JP2011014429A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable operation of a fuel cell at higher temperature while securing efficient operation of the fuel cell in a fuel cell system.SOLUTION: In the fuel cell system 10, used gas exhausted from an anode-side gas outlet 54 of a fuel cell stack 14 is made to return to a circulation flow passage 60 by increasing its humidity, or moisture of the used gas is made to return to the circulation flow passage 60 as it is without separation, and a dew point-adjusting part 70 to adjust the dew point θ of gas supplied to an anode-side gas inlet 52 is installed at a vapor-liquid separator 58. In a control device 80, a threshold temperature Tof a cooling water for the fuel cell preliminarily set when operated in high temperature operation conditions set close to the upper limit of efficient operation conditions of the fuel cell stack 14, a cooling water temperature Tdetected by a cooling water thermometer 36 are compared, and operation of the dew point adjustment part 70 is controlled according to a difference between the threshold temperature Tand the cooling water temperature T.

Description

  The present invention relates to a fuel cell system, and more particularly to a fuel cell system in which a gas-liquid separator is provided at an anode side gas outlet for discharging spent anode side gas for supplying fuel gas to the fuel cell.

  Since there is little impact on the environment, fuel cells are installed in vehicles. A fuel cell, for example, supplies a fuel gas such as hydrogen to the anode side of unit cells constituting a fuel cell stack, supplies an oxidizing gas containing oxygen, such as air, to the cathode side, and requires electric power required for reaction through an electrolyte membrane. Take out.

  At this time, water is generated as a reaction product on the cathode side. The generated water permeates through the electrolyte membrane to the anode side, so that the anode side of the electrolyte membrane also has an appropriate humidity, and the protons of hydrogen move under that humidity. Electricity is generated by the reaction. Therefore, in order to efficiently generate power, the electrolyte membrane needs to have an appropriate humidity.

  In addition, the used gas discharged from the anode side contains water due to the water permeating the anode side. The used gas discharged from the anode side is so-called exhaust gas, but contains hydrogen that has not been used for the reaction in the fuel cell, so that it is recovered and supplied to the anode side again. At this time, it is necessary to separate the liquid exhaust gas discharged from the anode side into a gas and a liquid, and a gas-liquid separator is used for this purpose.

  For example, in Patent Document 1, as a fuel cell system, a supply channel for supplying hydrogen, which is a fuel gas, to a fuel cell, and a hydrogen off-gas (fuel off-gas) discharged from the fuel cell at the junction of the hydrogen supply channel It is provided with a circulation channel for returning and an injector provided on the upstream side of the junction, and the exhaust channel is connected to the circulation channel via a gas-liquid separator and an exhaust drain valve. It has been. Here, it is disclosed that a pressure change arranged at a downstream position of the injector is used in order to estimate a purge amount for discharging the hydrogen off gas to the outside by the exhaust drain valve.

  In Patent Document 2, as the fuel cell system, the humidity inside the fuel cell is detected, and when the humidity is lower than a predetermined threshold, the anode off-gas that is discharged from the anode side is supplied to the cathode side. It is disclosed to send to the cathode inlet via a connecting passage.

  As a technique related to the gas-liquid separator related to the present invention, Patent Document 3 discloses a method for determining whether or not a magnetic iron-in-liquid piece is attracted by a magnet as a method for determining the freezing of the gas-liquid separator in a fuel cell system. In addition, it is determined by pressure detection indicating deformation of the rubber thin film that the volume expands due to freezing of water, and a part of the anode off-gas flows through the pipe that opens into the liquid of the gas-liquid separator. In this case, it is described that it is determined whether or not the pressure at the hydrogen pump becomes normal by being discharged into the liquid as bubbles and recovered again. In addition, when it determines with having frozen, it defrosts with the heater arrange | positioned in the vicinity of a gas-liquid separator.

  In Patent Document 4, in a direct methanol fuel cell device that generates electricity by reaction of a methanol solution and air to generate carbon dioxide gas and water, unreacted methanol, carbon dioxide gas and water as reaction products are mixed. It is stated that when gas-liquid separation is performed using a porous tube, if there is a temperature difference between the gas-liquid two-phase flow flowing through the porous tube and the gas-liquid separator, condensation will occur and the porous tube will be clogged. Yes. Here, it is disclosed that this temperature difference is reduced by using a heater or a cooling fan provided outside the container of the gas-liquid separator.

  Further, in Patent Document 5, as the fuel cell system, when the unreacted hydrogen discharged is recycled to the fuel cell, the unreacted hydrogen is about 70-80 ° C., and the supplied hydrogen combined with the unreacted hydrogen is about 30 ° C. Therefore, it is described that moisture in unreacted hydrogen is condensed and clogging occurs. Therefore, it has been disclosed that the unreacted hydrogen discharged is preliminarily removed by exchanging heat with the outside air or by exchanging heat with supplied hydrogen whose temperature has been increased. Examples of the temperature increase of the supply hydrogen include temperature increase due to reduced pressure, heating with exhaust air, heating with supply air, and heating with a heater. It is stated that the water recovered by removal can be used for other purposes such as humidification of the gas supplied to the fuel cell.

  In Patent Document 6, the gas-liquid separator of the fuel cell system is provided with means for cooling water contained in the exhaust gas to improve the water recovery efficiency, and the recovered water is used for spraying the radiator, humidifying the hydrogen gas, air It is stated that it is used for humidification. Here, as the cooling means, heat exchange with heat pipes, fins, and low-temperature refrigerant of the refrigeration cycle apparatus that performs heat exchange with the outside air is described.

  Patent Document 7 states that in a fuel cell system, a gas humidifier may not work at the start-up, and a bypass flow path may be used, and in these cases, an appropriate humidity cannot be given to the reaction gas. It has been. Here, it is disclosed that a heating humidifier including a housing for storing water obtained by the gas-liquid separator, a hollow fiber membrane, and a heater for heating the inside of the housing is provided in the bypass flow path.

JP 2008-293761 A JP 2008-288147 A JP 2004-286969 A JP 2008-243747 A JP 2003-317753 A JP 2002-313383 A JP 2002-117879 A

  For efficient power generation of the fuel cell, the electrolyte membrane needs to have an appropriate humidity. Therefore, the temperature of the fuel cell cannot be increased too much. That is, when the temperature of the fuel cell is increased, the dew point of the fuel gas and the dew point of the oxidizing gas are lowered, and the electrolyte membrane is easily dried. In particular, on the anode side of the electrolyte membrane, water produced on the cathode side permeates through the electrolyte membrane, but this moisture moves again to the cathode side as protons move, so compared to the cathode side It tends to dry easily.

