Fuel cell gas diffusion layer water vapor transmission test fixture

Abstract

The utility model discloses a fuel cell gas diffusion layer water vapor transmission test fixture which comprises a first end plate and a second end plate which are matched with each other and used for clamping a gas diffusion layer, the first end plate is provided with a first inlet and a first outlet, and the second end plate is provided with a second inlet and a second outlet. A first flow channel located between the first inlet and the first outlet is arranged in the first end plate, a second flow channel located between the second inlet and the second outlet is arranged in the second end plate, the first inlet is arranged to be used for introducing first gas or liquid water, and the second inlet is arranged to be used for introducing second gas or third gas. The water vapor transmission test fixture for the gas diffusion layer of the fuel cell can meet the measurement requirements of water transmission capability and gas transmission capability of the gas diffusion layer, and is simple in structure and convenient to use.

Description

Technical Field

[0001] The utility model belongs to the technical field of fuel cells. Specifically, the utility model relates to a test fixture for water vapor transmission of a fuel cell gas diffusion layer. Background Technique

[0002] During the operation of a fuel cell, the water vapor transmission has a great influence on the performance and durability of the cell. Water management is one of the key issues for the efficient operation of a PEM fuel cell. Improper water management will have a great impact whether the water content inside the cell is too low or too high. At low current density, less water is generated, and too low water content in the fuel cell will affect the proton conductivity of the membrane, thus directly affecting the ohmic loss of the cell. At high current density, more water is generated, and too high water content in the fuel cell, and even more, when excessive liquid water accumulates, it will cause flooding, affecting the transmission of reaction gases, and even lead to the occurrence of reversal, especially the huge damage of the anode reversal to the cell, which will cause serious losses in performance and durability.

[0003] The gas diffusion layer is one of the important components for water vapor transmission. It needs to transport the excess water generated by the catalyst layer to the flow channel through capillary action and then discharge it from the cell. At the same time, it needs to transport the reaction gases to the catalyst layer through molecular diffusion and Knudsen diffusion for reaction. Among them, the capillary action has a great relationship with the pore size structure and the hydrophilicity and hydrophobicity of the pores in the microporous layer. However, the pore size structure is relatively complex, and the hydrophilicity and hydrophobicity cannot be well measured, which leads to great difficulties in analyzing the water vapor transmission of the gas diffusion layer. On the other hand, the support layer of the gas diffusion layer is composed of disordered carbon fiber stacks, and the microporous layer is composed of carbon black particles and a hydrophobic agent (PTFE). Its irregular pore structure also causes great difficulties in analyzing the gas transmission of fuel cells.

[0004] Existing test methods often only test the contact angle, which is greatly affected by surface roughness and baseline selection and cannot well characterize the hydrophilicity and hydrophobicity inside the pores. In addition, the gas transmission tests of the gas diffusion layer are all based on the nitrogen vertical gas permeability and in-plane gas permeability, without considering the influence on gas permeability after humidification. And the vertical gas permeability and in-plane gas permeability are separated and not considered simultaneously.

[0005] The Chinese patent with the application number 202410046705.0 discloses a detection device for the water and gas permeability of a fuel cell gas diffusion layer, belonging to the technical field of fuel cells. The device includes a lower base plate (1), a gas source (8), an upper pressing plate (2), a water source (6), a water filter plate (3), a gas diffusion layer test specimen (5), an ammonia nitrogen sensor (4), a waste water recovery device (9), a water collecting box (10), and a sealing ring (7). Among them, the grooves of the upper pressing plate and the lower base plate are connected to each other to form an experimental chamber for water permeability testing and gas permeability testing. The lower base plate is provided with an air inlet hole and an air outlet hole communicating with an external gas source, and a water collecting box is provided at the front end of the air outlet hole. The upper pressing plate is provided with a water inlet hole connected to the water source and a water outlet connected to the waste water recovery device, and an ammonia nitrogen sensor is arranged in the water tank of the upper pressing plate.

