Tail exhaust liquid buffer pressure stabilizing device for membrane electrode test and test system

Abstract

This invention relates to a tail gas liquid buffering and stabilizing device and testing system for membrane electrode assembly (MEA) testing. The tail gas liquid buffering and stabilizing device includes a gas-liquid storage and buffering unit, which has an air inlet, an exhaust outlet, and a liquid outlet. The air inlet is located on the upper side wall of the unit and is connected to the air outlet of the test fixture via a pipeline. The exhaust outlet is located at the top of the unit and is connected to an external back pressure control unit or the atmosphere via a pipeline. The liquid outlet is located at the bottom of the gas-liquid storage and buffering unit for gravity discharge of liquid water. The interior of the gas-liquid storage and buffering unit forms a gas phase buffer space with a predetermined volume. The height H in the vertical direction and the maximum width W in the horizontal direction of the gas phase buffer space satisfy the relationship H / W≥1.5, forming a longitudinally extending buffer cavity structure. This invention can significantly reduce the periodic fluctuations in gas pressure during testing and improve the stability and repeatability of MEA test data.

Description

Technical Field

[0001] This invention relates to the field of membrane electrode testing, specifically to a tail gas liquid buffer and pressure stabilizing device and testing system for membrane electrode testing. Background Technology

[0002] The membrane electrode assembly (MEA) of a proton exchange membrane fuel cell (PEMFC) is the core component of the electrochemical reaction, and its performance directly determines the overall output characteristics of the fuel cell. During MEA performance testing, a special test fixture is typically used to clamp the membrane electrode, and a reaction gas (hydrogen on the anode side and air or oxygen on the cathode side) is introduced into the fixture to obtain key performance data such as polarization curves, voltage, and current density.

[0003] Existing MEA testing systems typically employ the following structure: the test fixture contains a serpentine or parallel flow channel. The reactant gas, regulated by a mass flow controller, enters the test fixture, participates in the electrochemical reaction, and then the unreacted gas and the resulting liquid water are discharged through a tailpipe. During the test, the system maintains a specific operating pressure via a back pressure control valve. However, the existing technology has the following technical problems: (1) Pressure drop problem caused by large system flow resistance: Existing test fixtures often adopt a serpentine flow channel structure, or due to complex fixture structure and small membrane electrode thickness (usually only a few hundred micrometers), the overall gas flow resistance of the system is large. Under the above conditions, the reaction gas will generate a significant pressure drop after passing through the test fixture, resulting in a significant pressure gradient between the inlet and outlet ends.

[0004] (2) Water seal phenomenon caused by liquid water accumulation: During the fuel cell reaction, a large amount of liquid water is generated by the electrochemical reaction on the cathode side. During MEA testing, this liquid water can easily enter the tailpipe along with unreacted gas. Since the tailpipe is usually connected by a small diameter pipe and often has local depressions or bends, liquid water gradually accumulates in it. When the liquid water in the tailpipe accumulates to a certain extent, it can easily form a water seal structure (i.e., liquid water forms a liquid column in the pipe and blocks the flow of tail gas).

[0005] (3) Impact of periodic pressure fluctuations on test data: After the water seal structure is formed, the exhaust gas can only intermittently discharge liquid water when the gas pressure rises to a level sufficient to drive the liquid water out. This process causes periodic fluctuations in the exhaust back pressure, which are further transmitted to the inlet end through the gas pipeline, causing synchronous fluctuations in the inlet end pressure. This pressure fluctuation directly affects the gas mass transfer process and reaction uniformity inside the membrane electrode, thus having a significant adverse impact on the stability and repeatability of the polarization performance data obtained during MEA testing.

[0006] While some gas-liquid separators or drainage devices have been reported for managing exhaust fluid in fuel cell systems, these devices are primarily used in fuel cell engine systems and are complex in structure, typically requiring active control components such as solenoid valves, level sensors, and control systems. For the specific application scenario of MEA performance testing, there is a lack of a solution that is simple in structure, requires no additional control system, is low in cost, and can effectively improve test stability. Therefore, there is an urgent need to develop an exhaust fluid buffer and pressure stabilization device suitable for MEA testing to address the aforementioned technical challenges. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a tail gas liquid buffer and pressure stabilizing device for membrane electrode testing. By setting a gas-liquid storage and buffering unit with a specific structure at the gas outlet of the test fixture, the continuous discharge of the reaction liquid water is achieved by gravity, while the buffering effect of the gas phase space is used to stabilize the pressure of the tail gas, thereby significantly reducing the periodic fluctuation of gas pressure during the test and improving the stability and repeatability of MEA test data.

