JP2010009855A - Fuel cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell device capable of efficiently separating gas in liquid, and improving power generating efficiency. <P>SOLUTION: The fuel cell device is equipped with an energizing part having an anode and a cathode and carrying out power generation by chemical reaction, a fuel tank, an anode passage 22 passing and circulating fuel through the anode of the energizing part, a cathode passage 24 supplying air through the cathode, a circulating pump 28 passing fuel through the anode passage, a gas-liquid separator 32 separating a gas-liquid two-phase flow discharged from the anode into liquid and gas, a temperature sensor 34 measuring a temperature of the liquid in the anode passage, a pressure adjusting part 35 adjusting a pressure of the anode passage, and a cell control part 16 calculating the pressure in the anode passage on the basis of the temperature of the liquid in the anode passage measured by the temperature sensor and adjusting the pressure by the pressure adjusting part such that the pressure in the anode passage is within a predetermined range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell device that includes a gas-liquid separator and is used as a power source for electronic equipment and the like.

  Currently, secondary batteries such as lithium ion batteries are mainly used as power sources for portable notebook personal computers (hereinafter referred to as notebook PCs) and mobile devices. In recent years, a small fuel cell with high output and no need for charging has been expected as a new power source due to an increase in power consumption accompanying the enhancement of functions of these electronic devices and a request for longer use. There are various types of fuel cells. In particular, a direct methanol fuel cell (hereinafter referred to as DMFC) using a methanol solution as a fuel is easier to handle than a fuel cell using hydrogen as a fuel. Since the system is simple, it is attracting attention as a power source for electronic devices.

  Usually, the DMFC includes a fuel tank in which methanol is stored, a liquid feed pump that pumps methanol to the electromotive unit, an air pump that supplies air to the electromotive unit, and the like. The electromotive unit includes a cell stack in which a plurality of single cells each having an anode and a cathode are stacked, and generates electricity by a chemical reaction by supplying methanol to the anode side and air to the cathode side. As reaction products accompanying power generation, unreacted methanol and carbon dioxide gas are generated on the anode side of the electromotive section, and water is generated on the cathode side. The reaction product water is exhausted as steam.

  In the gas-liquid two-phase flow of unreacted fuel and carbon dioxide produced at the anode, carbon dioxide inhibits the power generation reaction. Therefore, when the unreacted fuel generated at the anode is circulated and reused, it is necessary to separate and remove the gas component in the gas-liquid two-layer flow. Therefore, in the anode circulation system, a gas-liquid separator is provided between the anode outlet of the electromotive unit and the fuel tank. Unreacted methanol and carbon dioxide generated on the anode side of the electromotive section are sent to a gas-liquid separator, and methanol and carbon dioxide are separated. After the separation, methanol is sent to the fuel tank through the anode circulation system, and carbon dioxide gas is sent to the cathode channel through the exhaust path (for example, Patent Document 1).

There are various types of gas-liquid separators, but gas-liquid separators that are resistant to tilting conditions and are suitable for downsizing are proposed to be composed of a tube made of a porous gas-permeable membrane. (For example, patent document 2). The tube is disposed across the flow of the liquid, and the inside is decompressed by an exhaust device. Thereby, the gas contained in the liquid is exhausted into the tube through the tube of the gas-liquid separation membrane and separated from the liquid.
JP-A-2005-108718 Japanese Patent Laid-Open No. 4-4002

  In the fuel cell device configured as described above, the fuel separated by the gas-liquid separator is returned to the fuel tank and is used again for power generation. For this reason, the gas-liquid separator provided between the electromotive unit and the fuel tank can efficiently and reliably separate the liquid phase (fuel) and the gas phase (carbon dioxide) when using fuel efficiently. Is required.

  When gas-liquid separation is performed using a gas-permeable porous material for the gas-liquid separator, the internal pressure of the anode circulation system is used because the pressure difference between the liquid phase (anode circulation system) and the gas phase (usually the atmosphere) is used. Must be set to an optimal value. However, when the temperature of the anode circulating fluid changes with the power generation operation of the fuel cell device, the viscosity of the anode circulating fluid changes, and as a result, the internal pressure of the anode circulating system changes.

  If the pressure on the liquid phase side is too high, not only the carbon dioxide gas but also the anode circulated liquid will pass through the gas-permeable porous body, and the liquid will leak out of the fuel cell device. On the other hand, if the pressure on the liquid phase side is too low, the carbon dioxide gas cannot permeate the gas permeable porous material, and the carbon dioxide gas may remain in the anode circulation system, which may hinder power generation.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a fuel cell device capable of obtaining optimum gas-liquid separation performance regardless of temperature change and having improved power generation efficiency.

