JP2006114340A - Fuel cell and its operation method - Google Patents

Abstract

The fuel cell operating efficiency is improved by controlling the fuel supply to the anode or the oxidant supply to the cathode with high accuracy.
An anode, a fuel supply plate for supplying a fluid containing fuel to the anode, a cathode, an oxidant supply plate for supplying a fluid containing an oxidant to the cathode, and an electrolyte interposed between the anode and the cathode. In the method of operating a fuel cell, at least one selected from a fuel supply plate and an oxidant supply plate is divided into a plurality of reaction chambers, and each reaction chamber has an inlet for a fluid containing fuel or oxidant, and a fuel or oxidizer. An outlet for a fluid containing an agent, a supply pump for supplying a fluid containing a fuel or an oxidant to the reaction chamber at the inlet, and a reaction chamber for a fluid containing a fuel or an oxidant at the outlet An operation method in which a discharge valve is provided to prevent backflow into the pump and the supply pump is driven with an arbitrary pulse pattern.
[Selection] Figure 11

Description

  The present invention relates to a fuel cell and a method for operating the same. Specifically, at least one selected from a fuel supply plate and an oxidant supply plate is composed of a plurality of reaction chambers, and each reaction chamber contains a fluid containing a fuel or an oxidant. The present invention relates to a method of operating a fuel cell having a supply pump for transferring and a discharge valve.

  A fuel cell generates electric energy by electrochemically reacting a fuel and an oxidant gas. The fuel cell includes an anode, a fuel supply plate that supplies fuel to the anode, a cathode, an oxidant supply plate that supplies oxidant to the cathode, and an electrolyte interposed between the anode and the cathode. As the electrolyte interposed between the anode and the cathode, a polymer electrolyte is the mainstream. In particular, a polymer electrolyte made of perfluorocarbon sulfonic acid has attracted attention.

  FIG. 1 shows a structure of a main part of a general fuel cell. The anode and cathode that sandwich the electrolyte 11 are generally composed of a diffusion electrode 14. The diffusion electrode 14 includes a catalytic reaction layer 12 in contact with an electrolyte and a diffusion layer 13 that supports the catalyst reaction layer 12. The catalytic reaction layer 12 is mainly composed of carbon powder supporting a noble metal catalyst. For the diffusion layer 13, a base material having both air permeability and conductivity, such as carbon paper, is used. A combination of the electrolyte 11 and the anode and cathode sandwiching the electrolyte 11 is referred to as MEA (Membrane Electrode Assembly) 15.

  A fluid supply plate 17 that supplies fuel or an oxidant to the diffusion electrode 14 is disposed outside the diffusion electrode 14. A flow path 16 for fuel or oxidant is provided on the surface of the fluid supply plate 17 facing the diffusion electrode 14. A gas such as hydrogen or a liquid such as alcohol is introduced as fuel into the flow path 16 of the fluid supply plate 17 (fuel supply plate) on the anode side. A gas such as air or oxygen is usually introduced as an oxidant into the flow path 16 of the fluid supply plate 17 (oxidant supply plate) on the cathode side.

  When a high electromotive force is taken out, a plurality of single cells including the electrolyte 11, the diffusion electrode 14, and the fluid supply plate 17 as shown in FIG. 1 are stacked in series. The fluid supply plate 17 is usually made of a conductive material, and current is taken out through the fluid supply plate 17.

In recent years, use of a small fuel cell as a power source for portable electronic devices has been studied. As a small-sized fuel cell, a fuel cell using liquid fuel, such as a direct methanol fuel cell, is considered promising. A fuel cell that supplies liquid fuel directly to the anode does not require a process for reforming the fuel, and therefore has a reduced volume and is suitable as a power source for portable electronic devices (see Patent Documents 1 and 2).
Japanese National Patent Publication No. 10-507572 JP 2002-208419 A

  Conventionally, a fluid containing fuel or an oxidant is supplied to a fluid supply plate of a fuel cell using an external pump. However, when excess fuel is supplied to the diffusion electrode, the fuel moves to the cathode without being consumed at the anode, or the oxidant moves to the anode without being consumed at the cathode. Such a phenomenon is called cross leak. In order to reduce this problem, it is necessary to dilute the fuel with a solvent or to highly control the fluid flow path shape of the fluid supply plate.

  However, when the low-concentration fuel solution diluted with the solvent is circulated through the flow path of the fluid supply plate, a gradient occurs in the concentration of the fuel solution from the inlet to the outlet of the flow path. Therefore, it becomes difficult to maintain stable power generation near the exit.

