the influence of excessive pressure or pressure difference on the battery cells and sealing materials, is beneficial to avoiding the rupture of the battery cells, and thus is beneficial to avoiding internal leakage or external leakage of the fuel cell stack 23.

[0051] In one embodiment, as Figure 1 shown, a pressure reducing valve 3, a pressure sensor 2 and a pressure expansion tank 19 are arranged between the airtightness detector 16 and the second stop valve 20.

[0052] When detecting the leakage amount of the fuel cell stack 23 to be tested, the pressure expansion tank 19 supplies airtightness detection gas to the anode of the fuel cell stack 23 to be tested through the second stop valve 20; to ensure that the anode is in a non-oxidizing atmosphere at high temperatures, the volume of the pressure expansion tank 19 is larger than the volume of the anode chamber.

[0053] Preferably, the volume of the pressure expansion tank 19 is larger than the total volume of the anode flow channels in the fuel cell stack 23 to be tested.

[0054] During airtightness detection, even if the leakage amount of the anode in the fuel cell stack 23 to be tested is very large and all the original airtightness detection gas in it is exhausted, due to the existence of the pressure expansion tank 19, the pressure expansion tank 19 can supply airtightness detection gas to the anode in the fuel cell stack 23 to be tested, and can also ensure the positive pressure in the anode chamber and protect the anode of the fuel cell stack 23.

[0055] Through this embodiment, the pressure expansion tank 19 can supply airtightness detection gas to the anode in the fuel cell stack 23 to be tested, can ensure the positive pressure in the anode chamber, and protect the anode of the fuel cell stack 23.

[0056] In one embodiment, as Figure 1 shown, a cathode inlet stop valve 24 and a cathode outlet stop valve 25 are respectively arranged at the cathode inlet and the cathode outlet of the fuel cell stack 23 to be tested.

[0057] When detecting the overall leakage of the fuel cell stack 23 to be tested, the cathode inlet shut-off valve 24 and the cathode outlet shut-off valve 25 are in the open state to obtain the overall leakage of the fuel cell stack 23 to be tested.

[0058] When detecting the external leakage of the fuel cell stack 23 to be tested, the cathode inlet shut-off valve 24 and the cathode outlet shut-off valve 25 are in the closed state to obtain the external leakage of the fuel cell stack 23 to be tested.

[0059] The internal leakage of the fuel cell stack 23 to be tested is the difference between the overall leakage of the fuel cell stack 23 to be tested and the external leakage of the fuel cell stack 23 to be tested.

[0060] Through this embodiment, by respectively arranging the cathode inlet shut-off valve 24 and the cathode outlet shut-off valve 25 at the cathode inlet and the cathode outlet of the fuel cell stack 23 to be tested, the external leakage of the fuel cell stack 23 to be tested can be successfully obtained, and the internal leakage of the fuel cell stack 23 to be tested can be obtained by using the overall leakage of the fuel cell stack 23 to be tested and the external leakage of the fuel cell stack 23 to be tested.

[0061] In one embodiment, as Figure 1 shown, a hydrogen pressure reducing valve 3 and a hydrogen mass flowmeter 5 are arranged downstream of the hydrogen shut-off valve 1, and pressure sensors 2 are arranged on both sides of the hydrogen pressure reducing valve 3; a nitrogen pressure reducing valve 3 and a nitrogen mass flowmeter 10 are arranged downstream of the nitrogen shut-off valve 6, and pressure sensors 2 are arranged on both sides of the nitrogen pressure reducing valve 3; a hermeticity gas pressure reducing valve 3 is arranged between the first shut-off valve 12 and the hermeticity detector 16, and pressure sensors 2 are arranged on both sides of the hermeticity gas pressure reducing valve 3.

[0062] Through this embodiment, when needed, the supply amounts of hydrogen, nitrogen or hermeticity detection gas can be reduced, and their supply amounts can be accurately adjusted and controlled.

[0063] In one embodiment, the hermeticity detection gas is composed of nitrogen and hydrogen, and the content of hydrogen is between 5-20%.

[0064] Through this embodiment, it is ensured that the hermeticity detection gas is a non-oxidizing gas.

