JP2007073349A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell capable of uniformly supplying liquid fuel to fuel electrode side, without receiving effects from the pressure head of liquid fuel stored in a fuel tank. <P>SOLUTION: The fuel cell comprises the liquid fuel tank 21 storing liquid fuel; a film-electrode assembly 16 composed of a fuel electrode, an air electrode, and an electrolyte film 15 interposed between the fuel electrode and the air electrode; a fuel flow passage 22, having a flow passage resistance not less than a prescribed value leading out the liquid fuel F from the liquid fuel tank 21; a fuel impregnation layer 24 impregnating the liquid fuel F lead out from the liquid fuel tank 21; and a gas-liquid separation film 26 transmitting gaseous component of the liquid fuel F supplied from the fuel impregnation layer 24, and leading it to fuel electrode side. Appropriate quantity of the liquid fuel F can be supplied uniformly to fuel electrode side, without receiving effects from the pressure head of the liquid fuel F stored in the liquid fuel tank 21. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell, and more particularly to a small passive fuel cell.

  With the recent development of semiconductor technology, electronic devices such as OA equipment and audio equipment have been reduced in size, performance, and portability, and the demand for higher energy density of batteries used in these portable electronic equipment has increased. ing.

  Under such circumstances, small fuel cells are attracting attention. In particular, direct methanol fuel cells (DMFC) using methanol as fuel can avoid the difficulty of handling hydrogen gas compared to fuel cells using hydrogen gas, and reform organic fuel. Therefore, it is considered that the device for producing hydrogen is not necessary and is excellent in miniaturization.

  In DMFC, methanol is oxidatively decomposed at the fuel electrode to generate carbon dioxide, protons and electrons. On the other hand, in the air electrode, water is generated by oxygen obtained from air, protons supplied from the fuel electrode through the electrolyte membrane, and electrons supplied from the fuel electrode through an external circuit. In addition, power is supplied by electrons passing through the external circuit.

As a method of supplying fuel in the DMFC, the liquid fuel contained in the fuel tank is directly brought into contact with the main surface of the liquid fuel impregnation part, so that the liquid fuel impregnation part is impregnated and the liquid fuel is supplied to the fuel electrode side. Have been disclosed (for example, see Patent Documents 1-3).
JP 2000-268836 A JP 2004-171844 A Japanese Patent No. 3413111

  However, in the configuration of the conventional fuel cell described above, the liquid fuel accommodated in the fuel tank directly contacts the main surface of the liquid fuel impregnated portion, so that, for example, the liquid fuel is affected by the pressure head of the liquid fuel and excessively. Liquid fuel sometimes moved to the liquid fuel impregnation part. Furthermore, due to the non-uniform supply of the liquid fuel to the liquid fuel impregnation part, it may be difficult to supply the liquid fuel uniformly to the fuel electrode side. For example, when the remaining amount of liquid fuel decreases and the liquid fuel accumulated in the lower part of the fuel tank comes into contact with the liquid fuel impregnated part, the liquid fuel supplied to the fuel electrode side through the liquid fuel impregnated part In some cases, it becomes difficult to uniformly supply liquid fuel to the fuel electrode side. As described above, the non-uniformity of the fuel concentration in the liquid fuel-impregnated portion has a problem such as facilitating the occurrence of fuel crossover in the portion where the fuel is excessive.

  Accordingly, the present invention has been made to solve the above-described problem, and an appropriate amount of liquid fuel is uniformly applied to the liquid fuel impregnation portion without being affected by the pressure head of the liquid fuel accommodated in the fuel tank. It aims at providing the fuel cell which can be supplied to.

