JP2009104966A - Fuel cell system - Google Patents

Abstract

In a fuel cell system including a gas-liquid separation unit, a technique for raising the temperature of stored water when the temperature of stored water in the gas-liquid separation unit is below freezing point is provided.
A fuel cell system including a fuel cell, wherein off-gas is introduced from the fuel cell, water vapor in the off-gas is condensed, and water can be stored, and the off-gas is separated from the gas-liquid separator. A purge valve that purges as a purge gas from the fuel cell system to the outside of the fuel cell system, and when the temperature of the stored water stored in the gas-liquid separation unit is below freezing point, the purge valve And an adjustment unit for adjusting the purge amount of the purge gas,
Is provided.
[Selection] Figure 4

Description

  The present invention relates to a fuel cell system including a fuel cell.

  2. Description of the Related Art A fuel cell system that includes an off-gas introduced from a fuel cell, condenses water vapor in the off-gas, and includes a gas-liquid separator that can store water is known (see Patent Document 1).

JP 2006-147414 A

  In the gas-liquid separator of the fuel cell system, when the temperature of the stored water is below freezing point, the stored water is in a supercooled state, for example. As described above, in the gas-liquid separation unit, when the stored water is in a supercooled state, various problems may occur. For example, when the supercooled stored water is purged through the purge valve, it is frozen by the purge valve, and as a result, the purge valve may not be controlled. Further, in the gas-liquid separation unit, if the temperature of the stored water is below freezing and is in a frozen state, for example, the stored water cannot be purged from the gas-liquid separation unit, and there is a problem that water cannot be newly stored. There was a fear.

  The present invention has been made in view of the above problems, and in a fuel cell system including a gas-liquid separator, a technique for raising the temperature of the stored water when the temperature of the stored water in the gas-liquid separator is below freezing point. The purpose is to provide.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A fuel cell system including a fuel cell, wherein off-gas is introduced from the fuel cell, water vapor in the off-gas is condensed and water can be stored, and the off-gas is separated from the gas-liquid separator. When the temperature of the stored water stored in the gas-liquid separation unit is below freezing point, the amount of water vapor in the purge gas is not less than a predetermined amount. And a control unit that controls the purge valve and adjusts the purge amount of the purge gas.

  According to the fuel cell system configured as described above, when purging the purge gas, the temperature of the stored water in the gas-liquid separation unit can be sufficiently raised by the water vapor in the purge gas.

[Application Example 2]
In the fuel cell system according to Application Example 1, in the case where the stored water stored in the gas-liquid separation unit is in a supercooled state, the adjustment unit is configured such that the amount of water vapor in the purge gas is equal to or greater than the predetermined amount. The fuel cell system is characterized in that the purge valve is controlled to adjust the purge amount of the purge gas.

  In this way, when the purge water is purged when the stored water is in a supercooled state, the temperature of the stored water in the gas-liquid separation unit can be sufficiently raised by the water vapor in the purge gas.

[Application Example 3]
In the fuel cell system according to Application Example 1 or Application Example 2, the predetermined amount is an amount of water vapor necessary to raise the temperature of the stored water discharged from the gas-liquid separation unit from the freezing point by condensation heat. A fuel cell system comprising:

  If it does in this way, when purging purge gas, the temperature of the stored water of a gas-liquid separation part can fully be raised with the water vapor | steam in purge gas.

[Application Example 4]
In the fuel cell system according to any one of Application Examples 1 to 3, the pressure at the upstream position in the vicinity of the purge valve and in the direction in which the stored water is discharged from the purge valve is lower than the purge valve. A fuel cell system comprising a pressure drop unit.

  In this way, the purge amount of purge gas can be reduced. As a result, it is possible to suppress the purge gas from being purged excessively.

[Application Example 5]
The fuel cell system according to Application Example 4, further comprising a pressure adjusting unit capable of adjusting a reaction gas supplied to the fuel cell, wherein the gas-liquid separation unit includes the reaction gas adjusted by the pressure adjusting unit. The off-gas after being subjected to an electrochemical reaction in the fuel cell is introduced, and the pressure reducing unit reduces the pressure of the upstream position by reducing the pressure of the reactive gas in the pressure adjusting unit. A fuel cell system.

  In this way, the pressure at the upstream position can be easily reduced. Further, the purge amount of the purge gas can be reduced. As a result, it is possible to suppress the purge gas from being purged excessively.