[0065] In one embodiment, the fuel cell further includes a control system to realize the automatic control of the fuel cell.

[0066] Through this embodiment, it is beneficial to realize the automatic control of the fuel cell and ensure the safety of the fuel cell stack 23 to be tested.

[0067] This embodiment also provides a method for detecting the airtightness of the above fuel cell. The airtightness detection method includes the following steps: Before the airtightness detection, the fuel cell stack 23 to be tested is in a working state. At this time, the raw material gas supply system supplies hydrogen and nitrogen to the anode inlet of the fuel cell stack 23 to be tested. The hydrogen cut-off valve 1, the nitrogen cut-off valve 6, and the raw material gas main cut-off valve 11 are in the open state, and the anode outlet cut-off valve 22 is in the open state; after the reaction, the gas is discharged from the anode outlet; air enters the fuel cell stack 23 to be tested from the cathode inlet and is discharged from the cathode outlet; during the airtightness test, first, the fuel cell stack 23 to be tested is in an open-circuit voltage state, the hydrogen cut-off valve 1, the nitrogen cut-off valve 6, and the raw material gas main cut-off valve 11 are closed, and at the same time, the first cut-off valve 12 and the second cut-off valve 20 are opened. At this time, the airtightness detector 16 is in a pressure-holding mode to purge the anode of the fuel cell stack 23 to be tested; after the purging is completed, the first cut-off valve 12 and the anode outlet cut-off valve 22 are closed for airtightness detection. At this time, the airtightness detector 16 is in a detection mode to detect the leakage amount of the fuel cell stack 23 to be tested; after the detection is completed, if the airtightness detection is qualified, the second cut-off valve 20 is closed, and the hydrogen cut-off valve 1, the nitrogen cut-off valve 6, the raw material gas main cut-off valve 11, and the anode outlet cut-off valve 22 are opened to return the fuel cell stack 23 to be tested to the working state.

[0068] Using this detection method, during the detection, the anode inlet of the fuel cell can be connected to the gas source of the airtightness detection gas, so as to ensure that the anode is in a non-oxidizing atmosphere environment at high temperature, avoid anode oxidation, local thermal stress, avoid changes in the anode structure, avoid affecting the output performance of the stack 23, and avoid causing the battery chips to rupture, so as to avoid internal leakage in the stack 23, thereby detecting the airtightness of the fuel cell stack 23 to be tested at high temperature. At the same time, the structure of the fuel cell is conducive to realizing the on-line detection of the fuel cell stack 23 to be tested, that is, during the operation of the fuel cell, the operation of the fuel cell is stopped for airtightness testing, and then the operation of the fuel cell is continued without going through the processes of heating up and cooling down.

[0069] In one embodiment, when the fuel cell stack 23 to be tested is in a working state, both the cathode inlet cut-off valve 24 and the cathode outlet cut-off valve 25 are in the open state; when detecting the overall leakage amount of the fuel cell stack 23 to be tested, after the purging is completed, the cathode inlet cut-off valve 24 and the cathode outlet cut-off valve 25 are in the open state.

[0070] When detecting the overall leakage amount of the fuel cell stack 23 to be tested, the cathode inlet cut-off valve 24 and the cathode outlet cut-off valve 25 are in the open state to obtain the overall leakage amount of the fuel cell stack 23 to be tested.

[0071] Through this embodiment, the overall leakage amount of the fuel cell stack 23 to be tested can be successfully obtained.

[0072] In one embodiment, when detecting the external leakage amount of the fuel cell stack 23 to be tested, after the purging is completed, the cathode inlet stop valve 24 and the cathode outlet stop valve 25 are closed; the internal leakage amount of the fuel cell stack 23 to be tested is the difference between the overall leakage amount of the fuel cell stack 23 to be tested and the external leakage amount of the fuel cell stack 23 to be tested.

[0073] Through this embodiment, the external leakage amount of the fuel cell stack 23 to be tested can be successfully obtained, and the internal leakage amount of the fuel cell stack 23 to be tested can be obtained by using the overall leakage amount of the fuel cell stack 23 to be tested and the external leakage amount of the fuel cell stack 23 to be tested.