  For these reasons, the temperature of the cooling water for adjusting the temperature of the fuel cell cannot be so high, for example, when the fuel cell is mounted on a vehicle, it is lower than the temperature of the cooling water used for air conditioning. Set to temperature. Therefore, the temperature difference between the temperature of the cooling water for the fuel cell and the outside air temperature is smaller than that in the case of the cooling water for air conditioning, which limits the miniaturization of the cooling mechanism for the fuel cell.

  An object of the present invention is to provide a fuel cell system that enables higher temperature operation of the fuel cell while ensuring efficient operation of the fuel cell.

  A fuel cell system according to the present invention includes a supply flow path for supplying fuel gas to an anode side gas inlet of a fuel cell, a discharge flow path for discharging used gas from the anode side gas outlet of the fuel cell, and a discharge flow path. Provided between the circulation flow path connected between the supply flow path, the branch point of the discharge flow path and the circulation flow path, and the anode side gas outlet, to separate moisture from the used gas, The gas-liquid separator that returns the separated gas to the circulation flow path, the temperature detector that detects the temperature of the cooling water for the fuel cell, and the gas-liquid separator are provided to increase the humidity of the used gas and circulate it. A dew point adjustment unit that adjusts the dew point of the gas supplied to the anode side gas inlet, and returns it to the circulation channel without separating the water of the used gas without separating the water, and the efficient operating conditions of the fuel cell When operating under high temperature operating conditions set close to the upper limit The preset threshold temperature of the coolant for the fuel cell is compared with the coolant temperature acquired by the temperature detector, and the operation of the dew point adjuster is controlled according to the difference between the threshold temperature and the coolant temperature. And a control unit.

  Further, in the fuel cell system according to the present invention, the dew point adjustment unit includes a heater provided in the gas-liquid separator, and the control unit controls the operation of the heater according to a difference between the threshold temperature and the cooling water temperature, It is preferable to adjust the temperature of the stored water stored in the gas-liquid separator.

  Further, in the fuel cell system according to the present invention, the dew point adjustment unit branches from the cooling water circulation passage of the fuel cell, passes through the stored water stored in the gas-liquid separator, and returns to the cooling water circulation passage again. A cooling water adjustment valve provided in the cooling water branch flow path, and the control unit controls the operation of the cooling water adjustment valve according to a difference between the threshold temperature and the cooling water temperature, It is preferable to adjust the amount of branch cooling water flowing through the path.

  Further, in the fuel cell system according to the present invention, the dew point adjusting unit has one end connected to a branch point provided in the discharge flow path from the anode side gas outlet to the gas-liquid separator, and the other end to the gas-liquid separator. A branch pipe that opens into the stored water to be stored, and when used gas flows through it, it can return the used gas to the discharge channel while bubbling the stored water And a bubble regulating valve provided at the branch point, and the control unit controls the operation of the bubble regulating valve according to the difference between the threshold temperature and the cooling water temperature, and controls the used gas flowing through the bubble branching channel. The amount is preferably adjusted.

  Further, in the fuel cell system according to the present invention, the dew point adjusting unit includes a bypass channel that allows the used gas to flow from the anode side gas outlet to the circulation channel without going through the gas-liquid separator, and the bypass channel. The control unit controls the operation of the bypass adjustment valve according to the difference between the threshold temperature and the cooling water temperature, and the amount of used gas flowing through the bypass flow path from the anode side gas outlet side. Is preferably adjusted.

  Further, in the fuel cell system according to the present invention, the gas-liquid separator is provided separately from the drain valve for draining water that is gas-liquid separated and stored in the gas-liquid separator to the outside, and the gas-liquid separator. And an exhaust valve for exhausting the separated gas in the gas-liquid separator to the outside.

  The fuel cell system according to the present invention further includes an impedance detection unit that detects the impedance of the fuel cell, and the control unit previously determines the impedance of the fuel cell when the coolant temperature is higher than the threshold temperature by the temperature detection unit. It is preferable to control the operation of the dew point adjustment unit in accordance with the difference between the threshold impedance and the impedance acquired by the impedance detection unit and the threshold impedance in comparison with the determined threshold impedance.

  In the fuel cell system according to the present invention, the heater is preferably a heater having a characteristic that the resistance value increases as the temperature increases.

  In the fuel cell system according to the present invention, the bypass channel preferably has a heat insulating material provided on the outer periphery and thermally insulated from the outside.

  In the fuel cell system according to the present invention, the bypass channel is preferably made of a highly heat-insulating material.

  With the above configuration, the fuel cell system is provided in the gas-liquid separator, increases the humidity of the used gas and returns it to the circulation channel, or returns it to the circulation channel as it is without separating the moisture of the used gas, For fuel cells that have a dew point adjustment unit that adjusts the dew point of the gas supplied to the anode side gas inlet and that are set in advance when operating under high temperature operating conditions set close to the upper limit of the efficient operating conditions of the fuel cell The cooling water threshold temperature is compared with the cooling water temperature acquired by the temperature detection unit, and the operation of the dew point adjustment unit is controlled according to the difference between the threshold temperature and the cooling water temperature. Thus, the fuel cell can be operated at a high temperature while adjusting the dew point of the gas supplied to the anode side gas inlet according to the temperature of the cooling water to ensure the efficient operation of the fuel cell.

  In the fuel cell system, a heater is provided in the gas-liquid separator, and the heater operation is controlled according to the difference between the threshold temperature and the cooling water temperature, and the temperature of the stored water stored in the gas-liquid separator is adjusted. . By adjusting the temperature of the stored water, it is possible to increase the humidity of the used gas and return it to the circulation flow path, thereby adjusting the dew point of the gas supplied to the anode side gas inlet according to the temperature of the cooling water. be able to.

  Also, in the fuel cell system, a cooling water adjustment valve is provided in the cooling water branch passage that branches from the cooling water circulation passage of the fuel cell, passes through the stored water stored in the gas-liquid separator, and returns to the cooling water circulation passage again. The operation of the cooling water adjustment valve is controlled in accordance with the difference between the threshold temperature and the cooling water temperature to adjust the amount of branch cooling water flowing through the cooling water branch flow path. Since the temperature of the cooling water of the fuel cell is higher than the temperature of the stored water, the temperature of the stored water can be adjusted by adjusting the amount of the branch cooling water. As a result, the humidity of the used gas can be increased and returned to the circulation flow path.

  Further, in the fuel cell system, one end is connected to a branch point provided in the discharge flow path from the anode side gas outlet to the gas-liquid separator, and the other end is opened in the stored water stored in the gas-liquid separator. A branch pipe for bubbling that can return the used gas to the discharge flow path while bubbling the stored water when used gas flows therein, and a bubble provided at the branch point Including a regulating valve. By bubbling the stored water, it is possible to increase the humidity of the gas in the gas-liquid separator, thereby increasing the humidity of the used gas and returning it to the circulation channel.

