JP2005302518A - Fuel cell system and equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system and equipment equipped with the fuel cell system in which handleability can be made excellent. <P>SOLUTION: Recirculation piping 108 is installed to communicate the air chamber of the fuel cell 1 with a pure water tank 102. Since the water generated in the air chamber is housed in the pure water tank 102, leakage of water to outside of the fuel cell system 100 can be prevented, so that the water generated in the fuel cell 1 can be re-utilized. Furthermore, since the outside of the fuel cell 1 does not become frozen even when used in a cold district, the handleability of the fuel cell system 100 can be enhanced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system including a fuel cell and a device including the fuel cell system.

A fuel cell takes out electric energy by electrochemically reacting fuel and oxygen continuously supplied from the outside. Fuel cells have been attracting attention in recent years because environmental problems have become more prominent because they are more efficient and emit less carbon dioxide than other power generation methods.
For example, a polymer electrolyte fuel cell (PEFC) can operate at a low temperature, has a short start-up time, and can be downsized. This polymer electrolyte fuel cell is equipped with a MEA (Membrane Electrode Assembly) having a structure in which a polymer solid electrolyte membrane is sandwiched between an air side electrode and a fuel side electrode, and supplies air (oxygen) to the air side electrode. When a fuel such as methanol or reformed hydrogen is supplied to the side electrode, an electrochemical reaction occurs and electric power is generated (see, for example, Patent Document 1).

JP-A-8-162132

Among such polymer electrolyte fuel cells, the direct methanol fuel cell (DMFC), in particular, directly supplies methanol to the fuel cell as fuel to obtain electric energy. And a reformer for reforming the fuel and taking out hydrogen are not required. Therefore, direct methanol fuel cells are attracting attention as a replacement for conventional primary batteries and secondary batteries as portable power sources for portable devices such as mobile phones and laptop computers that need to be used continuously for a long time. ing.
However, in the fuel cell, water is generated by the reaction between oxygen and protons at the air side (cathode side) electrode. Normally, this water is normally released into the atmosphere in the form of water vapor, but when this fuel cell is used in a portable device, for example, there is a possibility that a large amount of water vapor causes problems such as wet clothes and heels. There is sex. Further, in cold regions, the water produced may freeze and the fuel cell may not operate well, so there are problems in handling such as careful handling at night.

  An object of the present invention is to provide a fuel cell system capable of improving the handleability and a device including the fuel cell system.

The fuel cell system of the present invention has an electrolyte membrane, an anode side reaction chamber, and a cathode side reaction chamber, supplies a fuel to the anode side reaction chamber to obtain electric energy, and is supplied to the fuel cell system. The fuel storage means for storing the fuel to be stored, the water storage means for storing the water supplied to the fuel cell system, and the communication pipe that communicates the cathode side reaction chamber and the water storage means. .
According to the present invention, the fuel reacts in the anode side reaction chamber of the fuel cell to generate protons and electrons. Protons pass through the electrolyte membrane and move to the cathode side reaction chamber, thereby generating electric energy at both ends of the electrolyte membrane. On the other hand, in the cathode side reaction chamber of the fuel cell, oxygen contained in air or the like reacts with protons that have permeated through the electrolyte membrane to generate water. Here, the cathode side reaction chamber of the fuel cell is provided with a communication pipe communicating with the water storage means, so that the water generated in the cathode side reaction chamber is accumulated in the water storage means through this communication pipe. The This water is supplied again to the fuel cell for reuse.

Since water generated in the cathode side reaction chamber is stored in the water storage means, a large amount of water vapor or water does not leak outside the fuel cell system. Therefore, for example, even when the fuel cell system is applied to a portable device, problems such as wetting of clothes are prevented, so the applicable range of the fuel cell system is widened. Further, for example, even when the fuel cell system is used in a cold region, problems such as freezing of water vapor released to the outside are solved, so that the handleability of the fuel cell system is improved.
Further, since the water generated in the cathode side reaction chamber is stored in the water storage means through the communication pipe and reused as the aqueous fuel solution of the fuel cell, the amount of water that must be secured in advance in the water storage means As a result, the water storage means can be reduced in size and weight, and the fuel cell system can be reduced in size and weight.