  It has also been proposed to make the flow channel shape serpentine or to control the direction of fluid flow in the flow channel with ribs, but if the flow channel shape is complicated, the pressure loss for transferring the fluid Becomes larger. When the pressure loss increases, the pump becomes larger and fluid leakage from the fuel cell may occur. Furthermore, even if the flow path shape is controlled, it is difficult to uniformly supply the fuel or the oxidant to the entire surface of the diffusion electrode.

The present invention relates to a fuel comprising an anode, a fuel supply plate for supplying a fluid containing fuel to the anode, a cathode, an oxidant supply plate for supplying a fluid containing an oxidant to the cathode, and an electrolyte interposed between the anode and the cathode. A battery operating method,
(A) dividing at least one selected from a fuel supply plate and an oxidant supply plate into a plurality of reaction chambers;
(B) Each reaction chamber is provided with a fluid inlet containing fuel or oxidant and a fluid outlet containing fuel or oxidant;
(C) The inlet is provided with a supply pump for supplying a fluid containing fuel or an oxidant to the reaction chamber,
(D) The outlet is provided with a discharge valve for preventing backflow of a fluid containing fuel or oxidant to the reaction chamber,
(E) It is related with the operating method which drives a supply pump by arbitrary pulse patterns.

The present invention also relates to an operation method in which a discharge valve drive pump that collectively controls opening and closing of the discharge valves is provided downstream of the plurality of discharge valves, and the discharge valve drive pump is driven in an arbitrary pulse pattern.
The plurality of discharge valves are preferably set to open at a predetermined pressure or higher and close at a pressure lower than the predetermined pressure.

  According to the above operating method, it is possible to control the fuel concentration or oxidant concentration in each reaction chamber and the pressure in each reaction chamber with high accuracy. Accordingly, a necessary and sufficient amount of fuel or oxidant can be supplied to each reaction chamber at an appropriate timing. As a result, the operating efficiency of the fuel cell is improved. In addition, the possibility that the amount of fuel or oxidant supplied to each reaction chamber will change over time is significantly reduced. The drive timing of the supply pump and the discharge valve drive pump is not particularly limited, and an appropriate drive timing may be selected according to the use of the fuel cell, the load status, and the like. Therefore, there are various pulse patterns. Also, the pulse pattern need not be constant. For example, the pulse pattern can be changed according to the load status. As a result, power generation can be controlled according to load fluctuations.

Examples of the pulse pattern include the following.
(1) The pulse pattern for driving the supply pump and the pulse pattern for driving the discharge valve driving pump are synchronized. In this case, the fuel utilization rate or the oxidant utilization rate is high, but the difference between the maximum output and the minimum output of the fuel cell is relatively large.
(2) The start time of applying the pulse for driving the discharge valve driving pump is delayed from the start time of applying the pulse for driving the supply pump. In this case, it is possible to operate in consideration of the balance between the fuel utilization rate or oxidant utilization rate and the output of the fuel cell.

Pattern (2) can be further divided into the following patterns.
(A) The start time of application of the pulse for driving the discharge valve driving pump is delayed from the end time of application of the pulse for driving the supply pump.
(B) The start time of application of the pulse for driving the discharge valve driving pump is made earlier than the end time of application of the pulse for driving the supply pump.

In the pattern (2), when the interval time between pulses for driving the supply pump is made longer than the application time of the pulses for driving the supply pump, the residence time of the fuel in the reaction chamber becomes very long and the fuel is used. The rate is extremely high.
In pattern (2), when the interval time between pulses for driving the supply pump is made shorter than the pulse application time for driving the supply pump, the fuel utilization rate decreases, but the fuel concentration in the reaction chamber is always high. The output of the fuel cell is stabilized at a high level.

  In the pattern (2), when the start time of application of the pulse for driving the supply pump and the end time of application of the pulse for driving the discharge valve drive pump are synchronized, simultaneously with the discharge of the fluid containing the low-concentration fuel Immediately, a fluid containing fresh high-concentration fuel is supplied, and the output of the fuel cell is stabilized.