[Application Example 6]
The fuel cell system according to Application Example 4 or Application Example 5, further comprising a pump for re-supplying the off-gas introduced into the gas-liquid separation unit to the fuel cell in order to reuse the pressure drop. The unit reduces the pressure at the upstream position by reducing the number of rotations of the pump.

  In this way, the pressure at the upstream position can be easily reduced. Further, the purge amount of the purge gas can be reduced. As a result, it is possible to suppress the purge gas from being purged excessively.

[Application Example 7]
7. The fuel cell system according to any one of Application Examples 1 to 6, wherein the adjustment unit sets the purge amount of the purge gas so that the amount of water vapor in the purge gas is equal to or greater than the predetermined amount. A fuel cell system that adjusts based on the temperature of the battery. In this way, it is possible to suppress purging of the purge gas excessively.

[Application Example 8]
The fuel cell system according to any one of Application Example 1 to Application Example 7, wherein the adjustment unit sets the purge amount of the purge gas so that the amount of water vapor in the purge gas is equal to or greater than the predetermined amount. The fuel cell system is adjusted based on a pressure at an upstream position with respect to a direction in which the stored water is discharged from the purge valve rather than the valve. In this way, it is possible to suppress purging of the purge gas excessively.

[Application Example 9]
In the fuel cell system according to any one of Application Example 1 to Application Example 8, the adjustment unit may determine the purge amount of the purge gas, the water vapor amount in the purge gas being the predetermined amount, and the purge amount. The fuel cell system is adjusted so as to minimize the fuel cell system. In this way, it is possible to suppress purging of the purge gas excessively.

[Application Example 10]
In the fuel cell system according to any one of Application Examples 1 to 9, the adjustment unit purges the purge gas at a minimum when the temperature of the stored water stored in the gas-liquid separation unit is below freezing point. A first purge amount that is a power amount and a second purge amount that includes the water vapor that is equal to or greater than the predetermined amount, and when the first purge amount is less than or equal to the second purge amount, the purge valve The purge gas is purged with the second purge amount, and when the first purge amount is greater than the second purge amount, the purge valve is controlled to purge the purge gas with the first purge amount. And a fuel cell system. In this way, it is possible to suppress purging of the purge gas excessively.

[Application Example 11]
A fuel cell system including a fuel cell, wherein off-gas is introduced from the fuel cell, water vapor in the off-gas is condensed and water can be stored, and the off-gas is separated from the gas-liquid separator. When the temperature of the stored water stored in the gas-liquid separation unit is below freezing point, the purge amount of the purge gas is equal to or greater than a predetermined amount. A fuel cell system comprising: an adjustment unit that controls the purge valve and adjusts a purge amount of the purge gas.

  According to the fuel cell system configured as described above, when purging the purge gas, the temperature of the stored water in the gas-liquid separation unit can be sufficiently raised by the water vapor in the purge gas.

[Application Example 12]
In the fuel cell system,
When the temperature of the stored water stored in the gas-liquid separation unit is below freezing point, the adjustment unit may adjust the purge amount of the purge gas from the fuel cell temperature or the purge valve so that the purge amount becomes a predetermined amount or more. The fuel cell system further comprising: controlling the purge valve and adjusting a purge amount of the purge gas based on a pressure at an upstream position with respect to a direction in which the stored water is discharged from the purge valve. In this way, it is possible to suppress purging of the purge gas excessively.

  The present invention can be realized in other aspects of the invention of the device, such as a purge valve control device, in addition to the fuel cell system described above. Further, the present invention is not limited to the device invention, and can be realized in the form of a method invention such as a control method of the fuel cell system. Further, aspects as a computer program for constructing those methods and apparatuses, aspects as a recording medium recording such a computer program, data signals embodied in a carrier wave including the computer program, etc. It can also be realized in various ways.

  Further, when the present invention is configured as a computer program or a recording medium that records the program, the entire program for controlling the operation of the apparatus may be configured, or only the portion that performs the functions of the present invention. It may be configured.

Hereinafter, embodiments of the present invention will be described based on examples.
A. First embodiment:
A1. Configuration of the fuel cell system 1000:
FIG. 1 is a block diagram showing a configuration of a fuel cell system 1000 as a first embodiment of the present invention. The fuel cell system 1000 of the present embodiment mainly includes a fuel cell 100, a hydrogen tank 200, a hydrogen cutoff valve 210, a variable regulator 215, a compressor 230, a hydrogen circulation pump 250, a control circuit 400, a refrigerant. Circulation pump 500, temperature sensors 520 and 530, pressure sensor 540, radiator 550, gas-liquid separator 600, and purge valve 610 are provided.