  Further, in the fuel cell system, a bypass adjustment valve is provided in a bypass channel that allows the used gas to flow from the anode side gas outlet to the circulation channel without going through the gas-liquid separator, and the threshold temperature and the cooling water temperature are The operation of the bypass adjusting valve is controlled according to the difference between the two. Since the temperature of the gas-liquid separator itself is lower than the temperature of the used gas, when the used gas enters the gas-liquid separator, moisture contained in the used gas is aggregated and the humidity of the used gas is reduced. descend. When the fuel cell is operated at a high temperature, the moisture contained in the used gas is originally low, so that the moisture is further reduced by passing through the gas-liquid separator. Therefore, in such a case, it is preferable to return the used gas to the circulation flow path without passing through the gas-liquid separator.

  According to the above configuration, since the operation of the bypass adjusting valve is controlled according to the temperature of the cooling water, when the fuel cell is operated at a high temperature and the humidity of the used gas is low, the gas-liquid separator is not passed. In addition, the used gas can be directly returned to the circulation channel via the bypass channel. Thus, the fuel cell can be operated at a high temperature while adjusting the dew point of the gas supplied to the anode side gas inlet according to the temperature of the cooling water to ensure the efficient operation of the fuel cell.

  In the fuel cell system, the gas-liquid separator is separated from the gas-liquid separated gas-liquid separator separately from the drain valve for draining water stored in the gas-liquid separator. An exhaust valve for exhausting the rear gas to the outside is provided. I want to store water in the gas-liquid separator and use this stored water to humidify the used gas, but on the other hand, exhaust gas when the concentration of impurity gas in the gas that has been gas-liquid separated to remove moisture has increased. What you want to do happens. According to the above configuration, drainage and exhaust can be performed at independent timings, and high-temperature operation of the fuel cell is possible while ensuring efficient operation of the fuel cell.

  Also, in the fuel cell system, when the coolant temperature is higher than the threshold temperature, the fuel cell impedance is further detected and compared with a predetermined threshold impedance, and the operation of the dew point adjustment unit is controlled according to the difference. Is done. As a result, fine control of high-temperature operation is possible while ensuring efficient operation of the fuel cell.

  In the fuel cell system, since the heater has a characteristic that the resistance value increases as the temperature increases, the runaway of the heater operation can be automatically suppressed.

  In the fuel cell system, since the bypass channel has a heat insulating material, aggregation of moisture contained in the used gas can be suppressed. In the fuel cell system, the bypass channel is made of a highly heat-insulating material, and in this case as well, aggregation of moisture contained in the used gas can be suppressed.

It is a figure explaining the structure of the fuel cell system in embodiment which concerns on this invention. FIG. 5 is a relational diagram that is the basis of the present invention and is a diagram for explaining the relation among the operating temperature of the fuel cell, the cell voltage, and the gas dew point at the anode side gas inlet. FIG. 5 is a relational diagram that is the basis of the present invention and is a diagram for explaining the relation between the cell voltage and the dew point of the gas at the anode side gas inlet with the operating temperature of the fuel cell being constant. In embodiment which concerns on this invention, it is a figure explaining the example which uses a heater for a gas-liquid separator. 4 is a flowchart illustrating a procedure for adjusting the dew point of gas supplied to an anode side gas inlet during high temperature operation of a fuel cell, taking as an example a heater provided in a gas-liquid separator in an embodiment according to the present invention. . In embodiment which concerns on this invention, it is a figure explaining the example which diverts the cooling water for fuel cells to a gas-liquid separator, and adjusts temperature. In embodiment which concerns on this invention, it is a figure explaining the example which provides a bubble mechanism in a gas-liquid separator. In embodiment which concerns on this invention, it is a figure explaining the example which provides the flow path which bypasses a gas-liquid separator. In embodiment which concerns on this invention, it is a figure explaining the example which provides an exhaust valve separately from a drain valve in a gas-liquid separator.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. Below, what is provided in the fuel cell mounted in a vehicle as a gas-liquid separator is demonstrated, However, You may provide in fuel cells other than vehicle-mounted. For example, a stationary fuel cell system may be used.

  In the following, as a fuel cell system, a hydrogen tank, a regulator, a hydrogen circulation pump, a gas-liquid separator, and a drain valve are arranged on the anode side, and an air source, an air compressor (ACP), a humidifier, Although the explanation will be made on the assumption that a pressure regulating valve and a cooling water system are arranged, this is an example for explanation, and other elements such as a gas shut valve, an appropriate gas bypass system, etc. are added. can do.

  In addition, materials, temperatures, and the like described below are illustrative examples, and can be appropriately changed according to the specifications of the fuel cell system.

  Below, the same code | symbol is attached | subjected to the same element in all the drawings, and the overlapping description is abbreviate | omitted. In the description in the text, the symbols described before are used as necessary.

  FIG. 1 is a diagram showing a configuration of a fuel cell system 10 mounted on a vehicle. The fuel cell system 10 is mounted on a hybrid vehicle and used as a power source for a rotating electric machine for traveling. FIG. 1 shows a load 8 that is not a component of the fuel cell system 10 but is driven by using the generated power. The load 8 includes all electric devices that use the power generated by the fuel cell system 10, but the load 8 directly connected to the fuel cell system 10 includes an inverter circuit for a rotating electrical machine, a DC / DC converter, and the like. It is.

  The fuel cell system 10 includes a system main body 12 and a control device 80 that controls the operation of each component of the system main body 12 as a whole based on a driving command from a vehicle driving command unit (not shown). The

  The system main body 12 includes a fuel cell main body called a fuel cell stack 14 in which a plurality of fuel cells are stacked, elements for supplying hydrogen gas arranged on the anode side of the fuel cell stack 14, and a cathode side. Each element for air supply is configured.

  The fuel cell stack 14 is an assembled battery configured to connect a plurality of unit fuel cells called single cells and take out a desired terminal voltage and output current. A single cell has a structure in which a catalyst layer, a diffusion layer, a porous electrode layer, and a separator are arranged on the cathode side and the anode side on both sides of the electrolyte membrane, and a fuel gas such as hydrogen is supplied to the anode side. In addition, an oxidizing gas containing oxygen, for example, air, is supplied to the cathode side, and it has a function of generating electric power by an electrochemical reaction through the electrolyte membrane and taking out necessary electric power.

  The oxygen supply source (AIR) 20 on the cathode side is an oxidizing gas source, but in reality, the atmosphere can be used. The filter 22 has a function of removing a foreign substance in the atmosphere, which is the oxygen supply source 20, so as to be in a state suitable for supplying the fuel cell stack 14.