[0008] To achieve the above objectives, a tail gas-liquid buffer and pressure stabilizing device for membrane electrode testing is designed, comprising a gas-liquid storage and buffer unit. The gas-liquid storage and buffer unit has an air inlet, an air outlet, and a liquid outlet. The air inlet is located on the upper side wall of the gas-liquid storage and buffer unit and is connected to the air outlet of the test fixture via a pipeline. The air outlet is located at the top of the gas-liquid storage and buffer unit and is connected to an external back pressure control unit or the atmosphere via a pipeline. The liquid outlet is located at the bottom of the gas-liquid storage and buffer unit and is used for gravity discharge of liquid water. The interior of the gas-liquid storage and buffer unit forms a gas phase buffer space with a predetermined volume. The height H in the vertical direction and the maximum width W in the horizontal direction of the gas phase buffer space satisfy the relationship H / W≥1.5 to form a longitudinally extending buffer cavity structure.

[0009] Furthermore, a gas disperser is provided at the air inlet, the gas disperser having multiple micropores or slits, the micropores or slits being used to disperse the incoming gas-liquid mixture into fine bubbles to enhance the gas-liquid separation effect, the micropore diameter being 0.5-2.0 mm, and the slit width being 0.3-1.0 mm.

[0010] Furthermore, the gas-liquid storage and buffer unit is a vertical container made of transparent material to facilitate observation of the internal liquid level; the transparent material is selected from at least one of glass, polycarbonate PC, polymethyl methacrylate PMMA, or polytetrafluoroethylene PFA.

[0011] Furthermore, the drain port is connected to a U-shaped liquid seal pipe or an automatic drain valve; when a U-shaped liquid seal pipe is used, the liquid seal height h of the U-shaped liquid seal pipe satisfies: ρgh≥ΔPmax, where ρ is the density of water, g is the gravitational acceleration, and ΔPmax is the maximum back pressure fluctuation amplitude of the system; when an automatic drain valve is used, the automatic drain valve is a float-type drain valve or an inverted bucket-type drain valve, and the principle of buoyancy is used to realize automatic opening when the liquid level reaches the set height and automatic closing when the liquid level drops.

[0012] Furthermore, the gas-liquid storage and buffer unit is equipped with a demister located between the air inlet and the exhaust port. The demister is used to capture tiny liquid droplets entrained in the gas. The demister is selected from at least one of a wire mesh demister, a baffle plate demister, or a cyclone separator.

[0013] Furthermore, the gas-liquid storage and buffer unit is equipped with a liquid level indicator, which is a magnetic float level gauge or a capacitive level sensor. The liquid level indicator is used to monitor the liquid level height inside the gas-liquid storage and buffer unit in real time.

[0014] Furthermore, the gas-liquid storage and buffer unit is equipped with a heating and insulation jacket, into which a constant temperature circulating medium is introduced. The heating and insulation jacket is used to maintain the internal temperature of the gas-liquid storage and buffer unit above the gas dew point temperature, preventing water vapor from condensing on the inner wall of the gas-liquid storage and buffer unit.

[0015] This invention also provides a membrane electrode testing system, including a test fixture, a gas supply unit, a back pressure control unit, a data acquisition unit, and the exhaust gas liquid buffer and pressure stabilizing device as described above, wherein... The test fixture is used to hold the membrane electrode assembly, and the test fixture has an inlet airflow channel and an outlet airflow channel; The gas supply unit includes a gas source, a mass flow controller, a humidifier, and a heater. The gas supply unit is used to provide the test fixture with reaction gas whose temperature, humidity, and flow rate are controllable. The back pressure control unit includes a back pressure control valve and a pressure sensor, and the back pressure control unit is used to control the back pressure of the test system. The tail gas liquid buffer and pressure stabilizing device is connected between the outlet gas channel of the test fixture and the back pressure control unit. The data acquisition unit includes a voltage sensor, a current sensor, a temperature sensor, and a pressure sensor. The data acquisition unit is used to acquire the performance data of the membrane electrode in real time. After the reaction gas is regulated to the predetermined temperature, humidity and flow rate by the gas supply unit, it enters the inlet gas channel of the test fixture; the gas undergoes an electrochemical reaction on the surface of the membrane electrode, and the unreacted gas and the generated liquid water are discharged through the outlet gas channel; the gas-liquid mixture first enters the tail gas-liquid buffer and pressure stabilizing device, where gas-liquid separation is completed: the liquid water settles to the bottom and is continuously discharged through the drain port, and the gas enters the gas phase buffer space; the gas after pressure stabilization and buffering enters the back pressure control unit through the exhaust port, and is finally discharged into the atmosphere or the recovery system.

