JP2005317436A - Fuel cell system and equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of simplifying the configuration and lengthening the lifetime, and to provide equipment having the fuel cell system. <P>SOLUTION: A methanol aqueous solution having concentration that is higher than that of an appropriate methanol aqueous solution in a fuel cell 1 is accommodated into a methanol aqueous solution tank 101. When a methanol concentration detection signal from a methanol sensor 104 is less than the lower limit of a prescribed range, the methanol aqueous solution is supplied. The supply of the methanol aqueous solution is stopped when the methanol concentration detection signal becomes larger than the upper limit of the prescribed range. Methanol is accommodated in the methanol aqueous solution tank 101 in the state of an aqueous solution in advance, thus dispensing with a mixing means and hence simplifying the configuration of the fuel cell system 100. Further, the methanol aqueous solution has high concentration, thus lengthening operating time in the fuel cell system 100 to the amount of methanol aqueous solution to be supplied, and lengthening the lifetime of the fuel cell system 100. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system 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, for example, a direct methanol fuel cell (DMFC) is different from PEFC in that it directly supplies methanol aqueous solution 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.

In a fuel cell system equipped with a direct methanol fuel cell, methanol and water are stored in separate tanks, and the concentration of the aqueous methanol solution supplied to the fuel cell is adjusted by adjusting the amount of methanol and water supplied, respectively. Some are adjusted to a predetermined density. However, such a supply method requires a mixing means such as a mixer in order to uniformly disperse methanol in water, which complicates the configuration of the fuel cell system.
In another fuel cell system, a methanol aqueous solution having a concentration suitable for supply to the fuel cell is stored in advance, and the methanol aqueous solution is circulated by always supplying a predetermined amount of the methanol aqueous solution to the fuel cell. There is. However, even in such a fuel cell system, a methanol aqueous solution having a predetermined concentration must be constantly supplied to the fuel cell regardless of the amount of methanol aqueous solution consumed by the fuel cell. The efficiency and life of the fuel cell system cannot be improved.

  An object of the present invention is to provide a fuel cell system capable of simplifying the configuration and promoting a long life, 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, and reacts fuel supplied to the anode side reaction chamber with oxygen supplied to the cathode side reaction chamber. A fuel cell for obtaining energy, a fuel supply means for storing an aqueous solution of fuel supplied to the fuel cell, and supplying an aqueous fuel solution to the anode reaction chamber, and a fuel concentration for detecting the concentration of fuel in the anode reaction chamber And a supply control means for controlling the operation of the fuel supply means based on a concentration detection signal from the fuel concentration detection means. It is characterized by high concentration.
According to this invention, since the aqueous fuel solution is stored in advance in the fuel supply means, the fuel is supplied to the fuel cell in a state of being uniformly dispersed in the aqueous solution. Therefore, the reaction efficiency in the fuel cell becomes good, and the output of the fuel cell is stabilized. In addition, since the fuel is stored in the state of an aqueous solution in advance, a mixing means such as a mixer is not necessary, and the configuration of the fuel cell system is simplified.
Further, since the concentration of the aqueous solution of fuel stored in the fuel supply means is higher than the set concentration of the fuel in the anode side reaction chamber, the operating time of the fuel cell system with respect to the amount of stored aqueous solution of fuel This increases the life of the fuel cell system. On the other hand, since the amount of the aqueous solution of the fuel for a predetermined operation time is reduced, downsizing of the fuel cell system is promoted.

In the present invention, the supply control means supplies an aqueous fuel solution from the fuel supply means to the anode reaction chamber when the concentration detection signal from the fuel concentration detection means is less than the lower limit of the predetermined range. It is desirable that the supply of the aqueous fuel solution from the fuel supply means is stopped when the upper limit of the range is exceeded.
According to the present invention, the supply control means supplies the aqueous solution of the fuel when the fuel concentration in the anode side reaction chamber becomes less than the lower limit of the predetermined range, and stops the supply of the aqueous solution of fuel when it exceeds the upper limit of the predetermined range. The concentration of the aqueous fuel solution in the reaction chamber is maintained within a predetermined range. Therefore, the reaction efficiency of the fuel in the anode side reaction chamber is stabilized, and the output of the fuel cell is stabilized. Further, since the supply control means operates the fuel supply means intermittently, labor saving of the fuel cell system is promoted, and this also promotes the extension of the life of the fuel cell system.

A device according to the present invention includes the above-described fuel cell system.
According to the present 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 configuration of the device can be simplified by simplifying the configuration of the fuel cell system. Simplify. Further, by promoting the labor saving of the fuel cell system, the life of the fuel cell system can be extended and the life of the device can be extended.

