JP2009070765A - Tube type fuel cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tube type fuel cell module which can improve uniformity of humidity on the outer peripheral surface of a tube type fuel cell and concentration of reactant gas supplied to the outer peripheral surface of the tube type fuel cell, and which can improve power generation characteristics. <P>SOLUTION: The tube type fuel cell module 10 includes: a tube type fuel cell 3 which is equipped with a membrane electrode assembly 5 in a hollow shape, an inner collector provided on the inner peripheral surface of the membrane electrode assembly, and an outer collector provided on the outer peripheral surface of the membrane electrode assembly; and a case member 1 which accommodates the tube type fuel cell, wherein gas supplied to the outer peripheral surface of the tube type fuel cell is supplied from the side surface of the case member and is discharged therefrom, and the gas flows along the outer peripheral surface of the tube type fuel cell. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  INDUSTRIAL APPLICABILITY The present invention can improve the uniformity of the humidity on the outer peripheral surface side of the tubular fuel cell and the concentration of the reaction gas supplied to the outer peripheral surface side of the tubular fuel cell, thereby improving the power generation characteristics. The present invention relates to a tubular fuel cell module.

  A fuel cell includes a membrane electrode structure (hereinafter referred to as “MEA”) including an electrolyte layer (hereinafter referred to as “electrolyte membrane”) and electrodes (anode and cathode) respectively disposed on both sides of the electrolyte membrane. The electric energy generated by the electrochemical reaction in (1) is taken out to the outside through current collectors arranged on both sides of the MEA. Among fuel cells, a polymer electrolyte fuel cell (hereinafter referred to as “PEFC”) used in a home cogeneration system or an automobile can be operated in a low temperature region. In addition, PEFC has attracted attention as a power source and portable power source for electric vehicles because it exhibits high energy conversion efficiency, has a short start-up time, and is compact and lightweight.

  Recently, for the purpose of improving the amount of power generation per unit volume, etc., research on a fuel cell in which a single cell is a columnar shape (hereinafter referred to as “tube type fuel cell”) has been advanced. A single cell of a tube type fuel cell (hereinafter sometimes referred to as a “tube type fuel cell”) is generally disposed on a hollow electrolyte membrane and on an inner peripheral surface side and an outer peripheral surface side of the electrolyte membrane, respectively. A hollow MEA including a hollow catalyst layer. For example, an electrochemical reaction is caused by supplying a hydrogen-containing gas to the inner peripheral surface side of the MEA and an oxygen-containing gas to the outer peripheral surface side, and the electric energy generated by the electrochemical reaction is It is taken out to the outside through current collectors arranged on the inner peripheral surface side and the outer peripheral surface side, respectively. That is, in the tube type fuel cell, one reaction gas (for example, hydrogen-containing gas) is provided on the inner peripheral surface side of the hollow MEA provided in each tube type fuel cell, and the other reaction gas (for example, the hydrogen gas is provided on the outer peripheral surface side). Since the electric energy is taken out by supplying the oxygen-containing gas), the reaction gases supplied to the outer peripheral surfaces of the two adjacent tubular fuel cells can be made the same. Therefore, according to the tube type fuel cell, a separator having gas shielding performance in the conventional flat plate type fuel cell is not required, and it becomes easy to improve the power generation amount per unit volume.

  In the fuel cell, water generated during the above-described electrochemical reaction is caused to flow together with surplus reaction gas. That is, the humidity varies depending on the position in the flow direction of the reaction gas. Also, the concentration of the reaction gas varies depending on the position in the flow direction of the reaction gas. Due to the difference in humidity and the concentration of the reaction gas, the problem is that power generation distribution occurs.

  For example, Patent Document 1 discloses an air electrode, a solid electrolyte layer, a fuel electrode, and an air electrode that are stacked in a multilayer hollow cylindrical shape as a technique for uniformly supplying a reaction gas to various portions of a fuel cell. Or an assembly of a plurality of cylindrical cells having an interconnector electrically connected to an inner electrode (inner surface electrode) of the fuel electrode and exposed to the outer surface of the cylinder, and the cylindrical cell assembly Are arranged such that the outer electrode (outer electrode) of the adjacent cylindrical cell and the interconnector are in contact with each other, and the hollow part and the outer peripheral part of the cylindrical cell are respectively air (oxidant) or gaseous fuel ( A cylindrical cell type solid oxide fuel cell that forms a flow path of gas), and a gas introduction pipe is provided in a space between cells defined by the outer peripheral surface of adjacent cylindrical cells. , Art relates to a solid electrolyte type fuel cell, wherein there is disclosed a from the gas introduction pipe is configured such that the gas in the cylindrical cell external surface is provided.