[0016] Furthermore, the testing system also includes a bypass pipeline, one end of which is connected to the outlet air passage of the test fixture, and the other end of which is connected to the exhaust port of the tail gas liquid buffer pressure stabilizing device. A bypass valve is provided on the bypass pipeline. The bypass pipeline is used to open the bypass valve during rapid purging or system startup to bypass the gas liquid storage and buffer unit and achieve rapid exhaust.

[0017] Furthermore, the drain port of the tail gas liquid buffer and pressure stabilizing device is connected to the liquid collection container. The liquid collection container 360 is equipped with a liquid level alarm device, which is used to issue an alarm when the collected liquid water reaches a predetermined liquid level. The tail gas liquid buffer and pressure stabilizing device includes an anode tail gas liquid buffer and pressure stabilizing device and a cathode tail gas liquid buffer and pressure stabilizing device. The anode tail gas liquid buffer and pressure stabilizing device and the cathode tail gas liquid buffer and pressure stabilizing device are respectively connected to the anode outlet end and the cathode outlet end of the test fixture.

[0018] Compared with the prior art, the present invention has the following advantages: (1) Significantly reduces pressure fluctuations and improves the stability of test data. This invention, through the volumetric buffering effect of the gas-phase buffer space, can reduce the fluctuation amplitude of the tail back pressure by more than 80%, transforming the pressure fluctuation frequency from intermittent fluctuations to a continuous and stable state, thereby significantly improving the stability and repeatability of polarization curve test data. Experiments show that, using the device of this invention, the deviation of the polarization curve from multiple tests of the same MEA sample can be controlled within 1%, while the deviation can reach 4% without this device.

[0019] (2) Simple structure, no additional control system required. The device of this invention relies entirely on physical structure (gravity separation, gas phase buffer) to achieve its function, without the need for active control components such as solenoid valves, liquid level sensors, and controllers, which greatly reduces the complexity and cost of the system. The device can operate stably for a long time and is easy to maintain, requiring only periodic cleaning of the liquid collection container.

[0020] (3) Continuous automatic drainage without manual intervention. This invention achieves continuous or quasi-continuous drainage of liquid water through gravity drainage and optional automatic drainage valve, avoiding the tedious operation of manual periodic drainage and avoiding test interruption due to forgetting to drain.

[0021] (4) High compatibility and easy integration. The device of this invention can be easily integrated into various existing MEA testing systems without major modifications to the test fixtures or gas supply system. The device uses standard pipeline interfaces, making installation simple.

[0022] (5) Improved testing safety. By separating and collecting liquid water in a timely manner, this invention avoids the accumulation and sudden discharge (water hammer phenomenon) of liquid water in the tailpipeline, thereby reducing the safety risks of the testing system.

[0023] In summary, the device of this invention, by setting a gas-liquid storage and buffer unit with a specific structure at the gas outlet of the test fixture, utilizes gravity to achieve continuous discharge of the reaction liquid water, while simultaneously using the buffering effect of the gas phase space to stabilize the pressure of the exhaust gas. This significantly reduces the periodic fluctuations in gas pressure during the test, improving the stability and repeatability of MEA test data. Moreover, this device can be easily integrated into the MEA test system, and throughout the entire test process, the exhaust liquid buffer and pressure stabilizing device continuously absorbs pressure fluctuations caused by the discharge of liquid water, maintaining the stability of the intake pressure and ensuring that the data acquisition unit obtains stable and repeatable polarization performance data. It is worthy of widespread application. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the tail gas exhaust liquid buffer and pressure stabilizing device according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the tail gas exhaust liquid buffer and pressure stabilizing device according to Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the membrane electrode testing system of Embodiment 3 of the present invention; Figure 4 This is a schematic diagram of the tail pressure fluctuation in the comparative experiment of the control group A in Embodiment 4 of the present invention; Figure 5 This is a schematic diagram of the tail pressure fluctuation in experimental group B during the comparative experiment of Embodiment 4 of the present invention; Figure 6 This is a comparative schematic diagram of control group A and experimental group B in the comparative experiment of embodiment 4 of the present invention; Figure 7 This is a table of single batteries and operating parameters according to an embodiment of the present invention; In the diagram: 110, Gas-liquid storage and buffer unit; 111, Gas phase buffer space; 112, Air inlet; 113, Exhaust outlet; 114, Liquid drain outlet; 220, Gas disperser; 310, Test fixture; 320, Gas supply unit; 330, Tail exhaust liquid buffer and pressure stabilizing device; 340, Back pressure control unit; 350, Data acquisition unit; 360, Liquid collection container. Detailed Implementation