  In order to achieve the above object, a fuel cell of the present invention comprises a fuel tank that contains liquid fuel, a fuel electrode, an air electrode, and an electrolyte membrane that is sandwiched between the fuel electrode and the air electrode. An electrode assembly, a fuel flow path having a flow path resistance greater than or equal to a predetermined value, and for deriving liquid fuel from the fuel tank; a fuel impregnation unit for impregnating the liquid fuel derived from the fuel flow path; and the fuel And a gas-liquid separation membrane that permeates the vaporized component of the liquid fuel supplied from the impregnation portion and guides it to the fuel electrode side.

  According to this fuel cell, since the liquid fuel is impregnated in the fuel impregnation portion through the fuel flow path having a flow resistance of a predetermined value or more, the influence of the pressure head of the liquid fuel accommodated in the fuel tank, etc. Therefore, an appropriate amount of liquid fuel can be uniformly supplied to the fuel electrode side.

  According to the fuel cell of the present invention, an appropriate amount of liquid fuel can be uniformly supplied to the liquid fuel impregnation portion without being affected by the pressure head of the liquid fuel accommodated in the fuel tank.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram schematically showing a cross section of a fuel cell 10 including a fuel cell module 10a constituting the fuel cell 10 of the first embodiment according to the present invention. FIG. 2 is a cross-sectional view taken along the line AA of FIG.

  As shown in FIGS. 1 and 2, the fuel cell 10 includes a plurality of fuel cell modules 10a, and each fuel cell module 10a has a fuel flow path provided corresponding to each fuel cell module 10a. The liquid fuel F is supplied from the liquid fuel tank 21 via 22. Here, FIG. 2 shows an example of the fuel cell 10 including six fuel cell modules 10a. However, the number of the fuel cell modules 10a is not limited to this and can be arbitrarily set. . Each fuel cell module 10a is configured to be electrically connected in series and to obtain a predetermined output.

  The fuel cell module 10 a includes a fuel electrode composed of an anode catalyst layer 11 and an anode gas diffusion layer 12, an air electrode composed of a cathode catalyst layer 13 and a cathode gas diffusion layer 14, and an anode catalyst layer 11 and a cathode catalyst layer 13. A membrane electrode assembly (MEA) 16 composed of a proton (hydrogen ion) conductive electrolyte membrane 15 sandwiched between the electrodes is configured as an electromotive unit.

  Examples of the catalyst contained in the anode catalyst layer 11 and the cathode catalyst layer 13 include platinum group elements such as single metals such as Pt, Ru, Rh, Ir, Os, and Pd, alloys containing platinum group elements, and the like. Can be mentioned. Specifically, it is preferable to use Pt—Ru or Pt—Mo having strong resistance to methanol or carbon monoxide as the anode catalyst layer 11 and platinum or Pt—Ni as the cathode catalyst layer 13. However, it is not limited to these. Further, a supported catalyst using a conductive support such as a carbon material, or a non-supported catalyst not using a conductive support may be used.

  Examples of the proton conductive material that constitutes the electrolyte membrane 15 include fluorinated resins having a sulfonic acid group, such as perfluorosulfonic acid polymer (Nafion (trade name, manufactured by DuPont), Flemion (trade name, Asahi Glass Co., Ltd.)), sulfonic acid group-containing hydrocarbon resins, and inorganic substances such as tungstic acid and phosphotungstic acid, but are not limited thereto.

  The anode gas diffusion layer 12 laminated on the anode catalyst layer 11 serves to uniformly supply fuel to the anode catalyst layer 11 and also serves as a current collector for the anode catalyst layer 11. On the other hand, the cathode gas diffusion layer 14 stacked on the cathode catalyst layer 13 serves to uniformly supply the oxidant to the cathode catalyst layer 13 and also serves as a current collector for the cathode catalyst layer 13. An anode conductive layer 17 is disposed on the surface of the anode gas diffusion layer 12, and a cathode conductive layer 18 is disposed on the surface of the cathode gas diffusion layer 14. The anode conductive layer 17 and the cathode conductive layer 18 are composed of a porous layer such as a mesh made of a conductive metal material such as gold.