In the present invention, it is desirable that a holding means for holding water overflowing from the water storage means is provided.
In the fuel cell system, the amount of water generated in the cathode reaction chamber is larger than the amount of fuel consumed. Therefore, if all the generated water is accumulated in the water storage means, the amount of water is reduced. May be excessive.
According to the present invention, since the holding means is provided, the water overflowing from the water storage means is held by the holding means without leaking to the outside, so that the handleability of the fuel cell system is improved. In addition, since the holding means is provided, the water storage means is configured to have a size that can store the amount of water required to be supplied to the fuel cell, and the holding means can store the surplus that cannot be stored in the water storage means. Since it can be held, the size of the water storage means is suppressed to the minimum necessary, and the downsizing of the water storage means is promoted.

In the present invention, it is desirable that the holding means includes a gel-like absorber that absorbs and holds water.
According to this invention, since the holding means includes the gel-like absorber, the water overflowing from the water storage means is reliably held by the gel-like absorber. Thereby, water leakage from the fuel cell system is surely prevented, the handleability of the fuel cell system is improved, and the reliability of the fuel cell system is improved.

In the present invention, it is desirable that the holding means includes a gel-like absorber that absorbs and holds water and a transpiration body that evaporates at least a part of the water into the atmosphere.
According to this invention, since the holding means is configured to include the gel absorber and the transpiration body, the water overflowing from the water storage means can be absorbed by the gel absorber so that the water from the fuel cell can be absorbed. Leakage is prevented and at least a portion of the water is evaporated to the atmosphere by the vaporizer, thus reducing the weight of the fuel cell system. In this case, since a part of the water is temporarily held by the transpiration body and is evaporated to the atmosphere, excessive water is not evaporated, and even when this fuel cell system is applied to a portable device, for example. Problems such as wetting clothes are prevented.

A device according to the present invention includes the above-described fuel cell system.
According to this invention, since the device includes the above-described fuel cell system, the same effect as that of the above-described fuel cell system can be obtained, and the handling property can be improved. In particular, when the device is a portable device, it is useful because water generated by the fuel cell leaks to the outside and inconveniences such as wetting of the user's clothes are eliminated.

  According to the fuel cell system and apparatus of the present invention, water is processed by accumulating water generated in the cathode side reaction chamber in the water storage means, so that a large amount of water is not released from the fuel cell. The effect that the handleability of a battery system can be improved is acquired.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a fuel cell system 100 according to an embodiment of the present invention. In FIG. 1, a fuel cell system 100 includes a fuel cell 1, a methanol tank (fuel storage means) 101 that stores methanol (fuel) supplied to the fuel cell 1, a fuel cell 1, and methanol A pure water tank (water storage means) 102 for storing pure water (water) to be diluted to a predetermined concentration and used for the reaction in the fuel cell 1, a methanol pump 103 for feeding methanol from the methanol tank 101, A pure water pump 104 for sending pure water from the pure water tank 102, a mixer 105 for mixing methanol and pure water and supplying a methanol aqueous solution having a predetermined concentration to the fuel cell 1, and a supply operation for methanol and pure water. A supply control means 106 for controlling and a waste liquid tank 107 as a waste liquid means for storing the waste liquid that has been reacted in the fuel cell 1 are provided.

  FIG. 2 shows a side sectional view of the fuel cell 1. The fuel cell 1 is a direct methanol fuel cell (DMFC). As shown in FIG. 2, the fuel cell 10 is housed in a case 11. In this embodiment, in order to simplify the description, a fuel cell 1 configured by a single fuel cell 10 is illustrated as shown in FIG. 2, but of course, the fuel cell 1 includes the fuel cell 10. A stack structure in which a plurality of sheets are stacked may be used.

