KR102494169B1 - Evaluating apparatus for fuel cell and evaluating method for fuel cell using thereof - Google Patents

Abstract

The present invention relates to a performance evaluation device for a fuel cell and a fuel cell performance evaluation method using the same, and relates to a membrane electrode assembly and a unit cell having a gas diffusion unit disposed on both sides of the membrane electrode assembly, connected to the unit cell unit, and a gas diffusion unit. It is characterized in that it includes a test unit for supplying gas and water to both sides of the unit cell unit so that water is transmitted through it, and a measurement unit for measuring the flow of water in the test unit.

Description

Performance evaluation device for fuel cell and fuel cell performance evaluation method using the same

The present invention relates to a fuel cell performance evaluation device and a fuel cell performance evaluation method using the same, and more particularly, to a fuel cell performance evaluation device for evaluating water permeability of a gas diffusion layer and a fuel cell performance evaluation method using the same.

In general, a fuel cell is a power reaction means that continuously produces electrical energy through a chemical reaction of continuously supplied fuel, and continuous research and development is being conducted as an alternative solution to global environmental problems.

Depending on the type of electrolyte used, fuel cells are classified into phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), and solid oxide fuel cells (SOFCs). It can be classified into polymer electrolyte membrane fuel cell (PEMFC), alkaline fuel cell (AFC) and direct methanol fuel cell (DMFC), and works with the type of fuel used. Depending on temperature, output range, etc., it can be applied to various application fields such as mobile power, transportation, and distributed power generation.

In order for hydrogen ions to pass through the electrolyte membrane during the operation of the fuel cell, the electrolyte membrane must contain a certain amount of water. The humidity of the electrolyte membrane can be achieved by a gas diffusion layer capable of widely diffusing hydrogen gas and an oxidizing agent to facilitate chemical reactions in the catalyst layer and permeating water generated by the electrochemical reaction. Therefore, the water permeability of the gas diffusion layer is an important factor influencing the performance of the fuel cell, and it is important to accurately determine the water permeability of the gas diffusion layer and select an appropriate gas diffusion layer.

However, the conventional apparatus or method for evaluating the water permeability of the gas diffusion layer has problems in that the evaluation process is cumbersome and difficult, and expensive equipment such as an optical accelerator is required, so there is a need to improve this.

On the other hand, the background art of the present invention is disclosed in Korean Patent Registration Publication No. 10-0864689 (registered on October 15, 2008, title of the invention: Fuel cell performance measuring device and fuel cell performance measuring method using the same).

An object of the present invention is to provide a fuel cell performance evaluation device capable of visualizing water permeation inside a unit cell and quantitatively measuring water permeation performance of a unit cell, and a fuel cell performance evaluation method using the same.

In order to solve the above problems, a performance evaluation apparatus for a fuel cell according to the present invention includes: a membrane electrode assembly and a unit cell unit provided with a gas diffusion unit disposed on both sides of the membrane electrode assembly; a test unit connected to the unit cell unit and supplying gas and water to both sides of the unit cell unit so that water permeates through the gas diffusion unit; and a measurement unit for measuring the flow of water in the test unit.

In addition, the test part permeates water by a diffusion action due to a difference in humidity between both sides of the unit cell part.

In addition, the test unit may include a first test member disposed facing one side of the unit cell unit and provided with a first flow path for providing a gas flow path; and a second test member disposed to face the other side of the unit cell unit and provided with a second flow path for providing a water flow path.

In addition, the water permeated from the second test member to the first test member through the gas diffusion part flows along the first flow path by the gas inside the first flow path.

In addition, the first test member is provided with a first scale portion extending along the flow direction of the first flow path, and the second test member is provided with a second scale portion extending along the flow direction of the second flow path.

In addition, the first test member and the second test member are provided with a transparent material.

In addition, the fuel cell performance evaluation method using the fuel cell performance evaluation device according to the present invention includes: an assembling step of assembling a unit cell unit and a test unit; A supply step of supplying gas and water to both sides of the unit cell unit through the test unit; Permeation step of permeating water from the second test member to the first test member through the gas diffusion unit; and a measuring step of measuring the water permeability of the gas diffusion unit through the flow of water inside the test unit.