  The anode sealing material 19 has a rectangular frame shape, is positioned between the anode conductive layer 17 and the electrolyte membrane 15, and surrounds the anode catalyst layer 11 and the anode gas diffusion layer 12. On the other hand, the cathode sealing material 20 has a rectangular frame shape, is located between the cathode conductive layer 18 and the electrolyte membrane 15, and surrounds the cathode catalyst layer 13 and the cathode gas diffusion layer 14. The anode sealing material 19 and the cathode sealing material 20 are made of, for example, a rubber O-ring, and prevent fuel leakage and oxidant leakage from the membrane electrode assembly 16.

  A partition plate 23 is disposed so as to cover the opening of the liquid fuel tank 21 that stores the liquid fuel F. A fuel channel 22 is formed in the partition plate 23 at a position corresponding to the lower portion of the liquid fuel tank 21. Further, a fuel impregnated layer 24 is disposed in contact with the surface of the partition plate 23 on the membrane electrode assembly 16 side, and the fuel impregnated layer 24 has a gas cut plate 25 on the membrane electrode assembly 16 side. A liquid separation membrane 26 is disposed. Further, a vaporized fuel storage chamber 28 is formed by disposing a frame 27 having a shape corresponding to the outer edge shape of the fuel cell 10 on the membrane electrode assembly 16 side of the gas-liquid separation membrane 26. The membrane electrode assembly 16 described above is disposed so that the anode conductive layer 17 is in contact with one opening side of the storage chamber 28.

  The fuel flow path 22 formed in the partition plate 23 is a flow path for guiding the liquid fuel F from the liquid fuel tank 21 to the fuel impregnated layer 24. The fuel flow path 22 is on the extension line of the inner bottom surface 21a of the liquid fuel tank 21 or more than the extension line in order to make maximum use of the liquid fuel F accommodated in the vertically long liquid fuel tank 21. It is preferable that the lower end surface 22a of the fuel flow path 22 is located below. Further, as shown in FIG. 2, the fuel flow path 22 is provided corresponding to each fuel cell module 10a, and the liquid fuel F is transferred from the liquid fuel tank 21 to each fuel cell module 10a via each fuel flow path 22. Is configured to be supplied. The cross-sectional shape perpendicular to the flow path direction in the fuel flow path 22 is not particularly limited, but is preferably rectangular or circular for reasons such as flow path balance and ease of processing. One fuel flow path 22 may be formed with a plurality of openings.

  In addition, when the liquid fuel F is fully contained in the liquid fuel tank 21, the fuel flow path 22 is supplied from the liquid fuel tank 21 to the fuel-impregnated layer 24 via the fuel flow path 22 with the head pressure. Is configured to have a flow path resistance equal to or higher than the head pressure.

  The partition plate 23 is formed of a material having solvent resistance and acid resistance. Specifically, the partition plate 23 is formed of PET (polyethylene terephthalate), PPS (polyphenyl sulfide), PEEK (polyether ether ketone), or the like. . Moreover, the partition plate 23 may be comprised with the impervious film | membrane formed, for example with PET (polyethylene terephthalate), PP (polypropylene), etc. which have solvent resistance and acid resistance.

  The fuel impregnation layer 24 has a configuration in which the liquid fuel F is moved from the liquid fuel tank 21 through the fuel flow path 22 by capillary force, and the liquid fuel F that has moved is impregnated. The fuel-impregnated layer 24 is composed of a foam, a porous body, a fibrous porous body, or the like made of particles, fillers, nonwoven fabrics and fibers. The porosity of this porous body is preferably about 30 to 90%. The porosity within this range is preferable because when the porosity is less than 30%, the capillary force decreases because the number of closed pores increases, and when the porosity is greater than 90%, the strength is high. It is because manufacture will become difficult while it falls.