[0074] In one embodiment, when detecting the leakage amount of the fuel cell stack 23 to be tested, the expansion tank 19 supplies the airtightness detection gas to the anode of the fuel cell stack 23 to be tested through the second stop valve 20; the volume of the expansion tank 19 is larger than the volume of the anode chamber.

[0075] Through this embodiment, the expansion tank 19 can supplement the airtightness detection gas to the anode in the fuel cell stack 23 to be tested, can ensure the positive pressure in the anode chamber, and protect the anode of the stack 23.

[0076] In one embodiment, during the detection process, when it is found that the leakage amount exceeds the volume of the anode chamber, the detection is immediately stopped, the airtightness detector 16 is switched to the pressure holding mode, and the first stop valve 12 and the anode outlet stop valve 22 are opened.

[0077] Through this embodiment, after the leakage amount exceeds the volume of the anode chamber, the anode of the fuel cell stack 23 to be tested is immediately purged to ensure that the anode is in a non-oxidizing atmosphere environment at high temperature, avoid anode oxidation, local thermal stress, avoid changes in the anode structure, avoid affecting the output performance of the stack 23, and avoid causing the battery chips to rupture, so as to avoid internal leakage of the stack 23, thereby detecting the airtightness of the fuel cell stack 23 to be tested at high temperature.

[0078] In one embodiment, in the purging state, the readings of the pressure sensor 2 between the expansion tank 19 and the airtightness detector 16 and the anode inlet pressure sensor 21 are both less than the preset pressure value, and the difference between the readings of the anode inlet pressure sensor 21 and the cathode inlet pressure sensor 26 is less than the preset pressure difference, and the outlet pressure of the airtightness detector 16 in the pressure holding state is the preset pressure value; after the purging is completed, when the readings of the pressure sensor 2 between the expansion tank 19 and the airtightness detector 16 and the anode inlet pressure sensor 21 stabilize at the preset pressure value, the airtightness detector 16 is switched from the pressure holding mode to the detection mode.

[0079] Through this embodiment, by monitoring various pressures and pressure differences in real time, it is beneficial to avoid the influence of excessive pressure or pressure difference on the battery cells and sealing materials, beneficial to avoid the rupture of the battery cells, and thus beneficial to avoid internal leakage or external leakage of the stack 23.

[0080] In one embodiment, the preset pressure value and the preset pressure difference are set according to the pressure-bearing characteristics of different fuel cell stacks 23 to be measured; both the preset pressure value and the preset pressure difference are not higher than 10 KPa.

[0081] Through this embodiment, it is beneficial to avoid the influence of excessive pressure or pressure difference on the battery cells and sealing materials, beneficial to avoid the rupture of the battery cells, and thus beneficial to avoid internal leakage or external leakage of the stack 23.

[0082] In one embodiment, both the preset pressure value and the preset pressure difference are between 3 - 5 KPa.

[0083] Through this embodiment, it is beneficial to further avoid the influence of excessive pressure or pressure difference on the battery cells and sealing materials, beneficial to avoid the rupture of the battery cells, and thus beneficial to avoid internal leakage or external leakage of the stack 23.

[0084] In one embodiment, the control system is communicatively connected to the hydrogen cut-off valve 1, nitrogen cut-off valve 6, raw material gas main cut-off valve 11, anode outlet cut-off valve 22, first cut-off valve 12, second cut-off valve 20, cathode inlet cut-off valve 24, cathode outlet cut-off valve 25, pressure reducing valve 3, pressure sensor 2, hydrogen mass flowmeter 5, nitrogen mass flowmeter 10, and airtightness detector 16, so as to realize the automatic control of the fuel cell.

[0085] Through this embodiment, it is beneficial to realize the automatic control of the fuel cell and ensure the safety of the fuel cell stack 23 to be measured.

[0086] In one embodiment, when the pressure is higher than the preset pressure value or when the pressure difference is higher than the preset pressure difference, the control system alarms to ensure the safety of the fuel cell stack 23 to be measured.

[0087] Through this embodiment, it is beneficial to further ensure the safety of the fuel cell stack 23 to be measured.