In order to achieve the above object, a fuel cell device according to an aspect of the present invention includes a cell having an anode and a cathode, an electromotive unit that generates power by a chemical reaction, a fuel tank that contains fuel, and the fuel tank. A circulation system having an anode flow path for circulating the supplied fuel through the anode of the electromotive section, a cathode flow path for supplying air through the cathode of the electromotive section, and circulation for flowing a liquid through the anode flow path A pump and a gas-liquid separator that is provided upstream of the fuel tank and separates liquid and gas. The gas-liquid separator is formed of a porous material and contacts a gas-liquid two-phase flow discharged from the anode. A gas-liquid separator having a surface and a second surface in contact with the air passing through the cathode flow path, the gas-liquid separator including a gas-permeable member that transmits gas in the gas-liquid two-phase flow;
A temperature sensor that is provided in the anode channel and measures the temperature of the liquid in the anode channel;
The pressure in the anode channel is calculated based on the pressure adjusting unit that adjusts the pressure in the anode channel, and the temperature of the liquid in the anode channel measured by the temperature sensor. A pressure control unit that adjusts the pressure of the pressure adjusting unit so that the pressure is within a predetermined range.

  According to the above configuration, an optimum gas-liquid separation performance can be obtained by adjusting the pressure of the liquid sent to the gas-liquid separator according to the temperature change, and a fuel cell device with improved power generation efficiency is provided. can do.

Hereinafter, a fuel cell device according to a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 schematically shows a circulation system configuration of a fuel cell device. As shown in FIG. 1, the fuel cell device 10 is configured as a DMFC using methanol as a liquid fuel. The fuel cell device 10 includes a cell stack 12 that constitutes an electromotive unit, a fuel tank 14, a circulation system 20 that supplies fuel and air to the cell stack, and a battery control unit 16 that controls the operation of the entire fuel cell device. Yes. The battery control unit 16 includes a microcomputer (CPU) and the like, and is electrically connected to the cell stack 12. Then, the battery control unit 16 supplies the power generated in the cell stack 12 to the electronic device 17 such as a notebook PC or a mobile phone.

  The fuel tank 14 has a sealed structure, and contains high-concentration methanol or a desired-concentration aqueous methanol solution as a liquid fuel. The fuel tank 14 may be formed as a fuel cartridge that is detachable from the fuel cell device 10.

  The circulation system 20 includes an anode flow path (fuel flow path) 22 for circulating the fuel supplied from the fuel supply port 14 a of the fuel tank 14 through the cell stack 12, and a cathode flow path for circulating a gas containing air through the cell stack 12. (Air channel) 24, having a plurality of auxiliary devices provided in the anode channel and in the cathode channel. The anode channel 22 and the cathode channel 24 are each formed by piping or the like.

  FIG. 2 shows the laminated structure of the cell stack 12, and FIG. 3 schematically shows the power generation reaction of each cell. As shown in FIGS. 2 and 3, the cell stack 12 includes a laminate formed by alternately laminating a plurality of, for example, four single cells 140 and five rectangular plate-like separators 142, and It has a frame 145 that supports the laminate. Each single cell 140 includes a substantially rectangular plate-like cathode (air electrode) 36 and an anode (fuel electrode) 37 each composed of a catalyst layer and carbon paper, and a substantially rectangular high electrode sandwiched between the cathode and anode. A membrane / electrode assembly (MEA) integrated with the molecular electrolyte membrane 144 is provided. The polymer electrolyte membrane 144 is formed in a larger area than the anode 37 and the cathode 36.

  The three separators 142 are stacked between two adjacent single cells 140, and the other two separators are stacked at both ends in the stacking direction. The separator 142 and the frame 145 are formed with a fuel channel 146 that supplies fuel to the anode 37 of each unit cell 140 and an air channel 147 that supplies air to the cathode 36 of each unit cell.

  As shown in FIG. 3, the supplied fuel and air chemically react with an electrolyte membrane 144 provided between the anode 37 and the cathode 36, thereby generating electric power between the anode and the cathode. The electric power generated in the cell stack 12 is supplied to the electronic device 17 via the battery control unit 16.

