Fuel cell system

Abstract

To provide a technology for supplying hydrogen gas without excessively cooling a component of a supply destination of the hydrogen gas.SOLUTION: A fuel cell system comprises: a stack unit including a fuel cell stack; and a hydrogen tank module. The hydrogen tank module includes: a plurality of hydrogen tanks, each of which has a valve; a temperature sensor for measuring a temperature of hydrogen gas to be supplied from each hydrogen tank to the stack unit; and a controller for changing over a state of supplying hydrogen gas from each tank to the stack unit by controlling the valve of each hydrogen tank. The controller selectively uses one of the plurality of hydrogen tanks as a current supply tank for supplying hydrogen gas to the stack unit, and changes over the current supply tank to another hydrogen tank when a hydrogen gas temperature measured by the temperature sensor is equal to or lower than a reference temperature.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to fuel cell systems. [Background technology]

[0002] 2. Description of the Related Art Conventionally, fuel cell systems are known in which hydrogen gas is supplied to a fuel cell stack from a plurality of hydrogen tanks (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-113154 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the inventors of the present disclosure have found that when the valves of multiple hydrogen tanks are opened and closed simultaneously, the internal temperature of all of the hydrogen tanks drops as hydrogen is consumed, and components used at the destination of the hydrogen gas supply are excessively cooled by the hydrogen gas, which may cause malfunctions of the components. Therefore, it is desirable to supply hydrogen gas without excessively cooling the components at the destination of the hydrogen gas supply. [Means for solving the problem]

[0005] (1) According to one aspect of the present disclosure, there is provided a fuel cell system. The fuel cell system includes a stack unit including a fuel cell stack, and a hydrogen tank module. The hydrogen tank module includes a plurality of hydrogen tanks, each having a valve, a temperature sensor for measuring the temperature of hydrogen gas supplied from each hydrogen tank to the stack unit, and a control device for switching the supply state of the hydrogen gas from each hydrogen tank to the stack unit by controlling the valve of each hydrogen tank. The control device selectively uses one of the plurality of hydrogen tanks as a current supply tank for supplying the hydrogen gas to the stack unit, and switches the current supply tank to another hydrogen tank when the hydrogen gas temperature measured by the temperature sensor becomes equal to or lower than a reference temperature. According to this fuel cell system, the current supply tank is switched when the temperature of the hydrogen gas supplied to the stack unit falls below a reference temperature, thereby preventing the hydrogen gas from excessively cooling components of the stack unit. (2) In the above fuel cell system, the multiple hydrogen tanks are arranged in parallel to the hydrogen outlet of the hydrogen tank module, and each hydrogen tank is provided with an internal tank temperature sensor as the temperature sensor for measuring the temperature inside the hydrogen tank, and the control device may select one of the multiple hydrogen tanks in order of highest internal tank temperature and use it in sequence as the current supply tank. According to this fuel cell system, when multiple hydrogen tanks are provided in parallel, the tank with the highest internal temperature is used as the current supply tank, thereby preventing frequent switching of the current supply tank. (3) In the fuel cell system, the multiple hydrogen tanks may be arranged in series with respect to the hydrogen outlet of the hydrogen tank module, and the control device may select one of the multiple hydrogen tanks in order of proximity to the hydrogen outlet and use it in sequence as the current supply tank. According to this fuel cell system, when multiple hydrogen tanks are arranged in series, the tank closest to the hydrogen outlet is used as the current supply tank, thereby preventing a sudden drop in hydrogen gas temperature and preventing frequent switching of the current supply tank. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a conceptual diagram showing the configuration of a fuel cell system. [Diagram 2] FIG. 2 is an explanatory diagram showing the configuration of a hydrogen tank module in the first embodiment. [Diagram 3] 4 is a timing chart showing an example of valve control of the hydrogen tank module in the first embodiment. [Figure 4] FIG. 11 is an explanatory diagram showing the configuration of a hydrogen tank module in a second embodiment. [Diagram 5] 10 is a timing chart showing an example of valve control of the hydrogen tank module in the second embodiment. [Figure 6] FIG. 11 is an explanatory diagram showing the configuration of a hydrogen tank module according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] 1 is a conceptual diagram showing the configuration of a fuel cell system 10. The fuel cell system 10 includes an anode gas supply system including a hydrogen tank module 100, a stack unit 200 including a fuel cell stack 210, and a cathode gas supply system including an air compressor 300. The fuel cell stack 210 generates electricity through a fuel cell reaction between hydrogen gas supplied as an anode gas and oxygen supplied as a cathode gas. The anode gas supply system may be configured to include an injector and an anode exhaust gas circulation system. The cathode gas supply system may be configured to include various valves and branch pipes.