  The air compressor (ACP) 24 is a gas booster that increases the pressure by compressing the volume of oxidizing gas by a motor (not shown). In addition, the ACP 24 has a function of providing a predetermined amount of oxidizing gas by changing the rotation speed (the number of rotations per minute) under the control of the control device 80. That is, when the required flow rate of the oxidizing gas is large, the rotational speed of the motor is increased. Conversely, when the required flow rate of the oxidizing gas is small, the rotational speed of the motor is decreased.

  As described above, since oxygen-containing air is supplied to the cathode side of the fuel cell stack 14 by the ACP 24 under the control of the control device 80, elements from the oxygen supply source 20 to the ACP 24 may be referred to as an oxygen supply device. it can.

  The oxidizing gas supply flow path connecting the ACP 24 and the cathode side gas inlet of the fuel cell stack 14 is a gas pipe having a function of supplying the oxidizing gas adjusted to an appropriate pressure and flow rate by the ACP 24 to the fuel cell stack 14. .

  The oxidizing gas discharge flow path connected to the cathode side gas outlet of the fuel cell stack 14 is used to convert the oxidizing gas used from the oxidation gas supplied from the cathode side gas inlet of the fuel cell stack 14 through an electrochemical reaction. It is a gas pipe to be discharged.

  The humidifier 26 arranged across the oxidizing gas supply channel and the oxidizing gas discharge channel is a gas exchange type humidifier having a function of humidifying the oxidizing gas supplied from the ACP 26 and supplying the humidified gas to the fuel cell stack 14. is there. Here, the used oxidizing gas containing water vapor as a reaction product discharged from the fuel cell stack 14 is used, and the water vapor is supplied to the oxidizing gas supplied from the ACP 26 through the hollow fiber and humidified.

  The pressure regulating valve 28 arranged and connected in series with the oxidizing gas discharge channel immediately downstream of the cathode side gas outlet is also called a back pressure valve, and adjusts the gas pressure at the cathode side gas outlet to oxidize the fuel cell stack 14. It is a valve having a function of adjusting the flow rate of gas.

  The used oxidizing gas from the pressure regulating valve 28 via the humidifier 26 is combined with water or water vapor as a reaction product in the fuel cell stack 14 as a cathode side exhaust gas via a diluter, a muffler or the like. It is discharged to the outside air (EX).

  The anode-side hydrogen gas source 40 is a tank that supplies hydrogen as a fuel gas. A plurality of tanks may be connected in parallel. The hydrogen gas source 40 is connected to regulators 44 and 46 via a shutoff valve 42 provided at a tank supply port. The regulators 44 and 46 have a function of adjusting the high gas pressure of the hydrogen gas source 40 to an appropriate pressure under the control of the control device 80. In the example of FIG. 1, the regulators 44 and 46 are connected in two stages in series, but this makes it possible to effectively lower the high gas pressure in the tank.

  The injector 48 provided on the downstream side of the regulator 44 is a kind of on-off valve having a function of adjusting the gas flow rate and the gas pressure by driving the valve body with an electromagnetic driving force at a predetermined driving cycle and separating it from the valve seat. It is. The operation of the injector 48 is controlled by the control device 80, whereby the flow rate of the hydrogen gas supplied to the fuel cell stack 14 can be adapted to the operation command.

  A fuel gas supply channel 50 provided between the output port of the injector 48 and the anode side gas inlet 52 of the fuel cell stack 14 has a function of actually supplying hydrogen, which is a fuel gas, to the fuel cell stack 14. It is piping.

  The discharge flow path 56 connected to the anode side gas outlet 54 of the fuel cell stack 14 is a fuel gas that has been used after the fuel gas supplied from the anode side gas inlet 52 of the fuel cell stack 14 undergoes an electrochemical reaction. It is gas piping which discharges.

  The circulation flow path 60 connected and disposed between the discharge flow path 56 and the supply flow path 50 uses the hydrogen gas in the used fuel gas discharged from the anode side gas outlet 54 again. The gas pipe has a function of returning to the anode side gas inlet 52.

  The hydrogen pump 62 provided in the circulation channel 60 is a gas pump having a function of appropriately pressurizing the gas returned to the circulation channel 60 and supplying it to the supply channel 50.

  The gas-liquid separator 58 disposed in the fuel gas discharge flow path 56 includes a used fuel gas mixed with moisture discharged from the anode side gas outlet 54, a gas containing a large amount of fuel gas having a small specific mass, and a specific mass. It is an apparatus having a function of separating into an impurity gas mixed with water having a large size. The gas containing a large amount of fuel gas separated by the gas-liquid separator 58 is returned again to the supply flow path 50 through the circulation flow path 60 as described above. Further, the hydrogen gas mixed with the water and the impurity gas separated by the gas-liquid separator 58 is discharged to the outside air (EX) via the drain valve 59 and as the anode side exhaust gas via the diluter 64.

  The gas-liquid separator 58 includes an inlet for introducing a liquid-mixed gas, a mechanism for separating the liquid-mixed gas into liquid and gas, an output port for outputting the separated gas, and a separated liquid. Or the container which has the discharge port which discharges | emits the gas mixed with a liquid is used. As a mechanism for separating liquid-mixed gas into gas and liquid, in addition to a configuration that uses the principle of separating gas and liquid due to the difference in specific mass between them, a separation by centrifugal force is used. The structure which uses or the structure using the separation by surface tension can be used.

  The dew point adjusting unit 70 provided in the gas-liquid separator 58 increases the humidity of the used gas from the anode side gas outlet 54 of the fuel cell stack 14 and returns it to the circulation channel 60 or separates the moisture of the used gas. This is a mechanism having a function of adjusting the dew point of the gas supplied to the anode side gas inlet 52 without returning to the circulation flow path 60 as it is.

  As the dew point adjusting unit 70, a heater or the like that adjusts the temperature of the stored water of the gas-liquid separator 58, or a bypass channel that bypasses the gas-liquid separator 58 and avoids water aggregation by the gas-liquid separator 58 is used. Can do. A specific configuration and operation of the dew point adjusting unit 70 will be described later.

  The cooling water circulation passage 30 is a pipe for flowing cooling water as a refrigerant in order to maintain the fuel cell stack 14 at an appropriate temperature. The cooling water circulation passage 30 is provided with a cooling water circulation pump 32 in the middle, and circulates the cooling water between the fuel cell stack 14 and the radiator 34 which is a heat exchanger.

Coolant temperature gauge 36 provided in the cooling water circulation passage 30 is a temperature detecting means having a function of detecting a coolant temperature T _FC. Coolant temperature T _FC, since through the fuel cell stack 14 as described above, so that is representative of the temperature of the fuel cell stack 14. The temperature of the fuel cell stack 14 affects the humidity of the electrolyte membrane in the single cell that constitutes the fuel cell stack 14. For example, when the temperature of the fuel cell stack 14 is high, the humidity of the electrolyte membrane decreases, and the fuel cell stack 14 becomes dry and the power generation efficiency decreases. On the other hand, when the temperature of the fuel cell stack 14 is low, the humidity of the electrolyte membrane increases, and in some cases, the electrolyte membrane is flooded with water, which makes it difficult for gas to move and hinders power generation.