  As shown in FIG. 1, a fuel pump 26 that functions as a fuel supply unit is connected to the anode flow path 22. The fuel pump 26 is connected to the fuel supply port 14 a of the fuel tank 14 by piping. The operation of the fuel pump 26 is controlled by the battery control unit 16 and supplies fuel from the fuel tank to the anode flow path 22. In the anode flow path 22, a circulation pump 28 that circulates fuel through the anode flow path 22 is provided on the upstream side of the cell stack 12. The circulation pump 28 is controlled in driving voltage or rotation speed by the battery control unit 16 and adjusts the flow rate of the fuel flowing through the anode flow path 22. Note that the flow rate of the fuel flowing through the anode flow path 22 may be controlled to be constant with the drive voltage or the rotation speed of the circulation pump being constant.

The output part of the anode 37 of the cell stack 12 is connected to the input part of the circulation pump 28 through the anode flow path 22. A gas-liquid separator 32 is provided in the anode flow path 22 between the output part of the cell stack 12 and the circulation pump 28. An exhaust fluid discharged from the anode 37 of the cell stack 12, that is, a gas-liquid two-phase flow including an unreacted aqueous methanol solution that has not been used for the chemical reaction and generated carbon dioxide (CO ₂ ), is supplied to the gas-liquid separator 32. Where the carbon dioxide is separated. The separated aqueous methanol solution is returned to the circulation pump 28 through the anode channel 22 and supplied to the anode 37 again. The carbon dioxide separated by the gas-liquid separator 32 is exhausted to the outside air through a purification filter (not shown).

  In the anode flow path 22, a temperature sensor 34 is provided between the output part of the cell stack 12 and the gas-liquid separator 32, and a pressure adjusting part 35 is provided between the gas-liquid separator 32 and the circulation pump 28. Is provided. The temperature sensor 34 detects the temperature of the fluid discharged from the cell stack 12 and sends the detection result to the battery control unit 16. The battery control unit 16 operates a cooler (not shown) based on the detection result sent from the temperature sensor 34, and maintains the temperature of the fuel sent to the cell stack 12 in an optimum state for power generation.

The pressure adjustment unit 35 includes, for example, a variable valve that opens and closes the anode flow path 22, and adjusts the opening of the variable valve under the control of the battery control unit 16, so that the anode fluid that flows through the anode flow path 22 Adjust the pressure. For example, by increasing the opening of the variable valve, the pressure of the fuel flowing through the anode flow path 22 can be reduced, and by reducing the opening, the fuel pressure can be increased. The pressure adjustment unit 35 has a sufficient adjustment range that can be adjusted to a reference pressure when the cell stack 12 is normally operated and a pressure that changes in both directions higher and lower than the reference pressure. The intake port 24a and the exhaust port 24b of the path 24 are each in communication with the atmosphere. The auxiliary equipment provided in the cathode flow path 24 is an air filter 40 provided in the vicinity of the inlet 24a of the cathode flow path 24 on the upstream side of the cell stack 12, and the cathode flow path between the cell stack 12 and the air filter. The connected air supply pump 42 and the exhaust filter 44 provided between the cell stack and the exhaust port 24b on the downstream side of the cell stack 12 are included.

  By operating the air supply pump 42, air is supplied to the cathode channel 24 from the intake port 24 a. The supplied air passes through the air filter 40 and is then supplied to the cathode 36 of the cell stack 12, where oxygen in the air is used for power generation. The air discharged from the cathode 36 passes through the cathode channel 24 and the exhaust filter 44 and is discharged from the exhaust port 24b to the atmosphere.

  The air filter 40 captures and removes dust in the air sucked into the cathode channel 24, impurities such as carbon dioxide, formic acid, fuel gas, methyl formate, and formaldehyde, and harmful substances. The exhaust filter 44 detoxifies the by-products in the gas exhausted from the cathode channel 24 to the outside, and captures the fuel gas and the like contained in the exhaust.

Next, the gas-liquid separator 32 will be described in detail. FIG. 4 shows the gas-liquid separator 32 in an enlarged manner.
As shown in FIG. 4, the gas-liquid separator 32 includes a separation tube 50 that defines a part of the anode flow path 22, and a hollow container 52 provided so as to cover the separation tube 50. Yes. The separation tube 50 is configured by forming a gas permeable membrane 54 made of a porous material, for example, a porous fluororesin and having a thickness of 1 to 2 mm into a cylindrical shape. A flow path through which a gas-liquid two-phase flow flows is defined by the first surface 54a of the gas permeable membrane 54, that is, the inner surface of the separation tube 50, and the separation tube 50 is defined by the outer surface (second surface) 54b of the gas permeable membrane 54. The outer surface is formed. The gas permeable membrane 54 permeates the gas in the gas-liquid two-phase flow that flows in the flow path.