[0008] 2 is an explanatory diagram showing the configuration of a hydrogen tank module 100 in the first embodiment. The hydrogen tank module 100 includes a hydrogen inlet 111, a hydrogen outlet 112, an inlet side connection part 121, an outlet side connection part 122, a pressure reducing unit 130, a plurality of hydrogen tanks 140, and a control device 150. Each hydrogen tank 140 is provided with a valve unit 160.

[0009] The hydrogen inlet 111 and the inlet side connector 121 are connected by an inlet pipe 171. The inlet side connector 121 is a branch connector including a plurality of branch ports, and each branch port is connected to a gas inlet of each valve unit 160 via a connecting pipe 172. The outlet side connector 122 is a collective connector including a plurality of inlets, and each inlet is connected to a gas outlet of each valve unit 160 via a connecting pipe 173. The outlet side connector 122 and the hydrogen outlet 112 are connected by an outlet pipe 174. A pressure reducing unit 130 is provided in the middle of the outlet pipe 174. The pressure reducing unit 130 includes a pressure reducing valve, and reduces the pressure of the hydrogen gas supplied to the hydrogen outlet 112 to a preset pressure.

[0010] In the first embodiment, the multiple hydrogen tanks 140 are connected in parallel to the hydrogen outlet 112 of the hydrogen tank module 100. In general, the hydrogen tank module 100 is configured to include N hydrogen tanks 140, where N is an integer equal to or greater than 2, and in the first embodiment, N=4. In the following, in order to distinguish between the four hydrogen tanks 140 included in the hydrogen tank module 100, they will be referred to as "Tank #1," "Tank #2," "Tank #3," and "Tank #4," respectively.

[0011] The valve unit 160 has an inlet pipe 161, an outlet pipe 162, and a common pipe 163. The inlet pipe 161 is connected to a gas inlet of the valve unit 160. The outlet pipe 162 is connected to a gas outlet of the valve unit 160. The common pipe 163 is connected to the inlet pipe 161 and the outlet pipe 162, and is in communication with the inside of the hydrogen tank 140 via a nozzle of the hydrogen tank 140. The inlet pipe 161 and the outlet pipe 162 are each provided with a check valve and a filter. The common pipe 163 is provided with a solenoid valve 165, and the outlet pipe 162 is provided with an opening / closing valve 164.

[0012] The on-off valve 164 is a manual valve for maintenance purposes, and is always kept open when the hydrogen tank module 100 is in use. The solenoid valve 165 is switched between an open state and a closed state by the control device 150 when the hydrogen tank module 100 is in use. When the solenoid valve 165 is in the open state, hydrogen gas in the hydrogen tank 140 flows out to the outside via the common pipe 163 and the outflow pipe 162. When the solenoid valve 165 is in the closed state, the outflow of hydrogen gas in the hydrogen tank 140 stops. However, when hydrogen gas is supplied to the gas inlet of the valve unit 160 with the solenoid valve 165 in the closed state, the hydrogen gas is guided downstream via the inlet pipe 161 and the outlet pipe 162. The latter characteristic is utilized in the series arrangement of the second embodiment described below.

[0013] The valve unit 160 further has an in-tank temperature sensor 166 that measures the temperature of the hydrogen gas inside the hydrogen tank 140. The temperature measured by the in-tank temperature sensor 166 is referred to as the "in-tank temperature." The in-tank temperature sensor 166 is used as a temperature sensor that measures the temperature of the hydrogen gas supplied from each hydrogen tank 140 to the stack unit 200. Note that instead of providing the in-tank temperature sensor 166 in each hydrogen tank 140, for example, a temperature sensor may be provided midway along the outflow pipe 174 to measure the temperature of the hydrogen gas supplied to the stack unit 200.