  According to the fuel cell system and the device of the present invention, it is possible to simplify the configurations of the fuel cell and the device and to promote the extension of the life.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic diagram of a fuel cell system 100 of the present embodiment. In FIG. 1, a fuel cell system 100 includes a fuel cell 1, a methanol aqueous solution tank (fuel storage means) 101 in which a methanol aqueous solution (fuel aqueous solution) supplied to the fuel cell 1 is stored, A pure water tank 102 in which pure water for adjusting the concentration of the aqueous methanol solution in the fuel cell 1 is stored at the beginning of startup, a pump 103 for feeding the aqueous methanol solution from the aqueous methanol tank 101 and the pure water tank 102, fuel A methanol sensor (fuel concentration detection means) 104 for detecting the methanol concentration of the aqueous methanol solution in the battery 1, a supply control means 105 for controlling the supply operation of the aqueous methanol solution, and the liquid that has finished the reaction in the fuel cell 1 as waste liquid And a waste liquid tank 106 for storing as follows.

  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 solid polymer electrolyte membrane 2 as an electrolyte membrane, the anode electrode 3 and the cathode electrode 4 that are integrally formed on both surfaces of the solid polymer 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. A waste liquid tank 106 is connected to the fuel discharge port 112.
A plurality of air supply ports 113 for supplying air to the air chamber 41 are formed on the cathode electrode 4 side of the case 11. The air supply port 113 has a structure in which the air supply to the air chamber 41 is a natural intake by being opened to the atmosphere. Note that. The air supply to the air chamber 41 may be a structure for forcibly supplying air to the air chamber 41 by an air pump or the like.

  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 a porous PTFE mass to obtain a microscopic structure that connects a number of micronodules and those micronodules that are three-dimensionally connected to each other. 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. Here, platinum etc. are employable as a catalyst, 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 aqueous solution tank 101 stores a methanol aqueous solution having a predetermined concentration, and includes a valve 101A that can open and close the flow path to the fuel chamber 31. This valve 101A is electrically connected to the supply control means 105, can be opened and closed by a command from the supply control means 105, and its opening degree can also be adjusted. It is desirable that the methanol aqueous solution tank 101 is a so-called cartridge type and can be attached to and detached from the fuel cell system 100 and can be easily replaced.
The pure water tank 102 stores a quantity of pure water necessary for starting the fuel cell 1 in order to adjust the concentration of the aqueous methanol solution in the fuel chamber 31 within a predetermined range when the fuel cell 1 is started. The pure water tank 102 includes a valve 102 </ b> A, and a pipe from the pure water tank 102 is connected to a pipe between the methanol aqueous solution tank 101 and the pump 103. Therefore, the pure water can be mixed with the methanol aqueous solution by adjusting the opening of the valve 102A. The valve 102A is electrically connected to the supply control means 105, can be opened and closed by a command from the supply control means 105, and its opening degree can also be adjusted. Note that another pump may be provided between the pure water tank 102 and the valve 102A to positively supply the pure water in the pure water tank 102 to the methanol aqueous solution. Further, like the methanol aqueous solution tank 101, the pure water tank 102 is preferably configured as a so-called cartridge type that can be attached to and detached from the fuel cell system 100, and is formed integrally with the methanol aqueous solution tank 101. It is desirable that When the pure water tank 102 is formed integrally with the methanol aqueous solution tank 101, the replacement operation can be simplified because the pure water tank 102 can be replaced when the methanol aqueous solution tank 101 is replaced.

The pump 103 is electrically connected to the supply control means 105, and ON / OFF of the pump 103 is controlled by a liquid feed command signal from the supply control means 105. In response to this liquid supply command signal, the pump 103 supplies a predetermined amount of aqueous methanol solution to the fuel chamber 31.
Here, in the present embodiment, the fuel supply means is configured to include the methanol aqueous solution tank 101, the valve 101A, and the pump 103.
The methanol sensor 104 is attached to the piping that connects the fuel chamber 31 and the waste liquid tank 106, the methanol concentration of the aqueous methanol solution in the waste liquid discharged from the fuel chamber 31, or filled in the fuel chamber 31. The methanol concentration of the aqueous methanol solution is detected. As this methanol sensor 104, an arbitrary system such as an infrared transmission absorption type optical methanol concentration sensor can be adopted.

