JP2016223941A - Gas diffusivity evaluation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily measure the gas diffusivity of a porous body.SOLUTION: The evaluation device for evaluating the gas diffusivity of a porous body includes: an oxygen consumption device facing a first surface of the porous body with a fluid passing between the first surface and the oxygen consumption device and consuming oxygen; a translucent shield plate facing a second surface of the porous body opposite to the first surface, having an oxygen quencher applied on the second surface which changes its light emission amount depending on the concentration of the oxygen, and capable of supplying a gas containing the oxygen to the second surface; a light source emitting an excitation light exciting the oxygen quencher; and an image taking machine taking an image of light emission by the excitation of the oxygen quencher.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an apparatus for evaluating gas diffusibility of a porous body.

  Patent Document 1 describes an apparatus for evaluating gas diffusibility of a porous body. This device can transmit light (excitation light) in a wavelength band that excites the oxygen quencher and light (luminescence light) that is emitted when the oxygen quencher is excited through the housing that contains the porous body to be evaluated. It is made of a simple material. An oxygen quencher is dispersed on the surface facing the internal space of the housing. An oxygen quencher is a substance that emits luminescence light upon receiving excitation light, but when the oxygen is present, the luminescence light is quenched according to the concentration of oxygen. At the time of evaluation, a porous body is accommodated in the internal space of the casing, and then a gas containing oxygen is supplied to the internal space of the casing while irradiating the casing with light (excitation light) in a wavelength band that excites the oxygen quencher. In addition, the gas diffusion of the porous material is measured by imaging and measuring the light in the wavelength band that excites the oxygen quencher (excitation light) and the light emitted by the oxygen quencher being excited (luminescence light) over time. Assess sex.

Japanese Patent Laid-Open No. 2008-29212

  However, in Patent Document 1, transient response is performed so that light in a wavelength band that excites the oxygen quencher (excitation light) and light emitted by the oxygen quencher being excited (luminescence light) are imaged over time. Is measuring. This complicates the introduction of gas and the control of the imaging timing. As a result, there is a problem that measurement becomes difficult and it is difficult to obtain high accuracy.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one aspect of the present invention, a gas diffusivity evaluation apparatus for a porous body is provided. The gas diffusivity evaluation apparatus is disposed in fluid communication with the first surface at a position facing the first surface of the porous body, consumes oxygen, and consumes the first of the porous body. A light-transmitting shielding plate disposed opposite to the second surface which is the surface opposite to the surface of the porous body, and capable of supplying the oxygen-containing gas to the second surface of the porous body. A shielding plate coated with an oxygen quencher whose light emission amount varies depending on the oxygen concentration on the second surface; a light source that emits excitation light that excites the oxygen quencher; and the excitation of the oxygen quencher And an imaging device for imaging the light emission by. According to this embodiment, after reaching an equilibrium state or a steady state, the in-plane distribution of the oxygen concentration on the second surface of the porous body is obtained using the luminous intensity of the light emitted by the excitation of the oxygen quencher measured by the imaging device. It is possible to acquire and measure the in-plane distribution (unevenness) of the gas diffusivity of the porous body from the in-plane distribution of the oxygen concentration at a predetermined oxygen consumption (consumption rate) in the oxygen consuming apparatus. Therefore, it is not necessary to measure the emission of the oxygen quencher over time. As a result, it is not necessary to supply a gas containing oxygen and to control the timing of imaging. That is, measurement becomes easy and high accuracy can be obtained.

(2) In the gas diffusivity evaluation apparatus according to the first aspect, the oxygen consuming apparatus may be a battery using the oxygen as an active substance. According to this aspect, the consumption of oxygen can be easily measured by measuring the current flowing through the battery. Alternatively, the consumption of oxygen can be easily controlled by controlling the current drawn from the battery.

(3) In the gas diffusivity evaluation apparatus according to the first or second aspect, the shielding plate may include a hole or a groove for supplying oxygen to the second surface. According to this embodiment, oxygen can be supplied to the second surface of the porous body using the holes or grooves.

(4) The gas diffusivity evaluation apparatus according to the third aspect may include a gas supply device that supplies oxygen or a gas containing oxygen to the hole or the groove, and the hole or the groove may be isolated from the atmosphere. . According to this embodiment, a gas having an arbitrary oxygen concentration can be supplied to the second surface of the porous body through the holes or grooves.