[0014] Pressure sensors 121p, 122p for measuring the pressure of hydrogen gas are provided at the inlet side connection part 121 and the outlet side connection part 122, respectively. A pressure sensor for measuring the pressure of hydrogen gas before and after decompression may also be provided at the decompression unit 130. However, some of these pressure sensors may be omitted.

[0015] The control device 150 controls the operation of the hydrogen tank module 100 using the hydrogen gas temperature measured by the in-tank temperature sensor 166. Specifically, the control device 150 switches the supply state of hydrogen gas from each hydrogen tank 140 to the stack unit 200 by controlling the opening and closing of the solenoid valve 165 of the valve unit 160 provided in each hydrogen tank 140. Note that the term "valve" in this disclosure refers to the solenoid valve 165 unless otherwise specified.

[0016] The hydrogen tank 140 used in this embodiment is a so-called Type 4 tank, which is a high-pressure hydrogen container for FCVs with an operating pressure of 70 MPa or less. When hydrogen gas is continuously supplied from such a hydrogen tank 140 to the stack unit 200, the temperature of the supplied hydrogen gas may drop to around minus 40°C. On the other hand, many of the components used in the stack unit 200 have a lower operating temperature limit in the range of minus 30°C to minus 10°C, and there is a risk of malfunction if they are exposed to hydrogen gas at a lower temperature than this. Therefore, in the first embodiment, the control device 150 controls the valve of the hydrogen tank module 100 so that the temperature of the hydrogen gas supplied from the hydrogen tank 140 is in a range higher than the lower operating temperature limit of the components of the stack unit 200.

[0017] Fig. 3 is a timing chart showing an example of valve control of the hydrogen tank module 100 in the first embodiment. Fig. 3 shows the supply hydrogen pressure Psup, the supply hydrogen temperature Tsup, and the open / closed states of the solenoid valves 165 of the four tanks #1 to #4. The supply hydrogen pressure Psup is the pressure of the hydrogen gas supplied from each hydrogen tank 140 to the decompression unit 130. The supply hydrogen temperature Tsup is the temperature of the hydrogen gas supplied from each hydrogen tank 140 to the decompression unit 130. In one embodiment, the internal tank temperature of each hydrogen tank 140 measured by the internal tank temperature sensor 166 may be taken as the supply hydrogen temperature Tsup.

[0018] In the first embodiment, the control device 150 selects one of the multiple hydrogen tanks 140 in descending order of internal tank temperature and uses it in sequence as the current supply tank. The "current supply tank" refers to the hydrogen tank that is currently supplying hydrogen gas to the stack unit 200. In the example of FIG. 3, it is assumed that the internal tank temperatures are highest in the order of tanks #1 to #4. It is preferable to use values ​​measured at the start-up of the fuel cell system 10 as the internal tank temperatures.

[0019] During the period from time t1 to t2 in FIG. 3, tank #1, which has the highest internal tank temperature among tanks #1 to #4, is selected and used as the current supply tank. During this period, the solenoid valve 165 of tank #1 is open, and the solenoid valves 165 of the other tanks #2 to #4 are closed. The supply hydrogen pressure Psup decreases monotonically from the initial pressure of tank #1. At time t2, the supply hydrogen temperature Tsup drops to or below a preset reference temperature Tref. It is preferable that the reference temperature Tref be set to a value higher than the highest value Tlim of the lower operating temperature limits of the multiple components that are cooled by hydrogen gas among the multiple components of the stack unit 200.

[0020] At time t2, the control device 150 switches the current supply tank from tank #1 to tank #2, and in response to this switching, the supply hydrogen pressure Psup rises to almost the initial pressure of tank #2. The supply hydrogen temperature Tsup also rises slightly at time t2 and then drops again. During the period from time t2 to t3, the solenoid valve 165 of tank #2 is open, and the solenoid valves 165 of the other tanks #1, #3, and #4 are closed. However, the solenoid valve 165 of tank #1, which was initially used as the current supply tank, may be kept open. This is because during the period from time t2 to t3, the pressure of tank #2 is higher than that of tank #1, so even if the solenoid valve 165 of tank #1 is open, only tank #2 actually functions as the current supply tank. In addition, since a check valve is provided in the outflow pipe 162 of the valve unit 160, there is no risk of hydrogen gas flowing into tank #1 even if the solenoid valve 165 of tank #1 is open. The supply hydrogen pressure Psup decreases monotonically again from time t2. At time t3, the supply hydrogen temperature Tsup drops below the reference temperature Tref.