  Desirably, the plurality of reaction chambers are each provided with an opening facing the anode or the cathode, and each reaction chamber is surrounded by a side wall perpendicular to the opening surface. That is, the reaction chamber is preferably in a container shape surrounded by a side wall perpendicular to the opening surface and closed on the side opposite to the opening side. According to such a configuration, fuel or oxidant is supplied directly from the opening to the anode or cathode, so that the pressure loss of the supply pump is reduced. In addition, the division of each reaction chamber is clarified, and more accurate control is possible with respect to the fuel concentration or oxidant concentration in each reaction chamber and the pressure in each reaction chamber.

  The arrangement method of the plurality of reaction chambers is not particularly limited, but it is preferable that they are arranged uniformly along the interface between the anode and the fuel supply plate or the interface between the cathode and the oxidant supply plate. The plurality of reaction chambers are preferably arranged along the interface in, for example, a lattice shape, a staggered lattice shape, or a honeycomb shape.

  The arrangement of the fluid inlet and outlet is not particularly limited. However, in the driving posture, it is desirable that the inlet is positioned above the outlet in the vertical direction in consideration of the fluid flow direction. When the inlet is located above the outlet, gravity can be used to transfer a fluid containing fuel or oxidant, and the capacity of the supply pump can be set relatively low. Further, the use of gravity stabilizes the fluid flow.

  It is desirable that the fluid inlet is disposed at a position (closed position) opposite to the reaction chamber opening, and the outlet is disposed on the side wall of the reaction chamber. According to such a configuration, gravity can be used for fluid transfer when the operating posture is such that the opening of the reaction chamber is parallel to the horizontal direction. Further, the inlet and the outlet can be arranged on different wall surfaces of the reaction chamber, respectively. According to such a configuration, when the operating posture is such that the opening of the reaction chamber is parallel to the vertical direction and the inlet is positioned above the outlet in the vertical direction, gravity can be used for fluid transfer. .

  The supply pump and the discharge valve drive pump are preferably driven using a control unit that controls them. It is desirable that the controller can control at least the drive of all the supply pumps included in the fuel cell to an arbitrary pulse pattern, and it is further desirable that the discharge valve drive pump can be controlled at the same time. Further, it is desirable that the control unit can individually control all the supply pumps according to the position of the reaction chamber and the load situation. The control unit may drive the pump with a certain pulse pattern.

Examples of fuel cells to which the operation method of the present invention can be applied are shown below.
(I) A fuel cell having a fuel supply plate comprising a plurality of reaction chambers, each reaction chamber having an inlet for supplying a fluid containing fuel to the reaction chamber, and a fluid containing fuel from the reaction chamber An outlet for discharging, the inlet having a supply pump for supplying a fluid containing fuel to the reaction chamber, and the outlet for discharging to prevent backflow of the fluid containing fuel to the reaction chamber Has a valve.

(Ii) A fuel cell having an oxidant supply plate composed of a plurality of reaction chambers, each reaction chamber having an inlet for supplying a fluid containing the oxidant to the reaction chamber and a fluid containing the oxidant. An outlet for discharging from the reaction chamber, the inlet having a supply pump for supplying a fluid containing oxidant to the reaction chamber, and the outlet for flowing back the fluid containing oxidant to the reaction chamber. Has a discharge valve to prevent.

(Iii) A fuel cell having a fuel supply plate composed of a plurality of reaction chambers and an oxidant supply plate composed of a plurality of reaction chambers, wherein each reaction chamber of the fuel supply plate supplies a fluid containing fuel to the reaction chamber And an outlet for discharging a fluid containing fuel from the reaction chamber, the inlet having a supply pump for supplying a fluid containing fuel to the reaction chamber, the outlet being a fuel Each of the reaction chambers of the oxidant supply plate has an inlet for supplying a fluid containing the oxidant to the reaction chamber, and an oxidant. An outlet for discharging the fluid containing the reaction chamber from the reaction chamber, the inlet has a supply pump for supplying the fluid containing the oxidant to the reaction chamber, and the outlet has a reaction chamber for the fluid containing the oxidant. It has a discharge valve to prevent back flow into the.

  The operation method of the present invention is most suitable for the fuel cell of (i) among the above (i) to (iii). When the fuel cell of (i) uses air as a fluid containing an oxidant, the oxidant supply plate having a conventionally known structure is advantageous in terms of miniaturization, weight reduction, and cost of the fuel cell. .

  According to the present invention, the diffusion electrode can be divided into a plurality of compartments corresponding to the plurality of reaction chambers, and a fluid containing fuel or oxidant can be supplied or discharged in each compartment. Therefore, highly accurate control is possible with respect to the fuel concentration or oxidant concentration in each reaction chamber and the pressure in the reaction chamber, and the operating efficiency of the fuel cell is improved. Further, by driving the supply pump with various pulse patterns, advanced control of the fuel utilization rate, the output of the fuel cell, and the like is possible as described above.