  The fuel cut plate 25 prevents the liquid fuel F from coming into contact with the gas-liquid separation membrane 26. For example, when the operation of the fuel cell 10 is stopped, the fuel cut plate 25 is provided between the fuel impregnation layer 24 and the gas-liquid separation membrane 26. The fuel cell 10 is removed during operation of the fuel cell 10, and the liquid fuel F is configured to contact the gas-liquid separation membrane 26. The fuel cut plate 25 is formed of a material having solvent resistance and acid resistance, and specifically, formed of PET (polyethylene terephthalate), PPS (polyphenyl sulfide), PEEK (polyether ether ketone), or the like. .

  The gas-liquid separation film 26 separates the vaporized component of the liquid fuel F and the liquid fuel F, and further vaporizes the liquid fuel F, and is formed of a material that is inert to the fuel and does not dissolve. Specific examples of the material forming the gas-liquid separation membrane 26 include materials such as silicone and PTFE (polytetrafluoroethylene).

  The vaporized fuel storage chamber 28 is a space surrounded by the frame 27, the gas-liquid separation film 26 and the anode conductive layer 17, and temporarily stores the vaporized component of the liquid fuel F that has permeated through the gas-liquid separation film 26. Furthermore, it functions as a space for making the fuel concentration distribution in the vaporized component uniform. The frame 27 is made of an electrically insulating material such as a thermoplastic polyester resin such as polyethylene terephthalate (PET), and an exhaust hole 29 is formed in at least a part thereof. Due to the exhaust holes 29, it is possible to suppress an increase in the pressure in the vaporized fuel storage chamber 28 due to the generated gas generated in the anode catalyst layer 11. Note that the vaporized fuel storage chamber 28 does not always need to communicate with the outside via the exhaust hole 29. For example, when the vaporized fuel storage chamber 28 is at a predetermined pressure, the vaporized fuel storage chamber 28 is stored. The chamber 28 may be communicated with the outside through the exhaust hole 29 to discharge the gas in the vaporized fuel storage chamber 28.

  The vaporized component of the liquid fuel F that has passed through the gas-liquid separation membrane 26 and the vaporized fuel storage chamber 28 is then divided and supplied to each fuel cell module 10a.

  Here, the liquid fuel F stored in the liquid fuel tank 21 is a methanol aqueous solution having a concentration exceeding 50 mol% or pure methanol. The purity of pure methanol is preferably 95% by weight or more and 100% by weight or less. The vaporization component of the liquid fuel F mentioned above means vaporized methanol when liquid methanol is used as the liquid fuel F, and vaporization of methanol when methanol aqueous solution is used as the liquid fuel F. It means an air-fuel mixture consisting of components and water vaporization components. The liquid fuel F is injected from, for example, a fuel supply hole (not shown) provided in an upper part of the vertically long liquid fuel tank 21. In addition, the installation position of the fuel supply hole is not particularly limited, and may be provided other than the upper portion of the liquid fuel tank 21.

  On the other hand, a moisturizing layer 30 is laminated on the cathode conductive layer 18 on the air electrode side. On the moisturizing layer 30, a surface layer 32 in which a plurality of air inlets 31 for taking in air as an oxidant is formed is laminated.

  The moisturizing layer 30 impregnates part of the water generated in the cathode catalyst layer 13 to suppress the transpiration of water, and uniformly introduces an oxidant into the cathode gas diffusion layer 14, thereby providing a cathode catalyst. It also has a function as an auxiliary diffusion layer that promotes uniform diffusion of the oxidizing agent into the layer 13. The moisturizing layer 30 is made of a material such as a polyethylene porous film, for example.

  The surface layer 32 is also made of a metal such as SUS304, for example, because it plays a role of pressurizing the laminated body including the membrane electrode assembly 16 to enhance its adhesion.

