JP2009289577A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system in which cooling of a reaction gas by a fuel cell is suppressed, the concentration of steam contained in the reaction gas is suppressed, and accordingly, flooding is suppressed inside the fuel cell, when starting power generation of the fuel cell. <P>SOLUTION: The fuel cell system has the fuel cell 1, to generate electric power by the reaction gas; a supply passage 2 to supply the reaction gas to the fuel cell 1; a humidifier 4 which is installed at the supply passage 2 and humidifies the reaction gas, before being supplied to the fuel cell 1; and a reaction gas temperature adjusting element to adjust temperature of the humidifier 4 so as to be able to adjust the temperature of the reaction gas before being supplied to the fuel cell 1. When power generation of the fuel cell 1 is started, a control device 5 controls the reaction gas temperature adjusting element 63 so that the temperature of the reaction gas can be maintained lower than that of the fuel cell 1, and controls the temperature of the reaction gas, before being supplied to the fuel cell 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell system having a humidifier for humidifying a reaction gas supplied to a fuel cell.

  A fuel cell system generally includes a fuel cell that generates electric power using a reaction gas, a supply path that supplies the reaction gas to the fuel cell, and a humidifier that humidifies the reaction gas before being supplied to the fuel cell. Yes. If the reaction gas before being supplied to the fuel cell is humidified, the ion conductivity of the ion conductive membrane of the fuel cell can be maintained high, and the power generation performance of the fuel cell can be enhanced.

  Patent Document 1 discloses a reformer that generates anode gas, a fuel cell, a detection unit that detects the temperature of the anode gas, a detection unit that detects the temperature of the fuel cell, and the temperatures of the fuel cell and the anode gas. A fuel cell system that controls the wet state of an ion conductive membrane of a fuel cell by controlling the difference is disclosed.

In Patent Document 2, when a fuel cell is started in a low temperature atmosphere where freezing occurs, the temperature of the fuel cell is detected, and when the temperature of the fuel cell where freezing occurs is low, humidification by a humidifier A fuel cell humidifier for reducing the amount is disclosed.
JP 2005-285562 A JP 2003-197237 A

  When the power generation of the fuel cell is started, the stability and uniformity of the temperature inside the fuel cell are not necessarily sufficient as compared with the steady operation of the fuel cell. For this reason, when the power generation of the fuel cell is started, flooding is likely to occur inside the fuel cell.

  Since Patent Document 1 does not include a humidifier that humidifies the reaction gas, it is not a technique related to the temperature of the reaction gas after humidification. Patent Document 2 relates to prevention of freezing of a fuel cell at the time of starting power generation of the fuel cell.

  The present invention has been made in view of the above circumstances, and at the time of power generation start of the fuel cell, the reaction gas supplied to the fuel cell is suppressed from being rapidly cooled inside the fuel cell, and as a result, An object of the present invention is to provide a fuel cell system in which the water vapor contained in the reaction gas is suppressed from condensing inside the fuel cell, and thus flooding inside the fuel cell is suppressed when the power generation of the fuel cell is started. .

  A fuel cell system according to the present invention includes: (i) a fuel cell that generates power using a reaction gas; a supply path that supplies the reaction gas to the fuel cell; and (ii) a supply path that is provided in the supply path before being supplied to the fuel cell. A humidifier for humidifying the reaction gas; (iii) a reaction gas temperature adjusting element for adjusting the temperature of the reaction gas before being supplied to the fuel cell by adjusting the temperature of the humidifier; and (iv) the fuel cell At the time of power generation start-up, while the temperature of the fuel cell and the reaction gas is raised, the reaction gas temperature adjusting element is controlled so that the temperature of the reaction gas is maintained lower than the temperature of the fuel cell, and before the fuel cell is supplied And a control device for controlling the temperature of the reaction gas.

  At the start of power generation of the fuel cell, the control device controls the temperature of the humidifier by controlling the reaction gas temperature adjusting element. Thereby, the control device controls the temperature of the reaction gas after being humidified and before being supplied to the fuel cell to be kept lower than the temperature of the fuel cell. As a result, the humidified reaction gas is suppressed from being cooled in the fuel cell by being supplied to the fuel cell. Therefore, it is suppressed that the reaction gas after humidification is cooled inside the fuel cell. Therefore, the water vapor contained in the reaction gas is suppressed from condensing inside the fuel cell. For this reason, flooding is suppressed inside the fuel cell when the power generation of the fuel cell is started. Flooding means that the gas flow path of the fuel cell is blocked by liquid phase water.

  According to the present invention, the fuel cell generates power with the reaction gas. The supply path supplies the reaction gas to the fuel cell. The humidifier is provided in the supply path, and humidifies the reaction gas before being supplied to the fuel cell. The reaction gas humidified by the humidifier may be a cathode gas or an anode gas. Both are good. The reaction gas temperature adjusting element adjusts the temperature of the reaction gas before being supplied to the fuel cell by adjusting the temperature of the humidifier. The reaction gas temperature adjustment element may be a method of adjusting the temperature of the humidifier with a heater, or the temperature of the humidifier is controlled by controlling the flow rate at which the off-gas after the power generation reaction discharged from the fuel cell is supplied to the humidifier. A method of adjusting the temperature of the humidifier may be used by controlling a flow rate at which the reaction gas before power generation reaction supplied to the fuel cell is supplied to the humidifier.

  The control device controls the reaction gas temperature adjustment element so that the temperature of the reaction gas after humidification is maintained lower than the temperature of the fuel cell at the time of power generation start of the fuel cell, and as a result, the control device supplies the fuel cell to the fuel cell. Control the temperature of the previous reaction gas. When power generation is started, in general, when supplying reaction gas to the humidifier, the time when power generation starts is the starting point, and the period of time until the temperature of the fuel cell reaches its target temperature stably. Say. The end point at the start of power generation can be the time when the temperature of the fuel cell reaches its target temperature. The target temperature of the fuel cell is set according to the type of the fuel cell system. Alternatively, the end point at the start of power generation can be a time when a predetermined time has elapsed from the time when the temperature of the fuel cell has reached the target temperature. The predetermined time is set according to the type of the fuel cell system, and can be set as an arbitrary value within a range of 1 second to 2 hours after the temperature of the fuel cell reaches the target temperature. The temperature of the fuel cell may be the temperature of a temperature sensor attached to the fuel cell, or if the fuel cell is provided with a cooling path through which the cooling medium flows, the cooling medium flowing through the inlet of the cooling path It may be the temperature Ti, may be the temperature To of the cooling medium flowing through the outlet of the cooling path, or may be the lower of the temperature Ti and the temperature To. Here, if any one of the temperature Ti and the temperature To is adopted as the temperature of the fuel cell, the probability that the temperature of the reaction gas after humidification is maintained lower than the temperature of the fuel cell is increased, and flooding is suppressed. The advantage of being advantageous is obtained.

  The present invention can preferably employ the following aspects.

  -Preferably, a humidifier has a humidification path which humidifies the reaction gas before being supplied to a fuel cell, and a moisture absorption path which reduces the water | moisture content of the off gas discharged | emitted from the fuel cell. In this case, the reaction gas temperature adjustment element is preferably a flow rate adjustment element that adjusts the flow rate of the off gas discharged from the fuel cell through the moisture absorption path of the humidifier. Examples of the flow rate adjusting element include a valve and a variable throttle. The control device preferably controls the heat transfer from the off-gas having heat to the humidifier by adjusting the flow rate of the off-gas discharged from the fuel cell through the moisture absorption path by controlling the flow rate adjusting element. . Off gas means the gas after the power generation reaction discharged from the fuel cell. The fuel cell generates heat and generates water by power generation operation. For this reason, in general, the off-gas has a relatively high humidity and temperature compared to the reaction gas before being supplied to the fuel cell. For this reason, when the flow rate of the off gas flowing through the moisture absorption path of the humidifier is adjusted, heat transfer and water transfer from the off gas to the humidifier are controlled. Thereby, the temperature of the humidifier is adjusted. As a result, the temperature of the reaction gas flowing through the humidifier is adjusted.