Thus, the cooling water temperature T _FC typically represents the temperature of the fuel cell stack 14 that affects the power generation of the fuel cell stack 14. Therefore, the cooling water temperature T _FC detected by the coolant temperature gauge 36, through an appropriate signal line is transmitted to the control device 80 is used for operation control of the fuel cell system 10.

  It should be noted that the state of humidity in the electrolyte membrane of the single cell constituting the fuel cell stack 14 can be evaluated by measuring the impedance Z of the single cell. That is, when the humidity of the electrolyte membrane is high, the impedance Z shows a low value. Conversely, when the humidity of the electrolyte membrane is low, the impedance Z shows a high value. The Z measuring device 66 is an impedance detection unit having a function of measuring the impedance Z of the single cell that constitutes the fuel cell stack 14. The impedance Z can be measured by a high frequency impedance measurement method or the like in addition to a method using voltage and current.

  The impedance Z typically indicates the humidity of the electrolyte membrane that affects the power generation of the fuel cell stack 14 as described above. Therefore, the impedance Z detected by the Z measuring device 66 is transmitted to the control device 80 via an appropriate signal line and used for operation control of the fuel cell system 10.

  The control device 80 controls each component of the system body 12 as a whole system in accordance with a fuel cell operation command from an operation command unit (not shown), and is sometimes called a so-called fuel cell CPU. For example, according to the fuel cell operation command, the operation of the ACP 24 is controlled to adjust the flow rate of the oxidizing gas supplied to the fuel cell stack 14, the operation of the pressure regulating valve 28 is controlled to adjust the pressure of the oxidizing gas, and the injector It has a function of controlling the operation of 48 and adjusting the flow rate of the fuel gas supplied to the fuel cell stack 14.

  Here, particularly, when operating under high temperature operating conditions set close to the upper limit of the efficient operating conditions of the fuel cell system 10, the operation of the dew point adjustment unit 70 is controlled, and the gas at the anode side gas inlet 52 is controlled. Has the function of adjusting the dew point appropriately. In order to show the evaluation point of the gas dew point at the anode side gas inlet 52, FIG. 1 shows a state in which a dew point evaluation means 68 for evaluating the dew point θ is provided immediately upstream of the anode side gas inlet 52. ing.

For this purpose, the control device 80 obtains the cooling water temperature acquisition processing unit 82 that acquires the cooling water temperature T _FC detected by the cooling water thermometer 36, the detected cooling water temperature T _FC, and the high temperature of the fuel cell system 10. A temperature comparison processing unit 84 that compares the threshold temperature T ₀ of the cooling water for the fuel cell set in advance during operation, and the dew point adjustment unit 70 according to the difference between the threshold temperature T ₀ and the cooling water temperature T _FC The dew point adjustment processing unit 86 is configured to control the operation.

  The control device 80 can be configured by a computer suitable for mounting on a vehicle. Each of the above functions can be realized by executing software. Specifically, these functions can be realized by executing a fuel cell operation program. Some of these functions may be realized by hardware.

FIG. 2 and FIG. 3 are diagrams for explaining the idea underlying the present invention. In these drawings, the relationship between the operating temperature of the fuel cell, the cell voltage that is the terminal voltage of the unit cell, and the gas dew point θ at the anode side gas inlet 52 is shown. That is, FIG. 2, the dew point θ at the anode side gas inlet 52 as a parameter, the cooling water temperature T _FC of the fuel cell stack 14 is taken on the horizontal axis, the cell voltage is taken on the vertical axis. 3 shows, as a state in which the cooling water temperature T _FC is constant, the horizontal axis represents the dew point θ of the gas in the anode gas inlet 52, the cell voltage is taken on the vertical axis.

In FIG. 2, the dew point θ of the gas at the anode side gas inlet 52 is θ ₃ > θ ₂ > θ ₁ . As shown in FIG. 2, as the cooling water temperature T _FC becomes high, the cell voltage decreases, the power generation efficiency of the fuel cell stack 14 is seen to decrease. Under general operating conditions, the cooling water temperature T _FC is set in a range where the cell voltage does not change much even if the cooling water temperature T _FC changes. Assuming that the upper limit cooling water temperature T _FC is the threshold temperature T ₀ , if the cooling water temperature T _FC is less than the threshold temperature T ₀ , the fuel cell system 10 can be efficiently operated regardless of the change in the cooling water temperature T _FC. You can drive.

In other words, when the cooling water temperature T _FC is equal to or higher than the threshold temperature T ₀ , the cell voltage is lowered as it is, and the power generation efficiency of the fuel cell system 10 is lowered. Incidentally, according to FIG. 2, even in such a case, it is possible to suppress a decrease in power generation efficiency of the fuel cell system 10 by increasing the gas dew point θ at the anode side gas inlet 52. For example, instead of the dew point theta _1, if it is possible to dew point theta _2, T _FC the start of reduction of the cell voltage extends to the high temperature side. If it is possible further to the dew point theta _3, can be extended beginning T _FC of cell voltage reduction significantly to the high temperature side. The situation is also shown in FIG.

That is, when operating at a high temperature operating condition set close to the upper limit of the efficient operating condition of the fuel cell system 10, look at the deviation from the preset threshold temperature T ₀ of the cooling water for the fuel cell. The dew point θ of the gas at the anode side gas inlet 52 may be increased according to the magnitude of the deviation. By doing in this way, high temperature operation of fuel cell system 10 is attained, maintaining cell voltage stably. If possible high temperature operation of the fuel cell system 10, since the difference between the temperature T _FC and the ambient temperature of the cooling water can be increased, can the radiator 34 for cooling the fuel cell stack 14 in a small, also the cooling water circulation pump Since the operation frequency of 32 is reduced, the size can be reduced.

That is, for high temperature operation of the fuel cell system 10 includes a threshold temperature T ₀ of the cooling water, it has been compared with the cooling water temperature T _FC obtained by the cooling water thermometer 36, the threshold temperature T ₀ and the cooling water temperature in accordance with the difference between T _FC, and controls the operation of the dew-point adjusting unit 70 may be adjusted to the dew point θ of the gas in the anode gas inlet 52. The control device 80 has a function for this purpose.