  The fuel cell 100 is a polymer electrolyte fuel cell that is relatively small and excellent in power generation efficiency. The fuel cell 100 includes a fuel cell 20, end plates 300A and 300B, a tension plate 310, insulators 330A and 330B, and terminals 340A and 340B. Specifically, the fuel cell 100 includes an end plate 300A, an insulator 330A, a terminal 340A, a plurality of fuel cells 20, a terminal 340B, an insulator 330B, and an end plate 300B, which are stacked in this order. By being coupled to the plate 300, each fuel cell 20 is structured to be fastened with a predetermined force in the stacking direction.

  The fuel battery cell 20 includes a membrane electrode assembly (not shown), an anode side separator (not shown), and a cathode side separator (not shown). The membrane electrode assembly includes an electrolyte membrane (not shown), a cathode (not shown) and an anode (not shown) as electrodes, and a gas diffusion layer (not shown). An electrolyte membrane formed on the surface is sandwiched between gas diffusion layers. The fuel battery cell 20 is configured by further sandwiching this membrane electrode assembly between an anode side separator and a cathode side separator.

  The hydrogen tank 200 is a storage device that stores high-pressure hydrogen gas, and is connected to the fuel cell 100 via a fuel gas supply channel 204. On the fuel gas supply flow path 204, a hydrogen cutoff valve 210 and a variable regulator 215 are provided in the order closer to the hydrogen tank 200. By opening the hydrogen shut-off valve 210, hydrogen gas is supplied to the fuel cell 100 as fuel gas. Instead of the hydrogen tank 200, hydrogen may be generated by a reforming reaction using alcohol, hydrocarbon, aldehyde, or the like as a raw material and supplied to the anode side.

  The variable regulator 215 is controlled by a control circuit 400 described later, and adjusts the pressure of the fuel gas supplied to the fuel cell 100 according to the operating state of the fuel cell system 1000.

  The compressor 230 is connected to the fuel cell 100 via the oxidizing gas supply channel 234, compresses air, and supplies it as an oxidizing gas to the cathode. Further, the fuel cell 100 is connected to the oxidizing gas discharge channel 236, and the oxidizing off-gas after being subjected to an electrochemical reaction at the cathode passes through the oxidizing gas discharge channel 236 to the outside of the fuel cell system 1000. Discharged.

  Inside the fuel cell 100, a fuel gas supply manifold (not shown) for supplying fuel gas to each fuel cell 20 and a fuel gas from each fuel cell 20 for discharging the fuel cell 100 to the outside A fuel gas discharge manifold (not shown), an oxidant gas supply manifold (not shown) for supplying an oxidant gas to each fuel cell 20, and an oxidant gas from each fuel cell 20 to the outside of the fuel cell 100 An oxidizing gas discharge manifold (not shown) for discharging, a refrigerant supply manifold (not shown) for supplying a refrigerant between the fuel cells 20, and the refrigerant supplied between the fuel cells 20 as fuel A refrigerant discharge manifold (not shown) for discharging to the outside of the battery 100 is provided.

  The fuel cell 100 (refrigerant supply manifold or refrigerant discharge manifold) is connected to the refrigerant circulation channel 510. A refrigerant circulation pump 500 and a radiator 550 are provided on the refrigerant circulation channel 510. The radiator 550 cools the refrigerant warmed by the fuel cell 100, and the refrigerant circulation pump 500 supplies the refrigerant cooled by the radiator 550 to the fuel cell 100. Thereby, the fuel cell 100 can be continuously cooled by the refrigerant. As the refrigerant, water, a mixed solution of water and ethylene glycol (antifreeze), or the like can be used.

  The temperature sensor 530 is a sensor for detecting the temperature [° C.] of the refrigerant discharged from the fuel cell 100, which is disposed at a connection portion between the refrigerant circulation channel 510 and the refrigerant discharge manifold of the fuel cell 100. . Here, since the refrigerant has a large heat capacity, the temperature of the refrigerant discharged from the fuel cell 100 can be regarded as the temperature of the fuel cell 100. Therefore, the refrigerant temperature detected by the temperature sensor 530 is also referred to as a fuel cell temperature Tf below.