[0025] As attached Figure 1 and attached Figure 2 As shown, this invention provides a tail gas liquid buffer and pressure stabilizing device for membrane electrode testing, including a gas-liquid storage and buffer unit 110. The gas-liquid storage and buffer unit 110 has an air inlet 112, an exhaust port 113, and a liquid drain port 114. The air inlet 112 is located on the upper side wall of the gas-liquid storage and buffer unit 110 and is connected to the air outlet of the test fixture 310 through a pipeline. The exhaust port 113 is located at the top of the gas-liquid storage and buffer unit 110 and is connected to an external back pressure control unit or the atmosphere through a pipeline. The liquid drain port 114 is located at the bottom of the gas-liquid storage and buffer unit 110 and is used for gravity discharge of liquid water. The interior of the gas-liquid storage and buffer unit 110 forms a gas phase buffer space 111 with a predetermined volume. The height H of the gas phase buffer space 111 in the vertical direction and the maximum width W in the horizontal direction satisfy the relationship H / W≥1.5 to form a longitudinally extending buffer cavity structure.

[0026] When pressure fluctuations occur in the tailpipeline due to the water seal effect, the gas-phase buffer space inside the gas-liquid storage and buffer unit acts as an "air cushion." According to the ideal gas law PV=nRT, when the upstream pressure rises instantaneously, the gas-phase space is compressed, absorbing the pressure shock; when the upstream pressure decreases, the gas-phase space expands, compensating for the pressure drop. This buffering effect significantly attenuates the amplitude and frequency of pressure fluctuations. Since the air inlet is located at the top, the exhaust outlet at the top, and the liquid drain outlet at the bottom, after the gas-liquid mixture enters the unit, the liquid water settles to the bottom under gravity, while the gas rises to the top. This longitudinal separation structure prevents liquid water from directly entering the tailpipeline and forming a water seal. Through the bottom drain outlet, liquid water can be discharged continuously or intermittently by gravity, without the need for additional pumps or valves, simplifying the system structure.

[0027] In a preferred embodiment, a gas disperser 220 is provided at the air inlet 112. The gas disperser 220 has multiple micropores or slits. The micropores or slits are used to disperse the incoming gas-liquid mixture into fine bubbles to enhance the gas-liquid separation effect. The micropore diameter is 0.5-2.0 mm and the slit width is 0.3-1.0 mm.

[0028] In another preferred embodiment, the gas-liquid storage and buffer unit 110 is a vertical container made of a transparent material to facilitate observation of the internal liquid level; the transparent material is selected from at least one of glass, polycarbonate (PC), polymethyl methacrylate (PMMA) or polytetrafluoroethylene (PFA).

[0029] In another preferred embodiment, the drain port 114 is connected to a U-shaped liquid seal pipe or an automatic drain valve; when a U-shaped liquid seal pipe is used, the liquid seal height h of the U-shaped liquid seal pipe satisfies: ρgh≥ΔPmax, where ρ is the density of water, g is the gravitational acceleration, and ΔPmax is the maximum back pressure fluctuation amplitude of the system; when an automatic drain valve is used, the automatic drain valve is a float-type drain valve or an inverted bucket-type drain valve, and the principle of buoyancy is used to realize automatic opening when the liquid level reaches the set height and automatic closing when the liquid level drops.

[0030] In another preferred embodiment, the gas-liquid storage and buffer unit 110 is provided with a demister, which is located between the air inlet 112 and the exhaust 113. The demister is used to capture tiny liquid droplets entrained in the gas. The demister is selected from at least one of a wire mesh demister, a baffle plate demister, or a cyclone separator.

[0031] In another preferred embodiment, the gas-liquid storage and buffer unit 110 is provided with a liquid level indicator, which is a magnetic float level gauge or a capacitive level sensor. The liquid level indicator is used to monitor the liquid level height inside the gas-liquid storage and buffer unit 110 in real time.