More specifically, for example, the following effects can be obtained.
First, it is possible to suppress the cross leak of fuel or oxidant, and the utilization rate of fuel or oxidant is increased. Moreover, it is possible to supply the fuel or the oxidant uniformly over the entire surface of the diffusion electrode. In addition, it is possible to change the power generation mode according to the load condition or to control the power generation according to the load fluctuation.

  Further, when the supply pumps provided in each reaction chamber can be individually controlled, even when there is a defect in a part of the diffusion electrode, only the fuel supply to the reaction chamber facing the defective portion can be stopped. Therefore, the operation of the fuel cell can be continued, and the reliability such as the life of the fuel cell is improved.

First, the structure of an example of a fuel cell to which the operation method of the present invention can be applied will be described with reference to the drawings. However, the structure of the fuel cell to which the operation method of the present invention can be applied is not limited to the following.
FIG. 2 shows the internal structure of the right half of the fuel cell 100 as a cross-sectional view taken along the line III-III in FIGS. 3 and 4. 3 and 4 are a cross-sectional view taken along line II and II-II in FIG. 2, respectively. FIG. 5 is a top view of the fuel cell 100 as viewed from the fuel supply plate 110 side.

  The fuel cell 100 includes an anode 101, a fuel supply plate 110 that supplies a fluid containing fuel to the anode 101, a cathode 102, an oxidant supply plate 120 that supplies a fluid containing an oxidant to the cathode 102, and an anode 101 and a cathode 102. The polymer electrolyte membrane 103 is interposed between the two. The periphery of the polymer electrolyte membrane 103 is covered with a seal packing 123, which prevents the fluid containing fuel and oxidant from leaking from the inside of the fuel cell 100.

  The fuel supply plate 110 has a two-layer structure, and the side facing the anode 101 forms a first layer made up of a plurality of reaction chambers 112 arranged in a lattice pattern. On the second layer outside the first layer, fuel tanks 114 for storing a fluid containing fuel are formed in a state of being divided into three rows. The reaction chamber 112 has an opening facing the anode 101 and has a container shape surrounded by a side wall 113. A partition wall 115 that partitions the first layer and the second layer is the bottom of the container-like reaction chamber 112.

FIG. 6 is a cross-sectional view excluding the outermost wall of the fuel supply plate 110 in order to show the arrangement state of the fuel tanks 114. FIG. 7 is a cross-sectional view excluding the partition wall 115 that partitions the first layer and the second layer in order to show the arrangement state of the reaction chambers 112.
The fluid containing fuel is introduced into the fuel supply plate 110 from the fuel inlet 118, and reaches the fuel tank 114 through the fuel flow groove 116 formed along one side of the fuel supply plate 110. The fluid containing the fuel stored in the fuel tank 114 is introduced into the reaction chamber 112 by the supply pump 111 provided in the partition wall 115 that partitions the first layer and the second layer. One supply pump 111 is provided for each reaction chamber 112. The fluid containing fuel stays in the reaction chamber 112. Since the reaction chamber 112 has an opening facing the anode 101, a part of the fuel staying in the reaction chamber 112 quickly reaches the anode 101 and is consumed.

  The fluid containing the fuel staying in the reaction chamber 112 for a certain period is sent from the discharge valve 117 provided on the side wall 113 of the reaction chamber to the fuel discharge groove 119 adjacent to the reaction chamber 112. The fuel discharge grooves 119 are arranged along the periphery of the three rows of fuel tanks 114 except for one side. All the fuel discharge grooves 119 finally merge and are discharged from the fuel outlet 121 to the outside.

  The discharge valve 117 may only have a function of preventing the fuel-containing fluid from flowing back into the reaction chamber 112, but the discharge valve 117 may be a discharge valve that opens at a predetermined pressure or higher and closes at a pressure lower than the predetermined pressure. Good. In the case of a discharge valve having only a function of preventing backflow, it is considered that the valve opens when the pressure inside the reaction chamber 112 increases, and closes when the pressure decreases. is there. On the other hand, if a discharge valve set to open at a predetermined pressure or higher and close at a pressure lower than the predetermined pressure is used, variation can be suppressed to some extent.

