JP2009170402A - Fuel cell and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize the electric output of a fuel cell stack and enhance the utilization efficiency of energy. <P>SOLUTION: The fuel cell has a power generation part having at least one membrane electrode assembly in which an electrolyte membrane is interposed between an anode and a cathode, and electric power is generated by supplying fuel to the anode and an oxidant to the cathode. In the fuel cell, an adiabatic heat insulating means adiabatically heat-insulating the power generation part by covering the power generation part is installed, and by supplying the oxidant through the adiabatic heat insulating means, the oxidant is heated by the heat generated in a heat generation part and supplied to the cathode. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell and a fuel cell system, and more particularly to a fuel cell system that uses a fuel cell in a power supply unit of an electronic device.

  In recent years, with the advancement of electronic technology, portable electronic devices such as mobile phones, notebook PCs, mini PCs (= pocket PCs), portable audio devices, and PDAs are rapidly spreading. These portable electronic devices occupy a large number of systems that operate using a secondary battery as a power source, and these systems are accelerating their functions from the viewpoint of user convenience. As these systems become more sophisticated in the market, the power consumption of the system tends to increase. Furthermore, since the portable electronic device is required to be used for a long time, the capacity of the secondary battery as a power source is increasing. In such a situation, the fuel cell is attracting attention. The fuel cell reaction basically takes out electrochemical energy in the process of producing water by reacting hydrogen and oxygen. Hydrogen used as a fuel is not necessarily hydrogen itself, and may be a compound containing a hydrogen group. Specific examples include alcohols and hydrocarbons. Similarly, oxygen is not necessarily oxygen, and air or the like is used as an oxidant.

  One type of fuel cell uses a polymer solid electrolyte. This type of fuel cell is characterized by low heat generation due to power generation loss, and has the advantage of high power generation efficiency at room temperature. On the other hand, when low-temperature power generation is used, the output is extremely small and the power generation efficiency is low. It also has the characteristic of lowering. In other words, the chemical reaction occurring in the fuel cell has a reaction rate that is a function of temperature. The reaction rate is low at low temperatures, and the reaction rate increases as the temperature increases. Therefore, if an attempt is made to extract power at a practical level, it is necessary to increase the reaction rate, and the fuel cell is required to generate electric power at an appropriate high temperature (so as not to cause a functional deterioration of materials used). Therefore, it is important to raise the fuel cell to an appropriate temperature for power generation, and it is also required to efficiently maintain the fuel cell temperature during power generation.

Several proposals have hitherto been made to meet such demands. For example, in Patent Document 1, air is supplied to the fuel cell and the cathode electrode of the fuel cell as a means for raising the temperature. In the fuel cell device comprising the air supply means, the temperature detection means for detecting the temperature of the fuel cell, and the air heating means for heating the supply air based on the temperature of the fuel battery cell detected by the temperature detection means As a result, a fuel cell device has been proposed that improves power generation efficiency at start-up and thaws ice in the device at low temperatures such as below freezing.
JP 2002-93445 A

  However, in Patent Document 1, energy consumption is large because air heating means is provided to heat the supply air to improve the power generation efficiency at the start. In addition, air in a room temperature environment is supplied to the cathode electrode of the fuel cell after the temperature of the fuel cell is raised, the temperature is lowered, and the power generation operation of the power generation unit becomes unstable.

  The present invention has been made to solve these problems, and an object of the present invention is to provide a fuel cell and a fuel cell system that can stabilize the electrical output of the fuel cell stack and increase the energy use efficiency.

  In order to solve the above problems, the fuel cell of the present invention has a power generation unit having at least one membrane electrode assembly in which an electrolyte membrane is sandwiched between an anode electrode and a cathode electrode, and supplies fuel to the anode electrode. Then, an oxidant is supplied to the cathode electrode to generate electricity. The fuel cell of the present invention is provided with a heat insulating and heating means that covers the power generation section and insulates and heats the power generation section. The oxidant is heated by the exhaust heat of the heat generating section through the heat insulation and heat insulation means to the cathode electrode. It is characterized by supply. Therefore, it is possible to provide a fuel cell in which the electric output of the fuel cell stack is stabilized and the energy utilization efficiency is high.