  FIG. 2 is an enlarged view around the gas-liquid separator 600. The gas-liquid separator 600 is connected to the fuel cell 100 (fuel gas discharge manifold) via the fuel gas discharge channel 206, and the fuel off-gas after being subjected to an electrochemical reaction at the anode of the fuel cell 100 is introduced. The This gas-liquid separator 600 is discharged as liquid water from the condensing unit 600A for condensing water vapor contained in the fuel off-gas, the condensed water condensed in the condensing unit 600A, and the fuel cell 100 through the fuel gas discharge channel 206. It is comprised from the storage part 600B which stores the water to be performed. Hereinafter, the water stored in the storage unit 600B is referred to as stored water. The gas-liquid separator 600 is provided with a purge valve 610. The purge valve 610 is connected to the exhaust / drain passage 620.

  The gas-liquid separator 600 is connected to the fuel gas supply channel 204 via the gas circulation channel 207. A hydrogen circulation pump 250 is provided on the gas circulation channel 207. The fuel off-gas discharged from the fuel cell 100 (fuel gas discharge manifold) to the gas-liquid separator 600 is introduced into the fuel gas supply flow path 204 as a fuel gas by the hydrogen circulation pump 250 via the gas circulation flow path 207. The In this way, hydrogen contained in the fuel off-gas is circulated and used again for power generation. Note that an ion exchange device that removes ions in the liquid water discharged from the fuel cell 100 may be provided at a connection portion between the gas-liquid separator 600 and the fuel gas discharge channel 206.

  Further, in the purge process described later, by opening the purge valve 610, the fuel off-gas having a high impurity (for example, nitrogen) concentration and the stored water in the storage unit 600B are used as the purge valve 610 and the exhaust drainage channel 620. And purge (discharge) the fuel cell system 1000 outside. In this case, as shown in FIG. 2, the water stored in the storage unit 600B is blown away by the fuel off-gas introduced into the condensing unit 600A, and the fuel cell system 1000 is passed through the purge valve 610 and the exhaust drainage channel 620. Is purged (discharged) to the outside. Hereinafter, the fuel off-gas discharged from the purge valve 610 while blowing the stored water is also referred to as purge gas. Hereinafter, the purge gas amount purged from the purge valve 610 is also referred to as a purge amount. A position upstream of the purge valve 610 with respect to the direction in which the stored water and fuel off-gas are discharged from the purge valve 610 is also referred to as upstream of the purge valve. Details of the purge process will be described later.

  The temperature sensor 520 is a sensor that is disposed on the bottom side of the storage unit 600B and detects the temperature of stored water in the storage unit 600B. Hereinafter, the temperature of the stored water detected by the temperature sensor 520 is also referred to as a stored water temperature Tc.

  The pressure sensor 540 is disposed upstream of the purge valve 610 in the gas-liquid separator 600 (condenser 600A) and at the inlet of the purge valve 610, and is a sensor for detecting the pressure at the inlet of the purge valve 610. Hereinafter, the pressure at the inlet of the purge valve 610 detected by the pressure sensor 540 is also referred to as a purge valve inlet pressure Pi.

  The control circuit 400 is configured as a logic circuit centered on a microcomputer, and more specifically, a CPU (not shown) that executes predetermined calculations in accordance with a preset control program, and various arithmetic processes performed by the CPU. A ROM (not shown) in which a control program and control data necessary for the above are stored in advance, a RAM 420 in which various data necessary for performing various arithmetic processes in the CPU are temporarily read and written, and various signals An input / output port (not shown) for inputting and outputting is provided. The control circuit 400 controls the hydrogen cutoff valve 210, the variable regulator 215, the compressor 230, the hydrogen circulation pump 250, the refrigerant circulation pump 500, the purge valve 610, and the like, that is, controls the entire fuel cell system 1000. .

  The control circuit 400 also functions as a purge control unit 410 and executes a purge process described later.

  By the way, as described above, when the stored water or purge gas in the storage unit 600B is purged, various problems may occur when the temperature of the stored water is below freezing and the stored water is in an overcooled state. there were. For example, when the stored water is purged via the purge valve 610, the stored water may be frozen by the purge valve 610, and the purge valve 610 may become uncontrollable. Therefore, in the purging process described later, when the stored water is in a supercooled state, when the stored water is blown off with the purge gas, the stored water is purged by raising the temperature of the stored water with the condensation heat of the water vapor in the purge gas. The overcooled state of is canceled. Here, the amount of water vapor in the purge gas necessary to eliminate the supercooled state of the stored water is also referred to as the temperature increase required steam amount Sth. Further, the purge amount necessary for containing the temperature increase required steam amount Sth is also referred to as the temperature increase required purge amount Mj. Note that the above-described required temperature rise Sth is appropriately determined based on the specific design of the fuel cell system 1000, such as the shape and volume of the reservoir 600B.