  Both ends of the separation tube 50 are connected to pipes 22a forming the anode flow path 22, respectively. As a result, the separation tube 50, which is a gas-permeable porous body, is provided in the anode channel 22 through which the exhausted fluid discharged from the anode 37, that is, the gas-liquid two-phase fluid containing unreacted aqueous methanol solution and generated carbon dioxide flows. Part of it.

  The container 52 is provided so as to cover the entire separation tube 50 and defines a sealed space 60 in contact with the outer surface of the separation tube 50. An exhaust pipe 62 is connected to the container 52, and the sealed space 60 communicates with the outside air through the exhaust pipe 62.

  According to the gas-liquid separator 32 configured as described above, the discharged fluid discharged from the anode 37 flows through the separation tube 50, and the outer surface of the separation tube 50 is converted into the outside air in the space 60, that is, the air. Touching. The discharged fluid is relatively hot and has a pressure higher by several K Pascals than the outside air. Therefore, a differential pressure is generated inside and outside the separation tube 50. As a result, the gas contained in the exhaust fluid, here carbon dioxide and gaseous methanol fuel component, pass through the gas permeable membrane 54 due to the pressure difference and are discharged to the outer space 60. The liquid in the discharged fluid, here, the fuel cannot flow through the gas permeable membrane 54 due to its surface tension, and flows through the flow path as it is. Thereby, the gas-liquid two-phase fluid is separated into a gas phase and a liquid phase. The separated fuel passes through the anode flow path 22 and is sent to the circulation pump 28 via the pressure adjusting unit 35 and is supplied to the cell stack 12 again. The separated gas is exhausted to the outside through the exhaust pipe 62 together with the outside air. A harmful substance removal filter may be provided near the exhaust port of the exhaust pipe 62.

  When gas-liquid separation is performed using a gas-permeable porous body for the gas-liquid separator 32, the pressure control on the liquid phase side is performed because the pressure difference between the liquid phase (anode circulation system) and the gas phase (atmosphere) is used. It becomes important. Therefore, the fuel cell device 10 includes the pressure adjusting unit 35 provided in the anode flow path 22 in order to properly maintain the pressure applied to the liquid phase (anode circulation system) side of the gas-liquid separator 32. Then, the battery control unit 16 calculates the pressure applied to the gas-liquid separator 32 based on the liquid temperature of the anode circulation system measured by the temperature sensor 34, and adjusts the pressure of the pressure adjusting unit 35 according to this pressure. .

  A pressure applied to the gas-liquid separator 32 and a calculation method thereof will be described. As shown in FIG. 5, when the pressure applied to the inlet of the gas-liquid separator 32 is Pin and the pressure applied to the outlet of the gas-liquid separator is Pout, these Pin and Pout are respectively adjusted by the pressure adjusting unit 35. , Pressure loss ΔP1 in the gas-liquid separator, and pressure loss ΔP2 of the anode flow path 22 between the outlet of the gas-liquid separator and the pressure adjusting unit 35 can be expressed as follows. Pin is the highest pressure in the gas-liquid separator 32, and Pout is the lowest pressure in the gas-liquid separator.

Pin = Preg + ΔP1 + ΔP2
Pout = Preg + ΔP2
Here, the pressure losses ΔP1 and ΔP2 can be obtained from the following calculation formula of the pressure loss ΔP.
ΔP = 32 ・ l / d ²・ η ・ u (in the case of a circular pipe)
l: Channel length of the corresponding section (in the gas-liquid separator if ΔP1)
d: Channel diameter
η: Fluid viscosity
u: Flow velocity In the above calculation formula, the flow channel length l and the flow channel diameter d are constants determined by the flow channel shape, so if the fluid viscosity η and the flow velocity u can be estimated, the gas-liquid separator 32 is applied. The pressure can be calculated. Here, the description is given using the formula in the case where the fluid flow path of the gas-liquid separator 32 is a circular pipe, but the relationship between the pressure loss, the fluid viscosity, and the flow rate does not change even in the case of a rectangular flow path.