  -Preferably, a humidifier has a humidification path which humidifies the reaction gas before being supplied to a fuel cell, and a moisture absorption path which reduces the water | moisture content of the off gas discharged | emitted from the fuel cell. In this case, the reaction gas temperature adjustment element is preferably a flow rate adjustment element that adjusts the flow rate of the reaction gas before being supplied to the fuel cell through the humidification path of the humidifier. The control device can control the amount of heat transfer from the humidifier to the reaction gas by controlling the flow rate adjustment element to adjust the flow rate of the reaction gas before being supplied to the fuel cell through the humidification path of the humidifier. preferable. When the flow rate of the reaction gas flowing through the humidification path of the humidifier is adjusted in this way, the amount of heat transferred from the humidifier to the reaction gas is controlled. As a result, the temperature of the reaction gas before being supplied to the fuel cell is adjusted.

  -Preferably, when the fuel cell is provided with a cooling path for cooling it, the temperature of the fuel cell can be the temperature of the cooling medium flowing through the cooling path of the fuel cell. When a temperature sensor and its wiring are provided inside the stack itself, it is required to improve the sealing performance of the reaction gas.

  Preferably, the fuel cell has a cooling path through which a cooling medium passes to cool the fuel cell. It is preferable that an inlet temperature sensor for detecting the temperature of the cooling medium flowing near or at the inlet of the cooling path and an outlet temperature sensor for detecting the temperature of the cooling medium flowing near or at the outlet of the cooling path are provided. In this case, the control device may select the lower one of the inlet side temperature detected by the inlet temperature sensor and the outlet side temperature detected by the outlet temperature sensor as the temperature of the fuel cell. preferable. At the time of power generation start-up of the fuel cell, the stability and uniformity of the temperature inside the fuel cell are not always sufficient. When the temperature of the cooling medium flowing through the inlet of the cooling path is Ti and the temperature of the cooling medium flowing through the outlet of the cooling path is To, Ti> To, To> Ti, or Ti = To To do. For example, even when the power generation of the fuel cell is started, Ti> To is likely to occur in the previous period when the fuel cell generates little heat. However, since heat generation in the fuel cell increases in the latter period, To> Ti tends to be satisfied. Therefore, if any one of the temperature Ti and the temperature To is adopted, the probability that the temperature of the reaction gas is kept lower than the temperature of the fuel cell is increased. Therefore, there is an advantage that it is advantageous for suppressing flooding.

  -Preferably, the fuel cell temperature rising element which heats up a fuel cell at the time of the power generation start-up of a fuel cell is provided. The fuel cell temperature raising element may be any element that can raise the temperature of the fuel cell, and examples thereof include an electric heater and a gas heater. Furthermore, the heat exchanger etc. which heat-exchange with a heat medium are illustrated. The control device raises the temperature of the fuel cell and the reaction gas at the time of starting the power generation of the fuel cell, and the temperature of the reaction gas after humidification is higher than the temperature of the fuel cell by a predetermined temperature Td (temperature of the fuel cell−temperature of the reaction gas). = Td) It is preferable to control the temperature of the reaction gas before it is supplied to the fuel cell so that it is kept low. The predetermined temperature Td is set based on experiments or the like according to the fuel cell system, and is set within a range of 1 to 20 ° C., for example, within a range of 1 to 10 ° C. However, it is not limited to this.

  -When the fuel cell power generation is started, the control device is a fuel cell temperature raising operation for raising the temperature of the fuel cell, a humidifier temperature raising operation for raising the temperature of the humidifier, and a reaction gas temperature adjustment for adjusting the temperature of the reaction gas. The operations are preferably performed in order. In the fuel cell temperature raising operation, the temperature of the fuel cell is raised by the fuel cell temperature raising element. In the humidifier temperature raising operation, the reaction gas is such that 60% or more of the flow rate of the reaction gas bypasses the humidification path of the humidifier when the temperature of the fuel cell is raised to a predetermined temperature rise range exceeding the normal temperature range. While suppressing the humidification of the fuel, the reaction gas is supplied to the fuel cell, and 60% or more of the flow rate of the off-gas discharged from the fuel cell is passed through the humidification passage of the humidifier to further raise the temperature of the humidifier. In the reaction gas temperature adjustment operation, 60% or more of the flow rate of the reaction gas is passed through the humidification passage of the humidifier to humidify the reaction gas, and the reaction gas is supplied to the fuel cell and discharged from the fuel cell. The off gas is discharged from the fuel cell while adjusting the flow rate of the off gas bypassing the moisture absorption path of the humidifier. The off-gas is often hotter and more humid than the reaction gas before being supplied to the fuel cell. Here, in the reaction gas temperature adjustment operation, 60% or more of the flow rate of the off gas flows through the moisture absorption path of the humidifier, so that the amount of heat transfer from the off gas to the humidifier is ensured, and the heating rate of the humidifier can be increased. . Examples of the above “60% or more” include 70% or more, 80% or more, 90% or more, and 100%.

  In the steady operation (rated operation) of the fuel cell, the stability and / or uniformity of the temperature inside the fuel cell is improved compared to when the power generation of the fuel cell is started, so that flooding is less likely to occur. Therefore, preferably, the control device controls the reaction gas temperature adjustment element so that the temperature of the reaction gas is maintained by a temperature Td lower than the temperature of the fuel cell at the start of power generation of the fuel cell, and the fuel cell In the steady operation (for example, rated operation), the reaction gas temperature adjustment element is controlled so that the temperature of the reaction gas is maintained by a temperature Td2 (Td2 <Td) lower than the temperature of the fuel cell. The rating is the limit of use guaranteed by the manufacturer so that the fuel cell can be operated continuously under specified conditions, and is generally indicated on the nameplate.

At the time of starting the power generation of the fuel cell, the stability and / or uniformity of the temperature inside the fuel cell is improved later than the previous period, so that flooding is less likely to occur. Therefore, preferably, the control device controls the reaction gas temperature adjusting element so that the temperature of the reaction gas is maintained lower than the temperature of the fuel cell by a temperature Td in the first period when the power generation of the fuel cell is started. The reaction gas temperature adjusting element is controlled so that the temperature of the reaction gas is maintained at a temperature Te (Te <Td) lower than the temperature of the fuel cell in the later stage when the battery is activated. Here, the latter term at the time of starting power generation refers to a period after the temperature T _cell of the fuel _cell is raised to a predetermined temperature Tx at the time of starting power generation. The first period at the time of power generation startup refers to a period until the temperature T _{cell of the} fuel cell rises to a predetermined temperature Tx. The predetermined temperature Tx can be set based on experiments or simulations according to the fuel cell system, and the fuel cell temperature T _cell before supplying the reaction gas to the fuel _cell and the fuel cell temperature T _set during steady operation It is a temperature located in the middle, and can be set, for example, within a range of 40 to 70 ° C.

  According to the present invention, the control device controls the reaction gas temperature adjusting element so that the temperature of the reaction gas is maintained lower than the temperature of the fuel cell at the time of starting the power generation of the fuel cell, and is supplied to the fuel cell. Control the temperature of the previous reaction gas. For this reason, when the reaction gas after humidification is supplied to the inside of the fuel cell when the power generation of the fuel cell is started, the reaction gas is suppressed from being cooled by the inside of the fuel cell. As a result, the water vapor contained in the reaction gas is suppressed from condensing inside the fuel cell. For this reason, the occurrence of flooding inside the fuel cell is suppressed when the power generation of the fuel cell is started.

(Embodiment 1)
FIG. 1 shows the concept of the first embodiment. The fuel cell system includes a fuel cell stack 1, a first supply path 2, a second supply path 3, a humidifier 4, and a control device 5. A stack 1 of a fuel cell generates power using an anode gas and a cathode gas which are reaction gases, and includes a cathode electrode 10 to which a cathode gas is supplied, an anode electrode 11 to which an anode gas is supplied, a cathode electrode 10 and an anode. An MEA having a solid polymer type ion conductive membrane 12 (for example, fluorine-based or hydrocarbon-based) that partitions the electrode 11 is provided. The MEA may be a sheet type or a tube type. Further, the stack 1 has a cooling path 15 through which a cooling medium passes in order to cool the stack 1. Examples of the cooling medium include a cooling liquid such as cooling water and a cooling gas. The cooling path 15 is provided with a fuel cell heating element 16 that raises the temperature of the stack 1 when the power generation of the stack 1 is started. The fuel cell heating element 16 is formed by an electric heater 17 and a heat exchanger 18 for heating the cooling medium. The heat exchanger 18 includes a heat exchanger that exchanges heat with the heat of the combustion exhaust gas of the reformer of the fuel cell system. One of the electric heater 17 and the heat exchanger 18 may be used.