  In the following, the operation of the above configuration, in particular, each function of the control device 80 will be described in detail in connection with the operation of some examples of the dew point adjusting unit 70 using FIGS. Among these, FIG. 4 to FIG. 7 show some of the dew point adjusting units that increase the humidity of the gas returned to the circulation flow path 60 by adjusting the temperature of the stored water stored in the gas-liquid separator 58. It is a figure which picks up and explains an example. FIG. 8 shows a flow path that bypasses the gas-liquid separator 58, avoids moisture aggregation by the gas-liquid separator 58, and leaves the moisture contained in the gas at the anode side gas outlet 54 as it is in the circulation flow path 60. It is a figure which picks up and explains the example of the dew point adjustment part to return. FIG. 9 is a diagram illustrating an example of a configuration in which the gas with a high impurity concentration can be exhausted while increasing the temperature of the stored water in the gas-liquid separator 58.

  As described above, FIG. 4 illustrates a heater 102 as a dew point adjusting unit 100 that increases the humidity of the gas returned to the circulation flow path 60 by adjusting the temperature of the stored water stored in the gas-liquid separator 58. It is a figure which shows the example using a heater controller.

  The water-mixed gas 90 that has entered the gas-liquid separator 58 from the anode-side gas outlet 54 is separated into gas and liquid by separating light gas 92 upward and heavy water in the direction of gravity due to the difference in specific mass of water and gas. The water 58 accumulates at the bottom of the vessel 58 and becomes the stored water 94. The gas discharged from the anode side gas outlet 54 includes an impurity gas such as nitrogen gas, part of which is contained in the stored water 94 and part of it is contained in the light gas separated from the water.

  In this way, the stored water 94 is collected at the bottom of the gas-liquid separator 58, but the heater 102 is disposed so as to enter the stored water 94. The heater 102 is an electric heater, and generates heat when electric power is supplied, and its temperature rises. The heater controller 104 receives a control signal from the control device 80 and controls on / off of the heater 102. When the heater 102 is turned on, the temperature of the stored water rises and the generation of water vapor 96 increases, so that the amount of moisture contained in the light gas 92 returned to the circulation channel 60 increases. If the heater 102 is turned off, generation of excess water vapor can be stopped.

  If the heater 102 is turned on when the stored water 94 is not sufficient, a so-called emptying state occurs, and the heater 102 may overheat. The drain valve 59 has a function of discharging the stored water 94 to the diluter 64, but the timing of the drainage is performed while monitoring the liquid level so that the heater 102 is sufficiently disposed in the stored water 94. It is preferable. For this purpose, a liquid level gauge can be provided.

A heater thermometer 106 is preferably provided to monitor overheating of the heater 102. Heater temperature meter 106 has a function of detecting the surface temperature T _H of the heater 102. When the heater surface temperature T _H is equal to or higher than a predetermined temperature, the heater controller 104 has a function of turning off the power to the heater 102 regardless of a command from the control device 80. Note that if the heater 102 is a heater having a characteristic that the resistance value increases as the temperature rises (Positive Coefficient of Temperature: PCT), overheating can be automatically suppressed.

  Further, when the gas-liquid separator 58 is already provided with a heater for preventing freezing of the stored water 94 or for dissolving the stored water 94 when it freezes, use the heater as it is, It may be used for adjusting the generation of water vapor 96 by increasing the temperature of the stored water 94 of the gas-liquid separator 58 under the control of the control device 80. Further, the heater described with reference to FIG. 5 may be used for preventing the stored water 94 from being frozen or for dissolving the stored water 94 when it is frozen.

FIG. 5 is a flowchart illustrating a procedure for adjusting the dew point of the gas supplied to the anode side gas inlet during the high temperature operation of the fuel cell in the example of the configuration of FIG. Each procedure corresponds to each processing procedure of the high temperature operation subroutine of the fuel cell operation program. Rises the fuel cell operating program, first, it obtains the coolant temperature T _FC is performed (S10). This step is executed by the function of the coolant temperature acquisition processing unit 82 of the control device 80. Specifically, data detected by the cooling water thermometer 36 is transmitted to the control device 80 and acquired.

Next, the obtained cooling water temperature T _FC is compared with a threshold temperature T ₀ set in advance for high temperature operation of the fuel cell system 10 to determine whether T _FC is equal to or higher than T ₀ ( S12). This step is executed by the function of the temperature comparison processing unit 84 of the control device 80. The threshold temperature T ₀ can be set to the cooling water temperature T _FC when the cell voltage starts to decrease, regardless of the dew point θ of the gas at the anode side gas inlet 52, according to the characteristic diagram described in FIG.

S12 is determined a is positive, that is, when the cooling water temperature T _FC is higher than the threshold temperature T _0, obtaining the impedance Z of the fuel cell stack 14 is performed. Specifically, the data detected by the Z measuring device 66 is transmitted to the control device 80 and acquired.

Then, a comparison with a predetermined threshold impedance Z ₀ is performed, and it is determined whether or not the acquired impedance Z is equal to or greater than the threshold impedance Z ₀ (S16).

Then, on / off of the heater 102 is controlled according to the result of S16 (S18). This control, Z is the heater ON uniformly if Z ₀ or higher (S20), Z is a heater OFF uniformly is less than Z ₀ (S22) may be, but the difference between the Z and Z ₀ The on-time may be set according to the above.

When the determinations at S12 and S14 are negative, the heater remains off. After the process of S18, the process returns to S10 again, and the above processing procedure is repeated. In this way, when the cooling water temperature T _FC becomes equal to or higher than the threshold temperature T ₀ , the heater 102 is turned on / off so that the impedance Z of the fuel cell stack 14 does not become equal to or higher than the threshold impedance Z ₀ . As a result, the fuel cell system 10 can be operated at a high temperature while suppressing a decrease in the cell voltage.

The heater 102 is preferably turned on when the single-cell electrolyte membrane constituting the fuel cell stack 14 begins to dry. In consideration of this, the threshold temperature T ₀ and the threshold impedance Z ₀ are set based on the characteristic diagram of FIG. Further, instead of the determination based on the threshold impedance Z ₀ , a threshold characteristic determined in advance for the current-voltage characteristic of the fuel cell stack 14 may be used. It should be noted that the steps S14 and S16 can be omitted when the threshold temperature T ₀ can be set sufficiently appropriately.

The dew point adjusting unit 110 shown in FIG. 6 replaces the heater of FIG. 5 with a cooling water branch channel 112 that branches from the cooling water circulation channel 30 and returns to the cooling water circulation channel 30 again. 94 is an example of passing through. Coolant temperature T _FC, since sufficiently higher than the temperature of the stored water 94 is usually thereby raising the temperature of the stored water 94 can increase the generation of steam 96.

  The dew point adjustment unit 110 further includes a cooling water adjustment valve 114 provided in the cooling water branch passage 112 and a cooling water adjustment valve controller 118 that adjusts the opening / closing operation of the cooling water adjustment valve 114 under the control of the control device 80. Have. The cooling water adjustment valve 114 includes an inlet side opening / closing valve 115 and an outlet side opening / closing valve 116 of the cooling water branch passage 112.