[0088] Example 1

[0089] Such as Figure 1As shown in the figure, this embodiment provides a fuel cell, which includes: a raw material gas supply system for supplying raw material gas to the fuel cell. The raw material gas supply system includes a hydrogen supply pipeline and a nitrogen supply pipeline connected in parallel, and the hydrogen supply pipeline and the nitrogen supply pipeline are connected in series with a raw material gas main cut-off valve 11; a hydrogen cut-off valve 1 is provided near the hydrogen source of the hydrogen supply pipeline; a nitrogen cut-off valve 6 is provided near the nitrogen source of the nitrogen supply pipeline; an airtightness test system, which includes a first cut-off valve 12, an airtightness detector 16, and a second cut-off valve 20 connected in sequence. The first cut-off valve 12 is provided adjacent to the gas source of the airtightness test gas and is located downstream of the gas source of the airtightness test gas; and a fuel cell stack 23 to be tested, with an anode outlet cut-off valve 22 provided at its anode outlet; wherein, the raw material gas supply system is connected in parallel with the airtightness test system and is connected to the anode inlet of the fuel cell stack 23 to be tested.

[0090] In the prior art, it is very difficult to detect the airtightness of the fuel cell stack 23 at high temperatures. The existing airtightness detection methods cannot ensure that the anode environment is a non-oxidizing atmosphere at high temperatures. It cannot avoid the oxidation of the anode, resulting in local thermal stress, and cannot avoid the change of the anode structure, which affects the output performance of the fuel cell stack 23, and even causes the battery chips to rupture, resulting in internal leakage of the fuel cell stack 23.

[0091] The fuel cell of this embodiment includes an airtightness test system, which can connect the anode inlet of the fuel cell to the gas source of the airtightness test gas, so as to ensure that the anode is in a non-oxidizing atmosphere environment at high temperatures, avoid anode oxidation and local thermal stress, avoid changes in the anode structure, avoid affecting the output performance of the fuel cell stack 23, avoid causing battery chip rupture, so as to avoid internal leakage of the fuel cell stack 23, thereby detecting the airtightness of the fuel cell stack 23 to be tested at high temperatures; wherein, the airtightness test gas is a non-oxidizing gas.

[0092] At the same time, the existing fuel cells cannot achieve online detection, that is, during the operation of the fuel cell, the operation of the fuel cell is stopped, the airtightness test is carried out, and then the operation of the fuel cell is continued, without going through the processes of heating up and cooling down.

[0093] The raw material gas supply system of the fuel cell of this embodiment is connected in parallel with the airtightness test system and is connected to the anode inlet of the fuel cell stack 23 to be tested.

[0094] Before the airtightness detection, the fuel cell stack 23 to be tested is in a working state. At this time, the raw material gas supply system supplies hydrogen and nitrogen to the anode inlet of the fuel cell stack 23 to be tested. The hydrogen cut-off valve 1, the nitrogen cut-off valve 6, and the raw material gas main cut-off valve 11 are in the open state, and the anode outlet cut-off valve 22 is in the open state; after the reaction, the gas is discharged from the anode outlet; air enters the fuel cell stack 23 to be tested from the cathode inlet and is discharged from the cathode outlet.

[0095] During the airtightness test, first, the fuel cell stack 23 to be tested is placed in an open-circuit voltage state. The hydrogen cutoff valve 1, nitrogen cutoff valve 6, and the total raw gas cutoff valve 11 are closed. At the same time, the first cutoff valve 12 and the second cutoff valve 20 are opened to supply an airtightness detection gas to the anode inlet of the fuel cell stack 23 to be tested. Here, the airtightness detection gas is a non-oxidizing gas. At this time, the airtightness detector 16 is in the pressure-holding mode to purge the anode of the fuel cell stack 23 to be tested.

[0096] After the purging is completed, the first cutoff valve 12 and the anode outlet cutoff valve 22 are closed for the airtightness detection. At this time, the airtightness detector 16 switches to the detection mode to detect the leakage rate of the fuel cell stack 23 to be tested.

[0097] After the detection is completed, if the airtightness detection is qualified, the second cutoff valve 20 is closed, and the hydrogen cutoff valve 1, nitrogen cutoff valve 6, the total raw gas cutoff valve 11, and the anode outlet cutoff valve 22 are opened to return the fuel cell stack 23 to be tested to the working state.