  FIG. 3 is a graph showing the relationship between the purge amount of the purge gas and the fuel cell temperature or the purge valve inlet pressure. Specifically, FIG. 3A is a graph showing the relationship between the purge amount and the fuel cell temperature when the amount of water vapor contained in the purge gas and the purge gas inlet pressure are constant. FIG. 3B is a graph showing the relationship between the purge amount and the purge valve inlet pressure when the amount of water vapor contained in the purge gas and the fuel cell temperature are constant. As shown in the graph of FIG. 3A, when the amount of water vapor contained in the purge gas is constant, the purge amount is reduced when the fuel cell temperature is high, and the purge amount is increased when the fuel cell temperature is low. I know you need to do that. That is, it can be seen that the purge amount necessary to contain a certain amount of water vapor is correlated with the fuel cell temperature. Further, as shown in the graph of FIG. 3B, when the amount of water vapor contained in the purge gas is constant, the purge amount can be reduced as the purge valve inlet pressure decreases, and the purge valve inlet pressure is increased. It turns out that the purge amount needs to be increased. That is, it can be seen that the purge amount necessary to contain a certain amount of water vapor is correlated with the purge valve inlet pressure. Therefore, the required temperature rise purge amount Mj is correlated with the fuel cell temperature Tf and the purge valve inlet pressure Pi. In the present embodiment, a relational expression representing the relationship between the required temperature rise purge amount Mj, the fuel cell temperature Tf and the purge valve inlet pressure Pi is detected in advance and stored in the RAM 420 as purge amount data Vr. The temperature increase required purge amount Mj can be detected based on the purge amount data Vr. In a purge process described later, purge gas corresponding to at least the temperature increase required purge amount Mj is purged.

A2. Purge process:
FIG. 4 is a flowchart of the purge process performed by the fuel cell system 1000 of the present embodiment. This purge process is a process for purging (discharging) impurities in the fuel off-gas and stored water in the storage unit 600B after the fuel cell system 1000 starts generating power, and periodically after the fuel cell system 1000 starts generating power. Executed.

  Specifically, the purge control unit 410 first calculates (detects) a minimum purge amount Mi, which is a minimum amount of purge gas to be purged (step S5). The purge control unit 410 detects the pressure regulation value of the variable regulator 215, the consumption amount of the fuel gas in the fuel cell 100, and the like, and calculates the minimum purge amount Mi based on them. Note that the amount of fuel gas consumed in the fuel cell 100 can be detected from the amount of power consumed by a load (not shown) connected to the fuel cell 100.

  Subsequently, the purge control unit 410 detects the stored water temperature Tc from the temperature sensor 520 (step S10).

Then, the purge control unit 410 determines whether or not the stored water in the storage unit 600B is in a supercooled state based on the stored water temperature Tc, that is, whether or not the stored water temperature Tc satisfies the following equation (1) ( Step S15). Note that Tk in Expression (1) is a value within a range of −40 ° C. to −20 ° C., and is appropriately determined based on a specific design of the fuel cell system 1000.
Tk ≦ Tc ≦ 0 (1)

  When the stored water is in a supercooled state (step S15: Yes), the purge control unit 410 detects the fuel cell temperature Tf from the temperature sensor 530 (step S20). Further, the purge control unit 410 detects the purge valve inlet pressure Pi (step S30).

  Then, the purge control unit 410 reads the purge amount data Vr from the RAM 420, and is necessary to contain the required temperature increase steam amount Sth from the fuel cell temperature Tf and the purge valve inlet pressure Pi based on the purge amount data Vr. The temperature increase required purge amount Mj is detected (step S40).

  Next, the purge control unit 410 determines whether or not the temperature increase required purge amount Mj is equal to or greater than the purge amount Mi (step S50).

  When the required temperature increase purge amount Mj is equal to or greater than the purge amount Mi (step S50: Yes), the purge control unit 410 controls the purge valve 610 to purge the purge gas by the required temperature increase purge amount Mj (step S60). ). Thereafter, the purge control unit 410 ends this process.

  When the required temperature rise purge amount Mj is smaller than the purge amount Mi (step S50: No), the purge control unit 410 controls the purge valve 610 to purge the purge gas by the minimum purge amount Mi (step S70). Thereafter, the purge control unit 410 ends this process.

  Further, when the stored water is not in the supercooled state (step S5: No), the purge control unit 410 controls the purge valve 610 to purge the purge gas by the minimum purge amount Mi (step S70). Thereafter, the purge control unit 410 ends this process.