[0032] In another preferred embodiment, the gas-liquid storage and buffer unit 110 is provided with a heating and insulation jacket, and a constant temperature circulating medium is introduced into the heating and insulation jacket. The heating and insulation jacket is used to maintain the internal temperature of the gas-liquid storage and buffer unit 110 above the gas dew point temperature and prevent water vapor from condensing on the inner wall of the gas-liquid storage and buffer unit 110.

[0033] As attached Figure 3 As shown, another aspect of the present invention provides a membrane electrode testing system, including a test fixture 310, a gas supply unit 320, a back pressure control unit 340, a data acquisition unit 350, and the exhaust gas liquid buffer and pressure stabilizing device 330 as described above, wherein, Test fixture 310 is used to hold the membrane electrode assembly. Test fixture 310 has an inlet airflow channel and an outlet airflow channel. The gas supply unit 320 includes a gas source, a mass flow controller, a humidifier, and a heater. The gas supply unit 320 is used to supply the test fixture 310 with reaction gas whose temperature, humidity, and flow rate are controllable. The back pressure control unit 340 includes a back pressure control valve and a pressure sensor. The back pressure control unit 340 is used to control the back pressure of the test system. The tail gas liquid buffer and pressure stabilizing device 330 is connected between the outlet gas channel of the test fixture 310 and the back pressure control unit 340. The data acquisition unit 350 includes a voltage sensor, a current sensor, a temperature sensor, and a pressure sensor. The data acquisition unit 350 is used to acquire the performance data of the membrane electrode in real time. The system's workflow is as follows: The reactant gas, after being regulated to a predetermined temperature, humidity, and flow rate by the gas supply unit 320, enters the inlet gas channel of the test fixture 310. An electrochemical reaction occurs on the surface of the membrane electrode, and unreacted gas and generated liquid water are discharged through the outlet gas channel. The gas-liquid mixture first enters the tail gas-liquid buffer and stabilizing device 330, where gas-liquid separation is completed: the liquid water settles to the bottom and is continuously discharged through the drain port 114, while the gas enters the gas phase buffer space 111. The pressure-stabilized and buffered gas enters the back pressure control unit 340 through the exhaust port 113, and is ultimately discharged into the atmosphere or a recovery system. Throughout the testing process, the tail gas-liquid buffer and stabilizing device continuously absorbs pressure fluctuations caused by liquid water discharge, maintaining stable inlet pressure and ensuring that the data acquisition unit obtains stable and repeatable polarization performance data.

[0034] In a preferred embodiment, the test system further includes a bypass pipeline, one end of which is connected to the outlet air passage of the test fixture 310, and the other end of which is connected to the exhaust port 113 of the tail gas liquid buffer pressure stabilizing device 330. A bypass valve is provided on the bypass pipeline. When performing rapid purging or during system startup, the bypass valve can be opened to bypass the gas liquid storage and buffer unit 110 and achieve rapid exhaust.

[0035] In another preferred embodiment, the drain port 114 of the tail exhaust liquid buffer pressure stabilizing device 330 is connected to the liquid collection container 360, which is equipped with a liquid level alarm device. The liquid level alarm device is used to issue an alarm when the collected liquid water reaches a predetermined level.

[0036] In another preferred embodiment, the tail gas exhaust buffer and pressure stabilizing device 330 of the test system includes an anode tail gas exhaust buffer and pressure stabilizing device and a cathode tail gas exhaust buffer and pressure stabilizing device, which are respectively connected to the anode exhaust end and the cathode exhaust end of the test fixture 310. Since the cathode reaction generates far more water than the anode, the device volume on the cathode side is usually designed to be 2-5 times the device volume on the anode side.

[0037] The following is in conjunction with the appendix Figure 1 To be continued Figure 7 The present invention will be further described as follows: Example 1: Basic type tail gas exhaust liquid buffer and pressure stabilizing device like Figure 1As shown, this embodiment provides a tail gas liquid buffer and pressure stabilizing device for membrane electrode testing, including a gas-liquid storage and buffer unit 110. The gas-liquid storage and buffer unit 110 is a cylindrical transparent glass container with an inner diameter of 50 mm and a height of 200 mm, forming a gas phase buffer space 111 inside. The ratio of the height H in the vertical direction to the maximum width W in the horizontal direction (i.e., the inner diameter of the cylinder) of the gas phase buffer space 111 is H / W = 200 / 50 = 4, which meets the design requirement of H / W ≥ 1.5.