  From the viewpoint of accurately controlling the opening and closing of the discharge valve 117, it is desirable to provide a discharge valve drive pump 124 that collectively controls the opening and closing of the plurality of discharge valves, as shown in FIG. By forcibly reducing the pressure on the downstream side of the discharge valve by the discharge valve driving pump 124, the discharge valve 117 can be reliably opened at a predetermined timing. A plurality of the discharge valve drive pumps 124 may be provided for each fuel cell, but it is more advantageous in terms of cost to control all the discharge valves collectively with one discharge valve drive pump.

  Further, a discharge valve driving pump that collectively controls the opening and closing of a plurality of discharge valves is used in combination with a discharge valve that is set to open at a predetermined pressure or higher and to be closed at a pressure lower than the predetermined pressure. It is possible to control the opening and closing of the door more highly. By controlling the opening / closing of the discharge valve 117, the fuel concentration in the reaction chamber 112 can be finely controlled.

  The oxidant supply plate 120 has a flow path 122 for retaining a fluid containing an oxidant on the side facing the cathode 102. The illustrated oxidant supply plate 120 has the same structure as the conventional one, but an oxidant supply plate having the same structure as the fuel supply plate 110 shown in FIGS. 2 to 7 can also be used.

  When each reaction chamber 112 has a dedicated supply pump 111 and a discharge valve 117, the reaction state is unlikely to vary depending on the position on the anode, so that the operation state of the fuel cell is likely to be stable. Further, when the control of each supply pump 111 is performed separately, it is possible to achieve an optimal fuel supply state for each reaction chamber according to the state of each reaction chamber 112.

  The positional relationship in the reaction chamber 112 between the supply pump 111 and the discharge valve 117 is not particularly limited, but when the fluid flow direction is taken into consideration, the supply pump 111 is positioned above the discharge valve 117 in the vertical direction. It is desirable. The supply pump 111 and the discharge valve 117 are preferably provided on different wall surfaces among the wall surfaces surrounding the container-like reaction chamber 112.

  The supply pump 111 and the discharge valve 117 are produced by using, for example, MEMS (Micro Electro Mechanical Systems) technology. The MEMS technology refers to a microfabrication technology applying a semiconductor manufacturing method such as an IC (integrated circuit), and is collectively referred to as MEMS in the United States, MST (Micro System Technology) in Europe, and micromachine technology in Japan. According to the MEMS technology, it is possible to produce a small pump and a small valve having a fine structure.

  Production of pumps and valves by MEMS technology is generally performed by repeating processes such as film formation, photolithography, and etching in a clean room. For example, a small silicon pump can be manufactured using a photoresist and a mask having a predetermined pattern. According to the MEMS technology, a plurality of small pumps and valves arranged at equal intervals can be formed on a semiconductor substrate, and the obtained semiconductor substrate can be used as the partition wall 115 that partitions the first layer and the second layer. . A side wall 113 surrounding the reaction chamber 112 can also be formed on the semiconductor substrate.

  In the case of manufacturing a supply pump on a semiconductor substrate, it is possible to form a wiring on the substrate that electrically connects the supply pump and a control unit that controls the supply pump. The control unit can be manufactured using an electronic circuit such as an IC or an LSI. The control unit can be provided inside the fuel cell, but can also be provided in an electronic device or the like on which the fuel cell is mounted.

  In the case of a fuel cell composed of a single cell, for example, a lead can be connected to any location of the fuel supply plate 110 and the oxidant supply plate 120 and current can be collected via the lead. The fuel supply plate 110 and the oxidant supply plate 120 are each made of a conductive material. The fuel supply plate 110 is electrically connected to the anode 101, and the oxidant supply plate 120 is electrically connected to the cathode 102. In order to obtain a high voltage, a plurality of single cells can be stacked and used as a stack. In a general laminated battery structure, a stack is sandwiched between end plates via a current collector plate and an insulating plate and fixed from both ends with a fastening rod. In that case, current collection is performed via a current collecting plate.

Next, an operation method of the fuel cell 100 will be described.
The fuel cell 100 is preferably installed and operated horizontally such that the fuel supply plate 110 is located at the top. If installed in this way, the fluid amount including the fuel in the fuel tank 114 decreases, and even if a gap is generated in the fuel tank 114, the fluid including the fuel is always supplied to the supply pump 111. Because.

