Membrane electrode inner leakage detection device

Abstract

The utility model discloses a membrane electrode inner leakage detection device which comprises an optical fiber hydrogen sensor, a lower end plate used for placing a membrane electrode to be detected and an upper end plate used for covering the membrane electrode to be detected, the upper end plate is provided with a monitoring hole covering a carbon paper area of the membrane electrode to be detected, and the optical fiber hydrogen sensor is aligned with the monitoring hole in position. According to the membrane electrode inner leakage detection device disclosed by the utility model, the positions of negative and positive electrode inner leakage of the membrane electrode can be quickly locked.

Description

Technical Field

[0001] The utility model belongs to the technical field of hydrogen fuel cell membrane electrodes, and specifically relates to a membrane electrode internal leakage detection device. Background Art

[0002] Hydrogen fuel cell vehicles have become one of the key development directions in the field of new energy vehicles. Proton exchange membrane fuel cells have many advantages, but a major problem that currently makes it difficult to quickly commercialize them is the durability and safety of proton exchange membrane fuel cells.

[0003] The sealing performance of the battery is critical to the safe operation and working efficiency of the battery. Fuel cell stacks are generally assembled with hundreds of single cells in series. If the sealing structure of any single cell leaks or gas is blowby, the battery performance will drop sharply and eventually lead to battery failure.

[0004] The sealing failure of MEA is mainly divided into leakage from the sealing cavity to the outside, gas leakage between the sealing cavity and the sealing cavity, and internal leakage between the cathode and cathode. The first two leakage modes are mainly determined by factors such as the sealing medium characteristics and compression rate. For the internal leakage of gas between the cathode and cathode, it is mainly caused by the damage of the proton membrane and the failure of the edge seal of the membrane electrode seal. For the detection of internal leakage of the cathode and cathode of the membrane electrode, the damage of the proton exchange membrane can be mainly detected by infrared thermal imaging or foaming method. The detection of the edge seal failure of the membrane electrode seal is that the membrane electrode seal is compressed and sealed by the end plate, and the gas that blows to the other side has an initial horizontal velocity and will move inside the gas diffusion layer (GDL). The gas will not rise immediately, and the point where the gas is finally generated is different from the actual internal leakage position of the membrane electrode seal. Therefore, the ordinary bubble method and thermal imaging method cannot accurately locate the internal leakage position of the cathode and cathode of the membrane electrode seal.

[0005] A Chinese patent with publication number CN117968950A discloses a device for detecting the internal leakage position of anode and cathode of a rubber frame-sealed integrated membrane electrode, comprising an upper end plate and a lower end plate, a rubber frame-sealed integrated membrane electrode to be tested is arranged between the upper end plate and the lower end plate, a membrane electrode sealing groove is arranged on the upper surface of the lower end plate, a rectangular array of thin film thermocouples is arranged at the bottom of the membrane electrode sealing groove, the temperature measuring point of the thin film thermocouple is aligned with the sealing line of the membrane electrode to be tested, an air inlet is arranged on the lower surface of the lower end plate, and a through hole array is arranged on the upper end plate, and the through hole array covers the carbon paper area of ​​the membrane electrode to be tested.

[0006] Therefore, it is hoped to provide a device that can quickly lock the location of internal leakage of the anode and cathode of the membrane electrode, detect and analyze the damage of the proton membrane or the internal leakage of the anode and cathode of the membrane electrode, which is very important for the subsequent improvement and enhancement of the sealing performance of the membrane electrode sealing structure. Utility Model Content

[0007] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model provides a membrane electrode internal leakage detection device, the purpose of which is to ensure that the location of the membrane electrode internal leakage occurring at the cathode and anode can be quickly locked.

[0008] In order to solve the above technical problems, the technical solution adopted by the utility model is: a membrane electrode internal leakage detection device, including a fiber optic hydrogen sensor, a lower end plate for placing the membrane electrode to be tested and an upper end plate for covering the membrane electrode to be tested, a monitoring hole covering the carbon paper area of ​​the membrane electrode to be tested is set on the upper end plate, and the fiber optic hydrogen sensor is aligned with the monitoring hole.

[0009] There are multiple monitoring holes, and all the monitoring holes are arranged in a matrix.