  An inlet temperature sensor 19 i that detects the temperature Ti of the cooling medium flowing through the inlet 15 i of the cooling path 15 of the stack 1 is provided. An outlet temperature sensor 19o that detects the temperature To of the cooling medium flowing through the outlet 15o of the cooling path 15 is provided. The temperature Ti signal from the inlet temperature sensor 19 i and the temperature To signal from the outlet temperature sensor 19 o are input to the control device 5. The control device 5 preferably employs the lower one of the temperature Ti and the temperature To as the temperature of the stack 1. However, it is not limited to this.

  The first supply path 2 supplies a cathode gas as a reaction gas to the cathode electrode 10 of the stack 1. The second supply path 3 supplies an anode gas as a reaction gas to the anode electrode 11 of the stack 1, has a heat exchanger 32, and is connected to the reformer 35. Further, a first discharge path 6 and a second discharge path 7 are provided. The first discharge path 6 discharges the cathode gas off-gas discharged from the outlet 10 o of the cathode electrode 10 of the stack 1. The second discharge path 7 discharges anode gas off-gas discharged from the outlet 11o of the anode 11 of the stack 1.

  The humidifier 4 is provided so as to straddle the first supply path 2 and the first discharge path 6, and humidifies the cathode gas before being supplied to the inlet 10 i of the cathode electrode 10 of the stack 1. The humidifier 4 partitions the humidification path 40 that humidifies the reaction gas before being supplied to the fuel cell, the moisture absorption path 41 that reduces the moisture of the off-gas discharged from the stack 1, and the humidification path 40 and the moisture absorption path 41. It has a film-like moisture holding member 42 and a housing 43 for holding them. The humidification path 40 communicates with the first supply path 2 and humidifies the cathode gas flowing through the first supply path 2. The moisture absorption path 41 communicates with the first discharge path 6 and absorbs moisture from the off-gas flowing through the first discharge path 6. The moisture holding member 42 is formed of a moisture holding film (for example, an ion conductive film) that can perform water transfer and heat transfer.

  In the first supply path 2, a blower 20 (transport source) for transporting the cathode gas, a flow meter 21, and an inlet valve 23 are provided upstream of the humidification path 40 of the humidifier 4. The inlet valve 23 is disposed on the inlet 10 i side of the cathode electrode 10 of the stack 1 via the humidifier 4, and is disposed between the humidifying path 40 and the blower 20 of the humidifier 4. A supply bypass 25 is branched with respect to the first supply path 2. The supply bypass circuit 25 bypasses the humidification path 40 of the humidifier 4 so that the cathode gas does not flow through the humidification path 40 of the humidifier 4. Therefore, the downstream of the supply bypass 25 is connected to the downstream of the humidification path 40 of the humidifier 4. The upstream of the supply bypass 25 is connected to the inlet valve 23 upstream of the humidification path 40 of the humidifier 4. In the first supply path 2, a first temperature sensor 27 is provided on the outlet 40 o side of the humidification path 40 of the humidifier 4. The first temperature sensor 27 detects the temperature Tc of the cathode gas immediately after humidification discharged from the outlet 40 o of the humidification path 40 of the humidifier 4 in the first supply path 2. That is, the first temperature sensor 27 detects the temperature Tc of the cathode gas immediately before being supplied to the inlet 10 i of the cathode electrode 10 of the stack 1. A signal of the temperature Tc detected by the first temperature sensor 27 is input to the control device 5.

  The second temperature sensor 33 detects the temperature Ta of the anode gas immediately after being discharged from the heat exchanger 32 in the second supply path 3. That is, the second temperature sensor 33 detects the temperature Ta of the anode gas immediately before being supplied to the inlet 11 i of the anode 11 of the stack 1. A signal of the temperature Ta detected by the second temperature sensor 33 is input to the control device 5.

  As shown in FIG. 1, an outlet valve 63 that functions as a flow rate adjusting element is disposed between the moisture absorption path 41 of the humidifier 4 and the cathode electrode 10 of the stack 1 in the first discharge path 6. The outlet valve 63 is provided on the outlet 10 o side of the cathode 10 of the stack 1. A discharge bypass 65 is branched from the first discharge path 6. The discharge bypass circuit 65 bypasses the moisture absorption path 41 of the humidifier 4 so that the off gas does not flow through the moisture absorption path 41 of the humidifier 4. Therefore, the upstream of the discharge bypass 65 is connected to the outlet valve 63 upstream of the moisture absorption path 41 of the humidifier 4. The downstream of the discharge bypass 65 is connected to the downstream of the moisture absorption path 41 of the humidifier 4. The control device 5 controls the opening degree of the inlet valve 23 and the outlet valve 63.

  According to the present embodiment, the outlet valve 63 can variably control the ratio between the flow rate of flowing gas to the discharge bypass 65 and the flow rate of flowing gas to the moisture absorption path 41. Alternatively, the outlet valve 63 alternately performs a first operation for flowing gas to both the discharge bypass circuit 65 and the moisture absorption path 41 and a second operation for flowing gas to the moisture absorption path 41 without flowing gas to the discharge bypass path 65. Can be switched. If the time tf of the first operation and the time ts of the second operation are alternately performed, the gas is caused to flow to the exhaust detour 65 and the moisture absorption path 41 of the humidifier 4 according to the ratio of ts / tf. The ratio to the flow rate can be variably controlled.

  The off-gas discharged from the outlet 10o of the stack 1 undergoes a power generation reaction and is at a higher temperature than the cathode gas before being supplied to the stack 1. Therefore, if the flow rate of the off gas flowing through the moisture absorption path 41 of the humidifier 4 is controlled, the amount of heat transferred from the off gas to the housing 43 and the moisture holding member 42 of the humidifier 4 can be controlled, and these temperatures can be adjusted. Therefore, according to the present embodiment, the reaction gas temperature adjusting element for adjusting the temperature of the humidifier 4 is formed by the outlet valve 63 and the discharge bypass 65.

The operation at the time of starting the power generation of the stack 1 will be described. First, the reforming operation of the reformer 35 is started before power generation is started, and anode gas is generated by the reformer 35. Further, the cooling medium warmed by the heater 17 and the heat exchanger 18 of the fuel cell temperature increasing element 16 is caused to flow to the cooling path 15 of the stack 1, so that the temperature T _cell of the stack 1 exceeds the normal temperature range ( For example, the temperature is raised to within a range of 45 to 55 ° C.

  Thereafter, power generation start of the stack 1 is started. At the start of power generation of the stack 1, the blower 20 is driven to cause the cathode gas (cathode active material-containing gas, oxygen-containing gas such as air) to flow from the first supply path 2 to the humidification path 40 of the humidifier 4 to be humidified. 1 is supplied to the cathode electrode 10. Similarly, the anode gas (anode active material-containing gas, hydrogen-containing gas, hydrogen gas) generated by the reformer 35 is supplied from the second supply path 3 to the anode 11 of the stack 1. As a result, power generation is started in the stack 1 in a state where the stack 1 is electrically connected to the electric load. The off-gas of the cathode gas is discharged from the outlet 10 o of the cathode electrode 10 of the stack 1 through the first discharge path 6. The off-gas of the anode gas is discharged from the outlet 11 o of the anode electrode 11 of the stack 1 through the second discharge path 7.