(5) The gas diffusivity evaluation apparatus according to any one of the first to fourth aspects may include a liquid injection apparatus that injects a liquid into the porous body. According to this embodiment, gas diffusivity when the porous body contains a liquid can be measured.

(6) The gas diffusivity evaluation apparatus according to the fifth aspect includes a porous sheet having water repellency on the first surface of the porous body, and the liquid injection device injects the liquid into the porous sheet. May be. According to this form, the liquid injected into the porous body can be diffused using the porous sheet.

(7) In the gas diffusivity evaluation apparatus according to any one of Embodiments 1 to 6, further, a light-transmitting portion disposed between the porous body and the oxygen consuming apparatus, wherein the first of the porous body A transparent light-transmitting portion in which a second oxygen quencher whose light emission amount varies depending on the concentration of oxygen is applied to a surface in contact with the surface of the substrate, and second excitation light for exciting the second oxygen quencher is emitted. You may provide the 2nd light source and the 2nd imaging device which images the light emission by the said excitation of the said 2nd oxygen quencher. According to this embodiment, the in-plane distribution of the oxygen concentration on the two surfaces of the porous body can be measured.

(8) In the gas diffusivity evaluation apparatus according to the seventh aspect, a first half mirror that reflects the excitation light toward the oxygen quencher and transmits light emitted by the excitation of the oxygen quencher to the imaging device; A second half mirror that reflects the second excitation light toward the second oxygen quencher and transmits light emitted by the excitation of the second oxygen quencher to the second imaging device. At least one may be provided. According to this aspect, it is possible to separate the excitation light and the light emission due to the excitation of the oxygen quencher, or the second excitation light and the light emission due to the excitation of the second oxygen quencher.

  Note that the present invention can be realized in various modes. For example, in addition to the gas diffusivity evaluation apparatus, it can be realized in the form of a gas diffusivity evaluation method and the like.

Explanatory drawing which shows a fuel cell (single cell) typically. Explanatory drawing which shows the gas-diffusion evaluation apparatus of 1st Embodiment. The captured image imaged with the imaging device of the porous body measured using the gas-diffusion evaluation apparatus of 1st Embodiment. Explanatory drawing which shows the gas-diffusion evaluation apparatus of 2nd Embodiment. The captured image imaged with the imaging device of the porous body measured using the gas-diffusion evaluation apparatus of 2nd Embodiment. Explanatory drawing which shows in-plane distribution of the oxygen concentration of the porous body measured using the gas-diffusion evaluation apparatus of 2nd Embodiment. Explanatory drawing which shows the gas-diffusion evaluation apparatus of 3rd Embodiment. Explanatory drawing which shows the gas-diffusion evaluation apparatus of 4th Embodiment.

Fuel cell configuration:
FIG. 1 is an explanatory diagram schematically showing a fuel cell 10 (single cell). The fuel cell 10 is a device that generates power using hydrogen and oxygen. The fuel cell 10 includes a membrane electrode assembly 100, a cathode gas diffusion layer 140, an anode gas diffusion layer 150, a cathode separator plate 160, and an anode separator plate 170. The membrane / electrode assembly 100 includes an electrolyte membrane 110, a cathode catalyst layer 120, and an anode catalyst layer 130.

  The electrolyte membrane 110 is formed of a proton conductive ion exchange membrane. As the ion exchange membrane, for example, a fluorine-based resin such as perfluorocarbon sulfonic acid polymer or a hydrocarbon-based resin can be employed. The cathode catalyst layer 120 is formed on the first surface of the electrolyte membrane 110, and the anode catalyst layer 130 is formed on the second surface opposite to the first surface of the electrolyte membrane 110. The cathode catalyst layer 120 includes catalyst-supporting particles and an electrolyte (ionomer). The same applies to the anode catalyst layer 130. The catalyst-carrying particles are those in which a catalyst is carried on a carrier such as carbon particles. In this embodiment, a platinum catalyst or a platinum alloy catalyst made of platinum and another metal is used as the catalyst. The material of the carrier and the catalyst is an example, and is not limited to the material described above. For example, carbon nanotubes may be used as the carrier, and the catalyst may be supported on the carbon nanotubes.