  Also, the viscosity of the liquid can be expressed as a function of temperature, like the viscosity of water shown in FIG. Therefore, by measuring the temperature of the anode circulating liquid, it becomes possible to estimate the viscosity of the anode circulating liquid from this measured temperature. As shown in FIG. 7, since the pressure loss of the liquid is proportional to the flow rate, if the viscosity of the liquid can be estimated, the flow rate of the anode circulating liquid can be determined from the drive state (drive voltage, rotation speed, etc.) of the circulation pump 28. And the pressure loss of the liquid can be obtained. Therefore, the pressure applied to the gas-liquid separator 32 can be calculated from the pressure loss of the liquid.

  The battery control unit 16 calculates the pressure applied to the gas-liquid separator 32 based on the liquid temperature detected by the temperature sensor 34, and this pressure is the optimum pressure for exerting the separation performance of the gas-liquid separator 32. The internal pressure of the anode flow path 22 is adjusted by the pressure adjusting unit 35 so as to be within the range. The pressure adjustment unit 35 has a sufficient adjustment range that can be adjusted to a reference pressure when the cell stack 12 is normally operated and a pressure that changes in both high and low directions than the reference pressure.

As shown in FIG. 8, the internal pressure of the anode channel 22 is controlled as follows. In addition, the meaning of the symbol in a figure is as follows.
Pin: Gas-liquid separator inlet pressure
Pout: Outlet pressure of gas-liquid separator
Preg: Pressure of the pressure adjustment unit
Pmax: Upper limit of pressure at which the gas-liquid separator functions
Pmin: Lower limit of pressure at which the gas-liquid separator functions
ΔP1: Pressure loss in the gas-liquid separator
ΔP2: Pressure loss between the gas-liquid separator outlet and the pressure adjusting unit First, the battery control unit 16 calculates the flow velocity of the fluid flowing through the anode flow path 22 from the activation state (drive voltage, rotation speed, etc.) of the circulation pump 28. (ST1). In addition, when the drive voltage and the rotation speed of the circulation pump 28 are always set to be constant, the flow rate is also almost constant, so that this step can be omitted.

  Subsequently, the battery control unit 16 measures the liquid temperature using the temperature sensor 34 (ST2), and calculates the viscosity of the circulating fluid from the liquid temperature (ST3). Battery control unit 16 calculates pressure losses ΔP1 and ΔP2 from the flow velocity and viscosity (ST4). Further, the battery control unit 16 calculates the inlet pressure Pin and the outlet pressure Pout of the gas-liquid separator 32 from the pressure Preg of the pressure adjusting unit 35 and the pressure losses ΔP1, ΔP2 (ST5, ST6).

  Next, the battery control unit 16 compares the inlet pressure Pin of the gas-liquid separator 32 with the upper limit pressure Pmax, and compares the outlet pressure Pout of the gas-liquid separator with the lower limit pressure Pmin (ST7). > Pmax (exceeding the upper limit of the pressure at which the gas-liquid separator 32 functions) or Pout <Pmin (lower than the lower limit of the pressure at which the gas-liquid separator functions), the pressure Preg of the pressure adjusting unit 35 Are adjusted to satisfy Pin <Pmax and Pout> Pmin (ST8). Thereby, the pressure of the gas-liquid two-phase fluid sent to the gas-liquid separator 32 can be set within the optimum pressure range for exhibiting the separation performance of the gas-liquid separator 32. Therefore, even when the operating state of the fuel cell device 10 and the temperature of the anode circulating fluid change, the gas-liquid separator 32 can fully exhibit the gas-liquid separation capability, and the gas-liquid two-phase fluid can be reliably gas-liquid separated. Can do.

  When the fuel cell device 10 configured as described above is used as a power source, the fuel pump 26, the circulation pump 28, and the air supply pump 42 are operated under the control of the battery control unit 16, and the pressure adjustment unit 35 is set to a reference pressure. Adjust to. Methanol is supplied from the fuel tank 14 to the anode flow path 22 by the fuel pump 26. Further, methanol is supplied to the anode 37 of the cell stack 12 through the anode flow path 22 by the circulation pump 28.

  On the other hand, outside air, that is, air is sucked into the cathode channel from the intake port 24a of the cathode channel 24 by the air supply pump 42. This air passes through the air filter 40, where dust and impurities in the air are removed. After passing through the air filter 40, the air is supplied to the cathode 36 of the cell stack 12 through the cathode channel 24.

  The methanol and air supplied to the cell stack 12 undergo an electrochemical reaction at the electrolyte membrane 144 provided between the anode 37 and the cathode 36, thereby generating electric power between the anode 37 and the cathode 36. The electric power generated in the cell stack 12 is supplied to an electronic device or the like via the battery control unit 16.