  In the power generation operation of the stack 1, the stack 1 generates heat and generates water. Accordingly, the off-gas after the power generation reaction discharged from the outlet 10o of the cathode electrode 10 of the stack 1 is relatively hot and humid than the cathode gas before the power generation reaction supplied to the inlet 10i of the cathode electrode 10 of the stack 1. is there. Therefore, by adjusting the opening degree of the outlet valve 63 and adjusting the flow rate of the off gas flowing through the discharge bypass circuit 65, the flow rate of the off gas supplied to the moisture absorption path 41 of the humidifier 4 is controlled. As a result, the amount of heat transmitted from the high-temperature off gas to the housing 43 and the moisture retaining member 42 of the humidifier 4 is controlled, and the temperature of the humidifier 4 is controlled. As a result, the temperature Tc of the cathode gas (before being supplied to the stack 1) before the power generation reaction flowing through the humidifying passage 40 of the humidifier 4 can be controlled. When the flow rate of the off gas flowing through the moisture absorption path 41 of the humidifier 4 is adjusted in this way, heat transfer and water transfer from the off gas to the humidifier 4 are controlled. Thereby, the temperature of the humidifier 4 is adjusted. As a result, the temperature of the cathode gas flowing through the humidification path 40 of the humidifier 4 is adjusted. In the present specification, the flow rate means a flow rate per unit time.

As described above, at the time of starting the power generation of the stack 1, the control device 5 sets the target temperature T _target that is lower than the temperature T _{cell of the} stack 1 by a temperature Ttd. Then, even if the temperature T _cell of the stack 1 rises, the opening degree of the outlet valve 63 is controlled so that the temperature Tc of the cathode gas before being supplied to the stack 1 is maintained at the target temperature T _target . That is, if the cathode gas temperature Tc is higher than the target temperature T _target or if the cathode gas temperature Tc is to be higher than the target temperature T _target , the control device 5 controls the opening degree of the outlet valve 63. In addition, the flow rate of the off gas flowing through the exhaust bypass circuit 65 is increased, and the flow rate of the off gas flowing through the moisture absorption path 41 of the humidifier 4 is decreased. This suppresses the amount of heat transfer from the high temperature and high humidity off gas to the humidifier 4. When the cathode gas temperature Tc is lower than the target temperature T _target , the control device 5 controls the opening degree of the outlet valve 63 to reduce the flow rate of the off-gas flowing in the discharge bypass circuit 65 and to absorb the moisture in the humidifier 4. The flow rate of off gas flowing through the passage 41 is increased. As a result, the amount of heat transferred from the off gas to the humidifier 4 is increased. In this way, the control device 5 controls the opening degree of the outlet valve 63 so that the cathode gas temperature Tc before being supplied to the stack 1 is maintained at the target temperature T _target , whereby the cathode gas temperature Tc. Raise the temperature.

In the present embodiment, when power generation of the stack 1 is started, as long as the temperature Tc of the cathode gas before being supplied to the stack 1 is maintained in the vicinity of the target temperature T _target , The total amount may be supplied to the humidifying passage 40 or may be supplied to both the humidifying passage 40 and the supply bypass 25.

FIG. 2 shows an example of a temperature raising process at the time of starting power generation of the stack 1. In FIG. 2, the characteristic line S indicates the temperature T _cell (fuel cell temperature) of the stack 1. A characteristic line G indicates the temperature Tc of the cathode gas (before being supplied to the stack 1) detected by the first temperature sensor 27. The time t2 indicates the time when the cathode gas and the anode gas are supplied to the stack 1 and the stack 1 starts power generation. Time t3 indicates the time when the temperature T _cell of the stack 1 has reached its target temperature T _set (for example, an arbitrary value within the range of 70 to 90 ° C.). Since the power generation operation of the stack 1 generates heat, the stack 1 gradually increases in temperature by power generation. Therefore, as shown by the characteristic lines S and G in FIG. 2, the control device 5 gradually raises the temperature T _{cell of the} stack 1 as time elapses, and raises the temperature of the humidifier 4 so that the temperature Tc of the cathode gas is increased. The temperature is gradually raised.

As described above, according to the present embodiment, the target temperature T _target of the cathode gas temperature Tc before being supplied to the stack 1 when the power generation of the stack 1 is started (time t2 to time t3) is The temperature is set to a temperature Td lower than the temperature T _cell . Therefore, the control device 5 controls the opening degree of the outlet valve 63 so as to maintain the cathode gas temperature Tc at the target temperature T _target (T _target = T _cell −Td). Here, the temperature Td is appropriately set based on experiments or simulations according to the fuel cell system. For example, the temperature Td is appropriately set within a range of 2 to 35 ° C., particularly within a range of 5 to 20 ° C. Can be set.

Even during the steady operation of the stack 1 (after time t3), it is preferable to suppress flooding inside the stack 1. Therefore, as shown in FIG. 2, the control device 5 determines that the target temperature T _target of the cathode gas temperature Tc before being supplied to the stack 1 is higher than the temperature T _{cell of} the stack 1 even after time t3 has elapsed. It is preferable to set the temperature as low as Td2. In this case, temperature Td2 = temperature Td may be set. Alternatively, during the steady operation of the stack 1, unlike the time when the power generation of the stack 1 is started, the temperature inside the stack 1 is highly stable and uniform, and therefore, the temperature Td2 <temperature Td may be satisfied.

By the way, when the power generation of the stack 1 is started, the stability and uniformity of the temperature inside the stack 1 are not necessarily sufficient. In this regard, according to the present embodiment, as described above, the target temperature T _target of the cathode gas temperature Tc is set to a temperature Td lower than the temperature T _{cell of the} stack 1 (T _target = T _cell − Td). Therefore, even when the stability and uniformity of the temperature inside the stack 1 are not necessarily sufficient, the flooding is suppressed inside the stack 1 in consideration of the temperature Td. When the temperature T _{cell of the} stack 1 reaches the target temperature T _set (time t3), the stack 1 shifts to a steady operation (rated operation), and thus the control device 5 ends the power generation start operation of the stack 1. .

By the way, according to the present embodiment, the control device 5 uses the temperature T _cell of the stack 1 as the temperature Ti of the cooling medium flowing through the inlet 15i of the cooling path 15, and the temperature To of the cooling medium flowing through the outlet 15o of the cooling path 15. It is preferred to select the lower of these temperatures. The reason is as follows. That is, at the time of power generation start-up of the stack 1, as described above, the stability and uniformity of the temperature inside the stack 1 are not necessarily sufficient. The detected temperature of the inlet temperature sensor 19i that detects the temperature of the cooling medium flowing through the inlet 15i of the cooling path 15 is Ti, and the detected temperature of the outlet temperature sensor 19o that detects the temperature of the cooling medium flowing through the outlet 15o of the cooling path 15 is To. Then, at the time of power generation activation of the stack 1, Ti> To, To> Ti, or Ti = To. For example, Ti> To is likely to occur in the first stage of startup when the stack 1 generates less heat. However, since heat generation of the stack 1 increases in the later stage of startup, To> Ti is likely to occur. Therefore, at the time of power generation start-up of the stack 1, it is preferable that the control device 5 selects the lower one of Ti and To as the temperature of the stack 1. For this reason, there is an advantage that the probability that the temperature of the cathode gas immediately before being supplied to the stack 1 is kept lower than the temperature of the stack 1 is increased. Therefore, there is an advantage that it is advantageous for suppressing flooding.

In some cases, the control device 5 uses the temperature T _cell of the stack 1 as the temperature Ti of the cooling medium flowing through the inlet 15i of the cooling path 15 and the temperature To of the cooling medium flowing through the outlet 15o of the cooling path 15. Either one may be adopted. Further, an intermediate value between the temperature Ti and the temperature To may be adopted. Therefore, an average value of the temperature Ti and the temperature To may be employed as the temperature T _cell of the stack 1.

  According to the present embodiment, the inlet valve 23 can variably control the ratio between the flow rate of flowing gas through the supply bypass 25 and the flow rate of flowing gas through the humidifying passage 40. Alternatively, the inlet valve 23 switches between a first operation for flowing gas to both the supply bypass 25 and the humidification passage 40 and a second operation for flowing gas to the humidification passage 40 without flowing the gas to the supply bypass 25. Can do. If the first operation and the second operation are performed alternately, the ratio between the flow rate of flowing gas through the supply bypass 25 and the flow rate of flowing gas through the humidifying passage 40 of the humidifier 4 can be variably controlled.