  As described above, in the fuel cell system 1000 according to the present embodiment, in the purge process, when the stored water is in the supercooled state, the purge valve is set so that the water vapor amount in the purge gas becomes the required steam temperature increase Sth. 610 is controlled to adjust the purge amount. In this way, when the purge water is purged when the stored water is in an overcooled state, the temperature of the stored water in the storage section 600B can be sufficiently raised by the water vapor in the purge gas. As a result, it is possible to suppress the stored water from passing through the purge valve 610 while keeping the supercooled state, and it is possible to suppress freezing of the purge valve 610.

  Further, in the fuel cell system 1000, the purge required purge amount Mj necessary for containing the required steam increase steam amount Sth in the purge process is determined based on the fuel cell temperature Tf and the purge valve inlet pressure Pi. I have to. In this way, it is possible to suppress an increase in the required temperature increase purge amount Mj, that is, it is possible to suppress the purge gas from being purged excessively, and hydrogen in the purge gas is removed from the outside of the fuel cell system 1000. Can be prevented from being released.

  In the fuel cell system 1000, the temperature of the stored water in the storage unit 600B is raised by the heat of condensation of water vapor without using other devices such as a heater, so the fuel cell system 1000 can be made smaller and lighter. , Reduction of the number of parts, reduction of manufacturing cost, and the like can be realized.

  In this embodiment, the gas-liquid separator 600 corresponds to the gas-liquid separator in the claims, the purge valve 610 corresponds to the purge valve in the claims, and the purge controller 410 corresponds to the adjusting unit in the claims. It corresponds to.

B. Second embodiment:
The fuel cell system 1000A of the second embodiment has the same configuration as that of the fuel cell system 1000 of the first embodiment, and the description of the configuration of each part is omitted. The fuel cell system 1000A of this embodiment executes a purge process different from the purge process performed by the fuel cell system 1000 of the first embodiment. The purge process performed by the fuel cell system 1000A of the second embodiment will be described below. In the description of the purge process of the present embodiment, the same step number is assigned to the same process as the purge process of the first embodiment, and the description is omitted.

  FIG. 5 is a flowchart of the purge process performed by the fuel cell system 1000A of the present embodiment. After detecting the purge valve inlet pressure Pi (step S30), the purge controller 410 subsequently determines whether or not the purge valve inlet pressure Pi is greater than the threshold value Pth (step S33).

  When the purge valve inlet pressure Pi is larger than the threshold value Pth (step S33: Yes), the purge control unit 410 controls the variable regulator 215 to lower the pressure regulation value of the variable regulator 215 and reduce the purge valve inlet pressure Pi. Lower to threshold value Pth (step S35). Thereafter, the purge control unit 410 reads the purge amount data Vr from the RAM 420, and detects the required temperature increase purge amount Mj from the fuel cell temperature Tf and the purge valve inlet pressure Pi based on the purge amount data Vr (step S40). .

  Moreover, the purge control part 410 transfers to the process of step S40, when the purge valve inlet pressure Pi is below the threshold value Pth (step S33: No).

  As described above, in the fuel cell system 1000A of the present embodiment, in the purge process, after the purge valve inlet pressure Pi is lowered, the purge temperature Mp is detected using the purge valve inlet pressure Pi. ing. In this way, the purge amount Mj required for temperature increase can be reduced as the purge valve inlet pressure Pi decreases (see FIG. 3B). As a result, it is possible to suppress the purge gas from being purged excessively and to suppress the release of hydrogen in the purge gas to the outside of the fuel cell system 1000A.

  In this embodiment, the purge control unit 410 corresponds to a pressure reduction unit in claims, and the variable regulator 215 corresponds to a pressure adjustment unit.

C. Third embodiment:
FIG. 6 is a flowchart of the purge process performed by the fuel cell system 1000B of the third embodiment. The fuel cell system 1000B of the third embodiment has the same configuration as the fuel cell system 1000A of the second embodiment, and the description of the configuration of each part is omitted. The fuel cell system 1000B of the present embodiment is basically the same as the purge process performed by the fuel cell system 1000A of the second embodiment, but executes a purge process in which some processes are different.

  Specifically, the purge control unit 410 detects the purge valve inlet pressure Pi (step S30), and if the purge valve inlet pressure Pi is greater than the threshold value Pth (step S33: Yes), the hydrogen circulation pump 250. , The rotational speed of the hydrogen circulation pump 250 is lowered, and the purge valve inlet pressure Pi is lowered to the threshold value Pth (step S35A). Thereafter, the purge controller 410 reads the purge amount data Vr from the RAM 420, and detects the required temperature increase purge amount Mj from the fuel cell temperature Tf and the purge valve inlet pressure Pi based on the purge amount data Vr (step S40). .