In addition, the permeation step may include a blocking step of blocking the discharge path of the water of the second test member; and a diffusion step of permeating water through a gas diffusion unit due to a difference in humidity between the first test member and the second test member.

The fuel cell performance evaluation apparatus according to the present invention can evaluate the water permeability of the unit cell part only by supplying gas and water to the test part, thereby reducing costs due to the use of expensive equipment such as an optical accelerator.

In addition, since the first test member and the second test member are made of a transparent material, the performance evaluation device for a fuel cell according to the present invention can visualize the flow of water penetrating the unit cell unit, making it easy to measure the water flow.

In addition, the performance evaluation device for a fuel cell according to the present invention can generate a flow of water passing through the unit cell unit using the flow of gas in the first flow path, so that the flow of water can be more effectively visualized.

In addition, since the performance evaluation device for a fuel cell according to the present invention can accurately measure the flow of water by the measuring unit, more accurate information on permeation performance of the unit cell unit can be obtained.

The performance evaluation method for a fuel cell according to the present invention can evaluate the water permeability of a unit cell part with a simple operation, and thus can perform a quick and efficient test.

In the performance evaluation method for a fuel cell according to the present invention, reliable experimental results can be obtained because all the water in the second flow path can penetrate the unit cell unit by the blocking step.

1 is an installation state diagram schematically illustrating an installation state of a performance evaluation device for a fuel cell according to an embodiment of the present invention.
2 is a perspective view schematically showing the configuration of a performance evaluation device for a fuel cell according to an embodiment of the present invention.
3 is a bottom perspective view schematically showing the configuration of a performance evaluation device for a fuel cell according to an embodiment of the present invention.
4 is a flowchart schematically illustrating an operation process of a method for evaluating performance of a fuel cell according to an embodiment of the present invention.
5 is a flowchart schematically illustrating a sequence of a performance evaluation method for a fuel cell according to an embodiment of the present invention.
6 is a flowchart schematically showing the sequence of the permeation step according to an embodiment of the present invention.

Hereinafter, an embodiment of a performance evaluation device for a fuel cell according to the present invention will be described with reference to the accompanying drawings.

In this process, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or operator. Therefore, definitions of these terms will have to be made based on the content throughout this specification.

In addition, in this specification, when a part is said to be “connected (or connected)” to another part, this is not only the case where it is “directly connected (or connected)”, but also “with another member in between” It also includes cases where it is indirectly connected (or connected). In this specification, when it is said that a certain part "includes (or includes)" a certain component, this does not exclude other components unless otherwise stated, but "includes (or includes)" other components. It means you can.

Also, like reference numerals may refer to like elements throughout this specification. Even if the same reference numerals or similar reference numerals are not mentioned or described in a particular drawing, the numerals may be described based on another drawing. In addition, even if there are parts not marked with reference numerals in specific drawings, the parts can be described based on other drawings. In addition, the number, shape, size, and relative difference of the detailed components included in the drawings of the present application are set for convenience of understanding, and may be implemented in various forms without limiting the embodiments.

1 is an installation state diagram schematically illustrating an installation state of a performance evaluation device for a fuel cell according to an embodiment of the present invention, and FIG. 2 is a perspective view schematically showing the configuration of a performance evaluation device for a fuel cell according to an embodiment of the present invention. 3 is a bottom perspective view schematically showing the configuration of a performance evaluation device for a fuel cell according to an embodiment of the present invention.

Referring to FIGS. 1 to 3 , a fuel cell performance evaluation device according to an embodiment of the present invention includes a unit cell unit 100, a test unit 200, a supply unit 300, and a measurement unit 400.

The unit cell unit 100 is provided to have the shape of a unit cell of a fuel cell, and functions as an object for performance evaluation by the test unit 200 described later. The unit cell unit 100 according to an embodiment of the present invention includes a membrane electrode assembly 110, a gas diffusion unit 120, and a gasket unit 130.

The Membrane Electrode Assembly (MEA) 110 includes a polymer electrolyte membrane capable of transporting hydrogen cations (protons) and a catalyst layer applied to both sides of the polymer electrolyte membrane.

The polymer electrolyte membrane includes sulfonated polyetheretherketone, sulfonated polyketone, sulfonated poly(phenylene oxide), sulfonated poly(phenylene sulfide), sulfonated polysulfone, sulfonated polycarbonate, The material may contain at least one selected from sulfonated polystyrene, sulfonated polyimide, sulfonated polyquinoxaline, sulfonated (phosphonated) polyphosphazene, and sulfonated polybenzimidazole. there is.