(flowchart)
3 and 4 show examples of flowcharts executed by the control device 5. The flowchart is not limited to this. As shown in FIG. 3, first, the control device 5 reads the temperature Ti of the inlet temperature sensor 19i and the temperature To of the outlet temperature sensor 19o (step S202). The control device 5 determines which of the temperature Ti and the temperature To is lower (step S204). When the temperature Ti is lower than the temperature To or when Ti = To, the control device 5 sets the temperature Ti as the temperature T _cell of the stack 1 (step S206). When the temperature To is lower than the temperature Ti, the control device 5 sets the temperature To as the temperature T _cell of the stack 1 (step S208), and returns to the main routine.

As shown in FIG. 4, the control device 5 reads the temperature Tc of the cathode gas detected by the first temperature sensor 27 (step S302), and further reads the temperature T _{cell of the} stack 1 (step S304). Next, the target temperature T _target is set by subtracting Td from the temperature T _cell (step S306). The control device 5 compares the cathode gas temperature Tc with the target temperature T _target (step S308). Here, if the temperature Tc of the cathode gas is higher than the target temperature T _target (including T _target = temperature Tc), the control device 5 controls the opening degree of the outlet valve 63 and flows to the discharge bypass 65. While increasing the gas flow rate, the flow rate of the gas flowing through the moisture absorption path 41 of the humidifier 4 is decreased (step S310). Thereby, the amount of heat transfer from the high temperature and high humidity off gas to the humidifier 4 is reduced, and the humidifier 4 is cooled.

Furthermore, if the temperature Tc of the cathode gas is lower than the target temperature T _target , the control device 5 controls the opening degree of the outlet valve 63 to reduce the flow rate of the gas flowing through the discharge bypass circuit 65, and the humidifier The flow rate of the gas flowing through the four moisture absorption paths 41 is increased (step S314). As a result, the control device 5 increases the amount of heat transferred from the high-temperature and high-humidity off-gas to the humidifier 4 and raises the temperature of the humidifier 4. Wait for a certain period of time to prevent hunting (step S316) and return to the main routine.

(Embodiment 2)
Since this embodiment has basically the same configuration and the same function and effect as those of the first embodiment, FIGS. 1 to 4 can be applied mutatis mutandis. At the time of power generation activation of the stack 1, the control device 5 adjusts the temperature of the reaction gas and the fuel cell temperature raising operation for raising the temperature of the stack 1, the humidifier temperature raising operation for raising the temperature of the humidifier 4, and the temperature of the reaction gas. The reaction gas temperature adjustment operation is performed in order. First, in the fuel cell temperature raising operation, the temperature of the cooling medium (for example, cooling liquid such as cooling water) in the cooling path 15 is raised by heat transfer from the heater 17 and the heat exchanger 18 constituting the fuel cell temperature raising element 16. The temperature T _cell of the stack 1 is gradually raised by circulating the cooling medium through the cooling path 15. Thereby, before the stack 1 starts power generation, the temperature T _{cell of the} stack 1 is raised to a predetermined temperature increase temperature range (for example, within a range of 45 to 55 ° C.). In this fuel cell temperature raising operation, since the cathode gas and the anode gas are not supplied to the stack 1, no power generation reaction occurs.

As described above, in the state where the temperature T _cell of the stack 1 of the fuel _cell is raised to a predetermined temperature rise temperature range (for example, within a range of 45 to 55 ° C.) exceeding the normal temperature range, the control device 5 performs the humidifier temperature raising operation. To implement. In the humidifier temperature raising operation, the control device 5 controls the opening degree of the outlet valve 63, and the entire amount (100%) of the off-gas flow rate discharged from the outlet 10 o of the cathode electrode 10 of the stack 1 is absorbed by the humidifier 4. Flow on path 41. Here, since the off-gas after the power generation reaction is higher in temperature and humidity than the cathode gas before being supplied to the stack 1 (before the power generation reaction), the temperature of the housing 43 and the moisture holding member 42 of the humidifier 4 is further increased. . Here, since the entire amount (100%) of the flow rate of the off gas flows through the moisture absorption path 41 of the humidifier 4, the temperature increase rate of the humidifier 4 is increased. Note that the lower the flow rate of the off gas flowing into the exhaust bypass circuit 65, the higher the flow rate of the off gas flowing through the moisture absorption path 41 of the humidifier 4, so that the heating rate of the humidifier 4 increases.

  Further, in the above-described humidifier temperature raising operation, the control device 5 controls the opening degree of the inlet valve 23 and bypasses the humidification path 40 of the humidifier 4 to bypass the entire amount (100%) of the cathode gas flow rate. 25. For this reason, the cathode gas is not allowed to flow through the humidification path 40 of the humidifier 4. The reason is as follows. That is, when power generation of the stack 1 is started, there is a possibility that excessive moisture remains inside the humidifier 4 due to the previous power generation operation of the stack 1. For this reason, if the cathode gas is allowed to flow through the humidification path 40 of the humidifier 4, the cathode gas before the power generation reaction may be excessively humidified by the humidifier 4. Furthermore, in the above-described humidifier temperature raising operation, the entire amount (100%) of the cathode gas flow is diverted through the humidification path 40 of the humidifier 4 and flows to the supply bypass circuit 25, so that the cathode gas takes the heat of the humidifier 4. Is suppressed, and a decrease in the heating rate of the humidifier 4 is suppressed. As described above, in the humidifier temperature raising operation, the cathode gas is supplied from the inlet 10 i to the cathode electrode 10 of the stack 1 while suppressing the humidification of the cathode gas.

Next, the control device 5 performs a reaction gas temperature adjustment operation. In this case, since the temperature T _{cell of the} stack 1 is considerably increased, if the cathode gas is not humidified before being supplied to the stack 1, the inside of the stack 1 may become dry. Therefore, the control device 5 controls the opening degree of the inlet valve 23, passes the entire amount (100%) of the flow rate of the cathode gas through the humidification path 40 of the humidifier 4, and humidifies the cathode gas in the humidification path 40. The cathode gas thus humidified is supplied to the cathode 10 of the stack 1 from the inlet 10i. Thereby, the drying inside the stack 1 is suppressed, the excessive drying of the ion conductive film 12 is suppressed, and the power generation reaction is favorably performed. Further, in the reaction gas temperature adjustment operation, the control device 5 controls the opening degree of the outlet valve 63. That is, the control device 5 discharges the off gas from the cathode electrode 10 of the stack 1 while adjusting the flow rate of the off gas discharged from the outlet 10 o of the cathode electrode 10 of the stack 1 bypassing the moisture absorption path 41 of the humidifier 4. Here, when the detour flow rate through which the off gas flows to the discharge detour route 65 increases and the flow rate through the moisture absorption path 41 of the humidifier 4 decreases, the amount of heat transferred from the heated off gas to the humidifier 4 is decreased, and the humidifier 4 The temperature drops. On the other hand, when the detour flow rate through which the off gas flows to the discharge detour route 65 decreases and the flow rate through the moisture absorption path 41 of the humidifier 4 increases, the amount of heat transferred from the heated off gas to the humidifier 4 increases, and the humidifier The temperature of 4 becomes high. Thus, in the reaction gas temperature adjustment operation, the control device 5 controls the opening degree of the outlet valve 63, and the temperature Tc of the cathode gas before being supplied to the stack 1 is the target temperature _Ttarget ( _Ttarget = T _cell -Td) is maintained.

  For this reason, also in the present embodiment, as in the first embodiment, the humidified cathode gas is suppressed from being cooled in the stack 1. For this reason, flooding inside the stack 1 is suppressed when the power generation of the stack 1 is started. The outlet valve 63 can variably control the ratio between the gas flow rate flowing through the moisture absorption path 41 of the humidifier 4 and the gas flow rate flowing through the discharge bypass circuit 65. As long as the temperature of the cathode gas immediately before being supplied to the stack 1 is maintained lower than the temperature of the stack 1, the inlet valve 23 may be a three-way valve or an on / off valve.