[0098] Obviously, the structure of this fuel cell is conducive to the on-line detection of the fuel cell stack 23 to be tested, that is, during the operation of the fuel cell, the operation of the fuel cell is stopped for the airtightness test, and then the operation of the fuel cell is continued without going through the processes of heating up and cooling down.

[0099] Using this fuel cell, the anode inlet of this fuel cell can be connected to the gas source of the airtightness detection gas, so as to ensure that the anode is in a non-oxidizing atmosphere environment at high temperature, avoid anode oxidation, local thermal stress, avoid changes in the anode structure, avoid affecting the output performance of the stack 23, avoid causing the battery chips to rupture, so as to avoid internal leakage of the stack 23, and thus detect the airtightness of the fuel cell stack 23 to be tested at high temperature. At the same time, the structure of this fuel cell is conducive to the on-line detection of the fuel cell stack 23 to be tested, that is, during the operation of the fuel cell, the operation of the fuel cell is stopped for the airtightness test, and then the operation of the fuel cell is continued without going through the processes of heating up and cooling down.

[0100] Embodiment 2

[0101] On the basis of Embodiment 1, the raw gas supply system includes a parallel hydrogen supply pipeline and nitrogen supply pipeline. As Figure 1 shown, the hydrogen supply pipeline is composed of a hydrogen cutoff valve 1, a pressure sensor 2, a pressure reducing valve 3, a pressure sensor 2, and a hydrogen mass flowmeter 5 connected in sequence, where the hydrogen cutoff valve 1 is connected to the hydrogen source. As Figure 1 shown, the nitrogen supply pipeline is composed of a nitrogen cutoff valve 6, a pressure sensor 2, a pressure reducing valve 3, a pressure sensor 2, and a nitrogen mass flowmeter 10 connected in sequence, where the nitrogen cutoff valve 6 is connected to the nitrogen source.

[0102] As shown Figure 1 in the figure, the parallel hydrogen supply pipeline and nitrogen supply pipeline are connected in series with the raw gas main shut-off valve 11 to form a raw gas supply system.

[0103] As shown Figure 1 in the figure, the airtightness test system is composed of a first shut-off valve 12, a pressure sensor 2, a pressure reducing valve 3, a pressure sensor 2, an airtightness detector 16, a pressure reducing valve 3, a pressure sensor 2, and a second shut-off valve 20 connected in sequence.

[0104] The raw gas supply system is connected in parallel with the airtightness test system and in series with the anode inlet pressure sensor 21. The other end of the anode inlet pressure sensor 21 is connected to the anode of the fuel cell stack 23 to be tested. An anode outlet shut-off valve 22 is provided at the anode outlet.

[0105] A cathode inlet pressure sensor 26 is provided at the cathode inlet.

[0106] The control system is communicatively connected to the hydrogen shut-off valve 1, the nitrogen shut-off valve 6, the raw gas main shut-off valve 11, the anode outlet shut-off valve 22, the first shut-off valve 12, the second shut-off valve 20, the pressure reducing valve 3, the pressure sensor 2, the hydrogen mass flowmeter 5, the nitrogen mass flowmeter 10, and the airtightness detector 16, so as to realize the automatic control of the fuel cell.

[0107] In addition, the fuel cell further includes an exhaust gas emission system, which includes a processing device and an emission pipeline behind the anode outlet and the cathode outlet.

[0108] Using this embodiment is beneficial to real-time monitoring of various pressures and pressure differences, avoiding the influence of too high pressure or pressure difference on the battery chips and sealing materials, being beneficial to avoiding the rupture of the battery chips, and thus being beneficial to avoiding internal leakage or external leakage of the fuel cell stack 23. At the same time, if necessary, the supply amounts of hydrogen, nitrogen or airtightness detection gas can be reduced, and their supply amounts can be accurately adjusted and controlled.