The content of the polymer in the polymer electrolyte membrane may be adjusted according to an appropriate ion exchange capacity (IEC) value required for an electrolyte membrane for a fuel cell to be applied. In the case of polymer synthesis for manufacturing a separator for a fuel cell, the content of the polymer may be determined by calculating the value of ion exchange capacity (IEC) meq./g = mmol/g. For example, the polymer content may be selected to be within the range of 0.5 ≤ IEC ≤ 3.

The catalyst layer is a place where the oxidation reaction of fuel or oxidant takes place, and a catalyst selected from the group consisting of platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy and platinum-transition metal alloy is preferably used. can Each of the catalyst layers may have a thickness of 3 μm or more and 30 μm or less. In this case, the catalyst layers disposed on both sides of the polymer electrolyte membrane may have the same thickness or different thicknesses. Catalysts included in the catalyst layer may be used by themselves or supported on a carbon-based carrier.

The gas diffusion units 120 are provided as a pair and are respectively disposed on both sides of the membrane electrode assembly 110 . The gas diffusion unit 120 is provided in a porous form so that water supplied through the test unit 200 can pass therethrough. The gas diffusion unit 120 according to an embodiment of the present invention includes a gas diffusion layer (GDL) and a microporous layer (MPL).

The gas diffusion layer is composed of porous carbon fibers and polytetrafluoroethylene-based hydrophobic materials through which gas and water can permeate. Carbon fiber cloth, carbon fiber felt, carbon fiber paper, and the like may be used as the gas diffusion layer according to an embodiment of the present invention.

The microporous layer is provided between the membrane electrode assembly 110 and the gas diffusion layer to assist diffusion of materials such as gas and water in the gas diffusion unit 120 . Micropores according to an embodiment of the present invention generally include conductive powder having a small particle size, for example, carbon powder, carbon black, acetylene black, activated carbon, carbon fiber, fullrene, carbon nanotube, carbon nanowire, A carbon nanohorn or a carbon nano-ring may be included. If the particle size of the conductive powder constituting the microporous layer is too small, the material diffusion may be insufficient due to severe pressure intensification, and if the particle size is too large, uniform diffusion of the material may be difficult. Therefore, in consideration of the diffusion effect of the material, a conductive powder generally having an average particle diameter in the range of 10 nm to 50 nm may be used.

The gasket unit 130 is provided between the test unit 200 and the membrane electrode assembly 110 to be described later to seal the unit cell unit 100 and the test unit 200, and unit cell unit 100 and the test unit 200. Absorbs the shock applied to the liver. The gasket portion 130 according to an embodiment of the present invention is formed along the edge of the membrane electrode assembly 110 . The gasket unit 130 may include an elastic material such as rubber or silicon to effectively maintain airtightness between the unit cell unit 100 and the test unit 200 .

The test unit 200 is connected to the unit cell unit 100 and supplies gas and water to both sides of the unit cell unit 100 so that water is transmitted through the gas diffusion unit 120 . More specifically, the test unit 200 supplies water to only one side of the unit cell unit 100 so that a difference in humidity is formed on both sides of the unit cell unit 100, and induces a diffusion action due to the difference in humidity in the gas diffusion unit 120. The water permeation performance of the gas diffusion unit 120 is tested by permeating water.

The test unit 200 according to an embodiment of the present invention includes a first test member 210 and a second test member 220.

The first test member 210 is disposed to face one side of the unit cell unit 100, more specifically, any one gas diffusion layer 120 of a pair of gas diffusion layers 120. The first test member 210 is provided to visualize the flow of gas or water therein. The first test member 210 according to an embodiment of the present invention is formed to have a hexahedral shape and is disposed on one side (upper side in FIG. 2) of the unit cell unit 100. The first test member 210 may be in close contact with one side of the unit cell unit 100 by screwing or the like, and may be in close contact with one side of the unit cell unit 100 by a separate pressing means such as a press. The first test member 210 may include a transparent material such as acrylic or glass to visualize the inside.