The supply control means 105 controls the supply amount of the aqueous methanol solution 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. In other words, the supply control means 105 adjusts the opening degree of the valves 101A and 102A to supply a methanol aqueous solution having a predetermined concentration, and based on the methanol concentration detection signal (fuel concentration detection signal) from the methanol sensor 104, The opening / closing operation and the opening degree of the valve 101A are controlled to control the concentration of the aqueous methanol solution supplied to the fuel chamber 31 within a predetermined concentration range.
Specifically, when the fuel cell system 100 is started, the supply control unit 105 adjusts the valves 101 </ b> A and 102 </ b> A to a preset opening degree so that the fuel cell 1 is filled with a methanol aqueous solution within a predetermined concentration range. During normal operation, on the basis of the methanol concentration detection signal from the methanol sensor 104, when the methanol concentration in the fuel chamber 31 is less than the lower limit of the predetermined concentration range, the valve 101A is opened and the methanol concentration is set to the predetermined concentration. When it is larger than the upper limit of the range, the valve 101A is closed.
Here, the predetermined range of the concentration of the methanol aqueous solution in the fuel chamber 31 is good in the reaction efficiency between methanol and the catalyst in the fuel chamber 31 and the crossover of the polymer solid electrolyte membrane 2 is well prevented. It is preferably set in a range, and is set as appropriate in consideration of the capacity of the fuel cell 1, the material of the polymer solid electrolyte membrane 2, the performance, etc., for example, in the range of 3% to 5% or 1 mol / l to 8 mol / l. Set within. The concentration of the methanol aqueous solution stored in the methanol aqueous solution tank 101 is set between 1% and 50%, and is set higher than the lower limit of the predetermined range of the methanol aqueous solution concentration in the fuel chamber 31. .

  The waste liquid tank 106 is connected to the fuel discharge port 112 and stores the waste liquid discharged from the fuel chamber 31. The waste liquid tank 106 may be provided separately from the methanol aqueous solution tank 101 and the pure water tank 102 so as to be individually replaceable. Further, it may be formed integrally with the methanol aqueous solution tank 101 and the pure water tank 102. In this case, when the methanol aqueous solution tank 101 and the pure water tank 102 are replaced by using up the methanol aqueous solution or pure water in the methanol aqueous solution tank 101 and the pure water tank 102, the waste liquid tank 106 can be replaced at the same time. The exchange operation is simple and handling is improved.

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 105. At this time, since the methanol aqueous solution in the methanol aqueous solution tank 101 has a higher concentration than the appropriate concentration supplied to the fuel chamber 31, it is necessary to dilute with pure water to an appropriate concentration. Therefore, the supply control means 105 adjusts the valves 101A and 102A to a preset opening degree by a methanol aqueous solution supply command signal, and drives the pump 103 to send the methanol aqueous solution and pure water at a predetermined ratio. As a result, the methanol aqueous solution and the pure water are uniformly mixed to have a concentration within a predetermined range, and are supplied to the fuel chamber 31 by the pump 103. When a predetermined amount of aqueous methanol solution is supplied to the fuel chamber 31, the supply control means 105 closes the valves 101A and 102A and stops the pump 103. Note that the amount of aqueous methanol solution supplied to the fuel chamber 31 is determined by measuring the flow rate of the aqueous methanol solution supplied to the fuel chamber 31 and the liquid feed speed of the pump 103 in advance, and after a predetermined time has passed. Any method such as a method of stopping the liquid can be adopted.

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, the proton H ⁺ and the electron e ⁻ that has reached the cathode electrode 4 after working through an external load are air in the air chamber 41 by the catalyst of the cathode electrode 4. It reacts with the oxygen O ₂ in it to produce a reduction reaction of formula (2).
3 / 2O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O (2)
The solution that has been reacted on the anode electrode 3 side is stored in the waste liquid tank 106 as a waste liquid. Moreover, the water produced | generated by the cathode electrode 4 side is open | released by the air through the air supply port 113 in the state of water vapor | steam.

As the reaction in the fuel chamber 31 proceeds, the methanol in the aqueous methanol solution is consumed and the water becomes rich. The methanol sensor 104 detects the methanol concentration of the aqueous methanol solution in the fuel chamber 31 and transmits it to the supply control means 105. The supply control means 105 monitors the methanol concentration detection signal from the methanol sensor 104, and outputs a liquid feed command signal to the valve 101A and the pump 103 when the methanol concentration falls below a predetermined range lower limit. In response to the liquid supply command signal, the valve 101A is opened and the pump 103 is driven to supply a high-concentration aqueous methanol solution from the aqueous methanol solution tank 101 to the fuel chamber 31.
The supply control means 105 monitors the methanol concentration detection signal from the methanol sensor 104 even during the aqueous methanol solution supply, and outputs a liquid feed stop command signal to the valve 101A and the pump 103 when the methanol concentration exceeds the predetermined range upper limit. . In response to this liquid supply stop command signal, the valve 101A is closed, the pump 103 is stopped, and the liquid supply of the methanol aqueous solution is stopped.
During the normal operation of the fuel cell system 100, the above operations are repeated.