Further, Patent Document 2 discloses a plurality of cylindrical fuel cells, a conductive member that connects an electric series direction along the axial direction of the fuel cells, and fuel gas around the fuel cells. A fuel cell comprising: a fuel gas flow path, and a fuel cell technology characterized in that an exposed surface of the fuel cell is formed on a fuel gas discharge side. By making the fuel gas flow path larger on the fuel gas discharge side than on the fuel gas supply side, the flow rate of the fuel gas on the fuel gas discharge side can be made slower than the fuel gas supply side, so that the fuel gas contacts the fuel cell. It is said that the time required for the fuel gas supply can be shortened on the fuel gas supply side and longer on the fuel gas discharge side. Further, Patent Document 3 includes a hydrogen gas supply source and a fuel cell, and the fuel cell includes a negative electrode portion that dissociates hydrogen gas into hydrogen ions and electrons, oxygen gas in the air as hydrogen ions and A positive electrode part that reacts with electrons to generate water, an electrolytic part that is disposed between the negative electrode part and the positive electrode part, and that allows movement of hydrogen ions from the negative electrode part to the positive electrode part; and A first plate disposed adjacent to the negative electrode portion and formed with a groove for supplying hydrogen gas so as to face the negative electrode portion; and disposed adjacent to the positive electrode portion and facing the positive electrode portion And a second plate in which an air supply groove is formed. The fuel cell is formed in a cylindrical shape as a whole and is rotatable in the circumferential direction. And The groove for supplying air has a first linear groove that extends between the peripheral edge and the center of the second plate and opens to the outside at the peripheral edge of the second plate. A fuel cell characterized in that a blade for promoting air intake into the first linear groove is formed at or near the peripheral edge of the second plate in the groove. The technology regarding the system is disclosed, and it is supposed that the water generated in the positive electrode portion of the fuel cell can be effectively removed by adopting such a configuration.
JP-A-8-203552 JP 2006-066387 A JP 2001-102081 A

  However, in the techniques disclosed in Patent Documents 1 and 2, when the oxygen-containing gas (air) is supplied to the outer peripheral surface side of the tube-type fuel cell, the longitudinal direction of the tube-type fuel cell However, it was difficult to improve the uniformity of humidity. In addition, the technique disclosed in Patent Document 3 is based on the assumption that flat fuel cells are used.

  Therefore, the present invention can improve the uniformity of the humidity on the outer peripheral surface side of the tubular fuel cell and the concentration of the reaction gas supplied to the outer peripheral surface side of the tubular fuel cell, thereby improving the power generation characteristics. It is an object of the present invention to provide a tube type fuel cell module that can be used.

In order to solve the above problems, the present invention takes the following means. That is,
The present invention relates to a hollow membrane electrode structure, an inner current collector disposed on the inner peripheral surface side of the membrane electrode structure, and an outer current collector disposed on the outer peripheral surface side of the membrane electrode structure, The reaction gas supplied to the outer peripheral surface side of the tube-type fuel cell is supplied / discharged from the side surface of the case member. At the same time, the reaction gas flows along the outer peripheral surface of the tube-type fuel cell, which is a tube-type fuel cell module.

  Here, the “membrane electrode structure” means a hollow electrolyte membrane, a first electrode formed on the inner peripheral surface side of the electrolyte membrane, and a second electrode formed on the outer peripheral surface side of the electrolyte membrane. And MEA. Furthermore, the “inner current collector disposed on the inner peripheral surface side of the membrane electrode structure” means an inner current collector when the inner peripheral surface of the first electrode is not provided with a diffusion layer and a water repellent layer. This means that the inner current collector is disposed in a form in which the outer peripheral surface of the body and the inner peripheral surface of the first electrode are in contact with each other. On the other hand, a diffusion layer or a water repellent layer on the inner peripheral surface of the first electrode (if a diffusion layer and a water repellent layer are provided, a diffusion layer, and if only a diffusion layer is provided, only the diffusion layer and the water repellent layer are provided. ) Means a water repellent layer, respectively (the same shall apply hereinafter)), the diffusion layer or water repellent layer and the outer peripheral surface of the inner current collector are in contact with each other. This means that an electric body is provided. Furthermore, the “outer current collector disposed on the outer peripheral surface side of the membrane electrode structure” refers to a contact with the second electrode when a diffusion layer and a water repellent layer are not provided on the outer peripheral surface of the second electrode. This means that the outer current collector is disposed in such a form. On the other hand, when a diffusion layer or a water repellent layer is provided on the outer peripheral surface of the second electrode, it means that the outer current collector is disposed in contact with the diffusion layer or the water repellent layer. Furthermore, the “reactive gas” is a gas required for power generation in the fuel cell, and means a hydrogen-containing gas or an oxygen-containing gas. “Reactive gas is supplied / discharged from the side surface of the case member” means that a plurality of openings are provided on the side surface of the case member, and gas is supplied / discharged from the openings. In addition, “the reaction gas flows along the outer peripheral surface of the tube-type fuel cell” means that the reaction gas supplied from some of the plurality of openings is the outer periphery of the tube-type fuel cell. After flowing along the surface, the reaction gas is discharged from the other openings among the plurality of openings.