  The operation control of the cooling water adjustment valve 114 is performed in the same procedure by replacing the heater ON with the cooling water adjustment valve opening and the heater OFF with the cooling water adjustment valve closing in the flowchart described in FIG. The opening and closing of the cooling water adjusting valve 114 are performed in synchronization with the inlet side opening / closing valve and the outlet side opening / closing valve. When the cooling water adjustment valve 114 is opened, the cooling water 115 flowing through the cooling water circulation passage 30 is branched and flows through the cooling water branch passage 112 as branch cooling water 117. When the cooling water adjustment valve 114 is closed, the branch cooling water 117 does not flow.

As described with reference to FIG. 5, the opening and closing of the cooling water adjustment valve 114 is uniformly opened if Z is equal to or greater than Z _{0 in} S16, and is uniformly closed if Z is less than Z _0. it may be, but may be set the valve opening time in accordance with the difference between Z and Z _0.

  In addition, it is good also as a structure which can transfer the heat | fever of the cooling water circulation flow path 30 to the stored water 94, for example using heat conductors, such as a metal, without providing the cooling water branch flow path 112. FIG. In this case, a heat conduction / shut-off mechanism using a heat conductor may be provided and controlled by the control device 80.

  The dew point adjusting unit 120 shown in FIG. 7 is an example in which a bubble mechanism is provided in the gas-liquid separator 58 instead of the heater in FIG. 5 and the cooling water branch flow path in FIG. The bubble mechanism is to generate bubbles, which are gas bubbles, in the stored water 94. Since the bubbles are accompanied with moisture when rising in the stored water 94, the generation of water vapor 96 in the gas-liquid separator 58 is prevented. Can be increased.

  As the bubble mechanism, one end is connected to a branch point provided in the discharge flow path 56 from the anode side gas outlet 54 toward the gas-liquid separator 58, and the other end of the stored water 94 stored in the gas-liquid separator 58. It can be configured to include a bubble branching channel 122 opened inside and a bubble adjusting valve 124 provided at the branching point. The opening and closing of the bubble adjustment valve 124 is adjusted under the control of the control device 80.

  The operation control of the bubble adjustment valve 124 is performed in the same procedure by replacing the heater ON as a bubble adjustment valve opening and the heater OFF as a bubble adjustment valve closing in the flowchart described in FIG. When the bubble adjusting valve 124 is opened, the gas 90 flowing through the discharge flow channel 56 is diverted to flow through the bubble branch flow channel 122 as the bubble gas 125, and the bubble 128 from the other end that opens into the stored water 94. Released as. The bubble 128 rises in the stored water 94 and merges with the gas 92 returned to the circulation flow path 60 as a gas containing water vapor from the surface of the stored water 94.

As described with reference to FIG. 6, the opening and closing of the bubble adjustment valve 124 is uniformly opened if Z is equal to or greater than Z _{0 in} S16, and is uniformly closed if Z is less than Z _0. it is also possible, but may set the valve opening time in accordance with the difference between Z and Z _0.

  In addition, since all of the methods of FIG. 4, FIG. 6, and FIG. 7 use the stored water of the gas-liquid separator and adjust the generation of water vapor therefrom, some of these methods are used in combination. It is also possible.

  The dew point adjustment unit 130 illustrated in FIG. 8 is a diagram illustrating an example in which a bypass channel 132 that bypasses the gas-liquid separator 58 is provided. The gas-liquid separator 58 is a kind of container, and its temperature is lower than the temperature of the gas discharged from the anode side gas outlet 54. Therefore, when the gas from the anode-side gas outlet 54 is introduced into the gas-liquid separator 58, the moisture contained in the gas is aggregated by the gas-liquid separator 58 having a low temperature. In other words, the water contained in the gas from the anode-side gas outlet 54 is reduced by passing the gas-liquid separator 58. When the fuel cell system 10 is operated at a high temperature, the moisture contained in the gas from the anode side gas outlet 54 is originally low. It will be returned to the road 60.

  Of course, it is possible to increase the humidity of the gas returned to the circulation flow path 60 by utilizing the evaporation of the gas-liquid separator 58 stored water 94 by the method described in FIGS. 4, 6, and 7. When the battery system 10 is operated at a high temperature, the moisture contained in the gas from the anode-side gas outlet 54 is originally low as described above, and the stored water 94 is often low as shown in FIG.

  Therefore, the dew point adjusting unit 130 shown in FIG. 8 includes a bypass channel 132, a heat insulating material 133 that wraps the bypass channel 132, and a bypass adjustment valve 134 provided in the bypass channel 132. The bypass adjustment valve 134 includes an inlet-side opening / closing valve 135 and an outlet-side opening / closing valve 136 of the bypass flow path 132. The opening and closing of the bypass adjustment valve 134 is adjusted under the control of the control device 80.

  The heat insulating material 133 is for thermally insulating the bypass flow path 132 from outside air having a low temperature so that moisture contained in the gas from the anode-side gas outlet 54 does not aggregate in the bypass flow path 132. Although not shown in FIG. 8, it is preferable that the bypass adjustment valve 134 is also covered with the heat insulating material 133. In addition to covering the bypass channel 132 and the like with the heat insulating material 133, the material of the bypass channel 132 itself is preferably made of a material having high heat insulation properties, for example, a resin material. By doing in this way, the heat insulating material 133 can be abbreviate | omitted depending on the case.

  Further, from the viewpoint of suppressing the aggregation of moisture contained in the gas from the anode side gas outlet 54, the circulation channel 60 is preferably protected by a heat insulating material, and the length of the circulation channel 60 is made as short as possible. preferable.

Similarly to the description with reference to FIG. 6 and the like, the opening and closing of the bypass adjusting valve 134 is uniformly opened when Z is equal to or greater than Z _{0 in} S16, and is uniformly closed when Z is less than Z _0. it may be, but may be set the valve opening time in accordance with the difference between Z and Z _0.

  Comparing the configuration of FIG. 8 with the configuration described in FIG. 4, the configuration of FIG. 8 does not require heater power. Compared with the configurations of FIGS. 6 and 7, the configuration of FIG. 8 does not require extra processing or the like in the gas-liquid separator 58 itself. As described above, according to the configuration of FIG. 8, a high-temperature operation of the fuel cell system 10 can be performed by adding a bypass flow path to the configuration of the conventional fuel cell system 10 and simply opening and closing the valve. .