  When the methanol aqueous solution in the methanol aqueous solution tank 101 is exhausted, the methanol aqueous solution tank 101 may be added or the methanol aqueous solution tank 101 may be replaced. At this time, when the pure water tank 102 is provided integrally with the methanol aqueous solution tank 101, the pure water tank 102 may be replaced simultaneously with the replacement of the methanol aqueous solution tank 101. Similarly, when a predetermined amount or more of waste liquid is stored in the waste liquid tank 106, the waste liquid in the waste liquid tank 106 may be discarded or replaced together.

According to this embodiment, the following effects can be obtained.
(1) Since a methanol aqueous solution having a predetermined concentration is stored in advance in the methanol aqueous solution tank 101, the methanol can be supplied to the fuel chamber 31 in a state in which methanol is dispersed to some extent. Therefore, methanol can be uniformly dispersed in the fuel chamber 31, and the reaction efficiency at the anode electrode 3 can be improved. Therefore, the output of the fuel cell 1 can be stabilized, and the operation of the fuel cell system 100 can be stabilized.
In addition, since the methanol aqueous solution is stored in advance in the methanol aqueous solution tank 101, it is not necessary to mix and supply methanol and pure water during normal operation, and a mixing means such as a mixer becomes unnecessary. Therefore, the configuration of the fuel cell system 100 can be simplified and the manufacturing cost can be reduced. Since the configuration of the fuel cell system 100 is simplified, the configuration of control by the supply control unit 105 is also simplified, so that labor saving of the fuel cell system 100 can be promoted.
Further, since the methanol aqueous solution tank 101 stores the high concentration methanol aqueous solution, the operating time of the fuel cell 1 can be extended with respect to the amount of the methanol aqueous solution in the methanol aqueous solution tank 101. Therefore, the life extension of the fuel cell system 100 can be promoted.

 (2) Since the methanol concentration of the methanol aqueous solution stored in the methanol aqueous solution tank 101 is set higher than the lower limit of the predetermined concentration range in the fuel chamber 31, by supplying the methanol aqueous solution intermittently, The aqueous methanol solution in the fuel chamber 31 can be maintained within a predetermined concentration range. Therefore, since it is not necessary to continuously operate the pump 103 and the valve 101A, the power consumption of the fuel cell system 100 can be reduced, and the labor saving of the fuel cell system 100 can also be promoted.

 (3) During normal operation of the fuel cell system 100, since a high-concentration aqueous methanol solution is supplied from the aqueous methanol solution tank 101, pure water for diluting the aqueous methanol solution becomes unnecessary. Therefore, since the amount of pure water stored in the pure water tank 102 can be suppressed to only the amount necessary when the fuel cell system 100 is started, the size and weight of the pure water tank 102 can be promoted.

(4) Based on the methanol concentration detection signal from the methanol sensor 104, the supply control means 105 opens the valve 101A when the methanol concentration is less than the predetermined range lower limit, and closes the valve 101A when the methanol concentration is greater than the predetermined range upper limit. Thus, the concentration of the methanol aqueous solution in the fuel chamber 31 can be controlled within a predetermined range. Therefore, the reaction efficiency in the fuel chamber 31 can be stabilized, and a stable power generation amount can be obtained from the fuel cell 1.
Further, since the supply control means 105 supplies the methanol aqueous solution when the methanol concentration of the aqueous methanol solution in the fuel chamber 31 is less than the predetermined range lower limit and exceeds the predetermined range upper limit, the supply of the methanol aqueous solution is stopped. The methanol concentration in the fuel chamber 31 can be controlled. Therefore, it is possible to prevent the pump 103 and the valve 101A from being frequently turned on and off, thereby reducing the power consumption of the fuel cell system 100 and promoting labor saving.

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.
The supply control means is not limited to the control that supplies the aqueous solution of the fuel when the methanol concentration becomes lower than the lower limit of the predetermined range and stops the supply when the methanol concentration becomes higher than the upper limit of the predetermined range. The supply control means 105 may include a calculation means for calculating the opening degree of the valve 101A based on the methanol concentration detection signal. In this case, the calculation means calculates the opening degree of the valve 101A and the driving time (liquid feeding time) of the pump 103 from the methanol concentration detection signal, and the supply control means 105 calculates the valve 101A and the pump 103 based on the calculation result. Can be controlled. According to such a configuration, since the timing of stopping the supply of the methanol aqueous solution is known in advance by the arithmetic means, it is not necessary to monitor the methanol concentration with the methanol sensor 104 during the supply of the methanol aqueous solution, and further labor saving can be achieved. .