  In the tube-type fuel cell module of the present invention, it is preferable that the cross-sectional shape in the direction orthogonal to the longitudinal direction of the case member is substantially circular.

  According to the present invention, the reaction gas supplied to the outer peripheral surface side of the tubular fuel cell is supplied / discharged from the side surface of the case member, and the reaction gas is along the outer peripheral surface of the tube fuel cell. To improve the uniformity of the humidity on the outer peripheral surface side of the tubular fuel cell and the concentration of the reaction gas supplied to the outer peripheral surface side of the tubular fuel cell, thereby improving the power generation characteristics. A possible tubular fuel cell module can be obtained.

  Moreover, in the tube type fuel cell module of the present invention, the reaction gas supplied to the outer peripheral surface side of the tube type fuel cell is made to be a tube by making the cross-sectional shape in the direction orthogonal to the longitudinal direction of the case member substantially circular. A tubular fuel cell module that smoothly flows on the outer peripheral surface side of the fuel cell can be obtained.

  Hereinafter, the tube type fuel cell module of the present invention will be specifically described with reference to the drawings. In the following description, an oxygen-containing gas (hereinafter referred to as “air”) is supplied to the outer peripheral surface side of the MEA, and a hydrogen-containing gas (hereinafter referred to as “hydrogen”) is supplied to the inner peripheral surface side of the MEA. The form is illustrated.

  FIG. 1 is a view schematically showing a tube type fuel cell module of the present invention. FIG. 1A is a side view seen from a direction perpendicular to the longitudinal direction, and the left-right direction on the paper is the longitudinal direction of the tubular fuel cell module. FIG. 1B is a cross-sectional view in a direction perpendicular to the longitudinal direction at the position indicated by bb ′ in FIG. 1A, and the back / front direction of the paper is the longitudinal direction of the tubular fuel cell module. Direction. FIG. 1C is a cross-sectional view in a direction perpendicular to the longitudinal direction at a location indicated by cc ′ in FIG. 1A, and the back / front direction of the paper is the longitudinal direction of the tubular fuel cell module. Direction. The arrows shown in FIG. 1A, FIG. 1B, and FIG. 1C indicate the direction of air flow. Further, in FIG. 1A, some symbols are omitted in order to prevent the figure from becoming complicated.

  As shown in FIG. 1, a tubular fuel cell module 10 of the present invention (hereinafter simply referred to as “module 10”) includes a case member 1 and a tubular fuel cell 3 accommodated in the case member 1 (hereinafter referred to as “module 10”). Simply “cell 3”).

  The side surface of the case member 1 is provided with a plurality of openings 2, 2,. Among these openings 2, 2, ..., some of the openings 2, 2, ... are supply ports 2a, 2a, ... for supplying air, and the other openings 2, 2, ... are discharge ports. 2b, 2b, ..., and the supply port 2a and the discharge port 2b are preferably provided alternately in the longitudinal direction of the module 10. Moreover, it is preferable that the openings 2, 2,... Are provided with an appropriate inclination in the longitudinal direction, as shown in FIG. By adopting such a configuration, it becomes easy to supply / discharge air.