  In addition, a double structure of the first member and the second member is formed, and a heat insulating and warming means that covers and heat-insulates the power generation unit by covering the power generation unit is provided, and in the space formed by the first member and the second member The oxidant is passed through and heated by the exhaust heat of the heat generating portion, and the heated oxidant is supplied to the cathode electrode. Therefore, the oxidizing agent supplied to the cathode electrode can be heated.

  Furthermore, by forming a pipe line in the space and supplying an oxidant supplied to the cathode electrode to the pipe line, the oxidant supplied to the cathode electrode can be heated.

  Moreover, heat insulation heat retention can be improved by providing a heat insulating material in the inner wall of a 1st member.

  Further, the oxidant is heated through the condenser, and the oxidant further heated by the exhaust heat of the heat generating portion is supplied to the cathode electrode through the heat insulating heat retaining means. Therefore, the oxidant supplied to the cathode electrode is heated in advance through a condenser, so that the temperature variation in each cell of the power generation unit can be reduced, and the stability of the output during the power generation operation of the power generation unit can be improved. .

  A fuel cell system according to another invention is characterized in that it has the fuel cell, a DC-DC converter, and a capacitor, and supplies electric power necessary for the operation of a load device connected as a load. Therefore, by preheating the oxidant supplied to the cathode electrode, it is possible to provide a fuel cell system that can reduce the temperature variation in each cell of the power generation unit and can improve the stability of the output during the power generation operation of the power generation unit. .

  The fuel cell control unit further controls the concentration of the fuel supplied to the anode electrode of the fuel cell and the flow rate of the oxidant supplied to the cathode electrode according to the load of the load device. The fuel cell control unit reduces the concentration of the fuel supplied to the anode electrode of the fuel cell and decreases the flow rate of the oxidant supplied to the cathode electrode when the load of the load device becomes low. Take control. Therefore, the efficiency of the fuel cell system can be improved by eliminating excessive consumption of energy for warming the fuel cell when the load device is under low load.

  According to the present invention, by preheating the oxidant supplied to the cathode electrode by the heat of exhaust from the power generation unit by the heat insulation and heat insulation means for heat insulation of the power generation unit of the fuel cell, the temperature variation in each cell of the power generation unit is reduced. It is possible to provide a fuel cell that can be reduced and can improve the stability of the output of the power generation unit during power generation operation. Also, by mounting such a fuel cell, the output stability of the fuel cell system can be improved.

  Hereinafter, among various fuel cells, a polymer electrolyte fuel cell using a methanol aqueous solution as a fuel will be described as an example. The fuel cell of the present embodiment is an example of a power source that takes out energy in the form of electric power when water is produced by chemically reacting hydrogen and oxygen, in particular forced circulation using oxidant (air) and methanol as fuel. Although a direct methanol fuel cell (DMFC) is used, it may have other structures such as using various liquids such as ethanol and dimethyl ether as fuel.

  FIG. 1 is a perspective view showing a configuration of a fuel cell. As shown in the figure, the fuel cell stack 1 using liquid as a fuel is generally generated by a stack in which a plurality of power generation single cells 2 are stacked because the voltage of one power generation single cell 2 is low. . As shown in FIG. 1, the fuel cell stack 1 is configured by connecting a plurality of power generation single cells 2 in series. Since the output voltage of the power generation unit cell 2 is less than 1 V, a larger output voltage can be obtained by connecting a plurality of power generation unit cells 2 in series. The power generation unit cell 2 includes an anode electrode 3, a cathode electrode 4, and a polymer electrolyte membrane 5. The anode 3 has a catalyst (methanol oxidation electrode catalyst) 6 for electrochemically oxidizing methanol. The cathode 4 has a catalyst (oxygen reduction electrode catalyst) that selectively electrochemically reduces oxygen. The polymer electrolyte membrane 5 is sandwiched between the anode electrode 3 and the cathode electrode 4. When methanol is supplied to the anode electrode 3 and oxidant (air) is supplied to the cathode electrode 4, electric power is generated between the anode electrode 3 and the cathode electrode 4, and carbon dioxide is generated on the anode electrode 3 side. And water is generated on the cathode 4 side. As described above, the fuel cell stack 1 generates power by supplying methanol as a fuel to the anode 3 and supplying an oxidant (air) to the cathode 4.