  Along with the electrochemical reaction, carbon dioxide is generated on the anode 37 side and water is generated on the cathode 36 side as reaction products in the cell stack 12. Carbon dioxide generated on the anode 37 side and unreacted methanol that has not been subjected to the chemical reaction are sent to the gas-liquid separator 32 through the anode flow path 22 where they are separated into carbon dioxide and methanol. The separated methanol is sent from the gas-liquid separator 32 to the circulation pump 28 through the anode channel 22 and is used again for power generation. The separated carbon dioxide is exhausted to the outside through the exhaust pipe 62 from the space 60 of the gas-liquid separator 32.

  Further, during the operation of the fuel cell device 10, the battery control unit 16 uses the pressure adjusting unit 35 to set the internal pressure of the anode flow path according to the liquid temperature detected by the temperature sensor 34 and the operating state of the circulation pump 28. The gas-liquid separator 32 is adjusted to an optimum pressure range for gas-liquid separation.

  According to the fuel cell device 10 configured as described above, the pressure of the anode fluid can be maintained in the optimum pressure range for the gas-liquid separator regardless of the temperature change of the anode fluid. Gas-liquid two-phase fluid can be efficiently gas-liquid separated. Therefore, it is possible to prevent leakage of liquid to the outside of the fuel cell device and retention of carbon dioxide gas, and as a result, a fuel cell device with improved power generation efficiency can be obtained.

Next explained is a fuel cell apparatus according to the second embodiment of the invention.
As shown in FIG. 9, according to the second embodiment, the gas-liquid separator 32 of the fuel cell device is configured to be incorporated in the cell stack 12. The cell stack 12 is configured by stacking a plurality of, for example, four single cells 140. Each single cell 140 includes a cathode flow path plate 152 formed with a plurality of air flow paths 150 through which air flows, an anode flow path plate 156 formed with a plurality of fuel flow paths 154 through which fuel flows, and these cathodes. A membrane / electrode assembly (MEA) 160 sandwiched between the channel plate and the anode channel plate. The MEA 160 is configured by integrating a substantially rectangular plate-like cathode and anode each composed of a catalyst layer and carbon paper, and a substantially rectangular polymer electrolyte membrane sandwiched between the cathode and anode. . The MEA 160 is sandwiched between the cathode channel plate 152 and the anode channel plate 156 with the cathode in contact with the air channel 150 and the anode in contact with the fuel channel 154.

  The four single cells 140 are sequentially stacked with a sheet-like gas permeable membrane 54 made of a porous material, for example, a porous fluororesin, interposed therebetween. A plurality of single cells are laminated in a state where the gas permeable membrane 54 is sandwiched between the anode flow path plate 156 of the lower unit cell 140 and the cathode flow path plate 152 of the upper unit cell 140. Yes. Each gas permeable membrane 54 has a first surface, here, a lower surface in contact with the fuel flow path 154 of the lower unit cell 140, and a second surface, here, the upper surface, the air channel 150 of the upper unit cell 140. Is in contact with

  In the uppermost layer, an end plate 164 in which a plurality of air flow paths 162 are formed is laminated. A gas permeable membrane 54 is sandwiched between the anode flow path plate 156 and the end plate 164 of the uppermost unit cell 140. The gas permeable membrane 54 has a lower surface in contact with the fuel flow path 154 of the lower unit cell 140 and an upper surface in contact with the air flow path 162 of the end plate.

  In the power generation operation, air is supplied to the air flow path 150 of each single cell 140 and methanol is supplied to the fuel flow path 154. In each single cell 140, the supplied fuel and air chemically react with the MEA, thereby generating electric power between the anode and the cathode. The electric power generated in the cell stack 12 is supplied to the electronic device via the battery control unit 16.

In addition, a gas-liquid two-phase flow including unreacted fuel that has not been used for the chemical reaction and generated carbon dioxide (CO ₂ ) flows through the fuel flow path 154 of each single cell 140, and at that time, the gas-liquid The two-phase flow has a relatively high temperature and a pressure higher by several K Pascals than the outside air. Therefore, a differential pressure is generated between the fuel flow path 154 and the air flow paths 150 and 162 facing each other across the fuel flow path and the gas permeable membrane 54. As a result, the gas contained in the gas-liquid two-phase flow, here carbon dioxide, passes through the gas permeable membrane 54 due to the pressure difference and is discharged to the upper air flow paths 150 and 162. Thereby, the gas-liquid two-phase flow is separated into a liquid phase, that is, an unreacted fuel and a gas phase, that is, carbon dioxide. The separated fuel passes through the fuel flow path 154 and is sent to the anode flow path of the fuel cell device, and the separated carbon dioxide passes through the air flow paths 150 and 162 and further passes through the cathode flow path. Exhausted outside.