(Embodiment 3)
Since this embodiment has basically the same configuration and the same function and effect as the first and second embodiments, FIGS. 1, 3, and 4 can be applied mutatis mutandis. FIG. 5 shows the temperature raising process at the time of starting the power generation of the stack 1. In FIG. 5, the characteristic line S indicates the temperature T _cell (fuel cell temperature) of the stack 1. A characteristic line G indicates the temperature Tc of the cathode gas detected by the first temperature sensor 27. Time t2 indicates the time when the stack 1 starts power generation. Time t3 indicates the time when the temperature T _cell of the stack 1 has reached its target temperature T _set (for example, an arbitrary value within the range of 70 to 90 ° C.). As shown by the characteristic lines S and G in FIG. 5, the control device 5 gradually raises the temperature T _{cell of the} stack 1 as time elapses, and gradually raises the temperature Tc of the cathode gas.

As can be understood from FIG. 5, the target temperature T _target of the cathode gas temperature Tc before being supplied to the stack 1 is set to a temperature Td lower than the temperature T _{cell of the} stack 1. Therefore, the control device 5 controls the opening degree of the outlet valve 63 so that the cathode gas temperature Tc is maintained at the target temperature T _target , and controls the flow rate of the off gas flowing in the moisture absorption path 41 of the humidifier 4. Temperature of the stack is to reach to this target temperature _{T set} (time t3). As shown in FIG. 5, even after the time t <b> 3 has elapsed, the control device 5 uses the target temperature T _target (T _target = T _cell −Td <b> 3) of the cathode gas temperature Tc before being supplied to the stack 1. It is set to temperature Td3 sentence a temperature lower than the temperature of the _{T cell.} Td = Td3 may be set. Or it is good also as Td> Td3.

If a predetermined time (Δt) has elapsed from time t3 when the temperature T _{cell of the} stack 1 reaches the target temperature T _set , the stack 1 is in the initial stage of steady operation, and the stability and uniformity of the temperature inside the stack 1 is reached. Is further improved. Therefore, according to the present embodiment, the target temperature T _target of the cathode gas temperature Tc is raised to the original target temperature Tc3 from time t4 (t4> t3) when a predetermined time Δt has elapsed from time t3, so that ΔTu is increased. Thus, the control device 5 controls the opening degree of the outlet valve 63. Therefore, at the time of steady operation (rated operation) of the stack 1, the target temperature T _target of the cathode gas temperature Tc (Tc3) before being supplied to the stack 1 is raised and is higher than the temperature T _{cell of the} stack 1 Td4 (Td4 <Td3, Td4 <Td) is set to a lower temperature.

(Embodiment 4)
Since this embodiment has basically the same configuration and the same function and effect as those of Embodiments 1 to 3, FIGS. 1, 3 and 4 can be applied mutatis mutandis. Also in this embodiment, as shown in FIG. 6, as in the first embodiment, the control device 5 uses the target temperature T _target of the cathode gas temperature Tc before being supplied to the stack 1 as the temperature T of the stack 1. _The temperature is set to a temperature Td lower than the _cell .

In the latter period when the temperature T _{cell of the} stack 1 rises and reaches the predetermined temperature Tx, even before the time t3, the stability and uniformity of the temperature inside the stack 1 compared with the first period when the power generation is started. Improved. Therefore, when the temperature T _{cell of the} stack 1 rises and reaches the predetermined temperature Tx, the control device 5 uses the target temperature T _target of the cathode gas temperature Tc before being supplied to the stack 1 as the temperature T of the stack 1. _The temperature is set to a temperature Te (Te <Td) lower than the _cell . The predetermined temperature Tx is located between the temperature before starting the stack 1 and the temperature T _set during steady operation (rated operation) of the stack 1, and is based on experiments or simulations depending on the fuel cell system. Can be set as appropriate.

(Embodiment 5A)
Since this embodiment has basically the same configuration and the same function and effect as the first to fourth embodiments, FIGS. 1, 2, 4, 4, and 6 can be applied mutatis mutandis. However, at the time of power generation startup of the stack 1, the control device 5 selects the temperature Ti on the inlet 15i side of the cooling path 15 as the temperature T _cell of the stack 1. Ti> To tends to be satisfied in the first period when power generation is started, and To> Ti tends to reverse in the latter period when power generation is started, which is advantageous for suppressing flooding in the second stage when power generation is started. Therefore, the outlet temperature sensor 19o may be eliminated. In this embodiment, at startup generation of stack 1, the control unit 5, the temperature Td sentence than the temperature Tc is the temperature T _cell stack 1 of the previous cathode gas to be supplied to the inlet 10i of the cathode 10 of the stack 1 The opening degree of the outlet valve 63 is controlled so as to be kept low. Furthermore, you may decide to control the opening degree of the inlet valve 23 as needed.

(Embodiment 5B)
Since this embodiment has basically the same configuration and the same function and effect as the first to fourth embodiments, FIGS. 1, 2, 4, 4, and 6 can be applied mutatis mutandis. However, at the time of starting power generation of the stack 1, the control device 5 selects the temperature To on the outlet 15 o side of the cooling path 15 as the temperature T _cell of the stack 1. Ti> To tends to be satisfied in the first period of power generation startup, and To> Ti tends to be satisfied in the second stage of power generation startup, which is advantageous for suppressing flooding in the first period of power generation startup. The inlet temperature sensor 19i may be eliminated.

In this embodiment, at startup generation of stack 1, the control unit 5, the temperature Td sentence than the temperature Tc is the temperature T _cell stack 1 of the previous cathode gas to be supplied to the inlet 10i of the cathode 10 of the stack 1 The opening degree of the outlet valve 63 is controlled so as to be kept low. Furthermore, you may decide to control the opening degree of the inlet valve 23 as needed.

(Embodiment 6)
Since this embodiment has basically the same configuration and the same function and effect as the first to fourth embodiments, FIGS. 1 to 6 can be applied mutatis mutandis. However, the outlet valve 63 is an on / off valve, and a first operation for flowing gas to both the discharge bypass circuit 65 and the moisture absorption path 41 and a second operation for flowing gas to the moisture absorption path 41 without flowing gas to the discharge bypass circuit 65. And can be switched.

  According to the present embodiment, immediately after the start of power generation of the stack 1 or in the previous period, the control device 5 controls the opening degree of the outlet valve 63, and does not flow off gas to the discharge bypass 65, but the off gas flows into the moisture absorption path 41. Perform a second operation to flush the entire volume. Thereby, the temperature increase rate of the humidifier 4 can be increased as much as possible. When the temperature of the stack 1 rises and reaches a predetermined temperature, the control device 5 controls the opening degree of the outlet valve 63 and performs the first operation and the second operation alternately after the latter period. In this case, by changing the ratio of the time tf of the first operation and the time ts of the second operation, the flow rate of the off-gas discharged from the outlet 10o of the cathode electrode 10 of the stack 1 and the discharge bypass route The ratio to the flow rate flowing to 65 is controlled. Thereby, the amount of heat transfer from the off gas to the humidifier 4 can be controlled, and the temperature increase rate of the humidifier 4 can be controlled.

In this embodiment, at startup generation of stack 1, the control unit 5, the temperature Td sentence than the temperature Tc is the temperature T _cell stack 1 of the previous cathode gas to be supplied to the inlet 10i of the cathode 10 of the stack 1 The opening degree of the outlet valve 63 is controlled so as to be kept low. Furthermore, you may decide to control the opening degree of the inlet valve 23 as needed.

(Embodiment 7)
Since this embodiment has basically the same configuration and the same function and effect as the first to fourth embodiments, FIGS. 1 to 6 can be applied mutatis mutandis. The inlet valve 23 is a three-way valve that can variably control the ratio of the gas flow rate flowing in the humidification path 40 of the humidifier 4 and the gas flow rate flowing in the supply bypass circuit 25. Also in the present embodiment, when the power generation of the stack 1 is started, the cathode gas is supplied from the first supply path 2 to the cathode electrode 10 through the humidifier 4 from the inlet 10i of the stack 1. At the start of power generation of the stack 1, the control device 5 controls the opening degree of the inlet valve 23 and variably controls the ratio between the flow rate of the cathode gas flowing through the humidifier 4 of the humidifier 4 and the flow rate flowing through the supply bypass 25. To do. Thereby, the control device 5 controls the heat transfer from the humidification path 40 of the humidifier 4 to the cathode gas, and consequently adjusts the temperature of the cathode gas Tc flowing through the humidification path 40 of the humidifier 4.