  When the concentration of the fuel supplied to the fuel cell stack 1 is increased too much, a “crossover phenomenon” occurs in which the fuel that has not reacted at the anode electrode 3 passes through the polymer electrolyte membrane 5 and reacts at the cathode electrode 4. Since the polarization at the pole 3 increases, the output decreases. For this reason, it is necessary to make the fuel concentration about several percent. If the fuel stored in the fuel tank is kept at a few percent, the fuel tank becomes very large. Therefore, a high concentration (for example, 100%) of fuel is placed in the fuel tank, and the concentration is reduced to a few percent in the circulation tank. It is desirable that the fuel cell is supplied after being diluted. The concentration of the fuel in the circulation tank is monitored by a fuel concentration sensor. When the concentration is higher than a preset value, water is replenished with a pump. Conversely, when the concentration is low, fuel is replenished with a pump. It is controlled so that the concentration is always constant.

  During power generation of the fuel cell stack, the temperature is about 50 ° C. to 80 ° C. due to heat generated by a chemical reaction, and the fuel in the circulation tank circulates through the fuel cell, so the fuel in the circulation tank is also close to that temperature. Become. On the other hand, regarding the supply of the oxidant, air at room temperature (room temperature) is taken in, and is lower than the stack temperature. When the oxidizing agent is supplied by the air blower, the vicinity of the supply port to the stack is cooled and the vicinity of the outlet is heated by the temperature of the stack. The apparent temperature is detected by detecting one point in the stack as the temperature control and feeding back the temperature, so it is judged that the desired temperature control has been achieved, but temperature variations occur within the single power generation cell. Therefore, a local output deviation occurs in the power generation unit cell, and damage to the power generation unit cell is induced. Therefore, in the present invention, stable output power is obtained by reducing the output deviation in the power generation unit cell by reducing the temperature variation in the power generation unit cell.

  FIG. 2 is a block diagram showing the configuration of the fuel cell system of the present invention. A fuel cell system 100 of the present invention shown in the figure includes a fuel cell 20 including a fuel cell control unit 10, a DC-DC converter 40, and a capacitor 50, and is necessary for the operation of an electronic device 200 serving as a load. It functions as a power supply system that supplies power.

  The fuel cell 20 is a block diagram showing the configuration of the fuel cell in the fuel cell system according to the first embodiment of the present invention, as shown in FIG. A sensor 22, a fuel tank 23, a fuel pump 24, a water recovery tank 25, a water pump 26, a circulation tank 27, a fuel concentration sensor 28, a circulation pump 29, an air blower 30, an aggregator 31, and a fan 32 are housed (not shown). ) Is a power generation device configured by being placed inside.

  Further, as shown in FIG. 2, the DC-DC converter 40 stabilizes the output voltage of the unstable fuel cell and then supplies power to a load such as an electronic device. The battery 50 is configured by a secondary battery, an electric double layer capacitor, or the like, and is charged with an output current from the cell stack of the fuel cell. The storage battery 50 functions as a main power supply, has a capacity capable of supplying sufficient power to a fluctuating load, and the fuel cell 20 functions as an auxiliary power supply for charging the storage battery 50. Auxiliary devices such as the fuel pump 24 and the air blower 30 constituting the fuel cell 20 are controlled by the microcomputer of the fuel cell control unit 10 and take out electric power necessary for operation from the output of the fuel cell 20.

Here, since the value of the internal resistance of the fuel cell 20 is larger than the internal resistance of the battery 50, the power loss W is expressed as W = I ² × R when the current is I and the output resistance is R. When power is supplied directly to a load such as an electronic device having a large load variation by a fuel cell alone, a large current flows when the load increases, resulting in a large loss in output resistance and poor efficiency. Therefore, by providing the capacitor 50, when the load requires a large current, not only the output current from the cell stack but also the current can be supplied from the capacitor 50, so that the power loss due to the internal resistance of the cell stack is reduced and the power source is efficient. The system can be configured.