[0006] It is desired to provide an improved test fixture for water vapor transmission of a fuel cell gas diffusion layer. Utility Model Content

[0007] The present utility model aims to solve at least one of the technical problems existing in the prior art. For this reason, the present utility model provides a test fixture for water vapor transmission of a fuel cell gas diffusion layer, aiming to meet the measurement requirements for realizing the water transmission ability and gas transmission ability of the gas diffusion layer.

[0008] To solve the above technical problems, the technical solution adopted by the present utility model is: A test fixture for water vapor transmission of a fuel cell gas diffusion layer includes a first end plate and a second end plate that cooperate to clamp the gas diffusion layer. A first inlet and a first outlet are provided on the first end plate, a second inlet and a second outlet are provided on the second end plate, a first flow channel located between the first inlet and the first outlet is arranged inside the first end plate, a second flow channel located between the second inlet and the second outlet is arranged inside the second end plate, the first inlet is configured to introduce a first gas or liquid water, and the second inlet is configured to introduce a second gas or a third gas.

[0009] The first gas is humidified nitrogen.

[0010] The second gas is pure dry oxygen.

[0011] The third gas is pure dry air.

[0012] An oxygen sensor is arranged at the first outlet, and a humidity sensor is arranged at the second outlet.

[0013] Mounting holes for installing thermocouples are provided on the first end plate and the second end plate.

[0014] The second end plate is connected to a condensate collection device, and the condensate collection device includes a container for collecting water, a condensate pipe connected to the container, and a collection pipe connected to the container.

[0015] The collecting tube is provided with discoloring silica gel.

[0016] The first end plate and the second end plate are made of transparent materials.

[0017] The water vapor transmission test fixture for the fuel cell gas diffusion layer of the present utility model can meet the measurement requirements for realizing the water transmission capacity and gas transmission capacity of the gas diffusion layer, has good versatility, a simple structure, and is convenient to use. Description of the Drawings

[0018] Figure 1 is a schematic structural view of the water vapor transmission test fixture for the fuel cell gas diffusion layer of the present utility model;

[0019] Figure 2 is a schematic structural view of the end plate;

[0020] Figure 3 is a schematic side view of the oxygen and water vapor diffusion rate test;

[0021] Figure 4 is a schematic side view of the GDL liquid water permeability; Figure 1 ;

[0022] Figure 5 is a schematic side view of the GDL liquid water permeability; Figure 2 ;

[0023] The markings in the above figures are all: 1, the first end plate; 2, the second end plate; 3, the first inlet; 4, the second outlet; 5, the mounting hole; 6, the fastening bolt; 7, the sealing element; 8, the sample to be tested; 9, the condensing tube; 10, the container; 11, the collecting tube. Detailed Embodiments

[0024] The following is a further detailed description of the specific embodiments of the present utility model with reference to the accompanying drawings through the description of the embodiments, aiming to help those skilled in the art have a more complete, accurate, and in-depth understanding of the concept and technical solution of the present utility model and facilitate its implementation.

[0025] It should be noted that when an element is referred to as being "fixed on" another element, it can be directly on the other element or there can be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower" and similar expressions used herein are only for the purpose of illustration.

[0026] It should be noted that in the following embodiments, the "first", "second" and "third" do not represent an absolute distinction relationship in terms of structure and / or function, nor do they represent the order of execution. They are only for the convenience of description.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this utility model belongs. The terms used in the description of the present utility model in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present utility model. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0028] As Figure 1 and Figure 2 As shown, the present utility model provides a test fixture for water vapor transmission of a fuel cell gas diffusion layer, which includes a first end plate 1 and a second end plate 2 that cooperate to clamp the gas diffusion layer. A first inlet 3 and a first outlet are provided on the first end plate 1, a second inlet and a second outlet 4 are provided on the second end plate 2. A first flow channel located between the first inlet 3 and the first outlet is provided inside the first end plate 1, and the first flow channel is communicated with the first inlet 3 and the first outlet. A second flow channel located between the second inlet and the second outlet 4 is provided inside the second end plate 2, and the second flow channel is communicated with the second inlet and the second outlet 4. The first inlet 3 is arranged to introduce a first gas or liquid water, and the second inlet is arranged to introduce a second gas or a third gas.