  Here, the movement of water from the cathode catalyst layer 13 side to the anode catalyst layer 11 side due to the osmotic pressure phenomenon is performed by changing the number and size of the air inlets 31 of the surface layer 32 installed on the moisturizing layer 30. It can be controlled by adjusting the area and the like. The moisturizing layer 30 is preferably installed, but the fuel cell module 10a may be configured without using the moisturizing layer 30.

  Next, the operation of the fuel cell 10 described above will be described. Here, the fuel cut plate 25 is in a removed state.

  The liquid fuel F (for example, aqueous methanol solution) in the liquid fuel tank 21 moves from the liquid fuel tank 21 via the fuel flow path 22 by the capillary force of the fuel impregnation layer 24 and is impregnated in the fuel impregnation layer 24. At this time, since the liquid fuel F moving from the liquid fuel tank 21 is moved by the capillary force of the fuel impregnated layer 24, an appropriate amount of the liquid fuel F gradually moves without excessive movement. .

Among the liquid fuel F impregnated in the fuel impregnated layer 24, the vaporized mixture of methanol and water vapor passes through the gas-liquid separation membrane 26 and is temporarily stored in the vaporized fuel storage chamber 28, and the concentration distribution is made uniform. . The air-fuel mixture once stored in the vaporized fuel storage chamber 28 is divided, passes through the anode conductive layer 17 of each fuel cell module 10a, is further diffused in the anode gas diffusion layer 12, and is supplied to the anode catalyst layer 11. The air-fuel mixture supplied to the anode catalyst layer 11 causes an internal reforming reaction of methanol represented by the following formula (1).
CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ Formula (1)

  In addition, when pure methanol is used as the liquid fuel F, since water vapor is not supplied from the liquid fuel tank 21, water generated in the cathode catalyst layer 13, water in the electrolyte membrane 15 and the like are described as methanol. The internal reforming reaction of the formula (1) is generated, or the internal reforming reaction is generated by another reaction mechanism that does not require water, regardless of the internal reforming reaction of the above formula (1).

Protons (H ⁺ ) generated by the internal reforming reaction are conducted through the electrolyte membrane 15 and reach the cathode catalyst layer 13. On the other hand, the air taken in from the air inlet 31 of the surface layer 32 passes through the moisturizing layer 30, diffuses in the cathode conductive layer 18 and the cathode gas diffusion layer 14 of each fuel cell module 10 a, and reaches the cathode catalyst layer 13. Supplied. The air supplied to the cathode catalyst layer 13 causes the reaction shown in the following formula (2). By this reaction, water is generated and a power generation reaction occurs.
(3/2) O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O Formula (2)

  By this reaction, water generated in the cathode catalyst layer 13 of each fuel cell module 10 a diffuses through the cathode gas diffusion layer 14 and reaches the moisture retention layer 30, and a part of the water is provided on the moisture retention layer 30. The surface layer 32 evaporates from the air inlet 31, but the remaining water is prevented from evaporating by the surface layer 32. In particular, when the reaction of Formula (2) proceeds, the amount of water whose transpiration is inhibited by the surface layer 32 increases, and the amount of water stored in the cathode catalyst layer 13 increases. In this case, the water storage amount of the cathode catalyst layer 13 becomes larger than the water storage amount of the anode catalyst layer 11 as the reaction of the formula (2) proceeds. As a result, a reaction in which water generated in the cathode catalyst layer 13 moves to the anode catalyst layer 11 through the electrolyte membrane 15 is promoted by the osmotic pressure phenomenon. Therefore, as compared with the case where the supply of moisture to the anode catalyst layer 11 is dependent only on water vapor evaporated from the liquid fuel tank 21, the supply of moisture is promoted, and the internal reforming reaction of methanol in the above-described formula (1) is promoted. Can be made. As a result, the output density can be increased and the high output density can be maintained for a long period of time.