[0038] The upper side wall of the gas-liquid storage and buffer unit 110 is provided with an air inlet 112, which is connected to the air outlet of the test fixture through a polytetrafluoroethylene pipe. The inner diameter of the air inlet 112 is 6 mm, and it is located 30 mm from the top of the unit.

[0039] The gas-liquid storage and buffer unit 110 has an exhaust port 113 at the top center, which is connected to the back pressure control valve via a pipeline. The inner diameter of the exhaust port 113 is 8 mm.

[0040] The gas-liquid storage and buffer unit 110 has a drain port 114 at the bottom center, which is connected to the liquid collection container through a pipeline. The inner diameter of the drain port 114 is 10 mm to ensure that liquid water can be discharged smoothly.

[0041] The gas-liquid mixture from the test fixture enters the gas-liquid storage and buffer unit 110 tangentially through the air inlet 112. Inside the unit, liquid water settles to the bottom under gravity and is continuously discharged through the drain port 114; the gas rises to the top and is discharged through the exhaust port 113. When pressure fluctuations occur in the tailpipe, the gas phase buffer space 111 absorbs the pressure shock through volume changes, thus stabilizing the pressure.

[0042] Example 2: Tail gas exhaust liquid buffer and pressure stabilizing device with gas disperser The difference between Example 2 and Example 1 is as follows: Figure 2 As shown, this embodiment 2 provides an improved tailpipe liquid buffer and pressure stabilizing device. The difference between this and embodiment 1 is that a gas disperser 220 is added at the air inlet 112. The gas disperser 220 is a sintered metal porous plate with multiple micropores of 1.0 mm in diameter, arranged in a honeycomb pattern. The gas disperser 220 disperses the incoming gas-liquid mixture into fine bubbles, increasing the gas-liquid contact area, promoting gas-liquid separation, and preventing liquid water from directly impacting the gas phase space in the form of a continuous liquid column.

[0043] Example 3: Membrane Electrode Testing System like Figure 3 As shown, this embodiment 3 provides a membrane electrode testing system, including: Test fixture 310: It adopts a graphite bipolar plate structure with an effective area of ​​25 cm² and a single serpentine flow channel, and is used to hold the MEA sample to be tested.

[0044] Gas supply unit 320 includes a hydrogen source 321, an air source 322, a mass flow controller 323, a humidifier 324, and a heater 325. The flow rates of hydrogen and air are regulated by the mass flow controller 323, humidified to 100% RH by the humidifier 324, and heated to 80°C by the heater 325 before entering the anode and cathode of the test fixture 310.

[0045] Tail exhaust liquid buffer and pressure stabilizing device 330: adopts the structure of Embodiment 1 or Embodiment 2, and is connected to the anode outlet end and cathode outlet end of the test fixture 310, respectively. The volume of the cathode-side device is designed to be 3 times that of the anode-side device to cope with the larger water production of the cathode.

[0046] Back pressure control unit 340: includes back pressure control valve 341 and pressure sensor 342, used to stabilize the system back pressure at a set value (e.g., 150 kPa gauge pressure).

[0047] Data acquisition unit 350 includes an electrochemical workstation 351, a voltage sensor 352, a current sensor 353, a temperature sensor 354, and a pressure sensor 355, used to acquire battery voltage, current, temperature, and pressure data in real time and plot polarization curves.

[0048] Liquid collection container 360: connected to the drain port of the tail exhaust liquid buffer and pressure stabilizing device 330, used to collect the separated liquid water.

[0049] Test Procedure: Assemble the MEA under test in the test fixture 310 and apply appropriate assembly pressure; turn on the gas supply unit 320 to introduce humidified hydrogen and air into the test fixture 310; turn on the back pressure control unit 340 and set the back pressure to 150 kPa; after the system stabilizes, perform polarization curve testing through the data acquisition unit 350; during the test, the liquid water generated by the reaction enters the tail exhaust liquid buffer and stabilizing device 330 with the tail exhaust gas, and after gas-liquid separation, the liquid water is discharged into the liquid collection container 360, and the gas is discharged through the back pressure control unit 340; due to the pressure stabilizing effect of the tail exhaust liquid buffer and stabilizing device 330, the pressure fluctuation during the test is significantly suppressed, and stable and repeatable polarization performance data are obtained.

[0050] Example 4: Comparative Experiment To verify the effectiveness of the present invention, a comparative experiment was conducted under the following conditions: MEA sample: effective area 25 cm², proton exchange membrane thickness 8 μm, Pt loading 0.4 mg / cm² (cathode) / 0.1 mg / cm² (anode).