  The cathode gas diffusion layer 140 is disposed so as to contact the cathode catalyst layer 120 of the membrane electrode assembly 100, and the anode gas diffusion layer 150 is disposed so as to contact the anode catalyst layer 130 of the membrane electrode assembly 100. Yes. The cathode gas diffusion layer 140 and the anode gas diffusion layer 150 are formed of a porous body having a large number of holes. As the porous material, for example, metal, ceramic, resin, and conductive carbon can be used. In the present embodiment, carbon paper coated with a water repellent is used as the cathode gas diffusion layer 140 and the anode gas diffusion layer 150.

  The cathode separator plate 160 is a plate-like member arranged so as to be in contact with the cathode gas diffusion layer 140, and the anode separator plate 170 is a plate-like member arranged so as to be in contact with the anode gas diffusion layer 150. The cathode separator plate 160 and the anode separator plate 170 are made of a conductive member such as metal or carbon, for example. A cathode gas channel 165 is formed on the cathode gas diffusion layer 140 side of the cathode separator plate 160, and a cathode gas channel 165 is formed on the cathode gas diffusion layer 140 side of the cathode separator plate 160, and the anode separator plate 170. An anode gas flow path 175 is formed on the anode gas diffusion layer 150 side. Although not provided in the configuration shown in FIG. 1, a porous member such as an expanded metal may be disposed between the cathode gas diffusion layer 140 and the cathode separator plate 160. It becomes possible to diffuse oxygen more. In this embodiment, hydrogen is used as the anode gas. Since hydrogen is easier to diffuse than oxygen, it is not necessary to provide a porous member such as expanded metal between the anode gas diffusion layer 150 and the anode separator plate 170 on the anode side. . However, a porous member such as expanded metal may be provided on the anode side.

First embodiment:
FIG. 2 is an explanatory diagram illustrating the gas diffusivity evaluation apparatus 200 according to the first embodiment. The gas diffusivity evaluation apparatus 200 includes an oxygen consuming apparatus 210, a current measurement / control apparatus 212, a control apparatus 214, a shielding plate 220, an oxygen flow path 230, a light source 240, and an imaging device 250. An oxygen consuming device 210 is disposed in fluid communication with the first surface at a position facing the first surface of the cathode gas diffusion layer 140 as the porous body to be measured, and the second surface opposite to the first surface. A shielding plate 220 is disposed facing the surface. The oxygen channel 230 is formed between the cathode gas diffusion layer 140 and the oxygen consuming device 210.

  The oxygen consuming device 210 may be any device that consumes oxygen. For example, a battery that uses oxygen as an active material or a device that contains a material that chemically or physically adsorbs oxygen is used. If a battery is employed as the oxygen consuming device 210, the amount of oxygen consumed can be measured from the battery current. Alternatively, the oxygen consumption can be controlled by the current drawn from the battery. In the case of a substance that adsorbs oxygen, the amount of oxygen consumption can be measured by measuring the weight before and after oxygen adsorption. Note that when a substance that adsorbs oxygen is used, a change in weight before and after the oxygen adsorption is not so large, and thus it is preferable to use a battery that can measure or control the amount of oxygen consumed by an electric current. As the battery, for example, an air zinc battery or a fuel cell can be used. In this embodiment, a battery is used as the oxygen consuming device 210. The current measurement / control device 212 measures the current flowing through the oxygen consuming device 210 or controls the current drawn from the oxygen consuming device 210. The control device 214 measures the amount of oxygen consumed in the oxygen consuming device 210 by controlling the current flowing through the oxygen consuming device 210 or the current drawn from the oxygen consuming device 210. In addition, the control device 214 controls the excitation light source 240 and the imaging device 250, and acquires the in-plane distribution of the oxygen concentration on the second surface of the cathode catalyst layer 140.