  When the supply pump 111 and the discharge valve drive pump 124 are driven so that the supply pump 111 and the discharge valve 117 always transfer a constant amount of fluid, the fuel cell 100 can be kept at a substantially constant output. Relationship between the output of the fuel cell, the amount of fluid supplied to each reaction chamber (that is, the output of the supply pump), the amount of fluid discharged from each reaction chamber (that is, the output of the discharge valve drive pump), and the operation time Is shown in a conceptual pattern in FIG.

  When the fuel cell 100 is operated in a general pattern as shown in FIG. 8, the fuel utilization rate is relatively low because the fluid containing fuel is always discharged from the outlet of the reaction chamber 112. For this reason, there is a limit to improving the output. In addition, it is essential to circulate and reuse a fluid containing fuel. In order to increase the fuel utilization rate, it is necessary to lengthen the residence time of the fuel in the reaction chamber 112. In order to lengthen the residence time of the fuel in the reaction chamber 112, it is effective to drive the supply pump 111 and / or the discharge valve drive pump 124 in a pulse manner.

  As described above, the fuel supply plate of the fuel cell 100 is divided into a plurality of reaction chambers. Each reaction chamber has an inlet and an outlet for a fluid containing fuel, and the fluid containing the fuel reacts at the inlet. A discharge pump for preventing backflow of fluid containing fuel to the reaction chamber at the outlet, and opening and closing them downstream of the plurality of discharge valves. It has a discharge valve drive pump that controls all at once. Therefore, a time lag is unlikely to occur between the drive timing of the supply pump and the discharge valve drive pump and the output fluctuation of the fuel cell corresponding to the drive timing, and highly accurate operation control is possible.

  The drive timing of the supply pump and the discharge valve drive pump is not particularly limited, and an appropriate drive timing may be selected according to the use of the fuel cell, the load status, and the like. Also, the pulse pattern need not be constant. Therefore, although a pulse pattern is illustrated below, the pulse pattern applicable to the operation method of the present invention is not limited to these.

First Pattern First, a case where the pulse pattern for driving the supply pump and the pulse pattern for driving the discharge valve driving pump are synchronized will be described. That is, as shown in a conceptual diagram in FIG. 9, the supply of the fluid containing fuel to the reaction chamber 112 and the discharge of the fluid containing fuel from the reaction chamber 112 are performed in pulses at the same timing.

According to the pulse pattern as shown in FIG. 9, since the fuel stays in the reaction chamber 112 during the period when the supply pump 111 is not driven, the residence time becomes longer and the fuel utilization rate is increased. However, during the period in which no fuel is supplied, the fuel concentration in the reaction chamber 112 continues to decrease with the passage of time, so the difference between the maximum output and the minimum output becomes relatively large.
Note that the exhaust valve does not exhaust all of the fluid containing the fuel in the reaction chamber in the open state, and a part of the exhaust valve needs to remain in the reaction chamber. The discharge valve discharges a part of the fluid having a low fuel concentration, and at the same time, a fluid containing a high concentration of fuel is supplied to the reaction chamber. The same applies to the following pulse patterns.

Second Pattern Next, a case where the application start time of the pulse for driving the discharge valve driving pump is delayed from the application start time of the pulse for driving the supply pump will be described.
The second pattern further includes a pattern (a) as shown in FIG. 10 in which the start time of application of the pulse for driving the discharge valve driving pump is delayed from the end time of application of the pulse for driving the supply pump, and the supply pump. The pattern is subdivided into a pattern (b) as shown in FIG. 11 in which the start time of application of a pulse for driving the discharge valve drive pump is earlier than the end time of application of the drive pulse.

  When the supply pump and the discharge valve drive pump are driven with a pulse pattern (a) as conceptually shown in FIG. 10, a certain time has elapsed after the supply of fluid containing fuel to the reaction chamber 112 is stopped. Then, a pulsed discharge of the fluid containing fuel from the reaction chamber 112 is performed. By controlling in this way, it is possible to prevent the fluid containing fresh fuel from being discharged immediately after being supplied to the reaction chamber, and the residence time of the fuel in the reaction chamber is also increased. Enhanced. Instead, the output fluctuation of the fuel cell 100 becomes relatively large.

  On the other hand, when the supply pump and the discharge valve drive pump are driven by the pulse pattern (b) as conceptually shown in FIG. 11, the fuel is supplied to the pulsed supply of the fluid including the fuel to the reaction chamber 112. The pulsed discharge of the contained fluid from the reaction chamber 112 is delayed, and the supply and discharge overlap. In this case, although the fuel utilization rate decreases, the fuel concentration in the reaction chamber 112 is always maintained at a high concentration, and the output of the fuel cell is stabilized at a high level.