[0029] Specifically, the first gas is humidified nitrogen, the second gas is pure dry oxygen, and the third gas is pure dry air.

[0030] An oxygen sensor is provided at the first outlet, and a humidity sensor is provided at the second outlet 4.

[0031] Mounting holes 5 for installing thermocouples are provided on the first end plate 1 and the second end plate 2.

[0032] The materials used for the first end plate 1 and the second end plate 2 are determined by specific tests. The first end plate 1 and the second end plate 2 can be made of high thermal conductivity materials such as graphite plates and aluminum alloys, and heating sheets are installed on both sides of the first end plate 1 and the second end plate 2. The heating sheets are used to heat the first end plate 1 and the second end plate 2 during the test, and thermocouples are installed on the first end plate 1 and the second end plate 2 to facilitate controlling the temperature during heating.

[0033] The second end plate 2 is connected to a condensate collection device, which includes a container for collecting water, a condensate pipe connected to the container, and a collection pipe connected to the container. A discolored silica gel is provided inside the collection pipe.

[0034] The first end plate 1 and the second end plate 2 are made of transparent materials. The first end plate 1 and the second end plate 2 are fixedly connected by fastening bolts 6, and a plurality of fastening bolts 6 are provided.

[0035] Embodiment 1

[0036] As Figures 1 to 3 shown, this embodiment provides a fuel cell gas diffusion layer water vapor transmission test fixture, which includes a first end plate 1 and a second end plate 2 that cooperate to clamp the gas diffusion layer. A first inlet 3 and a first outlet are provided on the first end plate 1. The first inlet 3 and the first outlet are respectively arranged on two side surfaces of the first end plate 1. A second inlet and a second outlet 4 are provided on the second end plate 2. The second inlet and the second outlet 4 are respectively arranged on two side surfaces of the second end plate 2. A first flow channel located between the first inlet 3 and the first outlet is provided inside the first end plate 1. The first flow channel communicates with the first inlet 3 and the first outlet. A second flow channel located between the second inlet and the second outlet 4 is provided inside the second end plate 2. The second flow channel communicates with the second inlet and the second outlet 4. The first inlet 3 is configured to introduce a first gas, and the second inlet is configured to introduce a second gas.

[0037] In this embodiment, the first gas is nitrogen and is humidified nitrogen, and the humidity of the first gas needs to reach the required value. The second gas is pure dry oxygen. The fuel cell gas diffusion layer water vapor transmission test fixture of this embodiment is used to clamp the gas diffusion layer when testing the gas transmission capacity of the fuel cell gas diffusion layer. When testing the oxygen and water vapor diffusion rates of the gas diffusion layer, a certain humidified first gas is introduced into the first end plate 1 through the first inlet 3. The first gas flows through the first flow channel to the gas diffusion layer and then into the second flow channel. The second gas is introduced into the second end plate 2 through the second inlet. The second gas flows through the second flow channel to the gas diffusion layer and then into the first flow channel. An oxygen sensor is provided at the first outlet, and a humidity sensor is provided at the second outlet 4. The oxygen sensor is used to detect the oxygen concentration at the first outlet, and the humidity sensor is used to detect the humidity at the second outlet 4.

[0038] As Figure 1 shown, mounting holes 5 for installing thermocouples are provided on the first end plate 1 and the second end plate 2. Heating sheets are installed on both sides of the first end plate 1 and the second end plate 2. The heating sheets are used to heat the first end plate 1 and the second end plate 2 respectively during the test. Thermocouples are also installed on the first end plate 1 and the second end plate 2 to facilitate controlling the temperature during heating.

[0039] In this embodiment, the first flow channel and the second flow channel are serpentine flow channels.