  Further, since the fuel cell 20 can extract less power per volume than the capacitor 50, the fuel cell 20 is used as a main power source, the fuel cell 20 is used as an auxiliary power source, and the fuel cell 20 is charged when the capacitor 50 is charged and the load capacity is increased. By having the function of assisting the battery 50, a small and lightweight fuel cell system can be configured.

Next, the operation of the fuel cell according to the present embodiment will be described.
The fuel tank 23 in FIG. 3 contains high concentration (almost 100%) methanol as liquid fuel. The fuel pump 24 sends the fuel in the fuel tank 23 to the circulation tank 27. Exhaust gas containing air and water (generated at the cathode electrode) is discharged from the cathode electrode of the cell stack 21, cooled through the condenser 31, and recovered as water in the water recovery tank 25. The recovered water is sent into the circulation tank 27 by the water pump 26. The circulation tank 27 is a tank for diluting the fuel from the fuel tank 23 with the water from the water recovery tank 25, and the fuel in the circulation tank 27 is adjusted to a constant value of several percent in the initial state. The concentration sensor 28 detects the fuel concentration in the circulation tank 27. The circulation pump 29 is arranged in the middle of the fuel supply path connecting the circulation tank 27 and the anode electrode, and supplies the fuel diluted in the circulation tank 27 to the anode electrode. The oxidizing agent (air) is supplied to the cathode electrode by the air blower 30. 2 monitors the fuel concentration in the circulation tank 27 detected by the concentration sensor 28, and when the fuel concentration in the circulation tank 27 is higher than a preset concentration set value, the water pump 26 Is intermittently operated to replenish water in the water recovery tank 25 to the circulation tank 27. When the fuel concentration in the circulation tank 27 is lower than the set value, the fuel pump 24 is intermittently operated to supply the fuel in the fuel tank 23 to the circulation tank 27. To replenish. Further, the fuel cell control unit 10 detects the amount of fuel in the circulation tank 27 with a sensor (not shown), and appropriately supplies fuel and water to the circulation tank 27.

  When taking out the output from the fuel cell, the chemical reaction that takes place in the fuel cell is a function of temperature, the reaction rate is slow at low temperatures, and the reaction rate increases at higher temperatures. If it is going to be taken out, it is necessary to increase the reaction rate, and the fuel cell is required to generate power at an appropriate high temperature. Therefore, in this embodiment, as shown in FIG. 3, the entire cell stack 21 that is a heat generating part is covered with a heat insulation and heat insulation package 33 as a heat insulation means. In this way, by covering the cell stack 21 with the heat insulation and heat insulation package 33, heat dissipation from the cell stack 21 can be kept in the heat insulation heat insulation package 33, so that the temperature drop of the cell stack 21 can be minimized. The operating temperature of the stack 21 can be maintained at an appropriate high temperature state, and the output can be prevented from decreasing due to the low temperature of the power generation unit. The temperature of the cell stack 21 needs to be maintained at an appropriate high temperature so as not to cause a functional deterioration of the materials to be used. For this purpose, the concentration of the fuel is adjusted as described later, or an oxidizing agent ( Control air supply rate.