[0021] In the period from time t3 to t4, tank #3 is used as the current supply tank. In the period from time t4 to t5, tank #4 is used as the current supply tank. The operation in these periods is almost the same as the operation in the period from time t2 to t3, so the explanation will be omitted.

[0022] As described above, in the first embodiment, the current supply tank is switched when the temperature of the hydrogen gas supplied to the stack unit 200 falls below the reference temperature Tref, thereby preventing the hydrogen gas from excessively cooling the components of the stack unit 200.

[0023] In the first embodiment, the multiple hydrogen tanks 140 are selected in descending order of internal tank temperature and used in sequence as the current supply tank, but the selection order is not limited to this, and any one of the multiple hydrogen tanks 140 may be selected as the current supply tank. However, when multiple hydrogen tanks 140 are provided in parallel, frequent switching of the current supply tank can be suppressed by using the current supply tank in descending order of internal tank temperature. Also, since it is estimated that the higher the internal tank temperature, the more hydrogen gas is remaining, so that using the current supply tanks in descending order of internal tank temperature allows the multiple hydrogen tanks 140 to be used without bias.

[0024] 4 is an explanatory diagram showing the internal configuration of a hydrogen tank module 100 in the second embodiment. The configuration of a fuel cell system 10 in the second embodiment is the same as that in the first embodiment. The second embodiment differs from the first embodiment in that a plurality of hydrogen tanks 140 of the hydrogen tank module 100 are provided in series with respect to a hydrogen outlet 112. That is, tank #1 is connected to tank #2 via a connecting pipe 175. Similarly, tank #2 is connected to tank #3 via a connecting pipe 176, and tank #3 is connected to tank #4 via a connecting pipe 177.

[0025] 5 is a timing chart showing an example of valve control of the hydrogen tank module 100 in the second embodiment. In the second embodiment, the control device 150 selects one of the multiple hydrogen tanks 140 in order of proximity to the hydrogen outlet 112 and sequentially uses it as the current supply tank. "Close to the hydrogen outlet 112" means that it is disposed further downstream in the serial hydrogen flow path. In the example of FIG. 4, the tanks #4, #3, #2, and #1 are closest to the hydrogen outlet 112 in that order.

[0026] 5, tank #4, which is closest to the hydrogen outlet 112 among tanks #1 to #4, is selected and used as the current supply tank. During this period, the solenoid valve 165 of tank #4 is open, and the solenoid valves 165 of the other tanks #1 to #3 are closed. The changes in the supply hydrogen pressure Psup and the supply hydrogen temperature Tsup are almost the same as those in the example of the first embodiment shown in FIG.

[0027] In the period from time t12 to t13, tank #3 is used as the current supply tank. In the period from time t13 to t14, tank #2 is used as the current supply tank. In the period from time t14 to t15, tank #1 is used as the current supply tank.

[0028] In the second embodiment described above, as in the first embodiment, the current supply tank is switched when the temperature of the hydrogen gas supplied to the stack unit 200 becomes equal to or lower than the reference temperature Tref, so that it is possible to prevent the hydrogen gas from excessively cooling the components of the stack unit 200. Furthermore, in the second embodiment, when multiple hydrogen tanks 140 are provided in series, the tank closest to the hydrogen outlet 112 is used as the current supply tank. As a result, it is possible to prevent a sudden drop in the temperature of the hydrogen gas and to prevent frequent switching of the current supply tank. Note that the order of selection of the hydrogen tanks 140 in the second embodiment is not limited to this, and any one of the multiple hydrogen tanks 140 may be selected as the current supply tank.