The inside of the first test member 210 is provided with a first flow path 211 providing a gas flow path. The side of the first flow path 211 facing the unit cell unit 100 is open. Accordingly, water that has passed through the unit cell unit 100 through the gas diffusion unit 120 can flow into the first flow passage 211, and the flow of the gas inside the first flow path 211 can be used to cause the water to flow. . The first flow passage 211 according to an embodiment of the present invention is formed concavely into the first test member 210 from the lower side (refer to FIG. 2) of the first test member 210. The first flow path 211 may be formed in the same shape as the channel-shaped flow path provided in the separator of the fuel cell. The area of the first flow path 211 may correspond to the area of the gas diffusion unit 120 or may be formed to have a larger area than the area of the gas diffusion unit 120 .

The first test member 210 is provided with a gas inlet 212, a water inlet 213, a gas outlet 214, and a water outlet 215. The gas inlet 212 and the gas outlet 214 are formed in the shape of a hole passing through the first test member 210, and one side communicates with the first flow path 211. The water inlet 213 and the water outlet 215 are formed in the shape of a hole penetrating the first test member 210 and communicate with a second flow path 221 to be described later. Specific arrangements of the gas inlet 212, the water inlet 213, the gas outlet 214, and the water outlet 215 are not limited to the arrangement shown in FIG. 2, and can be designed in various arrangements.

The first test member 210 may be provided with a first scale unit 216 providing flow information of gas and water inside the first flow path 211 . In this case, the flow information may be exemplified by speed, movement distance, location, and the like of gas and water. Accordingly, the first scale unit 216 digitizes the permeation performance of the gas diffusion unit 120 so that the measurement unit 400 can perform more accurate measurement. In the first scale part 216 according to an embodiment of the present invention, a plurality of lines disposed perpendicular to the gas flow direction of the first flow path 211 extend side by side in the gas flow direction of the first flow path 211. shape can be formed. The first scale portion 216 may be formed in a form printed on the surface of the first test member 210, and may be formed in an intaglio form otherwise.

The second test member 220 is disposed to face the other side of the unit cell unit 100, more specifically, the other gas diffusion layer 120 of the pair of gas diffusion layers 120. The second test member 220 is provided to visualize the flow of gas or water therein. The second test member 220 according to an embodiment of the present invention is formed to have a hexahedron shape and is disposed on the other side (lower side in FIG. 2) of the unit cell unit 100. The second test member 220 may be adhered to the other side of the unit cell unit 100 by screwing or the like, and may be adhered to the other side of the unit cell unit 100 by a separate pressing means such as a press. The second test member 220 may include a transparent material such as acryl or glass to visualize the inside.

The inside of the second test member 220 is provided with a second flow path 221 providing a flow path of water. The second flow passage 221 is in communication with the water inlet 213 provided in the first test member 210, and the side facing the other side of the unit cell unit 100 is open. Accordingly, the second flow path 221 may supply water received from the water inlet 213 to the gas diffusion unit 120 . The second flow passage 221 according to an embodiment of the present invention is provided separately from the second test member 220, and the second test member 220 through the upper side of the second test member 220 (refer to FIG. 2). ) can be inserted into the interior of In this case, the second flow path 221 may be formed in a shape corresponding to a 3D fine mesh flow path provided in the separator of the fuel cell. The area of the second flow path 221 may correspond to the area of the gas diffusion unit 120 or may be formed to have a larger area than the area of the gas diffusion unit 120 .

The second test member 220 may be provided with a second scale unit 222 providing information on the flow of water inside the second flow path 221 . In this case, the flow information may be exemplified by speed, movement distance, location, and the like of gas and water. Accordingly, the second scale unit 222 digitizes the permeation performance of the gas diffusion unit 120 so that the measurement unit 400 can perform more accurate measurement. In the second scale part 222 according to an embodiment of the present invention, a plurality of lines disposed perpendicular to the water flow direction of the second flow path 221 extend in parallel to the water flow direction of the second flow path 221. shape can be formed. The second scale unit 222 may be formed in a form printed on the surface of the second test member 220, and may be formed in an intaglio form otherwise.

The supply unit 300 is provided to supply gas and water to the test unit 200 and to discharge the gas and water supplied to the test unit 200 . The supply unit 300 according to an embodiment of the present invention includes a supply pipe 310 and a discharge pipe 320.