  The heat insulation and heat insulation package 33 has a double structure in which a guide wall 34 is formed on the inner side and a package 35 is formed on the outer side, and a space 36 is formed between the guide wall 34 and the package 35. The guide wall 34 is provided with an inlet 37 and an outlet 38, and an oxidant (air) is a space formed by the guide wall 34 and the package 35 of the heat insulation and heat insulation package 33 that keeps heat from the air blower 30 through the inlet 37. 36, guided along the guide wall 34, heated by the cell stack 21, and flows into the cathode electrode from the outlet 38. That is, the oxidant (air) supplied to the cathode electrode is guided to the space 36 formed by the guide wall 34 and the package 35, and the oxidant (air) is heated using the exhaust heat from the cell stack 21. is there. The oxidant (air) may be heated by using the entire area inside the heat insulation and heat insulation package 33 in the space 36 formed by the guide wall 34 and the package 35 for heat insulation and heat insulation. As described above, the space 36 formed by the guide wall 34 and the package 35 for heat insulation is maintained at a high temperature, so that the oxidant (air) can be heated, and the heated oxidant (air) is guided. After being guided in a space 36 formed by the wall 34 and the package 35, the light is supplied to the cathode electrode. The oxidant (air) heated by the exhaust heat is supplied to the cathode electrode, and specifically, supplied to the cathode electrode 4 via the separator 7 in FIG.

  Here, FIG. 4 shows a configuration of a separator that guides the oxidant into the power generation unit cell. The groove shape of (a) in the figure is a serpentine type flow path, the groove shape of (b) in the figure is a parallel type flow path, the solid circle is a place where the temperature is low, and the dotted line circle is the temperature. It is a high place. Thus, the battery characteristics fluctuate due to temperature variations in the power generation unit cell. On the other hand, in the present embodiment, a space 36 is formed by the guide wall 34 and the package 35 for heat insulation and heat, and the oxidant is heated in the space and supplied to the cathode electrode. Variations in temperature are reduced, and fluctuations in battery characteristics are suppressed.

  In the present embodiment, since the exhaust heat energy of the power generation unit is used to heat the oxidant (air), the power generation unit is cooled, so that energy for maintaining the power generation unit at a high temperature is required. However, since the oxidizer (air) also cools the power generation unit because of the low temperature in the conventional example, energy is required to maintain the power generation unit at a high temperature. In this embodiment, the oxidant (air) is exhausted compared to the conventional example. Since the oxidant (air) is heated using heat, the energy of that amount has already been taken into the oxidant (air), so by further heating the oxidant (air) with less energy The operating temperature can be maintained. That is, it can be said that there is almost no difference in the energy balance between the preheating of the oxidizing agent (air) of the present embodiment and the supply of the conventional example. Since the oxidizing agent (air) can be heated and supplied to the cathode electrode without adding extra energy, fluctuations in battery characteristics due to temperature deviation can be suppressed.

Next, an example of the configuration of the heat insulation and heat insulation package used in the present embodiment will be described.
FIG. 5 is a diagram showing an example of the configuration of the heat insulation and heat insulation package of FIG. (A) of the same figure is sectional drawing, (b) of the figure is AA 'line sectional drawing of (a) of the same figure. In the heat insulation and heat insulation package shown in the figure, a plurality of pipes 39 connected in parallel at both ends of the inlet 37 and the outlet 38 of the oxidant (air) are installed in parallel, and the oxidant (air) is guided by the guide wall surface. Are evenly guided and can be heated efficiently.

  FIG. 6 is a diagram showing another example of the configuration of the heat insulation and heat insulation package of FIG. (A) of the same figure is sectional drawing, (b) of the figure is B-B 'sectional view taken on the line of (a) of the same figure. The heat insulation and heat insulation package shown in the figure shows a configuration in which both ends of an inlet 37 and an outlet 38 of an oxidant (air) are connected by a single conduit 39, and the oxidant (air) passes through the guide wall surface. It is configured so that it can be heated more efficiently by lengthening the residence time in the space 36 formed by the guide wall 34 and the package 35 in which the oxidant (air) is insulated and heat-insulated, evenly guided. Yes.

  In addition, the surface which forms space with the guide wall and package which carry out heat insulation shown in FIG.5 and FIG.6 may be a plurality of surfaces, and a plurality of surfaces may be used for the pipe arrangement.

  7 is a cross-sectional view showing another example of the configuration of the heat insulation and heat insulation package of FIG. As shown in the figure, a heat insulating material 41 is provided on the inner wall of the package 35 in the heat insulating and heat insulating package 33 of FIG. 6 to improve the heat insulating heat insulating performance and prevent escape to the outside of the heat generated by the power generation unit. (Air) is heated and supplied to the cathode electrode at a higher temperature.