[0109] Embodiment Three

[0110] Based on Embodiment One or Embodiment Two, as shown Figure 1 in the figure, a cathode inlet shut-off valve 24 and a cathode outlet shut-off valve 25 are respectively provided at the cathode inlet and cathode outlet of the fuel cell stack 23 to be tested. Among them, the cathode inlet shut-off valve 24 is arranged close to the air source, and the cathode inlet pressure sensor 26 is located downstream of the cathode inlet shut-off valve 24.

[0111] When detecting the overall leakage amount of the fuel cell stack 23 to be tested, the cathode inlet shut-off valve 24 and the cathode outlet shut-off valve 25 are in the open state to obtain the overall leakage amount of the fuel cell stack 23 to be tested.

[0112] When detecting the external leakage of the fuel cell stack 23 to be tested, the cathode inlet shut-off valve 24 and the cathode outlet shut-off valve 25 are in the closed state to obtain the external leakage of the fuel cell stack 23 to be tested.

[0113] The internal leakage of the fuel cell stack 23 to be tested is the difference between the overall leakage of the fuel cell stack 23 to be tested and the external leakage of the fuel cell stack 23 to be tested.

[0114] Preferably, both the cathode inlet shut-off valve 24 and the cathode outlet shut-off valve 25 are communicatively connected to the control system.

[0115] Through this embodiment, by respectively arranging the cathode inlet shut-off valve 24 and the cathode outlet shut-off valve 25 at the cathode inlet and the cathode outlet of the fuel cell stack 23 to be tested, the external leakage of the fuel cell stack 23 to be tested can be successfully obtained, and the internal leakage of the fuel cell stack 23 to be tested can be obtained by using the overall leakage of the fuel cell stack 23 to be tested and the external leakage of the fuel cell stack 23 to be tested.

[0116] Embodiment 4

[0117] Based on Embodiment 1, Embodiment 2 or Embodiment 3, as Figure 1 shown, an expansion tank 19 is arranged on the side of the second shut-off valve 20 away from the anode inlet pressure sensor 21.

[0118] When detecting the leakage of the fuel cell stack 23 to be tested, the expansion tank 19 supplies the airtightness detection gas to the anode of the fuel cell stack 23 to be tested through the second shut-off valve 20; to ensure that the anode is in a non-oxidizing atmosphere at high temperature, the volume of the expansion tank 19 is larger than the volume of the anode chamber.

[0119] Preferably, the volume of the expansion tank 19 is larger than the total volume of the anode flow channels in the fuel cell stack 23 to be tested.

[0120] During the airtightness detection, even if the leakage of the anode in the fuel cell stack 23 to be tested is very large and all the original airtightness detection gas in it is exhausted, due to the existence of the expansion tank 19, the expansion tank 19 can supplement the airtightness detection gas to the anode in the fuel cell stack 23 to be tested and can also ensure the positive pressure in the anode chamber to protect the anode of the stack 23.

[0121] Through this embodiment, the expansion tank 19 can supplement the airtightness detection gas to the anode in the fuel cell stack 23 to be tested, can ensure the positive pressure in the anode chamber, and can protect the anode of the stack 23.

[0122] The airtightness detection method in this application is also applicable to the airtightness detection of fuel cells at normal temperature or low temperature.

[0123] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "bottom", "top", "front", "rear", "inner", "outer", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0124] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed, as long as they do not deviate from the spirit and scope of the present invention as defined by the appended claims. It should be understood that different dependent claims and the features described herein can be combined in a manner different from that described in the original claims. It should also be understood that the features described in connection with a single embodiment can be used in other described embodiments.

Claims

1. A fuel cell, characterized in that, Including: A raw gas supply system for supplying raw gas to a fuel cell, which includes parallel raw gas supply branches, and each raw gas supply branch is connected in series with a main raw gas shut-off valve; a branch shut-off valve is provided on the raw gas supply branch; An airtightness test system, which includes a first shut-off valve, an airtightness detector, and a second shut-off valve connected in sequence. The first shut-off valve is arranged adjacent to the gas source of the airtightness detection gas and is located downstream of the gas source of the airtightness detection gas; and, A fuel cell stack to be tested, with an anode outlet shut-off valve provided at its anode outlet; Wherein, the raw gas supply system is connected in parallel with the airtightness test system and is communicated with the anode inlet of the fuel cell stack to be tested.