The supply pipe 310 supplies gas and water to the first flow path part 211 and the second flow path part 221 , respectively. The supply pipe 310 according to an embodiment of the present invention may include a gas supply pipe 311 communicating with the gas inlet 212 and a water supply pipe 312 communicating with the water inlet 213 . Supply operations of the gas supply pipe 311 and the water supply pipe 312 may be controlled by a turbine module and a pump module, respectively.

The discharge pipe 320 receives gas and water discharged from the first flow path part 211 and the second flow path part 221 . The discharge pipe 320 according to an embodiment of the present invention may include a gas discharge pipe 321 communicating with the gas outlet 214 and a water discharge pipe 322 communicating with the water outlet 215 . Valves are provided in the gas discharge pipe 321 and the water discharge pipe 322 to adjust the discharge state of gas and water.

The measurement unit 400 is provided to measure the flow of water in the test unit 200 . More specifically, the measurement unit 400 continuously captures the flow information of the water provided by the first scale unit 216 and the second scale unit 222, and transmits the gas diffusion unit 120 through the captured information. measure the degree Accordingly, the measurement unit 400 may provide a user with a more accurate criterion for the transmission performance of the unit cell 100 . The measurement unit 400 according to an embodiment of the present invention may include an ultra-high-speed camera that captures 1000 or more frames per second.

Hereinafter, an embodiment of a performance evaluation method for a fuel cell according to the present invention will be described.

4 is a flowchart schematically illustrating an operation process of a performance evaluation method for a fuel cell according to an embodiment of the present invention, and FIG. 5 is a flowchart schematically illustrating a sequence of a performance evaluation method for a fuel cell according to an embodiment of the present invention. .

4 and 5 , the performance evaluation method for a fuel cell according to an embodiment of the present invention includes an assembly step (S100), a supply step (S200), a permeation step (S300), and a measurement step (S400).

The assembling step (S100) is a step of assembling the unit cell unit 100 and the test unit 200.

Looking at the process of the assembling step (S100) according to an embodiment of the present invention in detail, first, a pair of gas diffusion units 120 are disposed on both sides of the membrane electrode assembly 110 as a standard.

Thereafter, the first test member 210 and the second test member 220 are disposed to face each other with the pair of gas diffusion units 120, and are brought into close contact with the membrane electrode assembly 110. In this case, the first test member 210 and the second test member 220 may be closely attached to the membrane electrode assembly 110 by screwing, and unlike the membrane electrode assembly 110 and the membrane electrode assembly 110 by a separate pressing means. It is also possible to close.

Thereafter, airtightness between the first test member 210 and the second test member 220 may be maintained with the membrane electrode assembly 110 by the gasket part 130 .

The supply step (S200) is a step of supplying gas and water to both sides of the unit cell unit 100 through the test unit 200, respectively.

Looking at the process of the supply step (S200) according to an embodiment of the present invention in detail, first, gas and water are supplied to the gas supply pipe 311 and the water supply pipe 312 by the operation of the turbine module and the pump module, respectively.

Thereafter, gas flows into the first flow path 211 through the gas inlet 212 , and water flows into the second flow path 221 through the water inlet 213 .

The permeation step (S300) is a step of permeating water from the second test member 220 to the first test member 210 through the gas diffusion unit 120. More specifically, in the permeation step (S300), the water supplied to the second flow passage 221 is diffused into the first flow passage ( 211).

6 is a flowchart schematically showing the sequence of the permeation step according to an embodiment of the present invention.

Referring to FIG. 6 , the permeation step (S300) according to an embodiment of the present invention includes a blocking step (S310) and a spreading step (S320).

The blocking step (S310) is a step of blocking the water discharge path of the second flow passage 221 provided in the second test member 220.

Looking at the process of the blocking step (S310) according to an embodiment of the present invention in more detail, the inside of the first flow path 211 and the second flow path 221 is filled with gas and water by the supply step (S200), respectively. keep in state

Thereafter, the valve provided in the water discharge pipe 322 is operated to block the discharge of the water inside the second flow path 221 through the water outlet 215 . Accordingly, all of the water inside the second flow path 221 may be transmitted through the gas diffusion unit 120 .

Meanwhile, in the case of the first flow path 211 , a discharge path may be opened so that water passing through the gas diffusion unit 120 due to the flow of internal gas may flow along the first flow path 211 .