[0010] The optical fiber hydrogen sensor comprises a light source, an optical fiber, a first hydrogen-sensitive film and a second hydrogen-sensitive film. The first hydrogen-sensitive film and the second hydrogen-sensitive film are respectively covered on both sides of the optical fiber. The light source is connected to the optical fiber.

[0011] The optical fiber is connected to a demodulator, the demodulator is connected to an oscilloscope, and the oscilloscope is connected to a computer.

[0012] The lower end plate is provided with a sealing groove, and an air inlet is provided in the area surrounded by the sealing groove, and the air inlet is connected to an air source.

[0013] A pressure gauge is arranged between the air inlet and the air source.

[0014] Silicon rubber gaskets are provided at the joints between the frame of the membrane electrode to be tested and the upper end plate and the lower end plate.

[0015] Positioning holes are provided on the upper end plate and the lower end plate.

[0016] The membrane electrode internal leakage detection device of the utility model has the following beneficial effects:

[0017] (1) Using solid palladium alloy thin film hydrogen measurement technology, the detection of hydrogen is specific and is not affected by combustible gases such as CO, CH and NOx. It can work normally in both oxygen and oxygen-free conditions. It is applied to membrane electrode hydrogen leak detection to ensure that the location of the membrane electrode internal leakage can be quickly locked;

[0018] (2) Through the grid detection hole array and the grid-isolated distribution of the sensor probes, the hydrogen leakage concentration in the membrane electrode is detected. The light wave signal of the hydrogen concentration detected by the hydrogen sensor is converted into an electrical signal. The computer displays the hydrogen leakage value, change value, location, quantity and other information at each point of the membrane electrode according to the corresponding value of the standard concentration curve. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1It is a structural schematic diagram of the membrane electrode internal leakage detection device of the utility model;

[0020] Figure 2 is a schematic diagram of the structure of the upper end plate;

[0021] Figure 3 is a schematic diagram of the structure of the lower end plate;

[0022] The marks in the above figures are: 1. upper end plate; 2. silicone rubber gasket; 3. lower end plate; 4. air inlet; 5. membrane electrode to be tested; 6. positioning hole; 7. fixing groove; 9. monitoring hole; 10. sealing groove; 11. sealing rubber line of membrane electrode to be tested; 13. rubber sealing frame; 14. pressure gauge; 21. light source; 22. optical fiber; 23. first hydrogen-sensitive membrane; 24. second hydrogen-sensitive membrane; 25. oscilloscope; 26. computer; 27. gas source; 28. demodulator; DETAILED DESCRIPTION

[0023] The specific implementation methods of the utility model are further explained in detail below with reference to the accompanying drawings through the description of embodiments, with the aim of helping technicians in the field to have a more complete, accurate and in-depth understanding of the concept and technical solution of the utility model and facilitating its implementation.

[0024] It should be noted that when an element is referred to as being "fixed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower" and similar expressions used in this article are for illustrative purposes only.

[0025] It should be noted that, in the following embodiments, the “first” and “second” mentioned do not represent an absolute distinction in structure and / or function, nor do they represent a sequential order of execution, but are merely for the convenience of description.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly connected by technicians in the technical field to which the present invention belongs. The terminology used in the specification of the present invention is for the purpose of describing specific embodiments and is not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0027] like Figures 1 to 3As shown, the membrane electrode internal leakage detection device includes a fiber optic hydrogen sensor, a lower end plate 3 for placing the membrane electrode 5 to be tested, and an upper end plate 1 for covering the membrane electrode 5 to be tested. The upper end plate 1 is provided with a monitoring hole 9 covering the carbon paper area of ​​the membrane electrode 5 to be tested, and the fiber optic hydrogen sensor is aligned with the monitoring hole 9.

[0028] Specifically, for the detection of internal leakage of the anode and cathode of the membrane electrode, the damage of the proton exchange membrane can be mainly detected by infrared thermal imaging or foaming method. The detection of edge sealing failure of the membrane electrode seal is due to the membrane electrode seal is compressed and sealed by the end plate, the gas that blows to the other side has an initial horizontal velocity and will move inside the gas diffusion layer (GDL). The gas will not rise immediately, and the point where the gas is finally generated will deviate from the actual internal leakage position of the membrane electrode seal. Therefore, the ordinary bubble method and thermal imaging method cannot accurately locate the internal leakage position of the anode and cathode of the membrane electrode seal.