  As described above, it is possible to realize a fuel cell system in which a fuel cell system including a fuel cell that supplies a heated oxidant to the cathode electrode of the fuel cell and the electric output of the fuel cell stack is stable can be realized.

  Here, one method for raising the temperature of the cell stack is to use a crossover of fuel. The fuel cell control unit keeps the concentration of methanol, which is fuel in the circulation tank consumed by power generation, constant, thereby preventing a decrease in generated power accompanying a decrease in methanol concentration. The fuel cell control unit prevents the so-called crossover phenomenon by controlling the concentration of the aqueous methanol solution in the circulation tank to about several percent. The crossover phenomenon is a phenomenon in which when the fuel concentration is high, the fuel that has not reacted at the anode electrode passes through the electrolyte membrane, reaches the cathode electrode, and reacts at the cathode electrode. When the crossover phenomenon occurs, the cathode electrode Therefore, the potential difference between the anode and the cathode is reduced, and the power that can be taken out is reduced.

  On the other hand, crossover methanol is accompanied by heat of reaction when it reacts at the cathode, so it is also considered as a method for raising the temperature of the fuel cell stack. As described above, activation by temperature greatly contributes to the chemical reaction itself, and it is known that output power can be taken out at higher temperatures, and it is better to operate at a high temperature within an appropriate range.

  Here, crossover is caused, that is, the concentration of methanol fuel is increased, the temperature is increased by utilizing the reaction at the cathode, and the overall redox reaction activity is increased to increase the output. Control is performed at a temperature with good fuel efficiency by adjusting the balance between the decrease in output due to the polarization of the cathode electrode caused by crossover by changing the fuel concentration.

Next, the control at the time of low load or high load of an electronic device to be loaded in power generation control using crossover will be described.
In an electronic device or the like of a target load, the load is not constant, and there are many low-load states such as standby mode and sleep mode. At this time, if the fuel cell system is operated in the same manner as during a normal load, less power is consumed for fuel consumption, resulting in inefficiency. One method of improving efficiency is achieved by lowering the target value of temperature control of the fuel cell to reduce fuel consumption and performing control at an appropriate temperature so as to cover the required power. That is, it is effective to lower the fuel concentration as a means for lowering the temperature.

  The fuel cell system 100 shown in FIG. 2 receives a low load mode (for example, standby mode or sleep mode) state in the load device 200 such as an electronic device to be loaded, and receives a status signal indicating a low load mode operation from the load device 300 ( (I / F (interface) of the signal is not shown), the fuel cell control unit 10 sets the operating temperature of the fuel cell to the set temperature at the time of low addition, and the fuel pump 24 as shown in FIGS. The amount of the high-concentration methanol solution supplied to the circulation tank 27 is decreased, the concentration sensor 28 is monitored by the fuel cell control unit 10, and the control is performed to the set concentration target value in the operation operation at low load. Realize. Further, the low load mode determination of the load device 200 is performed when the load device 200 and the fuel cell system 100 as described above do not have an I / F for receiving and receiving the load state of the load device 200. This can also be realized by determining that the load device 200 is in the low load mode by the fuel cell control unit 10 when the load current is continuously small for a certain period of time.

  In addition, when the fuel concentration is lowered, the above-described control for reducing the crossover amount is performed, the reaction heat at the cathode electrode is reduced, and the stack temperature is lowered. If low concentration operation control is performed, fuel consumption is reduced and fuel consumption efficiency is improved. In addition, since the required power during low load conditions such as standby and sleep modes is small, it is possible to reduce the amount of oxidant (air) supplied to the cathode electrode and reduce the power supply to the air blower. Therefore, it is possible to reduce the power of the auxiliary equipment. The power consumption of the air blower is high in the auxiliary equipment of the forced methanol DMFC (Direct Methanol Fuel Cell) direct methanol fuel cell system that uses oxidizer (air) and methanol as fuel, and the power consumption of the air blower is reduced. Greatly contributes to improving the efficiency of the fuel cell system. In this control, even if the cell stack temperature is lowered, the amount of oxidant (air) supply to the cathode electrode is also reduced, so the heating of the oxidant (air) and the supply to the cathode electrode are relative to the stack temperature. The problem does not arise because it is a relationship.