The shielding plate 220 is a light-transmitting member, and an oxygen quencher 224 whose light emission amount varies depending on the oxygen concentration is applied to the surface of the shielding plate 220 on the cathode gas diffusion layer 140 side. The oxygen quencher 224 is a composition containing a luminescent species that receives excitation light and emits luminescence light (fluorescence or phosphorescence) depending on the concentration of oxygen, and is also referred to as “pressure-sensitive paint”. The oxygen quencher 224 (1) absorbs photons when irradiated with excitation light of a predetermined wavelength, transitions from the ground state to the excited state, and emits luminescence light having a specific wavelength when returning from the excited state to the ground state. To emit. Further, (2) when an oxygen molecule is touched in an excited state, energy is transferred to the oxygen molecule and the ground state is restored without emitting luminescence light. Accordingly, when the concentration of oxygen is high, the ratio of (2) increases, so the luminous intensity of the luminescence light decreases. Here, the relationship between the oxygen concentration and the luminous intensity of the luminescence light is described by the following Stern-Volmer equation (Sterm-Volmer equation).
Io / I = 1 + Ksv × [O ₂ ]
Here, [O ₂ ] is the concentration of oxygen, Io is the luminous intensity of the luminescence light when there is no oxygen (when the concentration of oxygen is zero), and I is the concentration of oxygen [O _2]. ] Is the luminous intensity of the luminescence light. Ksv is an index of the extinction speed and is called “Stern-Volmer constant”. The Stern-Volmer constant is determined when the gas diffusivity evaluation apparatus 200 is placed in a vacuum, that is, when the oxygen concentration is zero, the luminous intensity (Io) of the luminescence light, and the oxygen quencher 224 of the gas diffusivity evaluation apparatus 200. Can be easily determined by measuring the luminosity (I) of the luminescence light when the is opened to the atmosphere (the oxygen concentration is 21%).

  In the present embodiment, the oxygen quencher 224 includes platinum porphyrin (a complex of platinum and porphyrin) as the luminescent species. In general, a luminescent species absorbs light having a predetermined wavelength (excitation light) and emits light having a predetermined wavelength (luminescence light). The wavelength of the excitation light of platinum porphyrin is about 400 nm to 500 nm, and the wavelength of the luminescence light is about 560 to 710 nm. The material of the shielding plate 220 is preferably made of a material capable of transmitting the excitation light of platinum porphyrin and the luminescence light thereof. The oxygen quencher 224 may be a complex of a heterocyclic aromatic compound such as porphyrin or phthalocyanine and a transition metal such as ruthenium or osmium, or a polycyclic compound such as pyrene or perylene, instead of platinum porphyrin. Aromatic hydrocarbons may be included as luminescent species. The oxygen quencher 224 may contain a binder such as dimethylpolysiloxane (also referred to as “polydimethylsiloxane”) or room temperature curable silicone rubber, or a solvent such as toluene.

  The shielding plate 220 has a plurality of holes 222. The holes 222 are used for supplying air in the atmosphere to the cathode gas diffusion layer 140. When the shielding plate 220 has oxygen permeability, oxygen in the air can be supplied to the cathode gas diffusion layer 140, and thus the hole 222 may not be provided. However, even though the shielding plate 220 is permeable to oxygen, since there is a permeation resistance, oxygen in the cathode gas diffusion layer 140 is less than that in which the hole 222 is provided in the shielding plate 220. Is easy to supply. Regardless of the oxygen permeability of the shielding plate 220, the in-plane distribution of the oxygen concentration on the second surface of the cathode catalyst layer 140 can be obtained using the luminous intensity of the luminescence light.

  The oxygen channel 230 is a channel for supplying oxygen that has passed through the cathode gas diffusion layer 140 to the oxygen consuming device 210. A flow path forming wall 232 is provided at the outer edge of the oxygen flow path 230 to isolate the oxygen flow path 230 from the atmosphere. The flow path forming wall 232 can suppress supply of oxygen that does not pass through the cathode gas diffusion layer 140 to the oxygen consuming device 210.

  The light source 240 emits excitation light that excites the luminescent species in the oxygen quencher 224. The excitation light passes through the shielding plate 220 and excites the luminescent species in the oxygen quencher 224. Thereafter, the luminescent species emits luminescence light. The imaging device 250 images luminescence light emitted from the luminescent species. In addition, you may provide the half mirror for isolate | separating excitation light and luminescence light. Further, a filter that transmits luminescence light but does not transmit excitation light may be provided in front of the image pickup device 250. The excitation light and the luminescence light may be separated by a prism.