[0029] like Figures 1 to 3 As shown, a membrane electrode 5 to be tested is arranged between the upper end plate 1 and the lower end plate 3, a silicone rubber gasket 2 is arranged at the joint between the frame of the membrane electrode 5 to be tested and the upper end plate 1 and the lower end plate 3, a sealing groove 10 is arranged on the upper surface of the lower end plate 3, a monitoring hole 9 is arranged on the upper end plate 1, and the monitoring hole 9 covers the carbon paper area of ​​the membrane electrode 5 to be tested, and an air inlet 4 is arranged in the area surrounded by the sealing groove 10 of the lower end plate 3, and the air inlet 4 is connected to an air source 27, and a pressure gauge is arranged between the air inlet and the air source 27. A plurality of monitoring holes 9 are arranged, and all monitoring holes 9 are arranged in a matrix. The monitoring holes 9 are used to press the membrane electrode 5 to be tested and provide monitoring positioning holes for the optical fiber hydrogen sensor system. The monitoring holes 9 are air-permeable structures with an area of ​​0.5*0.5cm 2 or 1*1cm 2 The detection point of the optical fiber hydrogen sensor system is aligned with the sealing line of the membrane electrode 5 to be tested. The sealing groove 10 corresponds to the size and shape of the sealing part of the membrane electrode 5 to be tested.

[0030] The upper end plate 1 and the lower end plate 3 are provided with positioning holes 6, which are used for positioning pins to pass through to achieve the positioning and assembly of the upper end plate 1, the lower end plate 3 and the membrane electrode 5 to be tested. The upper surface of the lower end plate 3 is provided with a fixing groove 7 for placing the silicone rubber gasket 2, and the thickness of the silicone rubber gasket 2 is determined by the compression rate of the membrane electrode 5 to be tested.

[0031] The following describes the optical fiber hydrogen sensor system of the embodiment of the utility model. The optical fiber hydrogen sensor system consists of two parts: an optical fiber hydrogen sensor and a signal transmission part. The optical fiber hydrogen sensor includes a light source 21, an optical fiber 22, a first hydrogen-sensitive film 23 and a second hydrogen-sensitive film 24; the signal transmission part includes a demodulator 27, an oscilloscope 25 and a computer 26; the first hydrogen-sensitive film 23 and the second hydrogen-sensitive film 24 are respectively coated on both sides of the optical fiber 22; the light source 1 is connected to the optical fiber 2 coated with the first hydrogen-sensitive film 3 and the second hydrogen-sensitive film 4, and then connected to the demodulator 7, the demodulator 7 is connected to the oscilloscope 5, and the oscilloscope 5 is connected to the computer 6.

[0032] The optical fiber hydrogen sensors are evenly distributed in the center of the permeable structure of the monitoring hole array, covering the effective area of ​​the membrane electrode to be tested 5. The distance between adjacent optical fiber hydrogen sensors is 0.5-1cm, which is used to quantitatively test the hydrogen leakage of the membrane electrode to be tested. The dynamic response time of the optical fiber hydrogen sensor is ≤10s.

[0033] The first hydrogen sensitive film 23 and the second hydrogen sensitive film 24 both have good selectivity and sensitivity to hydrogen. The first hydrogen sensitive film 3 is 0.5-1 cm long and is a 10-40 nm palladium nano alloy film. This sensing area has accurate detection capability for low-concentration hydrogen and has high sensitivity and strong linearity. The second hydrogen sensitive film 4 is a 50 nm thick palladium metal film or palladium alloy film. This sensing area has good linearity and repeatability and has extremely high sensitivity in a hydrogen environment with a concentration greater than 14%. The oscilloscope displays the spectrum of the detection signal of the optical fiber 2 sensing area after being demodulated by the demodulator 7.