Here, in the unlikely event that the temperature Tc of the cathode gas before being supplied to the stack 1 is higher than the temperature T _{target of the} stack 1, the control device 5 controls the opening degree of the inlet valve 23 and supplies the supply bypass 25 The flow rate of the cathode gas flowing into the is increased. Thereby, the amount of heat transfer from the humidification path 40 of the humidifier 4 to the cathode gas is reduced. Therefore, the temperature Tc of the cathode gas before being supplied to the stack 1 is maintained at the target temperature T _target that is lower than the temperature T _{cell of the} stack 1 by a temperature Td.

In the present embodiment, at the time of power generation startup of the stack 1, as long as the temperature Tc of the cathode gas immediately before being supplied to the stack 1 is kept lower than the temperature T _cell stack 1, the first discharge passage 6 The total amount of off-gas may flow through the moisture absorption path 41, or may flow through both the moisture absorption path 41 and the discharge bypass 65.

  According to this embodiment, the cathode gas after humidification is suppressed from being cooled by being supplied to the cathode electrode 10 of the stack 1. Therefore, the water vapor contained in the cathode gas is suppressed from condensing at the cathode electrode 10 of the stack 1. For this reason, flooding is suppressed inside the stack 1 when the power generation of the stack 1 is started.

(Embodiment 8)
Since this embodiment has basically the same configuration and the same function and effect as the first to fourth embodiments, FIGS. 1 to 6 can be applied mutatis mutandis. However, the inlet valve 23 is an on / off valve, and performs a first operation for flowing gas to the supply bypass 25 and the humidification passage 40 and a second operation for flowing gas to the humidification passage 40 without flowing the gas to the supply bypass 25. Can be switched. The control device 5 can execute the first operation time tf and the second operation time ts of the inlet valve 23 alternately and repeatedly. By changing the ratio between the time tf and the time ts, the ratio of the flow rate flowing through the humidification path 40 and the flow rate flowing through the supply bypass circuit 25 is variably controlled for the cathode gas supplied to the cathode electrode 10 of the stack 1. Can do.

In this embodiment, at startup generation of stack 1, the control unit 5, a lower target temperature even if the temperature Tc of the cathode gas from the temperature T _cell stack 1 prior to supply to the inlet 10i of the cathode 10 of the stack 1 The opening degree of the inlet valve 23 is controlled so as to be maintained at T _target .

Note that when the power generation of the stack 1 is started, as long as the temperature Tc of the cathode gas before being supplied to the stack 1 is maintained in the vicinity of the target temperature T _target , the entire amount of off gas is transferred to the moisture absorption path 41 in the first discharge path 6. Or may flow through both the moisture absorption path 41 and the discharge bypass 65.

(Embodiment 9)
Since this embodiment has basically the same configuration and the same function and effect as the first to fourth embodiments, FIGS. 1 to 6 can be applied mutatis mutandis. According to the present embodiment, in the first half of the power generation start-up of the stack 1, the control device 5 adjusts the opening degree of the outlet valve 63, thereby setting the flow rate of the off gas flowing through the exhaust bypass 65 to 0, The whole is supplied to the moisture absorption path 41 of the humidifier 4. As a result, the amount of heat transferred from the off gas to the housing of the humidifier 4 and the moisture retaining member 42 is increased, and the temperature of the humidifier 4 is increased in a short time. Thus, the temperature Tc of the cathode gas before power generation reaction (before being supplied to the stack 1) flowing through the humidification path 40 of the humidifier 4 is raised to a predetermined temperature in a short time. The predetermined temperature is appropriately set based on experiments or simulations according to the fuel cell system, and is set, for example, within a range between a normal temperature range and a stack temperature during steady operation.

  Thereafter, the control device 5 controls the opening degree of the outlet valve 63 to cause the off gas to flow through both the discharge bypass circuit 65 and the moisture absorption path 41. In this case, the ratio of the flow rate of the off gas flowing through the exhaust bypass circuit 65 and the flow rate flowing through the moisture absorption path 41 of the humidifier 4 is controlled to be appropriately variable. Thereby, the temperature increase rate of the humidifier 4 is delayed, so that the temperature of the entire humidifier 4 is made uniform, and temperature unevenness in the humidifier 4 is reduced.

In the present embodiment, when the power generation of the stack 1 is started, as long as the temperature Tc of the cathode gas before being supplied to the stack 1 is maintained near the target temperature T _target , The entire amount of gas may flow through the supply bypass 25 or the cathode gas may flow through both the humidification path 40 and the supply bypass 25.

Also in this embodiment, at the time of power generation start-up of the stack 1 (time t2 to t3), the control device 5 sets a target temperature T _target that is lower than the temperature T _{cell of the} stack 1 by a temperature Ttd, and the humidifier 4 The temperature Tc of the cathode gas immediately after being discharged from the humidification path 40 is maintained at the target temperature T _target .

(Embodiment 10)
FIG. 7 shows a tenth embodiment. This embodiment has basically the same configuration and the same operational effects as the above-described embodiment. As shown in FIG. 7, the outlet valve 63 </ b> W is an on / off valve provided in the discharge bypass circuit 65, and the flow rate for flowing off gas to the discharge bypass circuit 65 and the off gas to the moisture absorption path 41 per unit time by on / off. The ratio to the flow rate can be variably controlled. Alternatively, the outlet valve 63W can alternately switch between a first operation for flowing off gas to the discharge bypass circuit 65 by opening and a second operation to close and not flow off gas to the discharge bypass circuit 65. If the time tf of the first operation and the time ts of the second operation are alternately performed, the flow rate of the gas to the discharge bypass circuit 65 per unit time and the moisture absorption path of the humidifier 4 according to the ratio of ts / tf The ratio of the flow rate of the gas to 41 can be variably controlled, so that the temperature of the humidifier 4 can be adjusted.

  As shown in FIG. 7, the inlet valve 23 </ b> W is an on / off valve provided in the supply bypass circuit 25, and the flow rate of the cathode gas to the supply bypass circuit 25 per unit time by the on / off and the cathode gas in the humidification path 40. The ratio of the flow rate to the flow rate of the gas can be controlled variably, so that the heat transfer from the humidifier 40 to the cathode gas can be controlled, whereby the temperature of the cathode gas can be adjusted.

  Alternatively, the outlet valve 63 </ b> W can alternately switch between a first operation for causing the cathode gas to flow in the supply bypass 25 by opening and a second operation for closing and not causing the cathode gas to flow in the supply bypass 25. If the time tf of the first operation and the time ts of the second operation are performed alternately, the flow rate of the cathode gas to the supply bypass circuit 25 per unit time and the humidification of the humidifier 4 according to the ratio of ts / tf The ratio of the flow rate of the cathode gas flowing through the passage 40 can be variably controlled, so that the heat transfer from the humidifier 40 to the cathode gas can be controlled, whereby the temperature of the cathode gas can be adjusted. Note that both the outlet valve 63W and the inlet valve 23W are on / off valves, but either one may be a three-way valve.

(Other)
According to Embodiment 1 described above, the cathode gas is humidified by the humidifier 4, but the present invention is not limited to this, and the anode gas may be humidified by the humidifier 4. The amount of heat transfer from the off gas to the humidifier 4 is controlled by controlling the flow rate of the off gas flowing through the moisture absorption path 41 of the humidifier 4 with the outlet valve 63. However, the present invention is not limited to this, and the humidifier is heated. An electric heater may be provided, and the controller 5 may control the temperature of the humidifier 4 by controlling the amount of heat generated by the electric heater. The inlet valve 23 may be provided not only in the branch portion between the supply bypass 25 and the first supply path 2 but also in the supply bypass 25. The outlet valve 63 may be provided not only in the branching portion between the discharge bypass circuit 65 and the first discharge path 6 but in any part of the discharge bypass circuit 65. The inlet valve 23 and the outlet valve 63 may be a three-way valve or an on / off valve. Instead of the inlet valve 23, a variable throttle may be provided in the supply bypass 25. Instead of the outlet valve 63, a variable throttle may be provided in the discharge bypass 65. The humidifier 4 and the stack 1 are installed next to each other so as to be able to directly transfer heat, and heat of the stack 1 is directly transferred to the humidifier 4 when the power generation of the stack 1 is started. You may decide to speed it up. In each of the above-described embodiments, it is preferable that the control device 5 selects the lower one of Ti and To as the temperature of the stack 1 when the power generation of the stack 1 is started. The present invention is not limited to the above-described embodiments, and can be implemented with appropriate modifications within a range not departing from the gist. The following technical idea can be understood from the description in the above specification.