  In the present embodiment, for example, after the consumption of oxygen reaches an equilibrium state or a steady state, a light emission (luminescence light) image from the oxygen quencher 224 is measured by the imaging device 250. The in-plane distribution of the first oxygen concentration on the shielding plate 220 side of the cathode gas diffusion layer 140 can be acquired using luminescence light. Then, from the in-plane distribution of the first oxygen concentration, in-plane gas diffusibility unevenness (distribution) of the cathode gas diffusion layer 140 can be evaluated. As described above, in this embodiment, since the emission (luminescence light) from the oxygen quencher 224 is measured after the oxygen consumption reaches an equilibrium state or a steady state, the emission of the oxygen quencher is measured over time. There is no need to supply oxygen-containing gas and control of imaging timing. As a result, measurement becomes easy. Further, there is no decrease in measurement accuracy due to a mismatch between the supply of gas containing oxygen and the timing of imaging, and high-precision measurement is possible.

  FIG. 3 is a captured image captured by the imaging device 250 of the cathode gas diffusion layer 140 measured using the gas diffusivity evaluation apparatus 200 of the first embodiment. The oxygen consuming device 210 is present in the back of the cathode gas diffusion layer 140 surrounded by the white square, and since oxygen is consumed, a gradient of oxygen concentration occurs, and oxygen passes through the cathode gas diffusion layer 140 from the oxygen channel 230. A region where the oxygen concentration is low due to diffusion through the oxygen consuming device 210 is observed. As described above, when there is an in-plane distribution of the oxygen diffusibility (gas diffusibility) of the cathode gas diffusion layer 140, it can be easily measured from the in-plane distribution of the oxygen concentration of the cathode gas diffusion layer 140.

Second embodiment:
FIG. 4 is an explanatory diagram illustrating a gas diffusivity evaluation apparatus 201 according to the second embodiment. In the explanatory diagrams (FIGS. 4, 7, and 8) after the second embodiment, the current measurement / control device 212 and the control device 214 are not shown. The gas diffusivity evaluation apparatus 201 is different from the gas diffusivity evaluation apparatus 200 of the first embodiment in the following points. In the gas diffusivity evaluation apparatus 201, the shielding plate 220 includes a groove 226 instead of the hole 222. The groove 226 forms a flow path for a gas containing oxygen. The groove 226 is isolated from air in the atmosphere. The groove 226 is preferably configured in the same shape as the cathode gas channel 165 shown in FIG. The gas diffusibility of the cathode gas diffusion layer 140 can be evaluated by simulating an actual fuel cell 10. In FIG. 4, two grooves 226 are illustrated, and rib portions 227 are formed between the two grooves 226 and on both sides of the groove 226. Note that the two grooves 226 are in communication with each other, and a gas containing oxygen can move. The number of grooves 226 may be two or more.

  The gas diffusivity evaluation apparatus 201 includes a gas supply apparatus 260. The gas supply device 260 includes an oxygen tank 261, a nitrogen tank 262, an oxygen flow rate adjustment unit 263, a nitrogen flow rate adjustment unit 264, and a gas supply pipe 265. The gas supply pipe 265 is connected to the groove 226. Using the oxygen flow rate adjustment unit 263 and the nitrogen flow rate adjustment unit 264, the concentration of oxygen in the gas containing oxygen supplied to the groove 226 can be arbitrarily adjusted from 0% to 100%. Note that when the oxygen concentration is 0%, it cannot be said that the gas contains oxygen. Therefore, a gas containing the oxygen concentration of 0% is referred to as “a gas that can contain oxygen”. In the present embodiment, it is preferable that the shielding plate 220 is made of a material that does not allow oxygen to pass therethrough in order to avoid an influence on the oxygen concentration in the gas that can contain oxygen supplied to the groove 226. However, since the in-plane distribution of the oxygen concentration on the second surface of the cathode catalyst layer 140 can be obtained using a luminous intensity image of luminescence light, the shielding plate 220 may be made of a material that transmits oxygen. .

  FIG. 5 is a captured image captured by the imaging device 250 of the cathode gas diffusion layer 140 measured using the gas diffusivity evaluation apparatus 201 of the second embodiment. Since the groove 226 is supplied with a gas containing oxygen, the oxygen concentration is high and the luminous intensity of the luminescence light is low. On the other hand, in the rib part 227, since the gas containing oxygen is difficult to be supplied, the oxygen concentration is low and the luminous intensity of the luminescence light is large.