  On the other hand, the cell 3 includes an MEA 5 having a hollow portion 4, an inner current collector (not shown) provided on the inner peripheral surface side of the MEA 5, and an outer current collector (not shown) provided on the outer peripheral surface side of the MEA 5. ing. As shown in FIGS. 1B and 1C, the MEA 5 includes an electrolyte membrane 6 and a first electrode 7 (hereinafter referred to as “anode electrode 7”) provided on the inner peripheral surface side of the electrolyte membrane 6. And a second electrode 8 (hereinafter referred to as “cathode electrode 8”) provided on the outer peripheral surface side of the electrolyte membrane 6. The electrolyte membrane 6 is a solid polymer membrane containing a proton conducting polymer that exhibits proton conducting performance when kept in a water-containing state in a temperature environment of about 80 ° C. Specifically, it is preferable to have a polymer having at least one of a sulfonic acid group, a phosphonic acid group, and a phosphoric acid group with a fluorine-containing polymer as a skeleton. For example, Nafion et al. (“Nafion” or “Nafion” is a registered trademark of DuPont, USA). In addition, a polymer having a hydrocarbon skeleton such as polyolefin may be included. In addition, the anode electrode 7 and the cathode electrode 8 are metal particles that function as a catalyst for causing an electrochemical reaction during the operation of the cell 3 (for example, platinum black particles or alloys thereof in addition to platinum. "Catalyst") and a proton conductive polymer. The inner current collector and the outer current collector are not particularly limited as long as the electric energy generated by the electrochemical reaction can be taken out of the MEA 5, and may be provided by a known means.

  In the module 10, as shown in FIG. 1B, air is supplied from the supply port 2 a to a space 9 formed between the case member 1 and the cell 3. The air supplied to the space 9 flows almost once along the circumferential direction of the cell 3 as shown in FIG. 1 (b) and FIG. 1 (c), and as shown in FIG. It is discharged from 2b. As shown in FIGS. 1B and 1C, the case member 1 has a substantially circular cross-sectional shape, so that air can smoothly flow around the cells 3. On the other hand, hydrogen is supplied to the hollow portion 4.

  The hydrogen supplied to the hollow portion 4 reaches the anode electrode 7, and the hydrogen reaching the anode electrode 7 is separated into protons and electrons under the action of the catalyst dispersed in the anode electrode 7. Protons generated at the anode electrode 7 are conducted by the proton conductive polymer contained in the anode electrode 7, the electrolyte membrane 6, and the cathode electrode 8, and reach the cathode electrode 8. On the other hand, electrons generated at the anode electrode 7 cannot pass through the electrolyte membrane 6. Therefore, the electrons include an inner current collector (not shown) disposed on the inner peripheral surface side of the anode electrode 7 and an outer current collector (not illustrated) disposed on the outer peripheral surface side of the cathode electrode 8. The cathode electrode 8 is reached through an external circuit. The protons and electrons that have reached the cathode electrode 8 through this process then react with oxygen contained in the air supplied to the cathode electrode 8 under the action of the catalyst dispersed in the cathode electrode 8, It becomes. In the cell 3, in this way, water is generated together with electric energy by an electrochemical reaction.

  As described above, in the module 10, the air used for the electrochemical reaction is supplied from the supply port 2 a provided on the side surface of the case member 1 and flows along the outer peripheral surface of the cell 3. Discharged from. By adopting such a configuration, in the longitudinal direction of the cell 3, the humidity on the outer peripheral surface side of the cell 3 and the uniformity of the oxygen concentration contained in the air supplied to the outer peripheral surface side of the cell 3 can be improved. The characteristics can be improved. The reason will be specifically described below.

  In a fuel cell, water generated on the cathode electrode side during power generation flows together with surplus reaction gas. That is, the humidity varies depending on the position in the flow direction of the reaction gas. Specifically, the humidity is low on the inlet side of the reaction gas, and the amount of water increases as it goes toward the outlet side, so the humidity increases. Also, the concentration of the reaction gas varies depending on the position in the flow direction of the reaction gas. Specifically, the concentration of the reaction gas increases on the inlet side of the reaction gas, but the concentration of the reaction gas decreases toward the outlet side. Therefore, for example, in the case where air is flowed along the longitudinal direction of the tubular fuel cell on the outer peripheral surface side of the tubular fuel cell, there is a difference in the concentration of humidity and oxygen in the longitudinal direction of the tubular fuel cell. As a result, power generation distribution may occur. In the case where air is supplied from one direction perpendicular to the longitudinal direction of the tubular fuel cell on the outer peripheral surface side of the tubular fuel cell, on the side where the air of the tubular fuel cell is supplied Since the oxygen concentration is high and it is in a dry state, and the oxygen concentration is low on the back side and the humidity is likely to be high, the power generation distribution may occur.

  However, in the module 10, as described above, air is supplied from the supply port 2a, flows substantially once along the outer peripheral surface of the cell 3, and then is discharged from the discharge port 2b. By setting it as this form, it can suppress that the difference of the humidity and oxygen concentration of the outer peripheral surface side of the cell 3 arises. That is, in the module 10, the humidity on the outer peripheral surface side of the cell 3 and the uniformity of the oxygen concentration supplied to the outer peripheral surface side of the cell 3 can be improved, and the power generation characteristics can be improved.