  According to the pattern as shown in FIG. 11, the fuel utilization rate is higher than when the fuel cell 100 is operated in the pattern as shown in FIG. 8, and the output fluctuation of the fuel cell is as shown in FIG. 9 and FIG. This is smaller than when the fuel cell 100 is operated in a simple pattern. As a result, the fuel cell can be operated with a balance between the fuel utilization rate and the output stability.

  In the second pattern, when the interval time between pulses for driving the supply pump is made longer than the application time of the pulses for driving the supply pump, the residence time of the fuel in the reaction chamber 112 is further increased, and the fuel utilization rate. Is more enhanced. On the other hand, in the second pattern, when the interval time between pulses for driving the supply pump is made shorter than the application time of the pulses for driving the supply pump, the fuel utilization rate is reduced, but the fuel concentration in the reaction chamber 112 is It is always maintained at a high concentration, and the output of the fuel cell is stabilized at a high level.

  In the second pattern, it is also desirable to synchronize the start time of application of the pulse for driving the supply pump and the end time of application of the pulse for driving the discharge valve drive pump. By controlling in this way, simultaneously with the discharge of the fluid containing the low concentration fuel, the fluid containing the fresh high concentration fuel is immediately supplied, and the output of the fuel cell is stabilized.

As described above, since the fuel cell 100 can be operated in various patterns, the most suitable operation pattern can be appropriately selected according to the load condition.
The fuel cell 100 is suitable as a fuel cell using a liquid fuel such as a direct methanol fuel cell, but can also be used as a fuel cell using a gas fuel such as hydrogen. Further, an injection nozzle may be provided in the supply pump 111, a liquid may be stored in the fuel tank 114 as a fluid containing fuel, and the liquid may be injected into the reaction chamber 112. In this case, for example, when the ejected fluid accumulates in a certain amount or more in the reaction chamber 112, the discharge valve 117 is opened by the suction force of the discharge valve driving pump 124, and the fluid is discharged from the reaction chamber 112.

  As described above, according to the present invention, it is possible to perform highly accurate control regarding the fuel concentration or oxidant concentration in the plurality of reaction chambers and the pressure in the plurality of reaction chambers, and the operation efficiency of the fuel cell is improved. The present invention is particularly effective in a method of operating a fuel cell using a liquid fuel such as a direct methanol fuel cell. In addition, since a fuel cell using liquid fuel has a high energy density, the operation method of the fuel cell of the present invention is suitable as a power source for portable electronic devices.

It is sectional drawing of the principal part of a common fuel cell. It is the top view seen from the fuel supply board side of the fuel cell concerning the present invention in the state where the right half was made into a section. It is the II sectional view taken on the line of FIG. It is the II-II sectional view taken on the line of FIG. It is the top view seen from the fuel supply board side of the fuel cell concerning the present invention. It is the top view seen from the fuel supply board side of the fuel cell concerning the present invention of the state where the outermost wall of the fuel supply board was removed. It is the top view seen from the fuel supply board side of the fuel cell concerning the present invention of the state where the partition which partitions off the 1st layer and the 2nd layer of a fuel supply board was removed. It is a conceptual diagram which shows the relationship between the output of a fuel cell, the output of a supply pump, the output of a discharge valve drive pump, and operation time in the general operating method of a fuel cell. It is a conceptual diagram which shows the relationship between the output of a fuel cell, the output of a supply pump, the output of a discharge valve drive pump, and the operation time in the operation method of the fuel cell according to the first pattern. It is a conceptual diagram which shows the relationship between the output of a fuel cell, the output of a supply pump, the output of a discharge valve drive pump, and the operation time in the fuel cell operation method according to the second pattern (a). It is a conceptual diagram which shows the relationship between the output of a fuel cell, the output of a supply pump, the output of a discharge valve drive pump, and operation time in the operation method of the fuel cell by the 2nd pattern (b).