[0029] Figure 6 is an explanatory diagram showing the internal configuration of a hydrogen tank module in the third embodiment. In the third embodiment, two hydrogen tank modules 100 similar to that shown in Figure 2 are connected in parallel for use. The hydrogen outlets 112 of the two hydrogen tank modules 100a, 100b are connected to a common hydrogen outlet 180. Hydrogen gas is supplied from this common hydrogen outlet 180 to the stack unit 200. The eight hydrogen tanks 140 included in the two hydrogen tank modules 100a, 100b are connected in parallel to the common hydrogen outlet 180.

[0030] The control devices 150a, 150b of the two hydrogen tank modules 100a, 100b are configured to be able to communicate with each other and function together as a single control device. As in the first embodiment, the control devices 150a, 150b select one of the multiple hydrogen tanks 140 in descending order of internal tank temperature and use it in sequence as the current supply tank. The method of valve control in the third embodiment is almost the same as that in the first embodiment shown in Figure 3, so a description will be omitted.

[0031] In the third embodiment, as in the first embodiment, the current supply tank is switched when the temperature of the hydrogen gas supplied to the stack unit 200 falls below the reference temperature Tref, thereby preventing the hydrogen gas from excessively cooling the components of the stack unit 200. Furthermore, when multiple hydrogen tanks 140 are provided in parallel, the tank with the highest internal temperature is used as the current supply tank, thereby preventing frequent switching of the current supply tank.

[0032] In each of the above-described embodiments, the stack unit 200 was used as the hydrogen supply destination of the hydrogen tank module 100, but the present disclosure is also applicable to cases where hydrogen is supplied to any supply destination device other than the stack unit 200.

[0033] Other forms: The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various forms without departing from the spirit of the present disclosure. For example, the present disclosure can be realized in the following aspects. The technical features in the above-mentioned embodiments corresponding to the technical features in each aspect described below can be appropriately replaced or combined in order to solve some or all of the problems of the present disclosure, or to achieve some or all of the effects of the present disclosure. Furthermore, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

[0034] The present disclosure may be realized in various forms other than a fuel cell system or a control method thereof, such as a hydrogen tank module or a control method thereof, a computer program for controlling a fuel cell system or a hydrogen tank module, or a non-transitory storage medium on which a computer program is recorded. [Explanation of symbols]

[0035] 10... fuel cell system, 100... hydrogen tank module, 111... hydrogen inlet, 112... hydrogen outlet, 121... inlet side connection part, 121p... pressure sensor, 122... outlet side connection part, 122p... pressure sensor, 130... pressure reducing unit, 140... hydrogen tank, 150... control device, 160... valve unit, 161... inlet pipe, 162... outlet pipe, 163... common pipe, 164... on-off valve, 165... solenoid valve, 166... ​​tank internal temperature sensor, 171... inlet pipe, 172... connecting pipe, 173... connecting pipe, 174... outlet pipe, 175... connecting pipe, 176... connecting pipe, 177... connecting pipe, 180... common hydrogen outlet, 200... stack unit, 210... fuel cell stack, 300... air compressor

Claims

1. 1. A fuel cell system comprising: a stack unit including a fuel cell stack; A hydrogen tank module; Equipped with The hydrogen tank module includes: A plurality of hydrogen tanks, each of which is provided with a valve; a temperature sensor for measuring the temperature of hydrogen gas supplied from each hydrogen tank to the stack unit; a control device for switching a supply state of the hydrogen gas from each hydrogen tank to the stack unit by controlling the valve of each hydrogen tank; having The control device selectively uses one of the multiple hydrogen tanks as a current supply tank that supplies the hydrogen gas to the stack unit, and switches the current supply tank to another hydrogen tank when the hydrogen gas temperature measured by the temperature sensor falls below a reference temperature.

2. 2. The fuel cell system according to claim 1, the plurality of hydrogen tanks are arranged in parallel with respect to a hydrogen outlet of the hydrogen tank module, Each hydrogen tank is provided with an in-tank temperature sensor that measures the temperature inside the hydrogen tank, The control device selects one of the plurality of hydrogen tanks in descending order of internal temperature and sequentially uses the selected tank as the current supply tank.

3. 2. The fuel cell system according to claim 1, the plurality of hydrogen tanks are arranged in series with respect to a hydrogen outlet of the hydrogen tank module; The control device selects one of the plurality of hydrogen tanks in order of proximity to the hydrogen outlet and sequentially uses the selected tank as the current supply tank.

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