  FIG. 6 is an explanatory diagram showing the in-plane distribution of the oxygen concentration of the cathode gas diffusion layer 140 measured using the gas diffusivity evaluation apparatus 201 of the second embodiment. It can be seen that the oxygen concentration is low in the rib portion 227 and the oxygen concentration is high in the groove 226.

  As described above, according to the second embodiment, the gas diffusibility of the cathode gas diffusion layer 140 can be measured in a state in which the actual fuel cell 10 is simulated. In addition, since the gas supply device 260 is provided, a gas containing oxygen having an arbitrary concentration can be supplied to the groove 226.

Third embodiment:
FIG. 7 is an explanatory diagram showing a gas diffusivity evaluation apparatus 202 according to the third embodiment. In addition to the configuration of the gas diffusibility evaluation apparatus 201 of the second embodiment, the gas diffusibility evaluation apparatus 202 includes a liquid injection apparatus 270, a liquid injection pipe 272, a pressure gauge 274, a liquid injection block 280, and a porous A body sheet 290. The liquid injection device 270 injects liquid into the porous sheet 290 using the liquid injection tube 272. This liquid is, for example, water. In a fuel cell in which oxygen and hydrogen are reacted, water is generated on the cathode side. This water may stay in the cathode gas diffusion layer 140 and affect the gas diffusibility of the cathode gas diffusion layer 140 in some cases. In the present embodiment, by supplying water to the cathode gas diffusion layer 140 through the porous sheet 290, the gas diffusibility of the cathode gas diffusion layer 140 can be measured while simulating the actual power generation state of the fuel cell 10. The pressure gauge 274 is provided in the liquid injection tube 272 and measures the liquid injection pressure. The porous sheet 290 is a water-repellent porous sheet, and is disposed on the surface of the cathode gas diffusion layer 140 opposite to the shielding plate 220. The porous sheet 290 diffuses the supplied water into the cathode gas diffusion layer 140. In addition, since water can be diffused into the cathode gas diffusion layer 140 without the porous sheet 290, the porous sheet 290 may be omitted. However, the presence of the porous sheet 290 allows water to be absorbed by the cathode gas diffusion layer 140. It becomes easy to diffuse. The liquid injection block 280 is disposed between the porous sheet 290 and the oxygen flow path 230. The liquid injection block 280 includes a communication path 282 that allows the porous sheet 290 and the oxygen flow path 230 to communicate with each other. The oxygen in the porous sheet 290 flows into the oxygen flow path 230 through the communication path 282.

  As described above, according to the third embodiment, the gas diffusibility of the cathode gas diffusion layer 140 can be measured by simulating the actual power generation state of the fuel cell 10.

Fourth embodiment:
FIG. 8 is an explanatory diagram showing a gas diffusivity evaluation apparatus 203 in the fourth embodiment. In addition to the configuration of the gas diffusivity evaluation apparatus 202 of the third embodiment, the gas diffusivity evaluation apparatus 203 of the fourth embodiment includes a first half mirror 300, a second light source 242, and a second An imaging device 252, a second half mirror 302, and a translucent unit 310 are provided.

  The first half mirror 300 includes an oxygen quencher 224 (second oxygen quencher) out of the light emitted from the light source 240 (referred to as “first light source 240” to distinguish it from the second light source 242). In order to distinguish it from H.225, it is referred to as “first oxygen quencher 224.” The light having a wavelength that is excited is reflected toward the first oxygen quencher 224. Further, the first half mirror 300 of the luminescence light from the first oxygen quencher 224 is referred to as the “first imager 250” in order to distinguish it from the second imager 252. It is transparent to the direction.