The fuel cell 10 is disposed on the side of the anode electrode 3, the polymer solid electrolyte membrane 2 as an electrolyte membrane, the anode electrode 3 and the cathode electrode 4 integrally formed on both surfaces of the polymer solid electrolyte membrane 2. The fuel diffusion layer 5, the air diffusion layer 6 disposed on the cathode electrode 4 side, and the fuel diffusion layer 5 and the air diffusion layer 6 are provided outside the air diffusion layer 6 and generated between the anode electrode 3 and the cathode electrode 4. Current collectors 7 and 8 for taking out the electrical energy. The fuel cell 10 is housed in a case 11 and is sandwiched from both sides of the polymer solid electrolyte membrane 2 by a gasket 12. Thereby, the inside of the case 11 is sealed and separated on the anode electrode 3 side and the cathode electrode 4 side with the polymer solid electrolyte membrane 2 interposed therebetween.
That is, the region between the inner wall of the case 11 and the anode electrode 3 is liquid-tight and serves as a fuel chamber 31 as an anode-side reaction chamber to which fuel is supplied. A region between the inner wall of the case 11 and the cathode electrode 4 is an air chamber 41 as a cathode side reaction chamber to which air is supplied. Note that a methanol (CH ₃ OH) aqueous solution is supplied as the fuel.

  On the anode electrode 3 side of the case 11, a fuel supply port 111 for supplying fuel to the fuel chamber 31 and a fuel discharge port 112 for discharging the fuel that has finished the reaction at the anode electrode 3 to the outside are formed. Has been. An air supply port 113 for supplying air to the air chamber 41 is formed on the case 11 on the cathode electrode 4 side. The air supply port 113 may have a structure in which the air supply to the air chamber 41 is a natural intake by being opened to the atmosphere, and air is forcibly supplied to the air chamber 41 by an air pump or the like. It may be a structure. In addition, on the cathode electrode 4 side of the case 11, a generated water discharge port 114 is formed for recovering water generated by the reaction at the cathode electrode 4. The product water discharge port 114 is connected to a recirculation pipe 108 (see FIG. 1) as a communication pipe through which the collected water flows, and the recirculation pipe 108 is connected to the pure water tank 102. Thus, the air chamber 41 and the pure water tank 102 communicate with each other.

  A substantially rectangular anode electrode 3 and cathode electrode 4 are integrally formed on both surfaces of the polymer solid electrolyte membrane 2 within a predetermined range separated by a predetermined width from the outer edge. The solid polymer electrolyte membrane 2 is formed by impregnating a porous solid portion of a stretched porous polytetrafluoroethylene (PTFE) film with a solid polymer electrolyte resin composed of a proton conductive polymer. It is configured. As the polymer solid electrolyte resin, for example, a perfluorosulfonic acid polymer such as Nafion (trademark of DuPont), a fluorine polymer, a hydrocarbon polymer, or the like can be employed. In some cases, a catalyst such as platinum, carbon powder, various ceramic powders and the like may be added to the solid polymer electrolyte resin as long as electronic conductivity does not occur.

  In addition, a stretched porous polytetrafluoroethylene (PTFE) film is obtained by stretching and porous PTFE lumps, and is a microscopic structure that connects many micronodules and three-dimensionally connects the micronodules. It is a porous PTFE film having a structure composed of fibers, and a large number of holes penetrating in the thickness direction are formed in this film. In the present embodiment, the stretched porous PTFE film has a thickness of 1 to 100 μm, preferably 3 to 30 μm, a pore diameter of 0.05 to 5 μm, preferably 0.5 to 2 μm, and a porosity of 60% to 98. %, Preferably 80 to 92%. If the film thickness is too thin, short circuits and gas leaks (cross leaks) are likely to occur, and if it is too thick, the electrical resistance increases. If the pore size is too small, it is difficult to impregnate the polymer solid electrolyte resin. If it is too large, the holding power of the polymer solid electrolyte resin is weakened, and the reinforcing effect is also weakened. If the porosity is too small, the resistance of the polymer solid electrolyte membrane is increased. If it is too large, the strength of PTFE itself is generally weakened and a reinforcing effect cannot be obtained.

The anode electrode 3 and the cathode electrode 4 are composed of a carbon catalyst electrode film carrying a catalyst for decomposing methanol. As a catalyst, platinum etc. are employable, for example. On the anode electrode 3 side, in order to prevent poisoning of carbon monoxide CO, which is an intermediate product generated by the reaction between methanol and the catalyst, at least the catalyst on the anode electrode 3 side includes an alloy of platinum and ruthenium, etc. Is more preferable.
Here, the polymer solid electrolyte membrane 2, the anode electrode 3, and the cathode electrode 4 are integrally formed to form a membrane electrode assembly 20.
The fuel diffusion layer 5 and the air diffusion layer 6 are porous membranes made of mesh metal foam (for example, steel wool) and diffuse the supplied fuel and oxygen to the anode electrode 3 and the cathode electrode 4, respectively. The fuel diffusion layer 5 and the air diffusion layer 6 may be made of aluminum, stainless steel or the like, respectively, a porous metal material such as sponge titanium, carbon paper supported on carbon, carbon cloth, or the like. It may be.
Further, lead wires (not shown) are connected to the current collectors 7 and 8, respectively, and are connected to an external load.