Further, the supply control unit may include a storage unit that stores, for example, an appropriate fuel supply amount with respect to the fuel concentration detection signal (the opening degree of the valve 101A in the above-described embodiment) as a table or a map. In this case, the supply control means may read the fuel supply amount (valve opening) corresponding to the detected fuel concentration detection signal with a table or the like stored in the storage means and control the fuel supply amount. . In this case, since the fuel supply amount with respect to the fuel concentration detection signal is stored in advance in the storage means, it is not necessary to perform calculation or the like by the supply control means, the control is simplified, and labor saving of the fuel cell system 100 is achieved. Can promote.
Furthermore, the supply control means is not limited to intermittently supplying the methanol aqueous solution to the anode side reaction chamber, and for example, continuously supplies the methanol aqueous solution and controls the supply amount continuously or intermittently. May be.
The concentration detection by the fuel concentration detection means is not limited to being performed continuously, but may be detected, for example, every predetermined time. With this configuration, it is possible to save electric power necessary for detecting the fuel concentration, so that labor saving can be promoted.

The concentration of the aqueous methanol solution supplied to the fuel cell is not limited to the case where the concentration is set higher than the lower limit of the predetermined range, and may be set higher than the upper limit of the predetermined range. It is only necessary to set the concentration higher than the appropriate concentration of the aqueous solution.
The pump is not always necessary. For example, when the fuel in the fuel cell is consumed, the volume is reduced and the pressure in the fuel cell becomes negative. May be supplied.

When the fuel is methanol, a gas-liquid separation membrane for separating carbon dioxide generated after the reaction between methanol and water may be provided outside the anode side reaction chamber. In this case, carbon dioxide generated by the reaction in the anode side reaction chamber is separated by the gas-liquid separation membrane and discharged to the outside, so that it is possible to reliably prevent carbon dioxide from staying in the anode side reaction chamber. . In addition, since the carbon dioxide in the anode side reaction chamber is removed by the gas-liquid separation membrane, the fuel comes into good contact with the catalyst in the anode side reaction chamber, so that the reaction efficiency of the fuel cell can be improved.
The fuel is not limited to methanol, and any material can be adopted. In addition, when the fuel cell system includes a reformer, any material such as organic hydride fuel such as decalin or borohydride fuel such as sodium borohydride is adopted as the fuel, in addition to alcohol fuel such as methanol. Has been.
Since the fuel cell system of the present invention can promote weight reduction and downsizing, it can be applied to portable devices such as mobile phones and notebook 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 view showing a fuel cell system according to an embodiment of the present invention. The side sectional view of a fuel cell.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Polymer solid electrolyte membrane (electrolyte membrane), 3 ... Anode electrode, 4 ... Cathode electrode, 31 ... Fuel chamber (anode side reaction chamber), 41 ... Air chamber (cathode side reaction chamber), 100 DESCRIPTION OF SYMBOLS ... Fuel cell system, 101 ... Methanol aqueous solution tank, 102 ... Pure water tank, 104 ... Methanol sensor (fuel concentration detection means), 105 ... Supply control means.

Claims (3)

A fuel cell having an electrolyte membrane, an anode-side reaction chamber, and a cathode-side reaction chamber, and obtaining electric energy by reacting a fuel supplied to the anode-side reaction chamber and oxygen supplied to the cathode-side reaction chamber; ,
A fuel supply means for storing an aqueous solution of the fuel supplied to the fuel cell and supplying the aqueous solution of the fuel to the anode reaction chamber;
Fuel concentration detection means for detecting the concentration of the fuel in the anode reaction chamber;
Supply control means for controlling the operation of the fuel supply means based on a concentration detection signal from the fuel concentration detection means,
The concentration of the aqueous solution of the fuel is higher than the set concentration of the fuel in the anode-side reaction chamber. The fuel cell system according to claim 1, wherein
The supply control means supplies the aqueous solution of the fuel from the fuel supply means to the anode reaction chamber when the concentration detection signal from the fuel concentration detection means is less than a predetermined range lower limit, and the concentration detection signal The fuel cell system is configured to stop the supply of the aqueous solution of the fuel from the fuel supply means when the value exceeds a predetermined range upper limit. An apparatus comprising the fuel cell system according to claim 1.

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