  The translucent part 310 is a transparent member disposed on the oxygen consuming device 210 side of the cathode gas diffusion layer 140, and the second oxygen quencher 225 is applied to the translucent part 310 on the cathode gas diffusion layer 140 side. Has been. The second oxygen quencher 225 may be the same component as the oxygen quencher 224. Here, transparent means excitation light for exciting the second oxygen quencher 225 (also referred to as “second excitation light” in order to distinguish it from excitation light for exciting the first oxygen quencher 224). ) And the wavelength of the luminescence light of the second oxygen quencher 225 (also referred to as “second luminescence light” in order to distinguish it from the luminescence light of the first oxygen quencher 224), for example, transmittance. Means 90% or more. The second light source 242 emits light having a wavelength that excites the second oxygen quencher 225. The second imaging device 252 images the second luminescence light from the second oxygen quencher 225. The second half mirror 302 reflects light having a wavelength excited by the second oxygen quencher 225 out of the light emitted from the second light source 242 toward the second oxygen quencher 225. Further, the second half mirror 302 transmits the second luminescence light from the second oxygen quencher 225 toward the second imaging device 252.

  According to the present embodiment, the in-plane distribution of the first oxygen concentration on the shielding plate 220 side of the cathode gas diffusion layer 140 is measured by measuring the luminescence light from the first oxygen quencher 224 with the imaging device 250. You can get it. Further, by measuring the luminescence light from the second oxygen quencher 225 with the second imaging device 252, the in-plane distribution of the second oxygen concentration on the light transmitting part 310 side of the cathode gas diffusion layer 140 is obtained. it can. The gas diffusibility of the cathode gas diffusion layer can be measured using the in-plane distribution of the first oxygen concentration and the in-plane distribution of the second oxygen concentration. It is also easy to measure the in-plane distribution of gas diffusivity. The cathode gas diffusion layer 140 is a carbon paper coated with a water repellent and is opaque. The excitation light of the first light source 240 and the luminescence light of the first oxygen quencher 224 are not imaged by the second imaging device 252, and conversely, the excitation light of the second light source 242 or the second oxygen The luminescence light of the quencher 225 is not imaged by the first imager 250.

  Further, according to the present embodiment, since the excitation light and the luminescence light can be separated using the first half mirror 302 and the second half mirror 302, in the first image pickup device 250 and the second image pickup device 252, Measurement error can be reduced. Note that the configuration may be such that one or both of the first half mirror 302 and the second half mirror 302 are not provided.

  The embodiments of the present invention have been described above based on some examples. However, the above-described embodiments of the present invention are for facilitating the understanding of the present invention and limit the present invention. It is not a thing. The present invention can be changed and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 100 ... Membrane electrode assembly 110 ... Electrolyte membrane 120 ... Cathode catalyst layer 130 ... Anode catalyst layer 140 ... Cathode gas diffusion layer 150 ... Anode gas diffusion layer 160 ... Cathode separator plate 165 ... Cathode gas flow path 170 ... Anode Separator plate 175 ... Anode gas flow path 200, 201, 202, 203 ... Gas diffusivity evaluation device 210 ... Oxygen consuming device 212 ... Current measurement / control device 214 ... Control device 220 ... Shielding plate 222 ... Hole 224 ... Oxygen quencher ( First oxygen quencher)
225 ... second oxygen quencher 226 ... groove 227 ... rib portion 230 ... oxygen channel 232 ... channel forming wall 240 ... light source (first light source)
242 ... Second light source 250 ... Imaging device (first imaging device)
252 ... Second imaging device 260 ... Gas supply device 261 ... Oxygen tank 262 ... Nitrogen tank 263 ... Oxygen flow rate adjustment unit 264 ... Nitrogen flow rate adjustment unit 265 ... Gas supply pipe 270 ... Liquid injection device 272 ... Liquid injection tube 274 ... Pressure 280 ... Liquid injection block 282 ... Communication passage 290 ... Porous sheet 300 ... First half mirror 302 ... Second half mirror 310 ... Translucent part

Claims (1)

An apparatus for evaluating gas diffusivity of a porous body,
An oxygen consuming device disposed in fluid communication with the first surface at a position facing the first surface of the porous body and consuming oxygen;
A translucent shielding plate disposed opposite to a second surface which is the surface opposite to the first surface of the porous body, wherein the oxygen is applied to the second surface of the porous body; A shielding plate that is capable of supplying a gas containing, and is coated with an oxygen quencher that changes the amount of light emission depending on the concentration of oxygen on the second surface;
A light source that emits excitation light for exciting the oxygen quencher;
An imager that images light emitted by the excitation of the oxygen quencher;
A gas diffusivity evaluation apparatus comprising:

Images