[0051] Test conditions: temperature 80°C, anode and cathode gas dew point 80°C (fully humidified), stoichiometric ratio H2 / Air = 1.5 / 2.5, back pressure 150 kPag.

[0052] Test item: Polarization curve (scan from open circuit voltage to 0.3 V).

[0053] Comparison Group A (Prior Technology): The cathode outlet of the test fixture is directly connected to the back pressure control valve, without a gas-liquid buffer device.

[0054] Experimental Group B (Invention): A tail gas exhaust liquid buffer and pressure stabilizing device (volume 300 mL, U-shaped liquid seal tube liquid seal height 350 mm) was connected between the cathode outlet of the test fixture and the back pressure control valve in Example 2.

[0055] Experimental results: like Figure 4 and Figure 5 As shown, the tail discharge pressure of control group A exhibits obvious periodic fluctuations, with a maximum fluctuation amplitude of 90 kPa. These periodic fluctuations are related to the intermittent discharge cycle of liquid water. The tail discharge pressure of experimental group B is basically stable, with the maximum fluctuation amplitude decreasing to below 14 kPa, and the pressure curve is smooth.

[0056] like Figure 6 As shown, polarization curve tests were performed on the same MEA sample: under the same current density of 1.0 A / cm², the three polarization test results of control group A showed significant dispersion, with a maximum voltage deviation of 32 mV. The three polarization test results of experimental group B were almost identical, with a maximum voltage deviation of 5 mV, demonstrating significantly improved repeatability. Figure 7 The table shown is a single battery and its operating parameters for an example.

[0057] The invention has been further described above with reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted.

[0058] The above description illustrates the implementation of the present invention through specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The terminology used in the embodiments of the present invention is for describing specific implementation schemes and is not intended to limit the scope of protection of the present invention. Test methods not specified with specific conditions in the above embodiments are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0059] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0060] This invention is not limited to the above-described embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of this invention shall be considered equivalent substitutions and shall be included within the scope of protection of this invention.

Claims

1. A tail gas exhaust liquid buffer and voltage stabilizing device for membrane electrode testing, characterized in that: It includes a gas-liquid storage and buffer unit (110), which has an air inlet (112), an exhaust outlet (113), and a liquid outlet (114), wherein, The air inlet (112) is located on the upper side wall of the gas-liquid storage and buffer unit (110) and is connected to the air outlet of the test fixture (310) through a pipeline. The exhaust port (113) is located on top of the gas-liquid storage and buffer unit (110) and is connected to the external back pressure control unit or the atmosphere through a pipeline; The drain port (114) is located at the bottom of the gas-liquid storage and buffer unit (110) and is used for gravity discharge of liquid water; The gas-liquid storage and buffer unit (110) forms a gas phase buffer space (111) with a predetermined volume inside. The height H in the vertical direction and the maximum width W in the horizontal direction of the gas phase buffer space (111) satisfy the relationship H / W≥1.5 to form a longitudinally extending buffer cavity structure.

2. The tail gas exhaust liquid buffer and voltage stabilizing device for membrane electrode testing as described in claim 1, characterized in that: A gas disperser (220) is provided at the air inlet (112). The gas disperser (220) has multiple micropores or slits. The micropores or slits are used to disperse the incoming gas-liquid mixture into fine bubbles to enhance the gas-liquid separation effect. The pore diameter of the micropores is 0.5-2.0 mm, and the width of the slits is 0.3-1.0 mm.

3. The tail gas exhaust buffer and voltage stabilizing device for membrane electrode testing as described in claim 1, characterized in that: The gas-liquid storage and buffer unit (110) is a vertical container made of transparent material to facilitate observation of the internal liquid level; the transparent material is selected from at least one of glass, polycarbonate PC, polymethyl methacrylate PMMA or polytetrafluoroethylene PFA.

4. The tail gas exhaust liquid buffer and voltage stabilizing device for membrane electrode testing as described in claim 1, characterized in that: The drain port (114) is connected to a U-shaped liquid seal pipe or an automatic drain valve. When a U-shaped liquid seal pipe is used, the liquid seal height h of the U-shaped liquid seal pipe satisfies: ρgh≥ΔPmax, where ρ is the density of water, g is the gravitational acceleration, and ΔPmax is the maximum back pressure fluctuation amplitude of the system. When an automatic drain valve is used, the automatic drain valve is a float-type drain valve or an inverted bucket-type drain valve, and the principle of buoyancy is used to realize automatic opening when the liquid level reaches the set height and automatic closing after the liquid level drops.