[0040] As Figure 1As shown in the figure, the first end plate 1 and the second end plate 2 are fixedly connected by fastening bolts 6. A plurality of fastening bolts 6 are provided, and bolt holes for the fastening bolts 6 to pass through are provided on the first end plate 1 and the second end plate 2. By tightening the fastening bolts 6, the first end plate 1 and the second end plate 2 are fixedly connected together, and the first end plate 1 and the second end plate 2 clamp the gas diffusion layer in the middle.

[0041] As Figure 3 shown in the figure, the edges of the gas diffusion layer are sealed with a sealing element 7 to ensure that the gas in the first end plate 1 below can only diffuse through the gas diffusion layer into the second end plate 2. Similarly, the edges of the gas diffusion layer are sealed with a sealing element 7 to ensure that the gas in the second end plate 2 below can only diffuse through the gas diffusion layer into the first end plate 1. A sealing element 7 is provided between the outer edge of the gas diffusion layer and the first end plate 1, and a sealing element 7 is also provided between the outer edge of the gas diffusion layer and the second end plate 2. In this way, during the test, the gas can only diffuse through the gas diffusion layer into the two end plates, and the gas cannot pass through the gap between the outer edge of the gas diffusion layer and the inner wall surface of the fixture, which helps to improve the accuracy of the test results.

[0042] In this embodiment, the sealing element 7 is a rubber sealing ring.

[0043] For the fuel cell gas diffusion layer water vapor transmission test fixture with the above structure, the process of testing the oxygen and water vapor diffusion rates is as follows:

[0044] The gas diffusion layer is encapsulated with a frame and placed in the fixture for testing. Among them, humidified nitrogen is introduced into the first inlet 3, an oxygen sensor is installed at the first outlet, pure dry oxygen or air is introduced into the second inlet, and a humidity sensor is installed at the second outlet 4; the first end plate 1 and the second end plate 2 are heated to simulate the temperature during the operation of the fuel cell. Nitrogen with a specific humidity is introduced into the first inlet 3, partial condensation simulates the real situation in the fuel cell, and part of the water vapor passes through the gas diffusion layer to reach the second end plate 2, and the water vapor humidity is detected by the humidity sensor at the second outlet 4. The oxygen in the second end plate 2 passes through the gas diffusion layer to reach the first end plate 1, and the oxygen concentration is detected at the first outlet.

[0045] The test results of the oxygen and water vapor diffusion rates are calculated according to the following formulas (1) and (2):

[0046]

[0047] Among them, D O2 is the diffusion rate of carbon paper oxygen in the gas diffusion layer, and the unit is m -2 ;

[0048] S 测试活性面积 is the active area, and the unit is m 2 ;

[0049] C 入 is the oxygen concentration at the second inlet;

[0050] C 出 is the oxygen concentration at the first outlet;

[0051] μ is the gas flow rate;

[0052] h is the thickness of the gas diffusion layer sample of the gas to be measured.

[0053]

[0054] Among them, ξ O2 is the diffusion rate of water vapor in the gas diffusion layer, with the unit of m -2 ;

[0055] S 测试活性面积 is the active area, with the unit of m 2 ;

[0056] η 入 is the nitrogen humidity at the first inlet 3;

[0057] η 出 is the humidity sensor reading at the second outlet 4;

[0058] μ is the gas flow rate;

[0059] h is the thickness of the gas diffusion layer sample of the gas to be measured.

[0060] Example Two

[0061] As Figure 1 , Figure 2 , Figures 4 to 5 shown, this example provides a fuel cell gas diffusion layer water vapor transmission test fixture, including a first end plate 1 and a second end plate 2 that cooperate to clamp the gas diffusion layer. A first inlet 3 and a first outlet are provided on the first end plate 1, and the first inlet 3 and the first outlet are respectively provided on two side surfaces of the first end plate 1. A second inlet and a second outlet 4 are provided on the second end plate 2, and the second inlet and the second outlet 4 are respectively provided on two side surfaces of the second end plate 2. A first flow channel located between the first inlet 3 and the first outlet is provided inside the first end plate 1, and the first flow channel is communicated with the first inlet 3 and the first outlet. A second flow channel located between the second inlet and the second outlet 4 is provided inside the second end plate 2, and the second flow channel is communicated with the second inlet and the second outlet 4. The first inlet 3 is configured to introduce liquid water, and the liquid water is deionized water. The second inlet is configured to introduce a third gas, and the third gas is pure dry air.