The methanol tank 101 and the pure water tank 102 include valves 101A and 102A that can open and close the flow path to the fuel chamber 31. These valves 101A and 102A are electrically connected to the supply control means 106, can be individually opened and closed by commands from the supply control means 106, and their opening degrees can also be adjusted. The methanol tank 101 and the pure water tank 102 are preferably configured so that the interior of the integral case is partitioned. For example, the methanol tank 101 and the pure water tank 102 can be easily and simultaneously formed in a so-called cartridge system. A replaceable structure is desirable.
FIG. 3 shows a schematic diagram of the methanol tank 101 and the pure water tank 102. In FIG. 3, the methanol tank 101 and the pure water tank 102 are integrally formed, and pipes communicating with the methanol pump 103 and the pure water pump 104 are connected to each other. In addition, a recirculation pipe 108 communicating with the air chamber 41 is connected to the pure water tank 102. The water generated in the air chamber 41 is stored in the pure water tank 102 by the recirculation pipe 108.

The pure water tank 102 is formed with a capacity capable of storing an amount of water necessary for the reaction in the fuel cell 1 with respect to the amount of methanol in the methanol tank 101. The pure water tank 102 is provided with an absorption pad 9 as a holding means for absorbing and holding water overflowing from the pure water tank 102.
The absorbent pad 9 is integrally configured by laminating a transpiration layer 91 as a transpiration body and an absorption layer 92 as an absorber. The transpiration layer 91 is disposed adjacent to the pure water tank 102, that is, in contact with one side surface of the pure water tank 102, and is made of an arbitrary material capable of retaining moisture. The transpiration layer 91 is provided with a pipe 93 communicating with the pure water tank 102. When excess water overflowing from the pure water tank 102 flows into the transpiration layer 91 through the pipe 93, the transpiration layer 91 is provided. Keeps this water temporarily inside and transcribes it from the surface to the atmosphere. Therefore, it is desirable that the transpiration layer 91 is disposed so as to face the atmosphere. For example, when the entire fuel cell system 100 is accommodated in the case, the case is provided with a plurality of vents and the transpiration layer 91 is ventilated. What is necessary is just to arrange | position facing a mouth. Further, the transpiration layer 91 is desirably configured to have a large surface area in order to increase the transpiration efficiency. ), The transpiration layer 91 protrudes around the pure water tank 102 to increase the transpiration area.

  The absorption layer 92 is a gel-like absorber made of an arbitrary material such as a polymer absorber, for example, absorbs moisture that cannot be absorbed and evaporated by the evaporation layer 91 and holds it inside. The dimensions of the absorption layer 92 are preferably formed in a plate shape (sheet shape) having the same area as the transpiration layer 91, and the amount of water generated in the air chamber 41, the amount of water that can be transpiration in the transpiration layer 91, etc. It is desirable to set as appropriate in consideration.

The methanol pump 103 and the pure water pump 104 are connected to the mixer 105, and send predetermined amounts of methanol and pure water from the methanol tank 101 and the pure water tank 102 to the mixer 105, respectively. These pumps 103, 104 are electrically connected to the supply control means 106, and ON / OFF of the pumps 103, 104 is controlled by a liquid feed command signal from the supply control means 106.
The mixer 105 is connected to the fuel supply port 111 and mixes methanol from the methanol tank 101 and pure water from the pure water tank 102 based on a mixing command signal from the supply control means 106, and the methanol is pure. This is a mixing means for preparing an aqueous methanol solution uniformly dispersed in water. When only methanol or pure water is supplied to the fuel chamber 31, the mixer 105 only mixes one type of liquid, and the liquid passes substantially without performing its function. Become.
Here, in this embodiment, a methanol supply means is configured by including the methanol tank 101, the valve 101A, and the methanol pump 103, and a water supply means is provided by having the pure water tank 102, the valve 102A, and the pure water pump 104. Is configured.