5. The tail gas exhaust liquid buffer and voltage stabilizing device for membrane electrode testing as described in claim 1, characterized in that: The gas-liquid storage and buffer unit (110) is equipped with a demister, which is located between the air inlet (112) and the exhaust port (113). The demister is used to capture tiny liquid droplets entrained in the gas. The demister is selected from at least one of a wire mesh demister, a baffle plate demister, or a cyclone separator.

6. The tail gas exhaust liquid buffer and voltage stabilizing device for membrane electrode testing as described in claim 1, characterized in that: The gas-liquid storage and buffer unit (110) is equipped with a liquid level indicator, which is a magnetic float level gauge or a capacitive level sensor. The liquid level indicator is used to monitor the liquid level height inside the gas-liquid storage and buffer unit (110) in real time.

7. The tail gas exhaust liquid buffer and voltage stabilizing device for membrane electrode testing as described in claim 1, characterized in that: The gas-liquid storage and buffer unit (110) is equipped with a heating and insulation jacket. A constant temperature circulating medium is introduced into the heating and insulation jacket. The heating and insulation jacket is used to maintain the internal temperature of the gas-liquid storage and buffer unit (110) higher than the gas dew point temperature, and to prevent water vapor from condensing on the inner wall of the gas-liquid storage and buffer unit (110).

8. A membrane electrode testing system, characterized in that: The system includes a test fixture (310), an air supply unit (320), a back pressure control unit (340), a data acquisition unit (350), and a tail gas liquid buffer and pressure stabilizing device (330) as described in any one of claims 1 to 7, wherein, The test fixture (310) is used to hold the membrane electrode assembly, and the test fixture (310) has an inlet airflow channel and an outlet airflow channel; The gas supply unit (320) includes a gas source, a mass flow controller, a humidifier and a heater. The gas supply unit (320) is used to provide the test fixture (310) with a reaction gas whose temperature, humidity and flow rate are controllable. The back pressure control unit (340) includes a back pressure control valve and a pressure sensor. The back pressure control unit (340) is used to control the back pressure of the test system. The tail gas liquid buffer and pressure stabilizing device (330) is connected between the outlet air passage of the test fixture (310) and the back pressure control unit (340); The data acquisition unit (350) includes a voltage sensor, a current sensor, a temperature sensor, and a pressure sensor. The data acquisition unit (350) is used to acquire the performance data of the membrane electrode in real time. After the reaction gas is regulated to the predetermined temperature, humidity and flow rate by the gas supply unit (320), it enters the inlet gas channel of the test fixture (310); the gas undergoes an electrochemical reaction on the surface of the membrane electrode, and the unreacted gas and the generated liquid water are discharged through the outlet gas channel; the gas-liquid mixture first enters the tail gas liquid buffer and pressure stabilizing device (330), and gas-liquid separation is completed inside the device: the liquid water settles to the bottom and is continuously discharged through the drain port (114), and the gas enters the gas phase buffer space (111); the gas after pressure stabilization and buffering enters the back pressure control unit (340) through the exhaust port (113), and is finally discharged into the atmosphere or the recovery system.

9. The membrane electrode testing system as described in claim 8, characterized in that: The test system also includes a bypass pipeline, one end of which is connected to the outlet air passage of the test fixture (310), and the other end of which is connected to the exhaust port (113) of the tail exhaust liquid buffer pressure stabilizing device (330). A bypass valve is provided on the bypass pipeline. The bypass pipeline is used to open the bypass valve during rapid purging or system startup to bypass the gas-liquid storage and buffer unit (110) and achieve rapid exhaust.

10. The membrane electrode testing system as described in claim 8, characterized in that: The drain port (114) of the tail gas venting buffer pressure stabilizing device (330) is connected to the liquid collection container (360). The liquid collection container (360) is equipped with a liquid level alarm device, which is used to issue an alarm when the collected liquid water reaches a predetermined liquid level. The tail gas venting buffer pressure stabilizing device (330) includes an anode tail gas venting buffer pressure stabilizing device and a cathode tail gas venting buffer pressure stabilizing device. The anode tail gas venting buffer pressure stabilizing device and the cathode tail gas venting buffer pressure stabilizing device are respectively connected to the anode outlet end and the cathode outlet end of the test fixture (310).

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