Explanation of symbols

11 Electrolyte 12 Catalytic Reaction Layer 13 Diffusion Layer 14 Diffusion Electrode 15 MEA
16 Fuel or Oxidant Flow Channel 17 Fluid Supply Plate 100 Fuel Cell 101 Anode 102 Cathode 103 Polymer Electrolyte Membrane 110 Fuel Supply Plate 111 Supply Pump 112 Reaction Chamber 113 Side Wall 114 Fuel Tank 115 Partition Wall 116 Fuel Flow Groove 117 Discharge Valve 118 Fuel Inlet 119 Fuel discharge groove 120 Oxidant supply plate 121 Fuel outlet 122 Flow path for retaining fluid containing oxidant 123 Packing 124 Discharge valve drive pump

Claims (17)

A fuel comprising an anode, a fuel supply plate for supplying a fluid containing fuel to the anode, a cathode, an oxidant supply plate for supplying a fluid containing an oxidant to the cathode, and an electrolyte interposed between the anode and the cathode A battery operating method,
(A) dividing at least one selected from the fuel supply plate and the oxidant supply plate into a plurality of reaction chambers;
(B) Each reaction chamber is provided with a fluid inlet containing fuel or oxidant and a fluid outlet containing fuel or oxidant;
(C) The inlet is provided with a supply pump for supplying a fluid containing fuel or oxidant to the reaction chamber,
(D) The outlet is provided with a discharge valve for preventing backflow of a fluid containing fuel or oxidant to the reaction chamber,
(E) An operation method for driving the supply pump with an arbitrary pulse pattern.   The operation method according to claim 1, wherein a discharge valve driving pump that collectively controls opening and closing of the discharge valves is provided downstream of the plurality of discharge valves, and the discharge valve driving pump is driven in an arbitrary pulse pattern.   The method of operating a fuel cell according to claim 2, wherein the plurality of discharge valves open at a predetermined pressure or higher and close at a pressure lower than the predetermined pressure.   The method of operating a fuel cell according to claim 2, wherein a pulse pattern for driving the supply pump and a pulse pattern for driving the discharge valve driving pump are synchronized.   3. The method of operating a fuel cell according to claim 2, wherein a start time of applying a pulse for driving the discharge valve driving pump is delayed from a start time of applying a pulse for driving the supply pump.   6. The method of operating a fuel cell according to claim 5, wherein an interval time between pulses for driving the supply pump is longer than an application time of a pulse for driving the supply pump.   6. The method of operating a fuel cell according to claim 5, wherein an interval time between pulses for driving the supply pump is shorter than an application time of a pulse for driving the supply pump.   6. The fuel cell operating method according to claim 5, wherein a start time of application of a pulse for driving the supply pump is synchronized with an end time of application of a pulse for driving the discharge valve driving pump.   6. The method of operating a fuel cell according to claim 5, wherein a start time of application of a pulse for driving the discharge valve driving pump is delayed from a time point of ending application of a pulse for driving the supply pump.   6. The method of operating a fuel cell according to claim 5, wherein a start time of application of a pulse for driving the discharge valve driving pump is made earlier than a time point of ending application of a pulse for driving the supply pump.   The fuel cell operating method according to claim 1, wherein the plurality of reaction chambers are each provided with an opening facing the anode or the cathode, and each reaction chamber is surrounded by a side wall perpendicular to the opening surface.   The method of operating a fuel cell according to claim 1, wherein the plurality of reaction chambers are arranged in a lattice shape, a staggered lattice shape, or a honeycomb shape.   The method of operating a fuel cell according to claim 1, wherein, in an operation posture, the inlet is positioned above the outlet in a vertical direction.   The fuel cell operating method according to claim 11, wherein the inlet is disposed at a position facing the opening, and the outlet is disposed on the side wall.   The method of operating a fuel cell according to claim 11, wherein the inlet and the outlet are respectively arranged on different wall surfaces of the side wall. A fuel comprising an anode, a fuel supply plate for supplying a fluid containing fuel to the anode, a cathode, an oxidant supply plate for supplying a fluid containing an oxidant to the cathode, and an electrolyte interposed between the anode and the cathode A battery,
At least one selected from the fuel supply plate and the oxidant supply plate comprises a plurality of reaction chambers,
Each reaction chamber has an inlet for a fluid containing fuel or oxidant and an outlet for a fluid containing fuel or oxidant;
The inlet has a supply pump for supplying a fluid containing fuel or oxidant to the reaction chamber;
The outlet has a discharge valve for preventing back flow of a fluid containing fuel or oxidant to the reaction chamber,
The fuel cell which has the discharge valve drive pump which controls those opening / closing collectively downstream of the said several discharge valve. The fuel cell according to claim 16, wherein the plurality of discharge valves open at a predetermined pressure or higher and close at a pressure lower than the predetermined pressure.

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