The supply control means 106 controls the supply amounts of methanol and water so as to maintain the concentration of the aqueous methanol solution in the fuel chamber 31 within a predetermined range set in advance. As the control of the supply amount of methanol and water, specifically, for example, a system in which a methanol aqueous solution having a concentration within a predetermined range is constantly supplied to the fuel chamber 31 by a constant amount to circulate the methanol aqueous solution in the fuel chamber 31, Further, a fuel cell system 100 such as a system in which methanol concentration detection means for detecting the concentration of the methanol aqueous solution in the fuel chamber 31 is provided and the concentration of the methanol aqueous solution supplied based on the detection signal from the methanol concentration detection means is adjusted. What is necessary is just to set suitably according to the use and specification.
Here, the predetermined range of the concentration of the methanol aqueous solution is set in a range in which the reaction efficiency between methanol and the catalyst in the fuel chamber 31 is good and the crossover of the polymer solid electrolyte membrane 2 is well prevented. It is preferably set in consideration of the capacity of the fuel cell 1, the material of the polymer solid electrolyte membrane 2, the performance, etc., for example, within the range of 3% to 5% or 1 mol / l to 8 mol / l. .

  The waste liquid tank 107 is connected to the fuel discharge port 112 and stores the waste liquid discharged from the fuel chamber 31. The waste liquid tank 107 may be provided separately from the methanol tank 101 and the pure water tank 102 so as to be individually replaceable. Further, it may be formed integrally with the methanol tank 101 and the pure water tank 102. In this case, when the methanol tank 101 and the pure water tank 102 are replaced by using up the methanol or pure water in the methanol tank 101 and the pure water tank 102, the waste liquid tank 107 can be replaced at the same time. Simple and easy to handle.

Next, the operation of the fuel cell system 100 will be described.
First, when the fuel cell system 100 is activated, the methanol aqueous solution is filled in the fuel chamber 31 by an initial methanol aqueous solution supply command output from the supply control means 106. In response to this command signal, the valves 101A and 102A are opened, and methanol and pure water are fed, respectively. At this time, the opening degree of the valves 101A and 102A is set in advance so that the concentration of the methanol aqueous solution is within a predetermined range. Methanol and pure water are sent to the mixer 105 by the methanol pump 103 and the pure water pump 104, mixed uniformly by the mixer 105, and then supplied to the fuel chamber 31.

In the fuel chamber 31, the methanol aqueous solution causes an oxidation reaction of the following formula (1) by the catalyst of the anode electrode 3, and this reaction generates carbon dioxide CO ₂ , protons H ^+, and electrons e ⁻ .
CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ (1)
Proton H ⁺ passes through the polymer solid electrolyte membrane 2 and moves to the cathode electrode 4 side, whereby a voltage is generated across the current collectors 7 and 8. When the proton H ⁺ reaches the cathode electrode 4 side, electrons e ⁻ that have reached the cathode electrode 4 after working through an external load and oxygen O ₂ in the air in the air chamber 41 are combined into the cathode electrode 4. The reduction reaction of Formula (2) occurs by reacting with a catalyst.
3 / 2O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O (2)
Carbon dioxide CO ₂ produced on the anode electrode 3 side, and by-products such as formic acid, formaldehyde, carbon monoxide, etc. produced by the reaction of methanol and water are used as waste liquid together with the finished liquid. It is stored in the tank 107. Further, the water generated on the cathode electrode 4 side is stored in the pure water tank 102 through the recirculation pipe 108. The stored water is sent again by the pure water pump 104 and used to dilute methanol into a methanol aqueous solution having a predetermined concentration.