  [Additional Item 1] A fuel cell that generates power using a reaction gas, a supply path that supplies the reaction gas to the fuel cell, a humidifier that is provided in the supply path and humidifies the reaction gas before being supplied to the fuel cell, and a fuel A fuel cell system comprising a reaction gas temperature adjusting element for adjusting a temperature of a humidifier so that a temperature of a reaction gas before being supplied to a battery can be adjusted. The temperature of the reaction gas before being humidified by the humidifier and supplied to the fuel cell can be adjusted by the reaction gas temperature adjusting element.

  [Additional Item 2] A fuel cell that generates power using the first reaction gas and the second reaction gas, a supply path for supplying one of the first reaction gas and the second reaction gas to the fuel cell, and a supply path A humidifier for humidifying the reaction gas before being supplied to the fuel cell, and a reaction gas temperature adjustment for adjusting the temperature of the humidifier so that the temperature of the reaction gas before being supplied to the fuel cell can be adjusted Control the reaction gas temperature adjustment element so that the temperature of the reaction gas is kept lower than the temperature of the fuel cell at the time of starting the power generation of the element and the fuel cell, and the temperature of the reaction gas before being supplied to the fuel cell A fuel cell system comprising a control device for controlling. The temperature of the reaction gas before being humidified by the humidifier and supplied to the fuel cell can be adjusted to a temperature lower than the temperature of the fuel cell by the reaction gas temperature adjusting element.

  The present invention can be used for, for example, a fuel cell system for stationary use, vehicle use, electric equipment use, electronic equipment use, portable use, and portable use.

It is a figure concerning Embodiment 1 and shows a fuel cell system which has a humidifier and a stack. 6 is a graph illustrating a temperature rise state of a stack temperature and a cathode gas temperature when the power generation of the stack is started according to the first embodiment. 6 is a flowchart executed by the control device according to the first embodiment. 6 is a flowchart executed by the control device according to the first embodiment. FIG. 10 is a graph showing a temperature rise state of the stack temperature and the cathode gas temperature when starting the power generation of the stack according to the third embodiment. FIG. 10 is a graph showing a temperature rise state of the stack temperature and the cathode gas temperature when starting the power generation of the stack according to the fourth embodiment. It is a figure concerning Embodiment 10 and shows a fuel cell system which has a humidifier and a stack.

Explanation of symbols

  1 is a stack (fuel cell), 10 is a cathode electrode, 15 is a cooling path, 16 is a fuel cell heating element, 17 is a heater, 18 is a heat exchanger, 2 is a first supply path, 23 is an inlet valve, 25 is Supply bypass circuit, 27 is a first temperature sensor, 3 is a second supply path, 4 is a humidifier, 40 is a humidification path, 41 is a moisture absorption path, 42 is a moisture retaining member, 43 is a housing, 5 is a control device, and 6 is The first discharge path, 63 is an outlet valve (flow rate adjustment element, reaction gas temperature adjustment element), 65 is a discharge bypass (reaction gas temperature adjustment element), and 7 is a second discharge path.

Claims (8)

A fuel cell that generates electricity using reactive gas; and
A supply path for supplying the reaction gas to the fuel cell;
A humidifier that is provided in the supply path and humidifies the reaction gas before being supplied to the fuel cell;
A reaction gas temperature adjusting element for adjusting the temperature of the reaction gas before being supplied to the fuel cell by adjusting the temperature of the humidifier;
The reaction gas temperature adjusting element is configured so that the temperature of the reaction gas after humidification is maintained lower than the temperature of the fuel cell while the temperature of the fuel cell and the reaction gas is raised during power generation startup of the fuel cell. And a control device for controlling the temperature of the reaction gas before being supplied to the fuel cell. 2. The humidifier according to claim 1, wherein the humidifier includes a humidification path that humidifies the reaction gas before being supplied to the fuel cell, and a moisture absorption path that reduces moisture of off-gas discharged from the fuel cell. ,
The reaction gas temperature adjustment element is a flow rate adjustment element that adjusts the flow rate of the off-gas discharged from the fuel cell through the moisture absorption path of the humidifier,
The control device controls the flow rate adjusting element to adjust a flow rate of the off gas discharged from the fuel cell through the moisture absorption path of the humidifier, and to transfer heat from the off gas to the humidifier. A fuel cell system that controls the temperature of the reaction gas before being supplied to the fuel cell by controlling. 2. The humidifier according to claim 1, wherein the humidifier includes a humidification path that humidifies the reaction gas before being supplied to the fuel cell, and a moisture absorption path that reduces moisture of off-gas discharged from the fuel cell. ,
The reaction gas temperature adjustment element is a flow rate adjustment element for adjusting a flow rate of the reaction gas supplied to the fuel cell through the humidification path of the humidifier.
The control device adjusts a flow rate of the reaction gas supplied to the fuel cell through the humidification path of the humidifier by controlling the flow rate adjusting element, and is transmitted from the humidifier to the reaction gas. A fuel cell system that controls the temperature of the reaction gas before being supplied to the fuel cell by controlling heat. The fuel cell according to claim 1, wherein the fuel cell has a cooling path through which a cooling medium passes to cool the fuel cell.
An inlet temperature sensor for detecting the temperature of the cooling medium flowing through the inlet of the cooling path, and an outlet temperature sensor for detecting the temperature of the cooling medium flowing through the outlet of the cooling path;
The said control apparatus is a fuel cell system which selects the temperature of the lower one of the temperature of the inlet side which the said inlet temperature sensor detected, and the temperature of the outlet side which the said outlet temperature sensor detected as the temperature of the said fuel cell.   5. The fuel cell temperature raising element for raising the temperature of the fuel cell at the time of starting the power generation of the fuel cell is provided according to claim 1, and the control device is configured to start the power generation of the fuel cell. A fuel cell system in which the temperature of the fuel cell is raised by the fuel cell temperature raising element. 6. The control device according to claim 5, wherein the control device is configured to start power generation of the fuel cell.
A fuel cell temperature raising operation for raising the temperature of the fuel cell by the fuel cell temperature raising element;
In a state where the temperature of the fuel cell is higher than the normal temperature range, the reaction gas is suppressed while suppressing the humidification of the reaction gas so that 60% or more of the flow rate of the reaction gas bypasses the humidification path of the humidifier. A humidifier temperature raising operation for supplying the fuel cell and causing the humidifier to further raise the temperature by flowing 60% or more of the flow rate of the off-gas discharged from the fuel cell to the moisture absorption path of the humidifier,
While supplying 60% or more of the flow rate of the reaction gas through the humidification path of the humidifier and humidifying the reaction gas with the humidifier, the reaction gas is supplied to the fuel cell, and the fuel cell A fuel cell system that sequentially performs a reaction gas temperature adjustment operation for discharging the off gas from the fuel cell while adjusting a flow rate of the off gas discharged from the dehumidifier bypassing the moisture absorption path of the humidifier.   7. The control device according to claim 1, wherein: (i) the temperature of the reaction gas is maintained at a temperature Td lower than the temperature of the fuel cell when power generation of the fuel cell is started. Controlling the reaction gas temperature adjusting element, and (ii) during the steady operation of the fuel cell, the temperature of the reaction gas is maintained at a temperature Td2 (Td2 <Td) lower than the temperature of the fuel cell. A fuel cell system for controlling the reaction gas temperature adjusting element.   7. The control device according to claim 1, wherein the control device is configured to maintain the temperature of the reaction gas at a temperature Td lower than the temperature of the fuel cell in the first period when the power generation of the fuel cell is started. The reaction gas temperature adjusting element is controlled, and the reaction is performed such that the temperature of the reaction gas is maintained at a temperature Te (Te <Td) lower than the temperature of the fuel cell in the latter period when the power generation of the fuel cell is started. A fuel cell system for controlling a gas temperature adjusting element.

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