  As described above, in the fuel cell system 1000B of the present embodiment, the purge valve inlet pressure Pi is lowered by lowering the rotational speed of the hydrogen circulation pump 250 in the purge process. In this way, the purge valve inlet pressure Pi can be easily reduced.

  In this embodiment, the purge control unit 410 corresponds to the pressure reduction unit in the claims, and the hydrogen circulation pump 250 corresponds to the pump in the claims.

D. Variations:
In addition, elements other than the elements claimed in the independent claims among the constituent elements in each of the above embodiments are additional elements and can be omitted as appropriate. The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

D1. Modification 1:
In the fuel cell system of the above embodiment, the purge control unit 410 detects the purge temperature required purge amount Mj only when the stored water is in the supercooled state in the purge process, and purge gas for at least the purge temperature necessary purge amount Mj. However, the present invention is not limited to this. For example, in the purge process, the purge control unit 410 detects the required temperature increase purge amount Mj in the case of the frozen state in addition to the case where the stored water is in the supercooled state, and at least the temperature increase required purge amount Mj. The purge gas may be purged. In this way, even if the stored water is frozen, the temperature of the stored water can be raised by the condensation heat of the water vapor in the purge gas.

D2. Modification 2:
In the fuel cell system described above, the purge control unit 410 detects the purge amount Mj required for temperature increase based on the purge valve inlet pressure Pi, which is the pressure at the inlet of the purge valve 610. However, the present invention is not limited to this. Instead, the purge amount Mj required for temperature increase may be detected based on the pressure at any location of the condensing unit 600A of the gas-liquid separator 600. Even if it does in this way, there can exist the effect of the said Example.

D3. Modification 3:
In the fuel cell system 1000A of the second embodiment, in the purge process, the purge control unit 410 controls the variable regulator 215 to reduce the purge valve inlet pressure Pi, and the fuel of the third embodiment. In the battery system 1000B, in the purge process, the purge control unit 410 controls the hydrogen circulation pump 250 to reduce the purge valve inlet pressure Pi, but the present invention is not limited to this. For example, the purge control unit 410 may control the variable regulator 215 and the hydrogen circulation pump 250 to reduce the purge valve inlet pressure Pi. In this case, the purge control unit 410 decreases the purge valve inlet pressure Pi by decreasing the rotational speed of the hydrogen circulation pump 250 while decreasing the pressure regulation value of the variable regulator 215. In this way, the purge valve inlet pressure Pi can be quickly reduced, and the purge process can be shortened.

D4. Modification 4:
In the fuel cell system of the above embodiment, the purge control unit 410 determines the purge amount Mj required for temperature increase based on the fuel cell temperature Tf and the purge valve inlet pressure Pi. It is not limited. For example, the purge control unit 410 may determine the temperature increase required purge amount Mj based on either the fuel cell temperature Tf or the purge valve inlet pressure Pi. Even if it does in this way, there can exist the effect of the said Example.

It is a block diagram which shows the structure of the fuel cell system 1000 as 1st Example of this invention. It is an enlarged view around the gas-liquid separator. It is a graph showing the relationship between the purge amount of purge gas, fuel cell temperature, or purge valve inlet pressure. It is a flowchart of the purge process which the fuel cell system 1000 of 2nd Example performs. It is a flowchart of the purge process which the fuel cell system 1000A of a present Example performs. It is a flowchart of the purge process which the fuel cell system 1000B of 3rd Example performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Fuel cell 200 ... Hydrogen tank 204 ... Fuel gas supply flow path 206 ... Fuel gas discharge flow path 207 ... Gas circulation flow path 210 ... Hydrogen cutoff valve 215 ... Variable Regulator 230 ... Compressor 234 ... Oxidizing gas supply channel 236 ... Oxidizing gas discharge channel 250 ... Hydrogen circulation pump 400 ... Control circuit 410 ... Purge controller 420 ... RAM
500 ... Refrigerant circulation pump 510 ... Refrigerant circulation flow path 520, 530 ... Temperature sensor 540 ... Pressure sensor 550 ... Radiator 600 ... Gas-liquid separator 600A ... Condenser 600B. ..Reservoir 610 ... Purge valve 620 ... Exhaust drain passage 1000, 1000A, 1000B ... Fuel cell system Tc ... Storage water temperature Tf ... Fuel cell temperature Pi ... Purge valve inlet Pressure Mi ... Minimum purge amount Mj ... Purge amount required for temperature increase Vr ... Purge amount data Sth ... Steam amount required for temperature increase