  Further, even when a methanol aqueous solution having a methanol concentration exceeding 50 mol% or pure methanol is used as the liquid fuel F, the water that has moved from the cathode catalyst layer 13 to the anode catalyst layer 11 is used for the internal reforming reaction. Therefore, it is possible to stably supply water to the anode catalyst layer 11. Thereby, the reaction resistance of the internal reforming reaction of methanol can be further reduced, and the long-term output characteristics and load current characteristics can be further improved. Further, the liquid fuel tank 21 can be downsized.

  As described above, according to the fuel cell 10 of the first embodiment, when the liquid fuel F is fully stored in the liquid fuel tank 21, the fuel flow path 22 having a flow path resistance equal to or higher than the head pressure. Is provided between the liquid fuel tank 21 and the fuel impregnated layer 24, and the liquid fuel F in the liquid fuel tank 21 is moved by moving the liquid fuel F through the fuel flow path 22 by the capillary force of the fuel impregnated layer 24. A predetermined amount of the liquid fuel F can be gradually moved toward the fuel impregnated layer 24 without being affected by the remaining amount.

  Further, by providing the fuel flow path 22 corresponding to each fuel cell module 10a, the liquid fuel F can be uniformly supplied from the liquid fuel tank 21 to each fuel cell module 10a via each fuel flow path 22. it can.

  Further, since the fuel impregnation layer 24 can be impregnated with the liquid fuel F without being affected by the remaining amount of the liquid fuel F in the liquid fuel tank 21, excess fuel may be supplied to the fuel impregnation layer 24. In addition, fuel crossover caused by excessive fuel can be prevented. Further, since the fuel impregnation layer 24 is impregnated with a predetermined required amount of the liquid fuel F without being affected by the remaining amount of the liquid fuel F in the liquid fuel tank 21, the remaining amount of the liquid fuel F is reduced to the liquid fuel. The remaining amount in the tank 21 can be accurately grasped.

  In the first embodiment described above, a fuel cell using an aqueous methanol solution or pure methanol as the liquid fuel F has been described. However, the present invention includes, for example, ethyl alcohol, isopropyl alcohol, butanol, dimethyl ether, etc. Alternatively, it can be applied to a liquid fuel direct supply type fuel cell using these aqueous solutions.

(Second Embodiment)
FIG. 3 is a diagram schematically showing a cross section of the fuel cell 40 including the fuel cell module 40a constituting the fuel cell 40 of the second embodiment according to the present invention. FIG. 4 is a diagram schematically showing a cross section of the fuel cell 40 when the arrangement direction of the fuel cell 40 of FIG. 3 is changed. In addition, the same code | symbol is attached | subjected to the same part as the structure of the fuel cell 10 of 1st Embodiment, and the overlapping description is simplified or abbreviate | omitted.

  As shown in FIG. 3, the fuel cell 40 includes a liquid fuel tank 21 of the fuel cell 10 according to the first embodiment. The second fuel-impregnated layer 41 that contacts the inner wall of the liquid fuel tank 21 that faces the flow path 22 is provided.

  Similar to the fuel impregnation layer 24, the second fuel impregnation layer 41 has a configuration in which the liquid fuel F is moved by a capillary force, and is a foam, a porous body or a fibrous porous body made of particles, fillers, nonwoven fabrics and fibers. It consists of a body. The porosity of this porous body is preferably about 30 to 90%. The porosity within this range is preferable because when the porosity is less than 30%, the capillary force decreases because the number of closed pores increases, and when the porosity is greater than 90%, the strength is high. It is because manufacture will become difficult while it falls.

  According to the fuel cell 40 of the second embodiment, the second fuel-impregnated layer 41 has one end in contact with the fuel-impregnated portion via the fuel channel 22 and the other end facing the fuel channel 22. Since the liquid fuel tank 21 is provided so as to be in contact with the inner wall of the liquid fuel tank 21, for example, as shown in FIG. 4, even when the liquid fuel tank 21 is arranged so that the longitudinal direction is on the lower side, the second fuel The liquid fuel F can be moved to the fuel impregnation layer 24 side by the capillary force of the impregnation layer 41.