2. The fuel cell according to claim 1, characterized in that, The raw gas supply system includes a parallel hydrogen supply pipeline and nitrogen supply pipeline. The hydrogen supply pipeline and the nitrogen supply pipeline are connected in series with the main raw gas shut-off valve; a hydrogen shut-off valve is provided near the hydrogen source on the hydrogen supply pipeline; a nitrogen shut-off valve is provided near the nitrogen source on the nitrogen supply pipeline.

3. The fuel cell according to claim 1, characterized in that, An anode inlet pressure sensor and a cathode inlet pressure sensor are respectively provided at the anode inlet and cathode inlet of the fuel cell stack to be tested.

4. The fuel cell according to claim 3, wherein , A pressure reducing valve, a pressure sensor, and an expansion tank are provided between the airtightness detector and the second shut-off valve.

5. The fuel cell according to claim 1, characterized in that, A cathode inlet shut-off valve and a cathode outlet shut-off valve are respectively provided at the cathode inlet and cathode outlet of the fuel cell stack to be tested.

6. The fuel cell according to claim 2, wherein A hydrogen pressure reducing valve and a hydrogen mass flowmeter are provided downstream of the hydrogen shut-off valve, and pressure sensors are provided on both sides of the hydrogen pressure reducing valve; A nitrogen pressure reducing valve and a nitrogen mass flowmeter are provided downstream of the nitrogen shut-off valve, and pressure sensors are provided on both sides of the nitrogen pressure reducing valve; An airtightness gas pressure reducing valve is provided between the first shut-off valve and the airtightness detector, and pressure sensors are provided on both sides of the airtightness gas pressure reducing valve.

7. The fuel cell according to claim 1, characterized in that, The airtightness detection gas is composed of nitrogen and hydrogen, and the content of hydrogen is between 5-20%.

8. The fuel cell according to claim 1, characterized in that, It also includes a control system to realize the automatic control of the fuel cell.

9. A method for detecting the airtightness of a fuel cell according to any one of claims 1-8, characterized in that, Including the following steps: Before the airtightness detection, the fuel cell stack to be tested is in a working state. At this time, the raw gas supply system supplies raw gas to the anode inlet of the fuel cell stack to be tested. The branch shut-off valve and the main raw gas shut-off valve are in the open state, and the anode outlet shut-off valve is in the open state; after the reaction, the gas is discharged from the anode outlet; Air enters the fuel cell stack to be tested from the cathode inlet and is discharged from the cathode outlet; During the airtightness test, first, the fuel cell stack to be tested is in an open-circuit voltage state. The branch shut-off valve and the main raw gas shut-off valve are closed. At the same time, the first shut-off valve and the second shut-off valve are opened. At this time, the airtightness detector is in a pressure-holding mode to purge the anode of the fuel cell stack to be tested; After the purging is completed, the first shut-off valve and the anode outlet shut-off valve are closed for airtightness detection. At this time, the airtightness detector is in a detection mode to detect the leakage amount of the fuel cell stack to be tested; After the detection is completed, if the airtightness detection is qualified, close the second shut-off valve, and open the branch shut-off valve, the raw gas main shut-off valve, and the anode outlet shut-off valve, so that the fuel cell stack to be tested returns to the working state.

10. The airtightness detection method of the fuel cell according to claim 9, characterized in that, When the fuel cell stack to be tested is in the working state, both the cathode inlet shut-off valve and the cathode outlet shut-off valve are in the open state; When detecting the overall leakage of the fuel cell stack to be tested, after the purging is completed, the cathode inlet shut-off valve and the cathode outlet shut-off valve are in the open state.

11. The airtightness detection method of the fuel cell according to claim 9, characterized in that, When detecting the external leakage of the fuel cell stack to be tested, after the purging is completed, close the cathode inlet shut-off valve and the cathode outlet shut-off valve; The internal leakage of the fuel cell stack to be tested is the difference between the overall leakage of the fuel cell stack to be tested and the external leakage of the fuel cell stack to be tested.