As can be seen from the above formulas (1) and (2), 3 mol of water is generated in the air chamber 41 with respect to 1 mol of methanol and pure water. Therefore, as the fuel cell system 100 is used, the water in the pure water tank 102 increases and becomes excessive. When the excess water overflows from the pure water tank 102, the excess water is supplied to the transpiration layer 91 of the absorption pad 9 through the pipe 93. Water from the pipe 93 is diffused over the entire surface of the transpiration layer 91, temporarily held in the transpiration layer 91, and transpiration from the surface of the transpiration layer 91 into the atmosphere by a certain amount.
Further, a further excessive amount of water that cannot be held and evaporated in the transpiration layer 91 moves from the transpiration layer 91 to the absorption layer 92 and is absorbed and held in the absorption layer 92.
When the methanol in the methanol tank 101 runs out, methanol and pure water may be added to the methanol tank 101 and the pure water tank 102, respectively, or the methanol tank 101 and the pure water tank 102 may be replaced. Similarly, when a predetermined amount or more of waste liquid is stored in the waste liquid tank 107, the waste liquid in the waste liquid tank 107 may be discarded or the whole waste liquid tank 107 may be replaced.
The absorption pad 9 may be replaced when a predetermined amount or more of water is absorbed. When the absorption pad 9 is provided integrally with the methanol tank 101 and the pure water tank 102, the methanol tank 101 and the pure water are used. When the tank 102 is replaced, the absorbent pad 9 may be replaced. At this time, the absorption capacity and the transpiration capacity of the absorption pad 9 are set in consideration of the amount of water generated when the methanol in the methanol tank 101 reacts in the fuel cell 1 according to the amount of methanol in the methanol tank 101. It is desirable that

According to this embodiment, the following effects can be obtained.
(1) Since the air chamber 41 and the pure water tank 102 are communicated with each other by the recirculation pipe 108, the water generated in the air chamber 41 can be stored in the pure water tank 102. Therefore, a large amount of water generated in the air chamber 41 does not leak to the outside of the fuel cell system 100, and the handleability of the fuel cell system 100 can be improved. This is particularly useful in the case where the fuel cell system 100 is used for a portable device and the like because it can prevent the clothes and the like from being wetted by the generated water. Further, since a large amount of water can be prevented from leaking outside the fuel cell system 100, the fuel cell 1 can be reliably prevented from freezing even when used in a cold region, thereby improving the handleability of the fuel cell system 100. In addition, the range of application of the fuel cell system 100 to equipment can be widened.

 (2) Since the recirculation pipe 108 is provided, the water generated in the air chamber 41 can be stored in the pure water tank 102 so that the water can be reused as water for diluting methanol. Accordingly, the amount of water stored in the pure water tank 102 in advance can be reduced, and the downsizing of the pure water tank 102 can be promoted. Therefore, the fuel cell system 100 can be reduced in size and weight.

 (3) Since the excess water overflowing from the pure water tank 102 is absorbed by the absorption pad 9, only the pure water for use in the fuel cell 1 can be stored in the pure water tank 102. Capacity can be minimized. Accordingly, it is possible to promote the miniaturization of the pure water tank 102 and the miniaturization of the fuel cell system 100.

(4) Since the absorption pad 9 includes the transpiration layer 91, a part of the excess water overflowing from the pure water tank 102 can be transpiration to the atmosphere. Therefore, it is not necessary to hold the entire amount of water generated in the air chamber 41 in the fuel cell system 100, and the weight reduction of the fuel cell system 100 can be promoted. In this case, the transpiration layer 91 temporarily holds water and transcribes a certain amount of the transpiration, so that the transpiration amount can be adjusted, and problems such as wetting the outside of the fuel cell system 100 can be favorably avoided.
Moreover, since the absorption pad 9 is provided with the absorption layer 92 comprised with a gel-like absorber, the moisture which cannot be hold | maintained by the evaporating layer 91 and cannot be evaporated can be absorbed and hold | maintained by the absorption layer 92. FIG. Therefore, the absorption of moisture by the absorption pad 9 can be more reliably performed, and the transpiration amount of the transpiration layer 91 can be maintained at an appropriate amount without being excessive.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
When the holding means is configured by laminating a transpiration body and an absorber, the transpiration body is not limited to the one adjacent to or in contact with the water storage means. For example, the absorption body is adjacent to the water storage means, It may be touched. In this case, a pipe that communicates with the water storage means is provided on the opposite side of the evaporation body across the absorber from the water storage means so that the water overflowing from the water storage means is supplied to the evaporation body. Good. Even in this case, if the transpiration body is disposed opposite to the atmosphere side, the transpiration of moisture from the transpiration body can be promoted. Further, since the transpiration body is not sandwiched between the water storage means and the absorber, the facing area to the atmosphere is increased, and the transpiration efficiency is improved.
The holding means may not necessarily be provided with a transpiration body. For example, the holding means may be provided with only an absorber, and the absorber may absorb and hold the entire amount of water overflowing from the water storage means. Good.
The holding means is not necessarily required. For example, if the storage capacity of the water storage means is set in consideration of the amount of water generated in the cathode reaction chamber, the entire amount of water is stored in the water storage means through the recirculation pipe. Therefore, it is not necessary to provide holding means.