[0062] The water vapor transmission test fixture for the fuel cell gas diffusion layer in this embodiment is used to clamp the gas diffusion layer and the proton exchange membrane when testing the water transmission ability of the fuel cell gas diffusion layer. When testing the liquid water permeability of the gas diffusion layer, liquid water is introduced into the first end plate 1 through the first inlet 3. The liquid water flows through the first flow channel to the proton exchange membrane, then to the gas diffusion layer, and finally diffuses into the second flow channel. The third gas is introduced into the second end plate 2 through the second inlet. The third gas flows through the second flow channel to the gas diffusion layer and then into the first flow channel. A humidity sensor is provided at the second outlet 4. The humidity sensor is used to detect the humidity at the second outlet 4. By detecting the humidity at the second outlet 4, the water transmission ability of the gas diffusion layer to liquid water can be obtained.

[0063] As Figure 1 shown, mounting holes 5 for installing thermocouples are provided on the first end plate 1 and the second end plate 2. Heating sheets are installed on both sides of the first end plate 1 and the second end plate 2. The heating sheets are used to heat the first end plate 1 and the second end plate 2 respectively during the test. Thermocouples are also installed on the first end plate 1 and the second end plate 2 to facilitate controlling the temperature during heating.

[0064] In this embodiment, the first flow channel and the second flow channel are serpentine flow channels.

[0065] As Figure 1 shown, the first end plate 1 and the second end plate 2 are fixedly connected by fastening bolts 6. A plurality of fastening bolts 6 are provided. Bolt holes for the fastening bolts 6 to pass through are provided on the first end plate 1 and the second end plate 2. By tightening the fastening bolts 6, the first end plate 1 and the second end plate 2 are fixedly connected together, and the first end plate 1 and the second end plate 2 clamp the gas diffusion layer in the middle.

[0066] As Figure 3 shown, the edges of the gas diffusion layer are sealed with a sealing element 7 to ensure that the liquid water in the lower first end plate 1 can only diffuse through the gas diffusion layer into the second end plate 2. Similarly, the edges of the gas diffusion layer are sealed with a sealing element 7 to ensure that the gas in the lower second end plate 2 can only diffuse through the gas diffusion layer into the first end plate 1. A sealing element 7 is provided between the outer edge of the gas diffusion layer and the first end plate 1, and a sealing element 7 is also provided between the outer edge of the gas diffusion layer and the second end plate 2. In this way, during the test, liquid water and gas can only diffuse through the gas diffusion layer into the two end plates, and liquid water and gas cannot pass through the gap between the outer edge of the gas diffusion layer and the inner wall surface of the fixture, which helps to improve the accuracy of the test results.

[0067] In this embodiment, the sealing element 7 is a rubber sealing ring.

[0068] For the fuel cell gas diffusion layer water vapor transmission test fixture with the above structure, the process of water transmission ability test is as follows:

[0069] The gas diffusion layer is encapsulated with a border and placed in a fixture for testing. Liquid water is introduced through the first inlet 3, and pure dry air is introduced through the second inlet. The first end plate 1 and the second end plate 2 are heated to simulate the temperature during the operation of the fuel cell. The humidity is detected by a humidity sensor at the second outlet 4.

[0070] The test results of the water transport capacity are calculated according to the following formula (3):

[0071]

[0072] where, ψ O2 is the permeability of liquid water in the gas diffusion layer, with the unit of m -2 ;

[0073] S 测试活性面积 is the active area, with the unit of m 2 ;

[0074] η liquid is the reading of the humidity sensor at the second outlet 4;

[0075] μ is the gas flow rate;

[0076] h is the thickness of the gas diffusion layer sample to be tested.