  In the configuration described above, the gas-liquid separator 58 has a drain valve 59. The drain valve 59 has a function of opening and discharging the stored water 94 stored in the gas-liquid separator 58 when the water reaches a certain amount. Since the stored water 94 also contains an impurity gas such as nitrogen gas, it can be called an exhaust / drain valve as an actual function. By the way, as shown in FIGS. 4, 6, and 7, when the humidity of the gas returned to the circulation flow path 60 is increased using the stored water 94, a certain amount of storage is performed for that purpose. An amount of water 94 is required. Accordingly, even when the impurity gas concentration is increased and exhaust drainage is desired, it may not be possible to perform exhaust drainage from the viewpoint of humidification.

  FIG. 9 shows an exhaust port 140 on the upper side of the gas-liquid separator 58, that is, a position where only gas can be discharged, separately from the drain valve 59 provided at the bottom of the gas-liquid separator 58, and after gas-liquid separation. It is a figure which shows the example which provides the exhaust valve 142 which exhausts this gas 93 outside. The timing for opening the exhaust valve 142 and the timing for opening the drain valve 59 may be independent of each other. By doing in this way, it becomes possible to make compatible the utilization of the stored water 94 and the exhaust of the gas 93 after the gas-liquid separation including the impurity gas.

  9 shows the case where the exhaust valve 142 is added to the configuration of FIG. 4, the exhaust valve 142 can be similarly added to the configurations of FIGS.

  The fuel cell system according to the present invention can be used for a stationary fuel cell system in addition to a fuel cell system mounted on a vehicle.

  8 Load, 10 Fuel cell system, 12 System main body, 14 Fuel cell stack, 20 Oxygen supply source, 22 Filter, 24 ACP, 26 Humidifier, 28 Pressure regulating valve, 30 Cooling water circulation channel, 32 Cooling water circulation pump, 34 Radiator 36, cooling water thermometer, 40 hydrogen gas source, 42 shutoff valve, 44, 46 regulator, 48 injector, 50 supply flow path, 52 anode side gas inlet, 54 anode side gas outlet, 56 discharge flow path, 58 gas-liquid separation 59, drain valve, 60 circulation flow path, 62 hydrogen pump, 64 diluter, 66 Z measuring device, 68 dew point evaluation means, 70, 100, 110, 120, 130 dew point adjustment unit, 80 control device, 82 cooling water temperature Acquisition processing unit, 84 temperature comparison processing unit, 86 dew point adjustment processing unit, 90, 92, 93 gas, 94 storage Distilled water, 96 water vapor, 102 heater, 104 heater controller, 106 heater thermometer, 112 cooling water branch flow path, 114 cooling water adjustment valve, 115, 135 inlet side opening / closing valve, 115 cooling water, 116, 136 outlet side opening / closing valve 117 branch cooling water, 118 cooling water adjustment valve controller, 122 bubble branch flow path, 124 bubble adjustment valve, 125 bubble gas, 128 bubble, 132 bypass flow path, 133 heat insulating material, 134 bypass adjustment valve, 140 exhaust port 142 Exhaust valve.

Claims (10)

A supply flow path for supplying fuel gas to the anode side gas inlet of the fuel cell;
A discharge passage for discharging spent gas from the anode side gas outlet of the fuel cell;
A circulation channel provided by connecting between the discharge channel and the supply channel;
A gas-liquid separator that is provided between the branch point of the discharge channel and the circulation channel and the anode side gas outlet, separates moisture from the used gas, and returns the separated gas to the circulation channel;
A temperature detector for detecting the temperature of the cooling water for the fuel cell;
A gas that is provided in the gas-liquid separator and increases the humidity of the used gas to return to the circulation channel, or returns to the circulation channel without separating the moisture of the used gas, and is supplied to the anode side gas inlet A dew point adjustment unit for adjusting the dew point of
The threshold temperature of the cooling water for the fuel cell set in advance when operating under the high temperature operating condition set close to the upper limit of the efficient operating condition of the fuel cell, and the cooling water temperature acquired by the temperature detector A control unit that controls the operation of the dew point adjustment unit according to the difference between the threshold temperature and the cooling water temperature;
A fuel cell system comprising: The fuel cell system according to claim 1, wherein
The dew point adjustment unit includes a heater provided in the gas-liquid separator,
The control unit controls the operation of the heater in accordance with a difference between the threshold temperature and the cooling water temperature, and adjusts the temperature of the stored water stored in the gas-liquid separator. The fuel cell system according to claim 1, wherein
The dew point adjuster
A cooling water branch passage branched from the cooling water circulation passage of the fuel cell, passing through the stored water stored in the gas-liquid separator, and returning to the cooling water circulation passage again;
A cooling water adjustment valve provided in the cooling water branch flow path,
The control unit controls the operation of the cooling water adjustment valve according to a difference between the threshold temperature and the cooling water temperature, and adjusts the amount of the branch cooling water flowing through the cooling water branch flow path. The fuel cell system according to claim 1, wherein
The dew point adjuster
A branch pipe having one end connected to a branch point provided in the discharge flow path from the anode side gas outlet to the gas-liquid separator and having the other end opened into the stored water stored in the gas-liquid separator, A branch flow path for bubbles that can return the used gas to the discharge flow path while bubbling the stored water when the used gas flows therein;
Including a bubble adjustment valve provided at a branch point,
The control unit controls the operation of the bubble adjustment valve according to the difference between the threshold temperature and the cooling water temperature, and adjusts the amount of used gas flowing through the bubble branch flow path. The fuel cell system according to claim 1, wherein
The dew point adjuster
A bypass flow path that allows the used gas to flow from the anode side gas outlet to the circulation flow path without going through the gas-liquid separator;
Including a bypass adjustment valve provided in the bypass flow path,
The control unit controls the operation of the bypass adjustment valve in accordance with the difference between the threshold temperature and the coolant temperature, and adjusts the amount of used gas flowing through the bypass flow path from the anode side gas outlet side. Battery system. The fuel cell system according to any one of claims 2 to 4,
The gas-liquid separator
A drain valve for draining water stored in the gas-liquid separator after being separated into gas and liquid;
An exhaust valve that is provided separately from the drain valve and exhausts the separated gas in the gas-liquid separator separated into gas and liquid;
A fuel cell system comprising: The fuel cell system according to any one of claims 1 to 6,
It has an impedance detector that detects the impedance of the fuel cell,
The control unit
When the coolant temperature is higher than the threshold temperature by the temperature detector, the impedance of the fuel cell is compared with a predetermined threshold impedance, and according to the difference between the threshold impedance and the impedance acquired by the impedance detector and the threshold impedance A fuel cell system for controlling the operation of the dew point adjustment unit. The fuel cell system according to claim 2, wherein
The fuel cell system, wherein the heater is a heater having a characteristic that a resistance value increases with an increase in temperature. The fuel cell system according to claim 5, wherein
The bypass channel is provided on the outer periphery, and has a heat insulating material that is thermally insulated from the outside. The fuel cell system according to claim 5, wherein
A fuel cell system, wherein the bypass channel is made of a highly heat-insulating material.

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