Claims (12)

A fuel cell system comprising a fuel cell,
Off-gas is introduced from the fuel cell, condenses water vapor in the off-gas, and can store water;
A purge valve that purges the off-gas as a purge gas from the gas-liquid separator to the outside of the fuel cell system;
When the temperature of the stored water stored in the gas-liquid separator is below freezing point, the purge valve is controlled and the purge amount of the purge gas is adjusted so that the amount of water vapor in the purge gas is equal to or higher than a predetermined amount. An adjustment unit;
A fuel cell system comprising: The fuel cell system according to claim 1,
The adjustment unit is
When the stored water stored in the gas-liquid separation unit is in a supercooled state, the purge valve is controlled so that the amount of water vapor in the purge gas is equal to or greater than the predetermined amount, and the purge amount of the purge gas A fuel cell system characterized by adjusting the pressure. The fuel cell system according to claim 1 or 2,
The fuel cell system according to claim 1, wherein the predetermined amount is an amount of water vapor required to raise the temperature of the stored water discharged from the gas-liquid separation unit from the freezing point by condensation heat. The fuel cell system according to any one of claims 1 to 3,
A fuel cell system comprising: a pressure reducing unit that reduces the pressure at an upstream position in the vicinity of the purge valve and with respect to the direction in which the stored water is discharged from the purge valve. The fuel cell system according to claim 4, wherein
A pressure adjusting unit capable of adjusting the reaction gas supplied to the fuel cell;
The off-gas after the reaction gas regulated by the pressure regulating unit is subjected to an electrochemical reaction in the fuel cell is introduced into the gas-liquid separation unit,
The pressure drop part is
The fuel cell system, wherein the pressure at the upstream position is lowered by lowering the pressure of the reaction gas in the pressure adjusting unit. The fuel cell system according to claim 4 or 5,
A pump for re-supplying the fuel cell in order to reuse the off-gas introduced into the gas-liquid separator;
The pressure drop part is
The fuel cell system, wherein the pressure at the upstream position is reduced by reducing the number of rotations of the pump. The fuel cell system according to any one of claims 1 to 6,
The adjustment unit is
The fuel cell system, wherein the purge amount of the purge gas is adjusted based on the temperature of the fuel cell so that the amount of water vapor in the purge gas is equal to or greater than the predetermined amount. The fuel cell system according to any one of claims 1 to 7,
The adjustment unit is
The purge amount of the purge gas is based on the pressure at the upstream position with respect to the direction in which the stored water is discharged from the purge valve rather than the purge valve so that the amount of water vapor in the purge gas is equal to or greater than the predetermined amount. A fuel cell system characterized by adjusting. The fuel cell system according to any one of claims 1 to 8,
The adjustment unit is
The fuel cell system, wherein the purge amount of the purge gas is adjusted so that the water vapor amount in the purge gas is the predetermined amount and the purge amount is minimized. The fuel cell system according to any one of claims 1 to 9,
The adjustment unit is
When the temperature of the stored water stored in the gas-liquid separation unit is below freezing point, the purge gas is purged at a first purge amount that is a minimum amount to be purged, and a second purge that contains the water vapor at a predetermined amount or more. When the first purge amount is less than or equal to the second purge amount, the purge valve is controlled to purge the purge gas with the second purge amount, and the first purge amount is The fuel cell system according to claim 1, wherein when the purge amount is larger than the second purge amount, the purge valve is controlled to purge the purge gas with the first purge amount. A fuel cell system comprising a fuel cell,
Off-gas is introduced from the fuel cell, condenses water vapor in the off-gas, and can store water;
A purge valve that purges the off-gas as a purge gas from the gas-liquid separator to the outside of the fuel cell system;
Adjustment that controls the purge valve and adjusts the purge amount of the purge gas so that the purge amount of the purge gas is equal to or higher than a predetermined amount when the temperature of the stored water stored in the gas-liquid separation unit is below freezing point And
A fuel cell system comprising: The fuel cell system according to claim 11, wherein
The adjustment unit is
When the temperature of the stored water stored in the gas-liquid separation unit is below freezing point, the purge amount of the purge gas is more than a predetermined amount from the fuel cell temperature or the purge valve rather than the purge valve. A fuel cell system, wherein the purge valve is controlled to adjust a purge amount of the purge gas based on a pressure at an upstream position with respect to a direction in which the stored water is discharged.

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