[0077] In this embodiment, the first end plate 1 and the second end plate 2 are made of a transparent material, which can be glass or transparent acrylic. During the test, the flow condition of liquid water in the flow channel can be observed through the transparent end plates, facilitating the observation of the water transport process and analyzing the water transport conditions in the flow channel and GDL.

[0078] As Figure 5 shown, in this embodiment, if the humidity is too high or there is too much condensation, it will cause a large error in the test results. A condensate collection device can be used to collect all the liquid water during the test to ensure the accuracy of the test results.

[0079] The condensate collection device includes a container 10 for collecting water, a condensate pipe 9 connected to the second outlet 4 of the second end plate 2 and the container 10, and a collection pipe 11 connected to the container 10. A color-changing silica gel is provided in the collection pipe 11. One end of the condensate pipe 9 is connected to the second outlet 4 of the second end plate 2, and the other end of the condensate pipe 9 is connected to the first opening of the container 10. The container 10 is a conical flask, and the second opening of the container 10 is connected to the collection pipe 11. The condensate pipe 9 is inclined, and the height of the container 10 is less than the height of the second outlet 4.

[0080] A collection pipe 11 filled with color-changing silica gel is connected to the second opening of the container 10. After the condensate water enters the collection pipe 11, the color-changing silica gel changes color, so that it can be determined whether the water is completely collected by observing the color change of the collection pipe 11.

[0081] During the test process, a cooling medium is introduced into the condenser 9. After the water with a certain humidity comes out from the second outlet 4 of the second end plate 2, it enters the condenser 9 for condensation. The container 10 collects the condensed water flowing out from the condenser 9. The second opening of the container 10 is connected to a collecting tube 11 filled with discolored silica gel, and the collecting tube 11 is used for collecting and determining whether the water is completely collected.

[0082] The above has made an exemplary description of the present utility model in conjunction with the accompanying drawings. Obviously, the specific implementation of the present utility model is not limited by the above methods. As long as various non-substantive improvements are made by adopting the method concept and technical solution of the present utility model, or the concept and technical solution of the present utility model are directly applied to other occasions without improvement, they are all within the protection scope of the present utility model.

Claims

1. Fuel cell gas diffusion layer water vapor transmission test fixture, characterized in that: It includes a first end plate and a second end plate that are cooperatively used to clamp a gas diffusion layer. A first inlet and a first outlet are provided on the first end plate, a second inlet and a second outlet are provided on the second end plate. A first flow channel located between the first inlet and the first outlet is arranged inside the first end plate, and a second flow channel located between the second inlet and the second outlet is arranged inside the second end plate. The first inlet is configured to introduce a first gas or liquid water, and the second inlet is configured to introduce a second gas or a third gas.

2. The fuel cell gas diffusion layer water vapor transmission test fixture according to claim 1, characterized in that: The first gas is humidified nitrogen.

3. The fuel cell gas diffusion layer water vapor transmission test fixture according to claim 1, characterized in that: The second gas is pure dry oxygen.

4. The fuel cell gas diffusion layer water vapor transmission test fixture according to claim 1, characterized in that: The third gas is pure dry air.

5. The fuel cell gas diffusion layer water vapor transmission test fixture according to any one of claims 1 to 4, characterized in that: An oxygen sensor is provided at the first outlet, and a humidity sensor is provided at the second outlet.

6. The fuel cell gas diffusion layer water vapor transmission test fixture according to any one of claims 1 to 4, characterized in that: Mounting holes for installing thermocouples are provided on the first end plate and the second end plate.

7. The fuel cell gas diffusion layer water vapor transmission test fixture according to any one of claims 1 to 4, characterized in that: The second end plate is connected to a condensate collection device, which includes a container for collecting water, a condensate pipe connected to the container, and a collection pipe connected to the container.

8. The fuel cell gas diffusion layer water vapor transmission test fixture according to claim 7, wherein: Desiccant silica gel is provided inside the collection pipe.

9. The fuel cell gas diffusion layer water vapor transmission test fixture according to any one of claims 1 to 4, characterized in that: The first end plate and the second end plate are made of a transparent material.

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