  As described above, in the cell stack 12, the air flow paths 150 of the single cells 140 of the second to fourth layers function as an air flow path for flowing air and a flow path for flowing separated carbon dioxide. The air flow path 150 provided in the lowermost unit cell 140 functions only as a flow path for flowing air, and the air flow path 162 provided in the uppermost end plate 164 flows for flowing exhausted carbon dioxide. Functions as a road.

  Except for the cell stack 12, the other configuration of the fuel cell apparatus is the same as that of the first embodiment described above, and a detailed description thereof will be omitted. Even when the gas-liquid separator incorporated in the cell stack 12 as described above is used, the same operational effects as those of the first embodiment described above can be obtained. Further, an independent gas-liquid separator can be omitted, and the entire apparatus can be downsized.

Next explained is a fuel cell apparatus according to the third embodiment of the invention.
FIG. 10 schematically shows a fuel cell device according to the third embodiment. According to the third embodiment, the pressure adjustment unit 35 includes a buffer tank 70 and a supply unit 72 that supplies water to the buffer tank, instead of the variable valve. The buffer tank 70 is connected to the anode flow path 22 between the gas-liquid separator 32 and the circulation pump 28, and temporarily stores fuel and water flowing through the anode flow path 22.

A pressure plate 74 is disposed in the buffer tank 70 so as to be movable up and down. The pressing plate 74 is pressed against the liquid surface of the liquid stored in the buffer tank by a plurality of urging members, for example, compression springs 76 disposed between the pressing plate and the buffer tank inner surface, Pressurized. When the amount of the liquid stored in the buffer tank 70 changes and the liquid level rises and falls, the pressing plate 74 also moves up and down in conjunction with this. As the pressing plate 74 moves up and down, the urging force of the compression spring 76 changes, and the pressure of the liquid changes. For example, when the amount of liquid increases and the pressing plate 74 is moved upward, the compression spring 76 contracts and the urging force increases. Thereby, the pressure applied to the liquid increases, and the pressure of the liquid itself, that is, the internal pressure of the anode channel 22 increases.
On the contrary, when the liquid amount stored in the buffer tank 70 is reduced and the liquid level is lowered, the pressing plate 74 is also lowered in conjunction with this. As a result, the compression spring 76 extends and the urging force decreases. Accordingly, the pressure applied to the liquid decreases, and the pressure of the liquid itself, that is, the internal pressure of the anode flow path 22 decreases.

  The supply unit 72 includes a water tank 78 that stores liquid, for example, water, and a water supply pump 80 that supplies water from the water tank to the anode flow path 22. The water tank 78 may be formed as a cartridge that can be attached to and removed from the fuel cell device 10. The operation of the water supply pump 80 is controlled by the battery control unit 16.

  By supplying water from the water tank 78 to the anode channel 22 by the water supply pump 80, the flow rate of the liquid in the anode channel increases, and the amount of liquid stored in the buffer tank 70 increases. Along with this, the urging force of the compression spring 76 provided in the buffer tank 70 increases, and the internal pressure of the anode flow path 22 increases. Thus, the internal pressure of the anode flow path 22 can be adjusted by controlling the water supply pump 80 by the battery control unit 16 and adjusting the amount of liquid stored in the buffer tank 70.

  As in the first embodiment described above, the internal pressure of the anode flow path is gas-liquid separated by the pressure adjusting unit 35 according to the temperature of the anode fluid or the operating state of the circulation pump under the control of the battery control unit 16. The pressure is adjusted within the optimum pressure range for the vessel 32. Thereby, the gas-liquid separator 32 can efficiently gas-liquid separate the gas-liquid two-phase fluid. Therefore, it is possible to prevent leakage of liquid to the outside of the fuel cell device and retention of carbon dioxide gas, and as a result, a fuel cell device with improved power generation efficiency can be obtained.

  Except for the pressure adjustment unit 35, the other configuration of the fuel cell device is the same as that of the first embodiment described above, and the same parts are denoted by the same reference numerals and detailed description thereof is omitted. Also in the third embodiment configured as described above, the same operational effects as those of the first embodiment described above can be obtained.

Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.
For example, in the gas-liquid separator, the shape of the gas permeable membrane is not limited to a cylindrical shape, but may be a sheet shape or any other shape. The gas exhausted from the gas-liquid separator is not limited to being directly discharged to the outside, but may be configured to be sent to the cathode flow path and discharged to the outside through a filter.

FIG. 1 is a diagram showing a circulation system of a fuel cell device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a cell stack of the fuel cell device. FIG. 3 is a diagram schematically showing a single cell of the cell stack. FIG. 4 is a sectional view showing a gas-liquid separator in the fuel cell device. FIG. 5 is a diagram showing the pressure and pressure loss of each part in the circulation system of the fuel cell device. FIG. 6 is a diagram showing the relationship between the viscosity of water and the temperature. FIG. 7 is a diagram showing the relationship between pressure loss and flow velocity. FIG. 8 is a flowchart showing an internal pressure control operation of the anode flow path. FIG. 9 is a cross-sectional view showing a cell stack of a fuel cell device according to a second embodiment of the present invention. FIG. 10 is a view showing a circulation system of a fuel cell device according to a third embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel cell apparatus, 12 ... Cell stack, 14 ... Fuel tank, 16 ... Battery control part,
20 ... circulation system, 22 ... anode passage, 24 ... cathode passage, 28 ... circulation pump,
32 ... Gas-liquid separator, 34 ... Temperature sensor, 35 ... Pressure adjusting part,
36 ... cathode (air electrode), 37 ... anode (fuel electrode), 54 ... separation tube,
54 ... Gas permeable membrane, 70 ... Buffer tank, 78 ... Water tank, 80 ... Water supply pump

Claims (6)

An electromotive unit comprising a cell having an anode and a cathode, and generating electricity by a chemical reaction;
A fuel tank containing fuel;
A circulation system comprising: an anode flow path for circulating fuel supplied from the fuel tank through the anode of the electromotive section; and a cathode flow path for supplying air through the cathode of the electromotive section;
A circulation pump for flowing fuel through the anode flow path;
A gas-liquid separator that is provided in the anode flow path on the outflow side of the electromotive unit and separates the gas-liquid two-phase flow discharged from the anode from a liquid and a gas, and is formed of a porous material, A gas-liquid separator having a first surface in contact with a gas-liquid two-phase flow discharged from the anode and a second surface in contact with air, and having a gas permeable member that transmits gas in the gas-liquid two-phase flow When,
A temperature sensor for measuring the temperature of the liquid in the anode channel;
A pressure adjusting unit for adjusting the pressure in the anode channel;
The pressure in the anode flow path is calculated based on the temperature of the liquid in the anode flow path measured by the temperature sensor, and the pressure adjusting unit adjusts the pressure in the anode flow path to be within a predetermined range. A battery controller for adjusting the pressure;
A fuel cell device comprising:   2. The fuel cell device according to claim 1, wherein the battery control unit adjusts the pressure of the pressure adjusting unit according to a temperature measured by the temperature sensor and a driving state of the circulation pump.   2. The fuel cell device according to claim 1, wherein the pressure adjusting unit includes a variable valve that is provided in the anode flow path and adjusts a flow rate of a liquid flowing through the anode flow path.   The pressure adjusting unit is provided in the anode flow path to store the liquid, and supplies the liquid to the buffer tank to adjust the amount of liquid stored in the buffer tank. The fuel cell device according to claim 1, further comprising a liquid supply unit that adjusts the pressure.   2. The fuel cell device according to claim 1, wherein the pressure adjusting unit has a reference pressure for normally operating the electromotive unit and an adjustment range in which the pressure can be adjusted in both directions higher and lower than the reference pressure.   The battery control unit calculates a pressure on the inflow side of the gas-liquid separator and a pressure on the outflow side of the gas-liquid separator based on the temperature measured by the temperature sensor, and the pressure on the inflow side However, when the upper limit of the pressure at which the gas-liquid separator functions is exceeded, or when the pressure on the outflow side is lower than the lower limit of the pressure at which the gas-liquid separator functions, the pressure adjusting unit The pressure on the inflow side is smaller than the upper limit of the pressure at which the gas-liquid separator functions, and the pressure on the outflow side is larger than the lower limit of the pressure at which the gas-liquid separator functions. The fuel cell device according to claim 1, wherein an internal pressure of the anode channel is adjusted.

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