  Further, the load device 200 may be in a high load state during continuous driving or depending on the initial mode. In such a case, the temperature of the cell stack 21 in FIG. 3 rises and may reach a limit temperature. As described above, when the high temperature state is continued by the heat insulation and heat insulation package 33, the functions of materials used for the cell stack are deteriorated. Therefore, when the limit value is approached in this way, the fuel concentration cannot be lowered, so the amount of oxidant (air) supply to the cathode electrode is increased to increase the amount of low-temperature oxidant (air). To reduce the temperature of the cell stack.

  FIG. 8 is a block diagram showing the configuration of the fuel cell in the fuel cell system according to the second embodiment of the present invention. In the figure, the same reference numerals as those in FIG. In the present embodiment shown in the figure, exhaust gas containing air and water (generated at the cathode electrode) is discharged from the cathode electrode of the cell stack 21, cooled through the condenser 31, and supplied to the water recovery tank 25 as water. Collected. The recovered water is sent into the circulation tank 27 by the water pump 26.

  By the way, when extracting the output from the fuel cell, the chemical reaction that takes place in the fuel cell is a function of temperature, the reaction rate is slow at low temperatures, and the reaction rate increases at higher temperatures. If it is going to be taken out, it is necessary to increase the reaction rate, and the fuel cell is required to generate power at an appropriate high temperature. Therefore, in this embodiment, as shown in FIG. 8, as the heat insulation and heat insulation means, the whole cell stack 21 that is a heat generating part is covered with a heat insulation heat insulation package 33 that insulates and heats, and the operation temperature of the cell stack 21 is appropriately set. While maintaining a high temperature state and preventing a decrease in output due to a low temperature of the power generation unit, the heat insulation and heat insulation package 33 has a double structure in which a guide wall 34 is formed on the inner side and a package 35 is formed on the outer side. A space 36 is formed between the package 35 and the package 35.

  On the other hand, the oxidant (air) from the air blower 30 flows into the space 36 formed by the guide wall 34 and the package 35 of the heat insulation and heat insulation package 33 that heats and insulates through the condenser 31 and further through the inlet 37. 34, is heated by the cell stack 21, and flows into the cathode electrode from the outlet 38. That is, the oxidant (air) from the air blower 30 is preheated by the condenser 31, and the oxidant (air) supplied to the cathode electrode is guided to the space 36 formed by the guide wall 34 and the package 35. The oxidant (air) is further heated by utilizing the exhaust heat from 21. Exhaust gas containing air and water generated at the cathode electrode flows into the condenser 31 from the cathode electrode of the fuel cell. Since the exhaust itself is heated by the fuel cell, the condenser 31 is at a high temperature. Therefore, the oxidant that has passed through the condenser 31 is heated.

  Here, FIG. 9 shows the configuration of the condenser in the fuel cell of the present embodiment. In addition, (b) of the same figure is the C-C 'sectional view taken on the line of (a) of the same figure. As shown in FIGS. 4A and 4B, the fuel cell condenser 31 in the fuel cell system according to the present embodiment includes a conduit 42 through which exhaust flows and a conduit 42 through which oxidant passes. A two-layer structure separated by the partition wall 43 is formed. The reason why the inside of the pipe line 42 is divided into two layers by the partition wall 43 is that mixing of the exhaust gas and the oxidant is prevented, and the oxidant is heated by the heat of the exhaust gas through the partition wall 43 in the pipe line 42. This is for heat exchange. In addition, it is good to use the member of the pipe line 42 or the partition 43 for a high thermal conductivity.