(Example)
Next, even when the liquid fuel F is fully stored in the liquid fuel tank 21, by providing the fuel flow path 22, the liquid fuel F is gradually moved to the fuel-impregnated layer 24 by the capillary force of the fuel-impregnated layer 24. Explain that it is possible.

  Here, when the liquid fuel F is fully contained in the liquid fuel tank 21, the analysis model 100 corresponding to the specification provided with the fuel flow path 22 having a flow path resistance equal to or higher than the head pressure, and the liquid fuel tank 21 When the liquid fuel F is fully contained, the analysis model 200 corresponding to the specification provided with the fuel flow path 201 having a flow path resistance smaller than the head pressure is analyzed from the liquid fuel tank 21 to the fuel impregnation layer. A state in which the liquid fuel F was impregnated in 24 was simulated. The analysis model 100 has a configuration corresponding to the fuel cell of the present invention, while the analysis model 200 is a comparative example that does not have the configuration of the fuel cell of the present invention.

  FIG. 5 is a perspective view of the analysis model 100 in the specification with the fuel flow path 22, and FIG. 6 is a perspective view of the analysis model 200 in the specification with the fuel flow path 201.

  As shown in FIG. 5, in the analysis model 100, the height (h1) is 0.5 mm and the width (width) at a predetermined interval below the partition plate 23 having a width (L1) of 55 mm and a thickness (t1) of 2 mm. The fuel flow paths 22 having a length of L2) are formed at six locations. The thicknesses of the liquid fuel tank 21 and the fuel impregnated layer 24 were both 2 mm.

  As shown in FIG. 6, in the analysis model 200, the height (h2) extends in the width direction of the partition plate 23 at the lower portion of the partition plate 23 having a width (L3) of 55 mm and a thickness (t2) of 2 mm. A slit-like fuel flow path 201 having a diameter of 0.5 mm is formed. The thicknesses of the liquid fuel tank 21 and the fuel impregnated layer 24 were both 2 mm.

  The liquid fuel tank 21 in each of the analysis models 100 and 200 described above is assumed to be fully filled with the liquid fuel F in the initial state, and the liquid impregnation layer 24 is impregnated with the liquid fuel F from the liquid fuel tank 21 after the simulation starts. As a result, a simulation was performed. In addition, the case where pure methanol was used for the liquid fuel F was assumed.

  FIG. 7 shows the state of movement of the liquid fuel F in the analysis model 200 0.2 seconds after the start of the simulation. FIG. 8 shows the state of movement of the liquid fuel F in the analysis model 100 0.2 seconds after the start of the simulation. In addition, the numerical value shown in the figure is the fuel concentration ratio in each region when the fuel concentration is 1. For example, a region where the fuel concentration ratio is 0 means a region where no fuel exists.

  As shown in FIGS. 7 and 8, the movement of fuel from the liquid fuel tank 21 to the fuel-impregnated layer 24 in the analysis model 100 having the specification with the fuel flow path 22 proceeds rapidly even after the simulation is started. It turned out that it moved gradually. Further, this movement is considered to have moved to the capillary force in the fuel-impregnated layer 24.

  On the other hand, it was found that the movement of the fuel from the liquid fuel tank 21 to the fuel-impregnated layer 24 in the analysis model 200 having the specification with the fuel flow channel 201 proceeds rapidly almost simultaneously with the start of the simulation.

  In addition, the fuel concentration distribution in the fuel impregnated layer 24 during power generation after the start of the simulation was substantially uniform throughout the analysis model 100 and the analysis model 200. In addition, the amount of fuel supplied to the fuel-impregnated layer 24 during power generation was substantially the same in the fuel-impregnated layer 24 in the analysis model 100 and the analysis model 200.