The diffusion step (S320) is a step in which water is transmitted through the gas diffusion unit 120 by a diffusion action caused by a difference in humidity between the first test member 210 and the second test member 220.

Looking at the diffusion step (S320) according to an embodiment of the present invention in more detail, only gas exists in the first flow path 211 of the first test member 210, and the second test member 220 As only water exists in the flow path 221, a humidity difference occurs between both sides of the unit cell unit 100.

Due to this humidity difference, water inside the second flow passage 221 diffuses in a direction toward the first flow passage 211 and passes through the gas diffusion unit 120 .

The measuring step (S400) is a step of measuring the water permeability of the gas diffusion unit 120 through the flow of water inside the test unit 200.

Looking at the process of the measuring step (S400) according to an embodiment of the present invention in more detail, water passing through the gas diffusion unit 120 from the second flow path 221 is introduced into the first flow path 211. .

Thereafter, the water introduced into the first flow path 211 flows along the first flow path 211 by the flow of the gas flowing through the first flow path 211, and the water flowing along the first flow path 211 Silver is discharged through the gas outlet 214 .

As the above process is repeatedly performed, the water inside the second passage 221 continuously passes through the gas diffusion unit 120, and the flow of water also occurs inside the second passage 221.

In this process, the measurement unit 400 continuously photographs the first scale unit 216 and the second scale unit 221 .

Thereafter, the measurement unit 400 calculates the flow distance of the water moved before and after the photographing through the number of scales of the first scale part 216 and the second scale part 221, or the flow speed of the water through the photographing time and the water flow distance. By calculating the water permeability of the gas diffusion unit 120 is measured. Then, the user determines the water permeability of the gas diffusion unit 120 based on the result measured by the measurement unit 400 .

The present invention has been described with reference to the embodiments shown in the drawings, but this is merely exemplary, and those skilled in the art to which the technology belongs can make various modifications and equivalent other embodiments. will understand

Therefore, the true technical protection scope of the present invention should be determined by the claims below.

100: unit cell unit 110: membrane electrode assembly
120: gas diffusion unit 130: gasket unit
200: test unit 210: first test member
211: first flow path 212: gas inlet
213: gas outlet 214: water inlet
215: water outlet 216: first scale
220: second test member 221: second flow path
222: second scale unit 300: supply unit
310: supply pipe 311: gas supply pipe
312: water supply pipe 320: discharge pipe
321: gas discharge pipe 322: water discharge pipe
400: measuring unit

Claims (8)

a unit cell unit provided with a membrane electrode assembly and gas diffusion units disposed on both sides of the membrane electrode assembly;
a test unit connected to the unit cell unit and supplying gas and water to both sides of the unit cell unit so that water permeates through the gas diffusion unit; and
Including; measuring unit for measuring the flow of water in the test unit,
The test unit permeates water by a diffusion action due to a difference in humidity between both sides of the unit cell unit.
delete According to claim 1,
The test section,
a first test member disposed to face one side of the unit cell unit and provided with a first flow path for providing a gas flow path; and
A fuel cell performance evaluation device comprising a; second test member disposed to face the other side of the unit cell unit and provided with a second flow path for providing a water flow path.
According to claim 3,
The performance evaluation device for a fuel cell, characterized in that the water permeated from the second test member to the first test member through the gas diffusion unit flows along the first flow path by the gas inside the first flow path.
According to claim 3,
The first test member is provided with a first scale extending along the flow direction of the first flow path,
The performance evaluation device for a fuel cell, characterized in that the second test member is provided with a second scale part extending along the flow direction of the second flow path.
According to claim 3,
The first test member and the second test member are performance evaluation apparatus for a fuel cell, characterized in that provided with a transparent material.
Assembling step of assembling the unit cell unit and the test unit;
A supply step of supplying gas and water to both sides of the unit cell unit through the test unit;
Permeation step of permeating water from the second test member to the first test member through the gas diffusion unit; and
and a measuring step of measuring the water permeability of the gas diffusion part through the flow of water inside the test part.
According to claim 7,
In the permeation step,
A blocking step of blocking the water discharge path of the second test member; and
and a diffusion step of permeating water through a gas diffusion unit based on a difference in humidity between the first test member and the second test member.

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