  According to the fuel cell system of the present embodiment using the condenser 31 having such a configuration, the exhaust gas containing air and water generated at the cathode electrode is discharged from the cathode electrode of the fuel cell. Enters from the supply port at one end of the condenser 31, passes through the conduit 42 in the condenser 31, and exits from the discharge port. When the exhaust gas passes through the pipe line 42 in the condenser 31, heat is taken away through the heat radiation fins of the condenser 31 and cooled to become water. At the same time, the oxidant (air) supplied from the air blower 30 enters from the end surface supply port opposite to the exhaust supply port, passes through the conduit 42 in the condenser 31, and discharges on the side opposite to the exhaust discharge side. It exits from the outlet and is supplied to the heat generating portion 21. Therefore, by preheating the oxidant supplied to the cathode electrode of the heat generating part 21, the temperature variation in each cell of the heat generating part 21 can be reduced, and the stability of the output during power generation operation of the power generating part can be improved. it can.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications and substitutions are possible as long as they are described within the scope of the claims.

It is a perspective view which shows the structure of a fuel cell. It is a block diagram which shows the structure of the fuel cell system of this invention. It is a block diagram which shows the structure of the fuel cell in the fuel cell system which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows the structure of a separator. It is a figure which shows an example of a structure of the heat insulation heat retention package of FIG. It is a figure which shows the other example of a structure of the heat insulation heat retention package of FIG. It is sectional drawing which shows the other example of a structure of the heat insulation heat retention package of FIG. It is a block diagram which shows the structure of the fuel cell in the fuel cell system which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structure of the condenser in the fuel cell of 2nd Embodiment.

Explanation of symbols

1; fuel cell stack, 2; single power generation cell, 3; anode electrode,
4; cathode electrode, 5; polymer electrolyte membrane, 6; catalyst,
7; separator, 10; fuel cell control unit, 20; fuel cell,
21; cell stack, 22; temperature sensor, 23; fuel tank,
24; fuel pump, 25; water tank, 26; water pump,
27; Circulation tank, 28; Concentration sensor, 29; Circulation pump,
30; Air blower, 31; Condenser, 32; Fan,
33; heat insulation and heat insulation package; 34; guide wall; 35; package;
36; space, 37; inlet, 38; outlet, 39, 42;
40; DC-DC converter, 41; heat insulating material, 43; partition wall, 50;
100: Fuel cell system, 200: Load device.

Claims (8)

A fuel that has a power generation unit having at least one membrane electrode assembly in which an electrolyte membrane is sandwiched between an anode electrode and a cathode electrode, supplies fuel to the anode electrode, and supplies oxidant to the cathode electrode to generate electricity In batteries,
A heat insulating and heat insulating means for insulating and heat insulating the power generating section is provided so as to cover the power generating section, and the oxidant heated by the exhaust heat of the heat generating section is supplied to the cathode electrode through the heat insulating and heat insulating means. The fuel cell characterized by the above-mentioned.   The heat insulation and heat retaining means has a double structure of a first member and a second member for heat insulation and heat, and supplies the cathode electrode in a space formed by the first member and the second member. The fuel cell according to claim 1, wherein an oxidant is supplied.   The fuel cell according to claim 2, wherein a pipe line is formed in the space, and an oxidant supplied to the cathode electrode is supplied to the pipe line.   The fuel cell according to claim 2, wherein a heat insulating material is provided on an inner wall of the first member.   The oxidizing agent is heated through a condenser, and the heated oxidizing agent is further supplied to the cathode electrode by the exhaust heat of the heat generating portion via the heat insulating heat retaining means. Item 2. The fuel cell according to Item 1.   A fuel cell comprising the fuel cell according to any one of claims 1 to 5, a DC-DC converter, and a capacitor, and supplying electric power necessary for operation of a load device connected as a load. system.   The fuel cell control unit according to claim 6, further comprising a fuel cell control unit configured to control a concentration of fuel supplied to the anode electrode of the fuel cell and a flow rate of oxidant supplied to the cathode electrode according to a load of the load device. Fuel cell system.   The fuel cell control unit lowers the concentration of fuel supplied to the anode electrode of the fuel cell and decreases the flow rate of oxidant supplied to the cathode electrode when the load of the load device becomes low. The fuel cell system according to claim 7, wherein the control is performed as described above.

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