  When the holding means includes a transpiration body, a heating means for heating the transpiration body may be provided to promote the transpiration of water from the transpiration body. In this case, as the heating means, for example, a heating element provided in the vicinity of the vaporizer may be used, or the amount of heat generated in the fuel cell may be used within a range in which the reaction efficiency of the fuel cell can be satisfactorily maintained. Moreover, as a transpiration | evaporation acceleration | stimulation means which promotes transpiration | evaporation of a transpiration | evaporation body, you may provide a ventilation means other than what provides a heating means, for example.

The water stored in the water storage means by the communication pipe is used for diluting the fuel of the fuel cell to create an aqueous solution, for example, sending a small amount of water together with air to the cathode reaction chamber to bring the electrolyte membrane to an appropriate humidity. It may be used to hold.
Alternatively, the water stored in the water storage means by the communication pipe is supplied to the reformer, for example, in the case where the fuel cell system has a reformer in addition to the use of preparing an aqueous solution of the fuel supplied to the fuel cell. You may use for the use which produces the aqueous solution of the fuel which is.
The fuel is not limited to methanol, and any material supplied to the fuel cell in the form of an aqueous solution can be adopted. In addition, when the fuel cell system includes a reformer, any material such as an organic fuel such as decalin or a borohydride fuel such as sodium borohydride is used as the fuel in addition to an alcohol fuel such as methanol. Has been.
Since the fuel cell system of the present invention can promote downsizing and does not release a large amount of water and has good handling properties, it can be applied to portable devices such as mobile phones and laptop computers, cars, and other arbitrary devices.

The best configuration, method and the like for carrying out the present invention have been disclosed in the above description, but the present invention is not limited to this. That is, the invention has been illustrated and described primarily with respect to particular embodiments, but may be configured for the above-described embodiments without departing from the scope and spirit of the invention. Various modifications can be made by those skilled in the art in terms of materials, quantity, and other detailed configurations.
Therefore, the description limited to the shape, material, etc. disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. The description by the name of the member which remove | excluded the limitation of one part or all of such restrictions is included in this invention.

1 is a schematic configuration diagram showing a fuel cell system according to an embodiment of the present invention. The side sectional view of a fuel cell. The perspective view which shows a water storage means and a holding means.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Polymer solid electrolyte membrane (electrolyte membrane), 3 ... Anode electrode, 4 ... Cathode electrode, 9 ... Absorption pad (holding means), 31 ... Fuel chamber (anode side reaction chamber), 41 ... Air Chamber (cathode side reaction chamber), 91 ... transpiration layer (vaporizer), 92 ... absorption layer (absorber), 100 ... fuel cell system, 101 ... methanol tank (fuel storage means), 102 ... pure water tank (water storage) Means), 108... Recirculation piping (communication piping).

Claims (5)

A fuel cell having an electrolyte membrane, an anode side reaction chamber, and a cathode side reaction chamber, and supplying fuel to the anode side reaction chamber to obtain electric energy;
Fuel storage means for storing fuel supplied to the fuel cell system;
Water storage means for storing water supplied to the fuel cell system;
A fuel cell system comprising: a communication pipe communicating the cathode side reaction chamber and the water storage means. The fuel cell system according to claim 1, wherein
A fuel cell system, wherein holding means for holding water overflowing from the water storage means is provided. The fuel cell system according to claim 2, wherein
The fuel cell system, wherein the holding means includes a gel-like absorber that absorbs and holds water. The fuel cell system according to claim 2 or 3,
The holding means includes an absorber that absorbs and holds water, and a transpiration body that evaporates at least a part of the water to the atmosphere.   An apparatus comprising the fuel cell system according to any one of claims 1 to 4.

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