12. The airtightness detection method of the fuel cell according to claim 9, characterized in that, An anode inlet pressure sensor and a cathode inlet pressure sensor are respectively arranged at the anode inlet and the cathode inlet of the fuel cell stack to be tested, and a pressure reducing valve, a pressure sensor, and an expansion tank are arranged between the airtightness detector and the second shut-off valve; When detecting the leakage of the fuel cell stack to be tested, the expansion tank supplies airtightness detection gas to the anode of the fuel cell stack to be tested through the second shut-off valve; The volume of the expansion tank is larger than the volume of the anode chamber.

13. The airtightness detection method of the fuel cell according to claim 12, characterized in that, During the detection process, if it is found that the leakage exceeds the volume of the anode chamber, immediately stop the detection, switch the airtightness detector to the pressure holding mode, and open the first shut-off valve and the anode outlet shut-off valve.

14. The airtightness detection method of the fuel cell according to claim 9, characterized in that, An anode inlet pressure sensor and a cathode inlet pressure sensor are respectively arranged at the anode inlet and the cathode inlet of the fuel cell stack to be tested, and a pressure reducing valve, a pressure sensor, and an expansion tank are arranged between the airtightness detector and the second shut-off valve; In the purging state, the readings of the pressure sensor between the expansion tank and the airtightness detector and the anode inlet pressure sensor are both less than the preset pressure value, and the difference between the readings of the anode inlet pressure sensor and the cathode inlet pressure sensor is less than the preset pressure difference, and the outlet pressure of the airtightness detector in the pressure holding state is the preset pressure value; after the purging is completed, when the readings of the pressure sensor between the expansion tank and the airtightness detector and the anode inlet pressure sensor are stable at the preset pressure value, the airtightness detector switches from the pressure holding mode to the detection mode.

15. The airtightness detection method of the fuel cell according to claim 14, characterized in that, The preset pressure value and the preset pressure difference are set according to the pressure-bearing characteristics of different fuel cell stacks to be tested; both the preset pressure value and the preset pressure difference are not higher than 10 KPa.

16. The airtightness detection method of the fuel cell according to claim 14, characterized in that, Both the preset pressure value and the preset pressure difference are between 3 - 5 KPa.

17. The airtightness detection method of the fuel cell according to claim 9, characterized in that The raw gas supply system includes a hydrogen supply pipeline and a nitrogen supply pipeline connected in parallel, and the hydrogen supply pipeline and the nitrogen supply pipeline are connected in series with the raw gas main shut-off valve; a hydrogen shut-off valve is arranged near the hydrogen source on the hydrogen supply pipeline; a nitrogen shut-off valve is arranged near the nitrogen source on the nitrogen supply pipeline; An anode inlet pressure sensor and a cathode inlet pressure sensor are respectively arranged at the anode inlet and the cathode inlet of the fuel cell stack to be tested; A pressure reducing valve, a pressure sensor and an expansion tank are arranged between the airtightness detector and the second stop valve; A cathode inlet stop valve and a cathode outlet stop valve are respectively arranged at the cathode inlet and the cathode outlet of the fuel cell stack to be tested; A hydrogen pressure reducing valve and a hydrogen mass flowmeter are arranged downstream of the hydrogen stop valve, and pressure sensors are arranged on both sides of the hydrogen pressure reducing valve; A nitrogen pressure reducing valve and a nitrogen mass flowmeter are arranged downstream of the nitrogen stop valve, and pressure sensors are arranged on both sides of the nitrogen pressure reducing valve; An airtightness gas pressure reducing valve is arranged between the first stop valve and the airtightness detector, and pressure sensors are arranged on both sides of the airtightness gas pressure reducing valve; The control system is communicatively connected to the hydrogen stop valve, the nitrogen stop valve, the raw material gas main stop valve, the anode outlet stop valve, the first stop valve, the second stop valve, the cathode inlet stop valve, the cathode outlet stop valve, the pressure reducing valve, the pressure sensor, the hydrogen mass flowmeter, the nitrogen mass flowmeter and the airtightness detector, so as to realize the automatic control of the fuel cell.

18. The airtightness detection method of the fuel cell according to claim 17, characterized in that, When the pressure is higher than the preset pressure value or when the pressure difference is higher than the preset pressure difference, the control system alarms to ensure the safety of the fuel cell stack to be tested.

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