[0034] The membrane electrode 5 to be tested is assembled between the upper end plate 1 and the lower end plate 3. After purging, the gas temperature and pressure are stabilized. The internal leakage hydrogen diffuses through the monitoring holes 9 on the upper end plate 1. The palladium alloy thin film hydrogen sensor detects the hydrogen concentration in the monitoring hole 9 through the sensor probe. When the light wave is injected from one end of the optical fiber 22 to the other end of the optical fiber 22, the light wave is reflected on the surface of the palladium film at the end of the optical fiber 22. The palladium film will produce a reversible chemical reaction with hydrogen, resulting in the refractive index of the newly generated hydride on the end face of the palladium film changing with the change of the hydrogen concentration value, thereby changing the intensity of the reflected light wave. Different concentrations of hydrogen lead to different refractive indices of hydrides. The relationship between the hydrogen concentration and the change of the reflected light intensity can be established based on the standard sample: the optical signal of the reaction hydrogen concentration information is converted into an electrical signal, and the electrical signal is converted into a digital signal. The computer completes the conversion, processing, analysis and storage of the data, and displays the internal leakage hydrogen value, change value, location, quantity and other information at each point of the membrane electrode.

[0035] The following describes the detection method of the embodiment of the utility model. A membrane electrode internal leakage detection and positioning method comprises the following steps:

[0036] 1. Place the silicone rubber gasket 2, the positioning pin, and the membrane electrode to be tested 5 into the corresponding sealing groove 10 of the lower end plate 3 in sequence, align and overlap the upper end plate 1, and clamp and fix them by tightening the screws;

[0037] 2. Open the nitrogen inlet valve under computer control, and introduce 100% concentration nitrogen into the test fixture to exhaust all the air.

[0038] 3. Turn on the heater to heat the dry gas to 60-80°C, pass the hot gas into the air inlet, and stop the ventilation when the temperature of the membrane electrode 5 to be tested reaches 60°C and the pressure reaches 30-50kpa; use the optical fiber hydrogen sensor system to observe the oscilloscope display in all monitoring holes as the spectrum of the optical fiber 2 detection signal after demodulation by the demodulator 7. Use the standard sample linear relationship analysis of the computer 6 to determine the current hydrogen leakage amount, leakage location and quantity, and determine the change in hydrogen concentration by the size of the real-time change, thereby realizing real-time monitoring and analysis of hydrogen concentration.

[0039] The utility model is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the utility model is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the utility model, or the concept and technical solution of the utility model are directly applied to other occasions without improvement, they are all within the protection scope of the utility model.

Claims

1. A membrane electrode internal leakage detection device, characterized in that: It includes an optical fiber hydrogen sensor, a lower end plate for placing the membrane electrode to be tested, and an upper end plate for covering the membrane electrode to be tested. The upper end plate is provided with a monitoring hole covering the carbon paper area of ​​the membrane electrode to be tested, and the optical fiber hydrogen sensor is aligned with the monitoring hole.

2. The membrane electrode internal leakage detection device according to claim 1, characterized in that: There are multiple monitoring holes, and all the monitoring holes are arranged in a matrix.

3. The membrane electrode internal leakage detection device according to claim 1, characterized in that: The optical fiber hydrogen sensor comprises a light source, an optical fiber, a first hydrogen-sensitive film and a second hydrogen-sensitive film. The first hydrogen-sensitive film and the second hydrogen-sensitive film are respectively covered on both sides of the optical fiber. The light source is connected to the optical fiber.

4. The membrane electrode internal leakage detection device according to claim 3 is characterized in that: The optical fiber is connected to a demodulator, the demodulator is connected to an oscilloscope, and the oscilloscope is connected to a computer.

5. The membrane electrode internal leakage detection device according to any one of claims 1 to 4, characterized in that: The lower end plate is provided with a sealing groove, and an air inlet is provided in the area surrounded by the sealing groove, and the air inlet is connected to an air source.

6. The membrane electrode internal leakage detection device according to claim 5, characterized in that: A pressure gauge is arranged between the air inlet and the air source.

7. The membrane electrode internal leakage detection device according to any one of claims 1 to 4, characterized in that: Silicon rubber gaskets are provided at the joints between the frame of the membrane electrode to be tested and the upper end plate and the lower end plate.

8. The membrane electrode internal leakage detection device according to any one of claims 1 to 4, characterized in that: Positioning holes are provided on the upper end plate and the lower end plate.

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