  In the description so far, as an example of the form of the tube type fuel cell module of the present invention, an example in which air is supplied to the outer peripheral surface side of the MEA 5 and hydrogen is supplied to the inner peripheral surface side of the MEA 5 is illustrated. However, in the tube type fuel cell module of the present invention, the outer periphery of the tube type fuel cell is provided even when air is supplied to the inner peripheral surface side of the MEA and hydrogen is supplied to the outer peripheral surface side of the MEA. The effect of improving the uniformity of the concentration of hydrogen supplied to the surface side can be obtained. However, from the viewpoint of improving the humidity uniformity of the tube-type fuel cell, a mode in which air is supplied to the outer peripheral surface side of the MEA and hydrogen is supplied to the inner peripheral surface side of the MEA is preferable.

  Further, in the description of the tube type fuel cell module of the present invention so far, the mode in which the cross-sectional shape in the direction perpendicular to the longitudinal direction of the case member 1 is substantially circular like the module 10 is illustrated. The tube type fuel cell module is not limited to such a form. Any configuration may be used as long as it has a space in which the reaction gas supplied / exhausted from the side surface of the case member can flow between the case member and the tube-type fuel cell, for example, the longitudinal direction of the case member. The cross-sectional shape in the direction perpendicular to may be a substantially polygonal shape or a substantially flat circular shape. However, from the viewpoint of more smoothly flowing the reaction gas supplied to the outer peripheral surface side of the tubular fuel cell, a form in which the cross-sectional shape in the direction perpendicular to the longitudinal direction of the case member is substantially circular is preferable.

  Further, in the description of the tube type fuel cell module of the present invention so far, the form in which the opening portions 2, 2,... Provided on the side surface of the case member 1 protrude is illustrated, but the tube type fuel cell of the present invention is illustrated. The module is not limited to such a form, and may have a form in which the openings are flush with each other. However, from the viewpoint of easily supplying / discharging the reaction gas, it is preferable that the opening is provided in a form protruding as shown in FIG.

  In the description of the tube type fuel cell module of the present invention, the MEA 5 includes the electrolyte membrane 6, the anode electrode 7, and the cathode electrode 8. However, the present invention is limited to such a form. Instead, the gas diffusion layer may be provided on the inner peripheral surface side of the anode electrode and / or the outer peripheral surface side of the cathode electrode. The gas diffusion layer may be any material that can withstand the environment during operation of the tubular fuel cell, can diffuse the gas, and has conductivity, and specific examples of the diffusion layer that can be used in the present invention include: Examples thereof include carbon paper and carbon cloth.

  In the description of the present invention so far, one tube type fuel cell module has been described. However, a plurality of the tube type fuel cell modules of the present invention can be used in combination. For example, a plurality of the tube-type fuel cell modules of the present invention can be arranged in the longitudinal direction, and each can be electrically connected for use. It is also possible to arrange a plurality of the tubular fuel cell modules of the present invention in a direction orthogonal to the longitudinal direction and to electrically connect each of them. However, from the viewpoint of simplifying the structure, a form in which a plurality are arranged in the longitudinal direction is preferable.

It is the figure which showed schematically the tube type fuel cell module of this invention. (A) is the side view seen from the direction perpendicular | vertical to a longitudinal direction. (B) is sectional drawing of the direction perpendicular | vertical to the longitudinal direction in the location shown by bb 'in (a). (C) is sectional drawing of the direction perpendicular | vertical to the longitudinal direction in the location shown by cc 'in (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case member 2 Opening part 2a Supply port 2b Discharge port 3 Tube type fuel cell 4 Hollow part 5 MEA (membrane electrode structure)
6 Electrolyte membrane 7 Anode electrode (first electrode)
8 Cathode electrode (second electrode)
9 Space 10 Tube type fuel cell module

Claims (2)

A hollow membrane electrode structure, an inner current collector disposed on the inner peripheral surface side of the membrane electrode structure, and an outer current collector disposed on the outer peripheral surface side of the membrane electrode structure A tubular fuel cell;
A case member that accommodates the tubular fuel cell,
The reactive gas supplied to the outer peripheral surface side of the tubular fuel cell is supplied / discharged from the side surface of the case member, and the reactive gas is along the outer peripheral surface of the tubular fuel cell. A tubular fuel cell module, characterized by flowing. 2. The tube type fuel cell module according to claim 1, wherein a cross-sectional shape in a direction orthogonal to a longitudinal direction of the case member is substantially circular.

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