  From the above results, when the liquid fuel F is fully stored in the liquid fuel tank 21, the fuel impregnation layer 24 is provided from the liquid fuel tank 21 by providing the fuel flow path 22 having a flow path resistance equal to or higher than the head pressure. It has been found that the movement of the liquid fuel F toward the fuel gradually progresses due to the capillary force of the fuel impregnated layer 24, so that the rapid and excessive movement of the liquid fuel F toward the fuel impregnated layer 24 can be suppressed. For this reason, it has been found that providing the fuel flow path 22 having this configuration is effective in preventing fuel crossover caused by excessive fuel.

1 is a cross-sectional view of a fuel cell including a fuel cell module that constitutes a fuel cell according to a first embodiment of the present invention. AA sectional drawing of FIG. Sectional drawing of the fuel cell containing the fuel cell module which comprises the fuel cell of 2nd Embodiment which concerns on this invention. Sectional drawing of a fuel cell when the arrangement direction of the fuel cell of FIG. 3 is changed. The perspective view of the analysis model of the fuel cell concerning this invention. The perspective view of the analysis model of the fuel cell which concerns on a comparative example. The figure which shows the state of the movement of the liquid fuel in the analysis model of the fuel cell which concerns on this invention. The figure which shows the state of the movement of the liquid fuel in the analysis model of the fuel cell which concerns on a comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 10a ... Fuel cell module, 11 ... Anode catalyst layer, 12 ... Anode gas diffusion layer, 13 ... Cathode catalyst layer, 14 ... Cathode gas diffusion layer, 15 ... Electrolyte membrane, 16 ... Membrane electrode assembly, 17 DESCRIPTION OF SYMBOLS ... Anode conductive layer, 18 ... Cathode conductive layer, 19 ... Anode seal material, 20 ... Cathode seal material, 21 ... Liquid fuel tank, 21a ... Inner bottom surface, 22 ... Fuel flow path, 22a ... Lower end surface, 23 ... Partition plate, 24 ... Fuel impregnated layer, 25 ... Fuel cut plate, 26 ... Gas-liquid separation membrane, 27 ... Frame, 28 ... Vaporized fuel storage chamber, 29 ... Exhaust hole, 30 ... Moisturizing layer, 31 ... Air inlet, 32 ... Surface layer , F ... Liquid fuel.

Claims (7)

A fuel tank containing liquid fuel;
A membrane electrode assembly composed of a fuel electrode, an air electrode, and an electrolyte membrane sandwiched between the fuel electrode and the air electrode;
A fuel flow path having a flow path resistance greater than or equal to a predetermined value, and leading out liquid fuel from the fuel tank;
A fuel impregnation part for impregnating liquid fuel derived from the fuel flow path;
A fuel cell comprising: a gas-liquid separation membrane that permeates a vaporized component of the liquid fuel supplied from the fuel impregnation unit and guides the vaporized component to the fuel electrode side.   2. The fuel cell according to claim 1, wherein the fuel flow path is configured by an opening formed in a partition plate interposed between the fuel tank and the fuel impregnation portion.   2. The fuel cell according to claim 1, wherein the fuel flow path is configured by an opening formed in an impermeable film interposed between the fuel tank and the fuel impregnation portion.   4. The flow path resistance equal to or higher than the predetermined value is a flow path resistance equal to or higher than a head pressure applied when the fuel tank is fully filled with liquid fuel. Fuel cell.   The said fuel impregnation part is comprised with the porous body, and moves a liquid fuel from the said fuel tank via the said fuel flow path by capillary force, The Claim 1 characterized by the above-mentioned. Fuel cell.   A porous body disposed in the fuel tank with one end in contact with the fuel impregnated portion via the fuel flow path and the other end in contact with the inner wall of the fuel tank facing the fuel flow path. The fuel cell according to any one of claims 1 to 5, further comprising:   The fuel cell according to claim 1, wherein the fuel flow path is formed corresponding to a membrane electrode assembly to be installed.

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