JP2007305511A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve recovery efficiency of moisture contained in offgas exhausted from a fuel cell, in a fuel cell system circulating anode offgas exhausted from the fuel cell back to the fuel cell. <P>SOLUTION: The fuel cell system is provided with a fuel cell 1 generating power by electrochemical reaction of hydrogen and oxidizing gas, an offgas circulating channel 32 guiding anode offgas exhausted from the fuel cell 1 at an anode side to the fuel cell, an offgas pump 3 fitted to the offgas circulation channel 32 for pressure-pumping the anode offgas of the offgas circulating channel to the fuel cell 1, a channel cooling means 20 cooling at least a part of the offgas circulation channel 32 with a heating medium, and a gas liquid separating means 4 for separating moisture contained in the anode offgas flowing in the offgas circulation channel cooled by the channel cooling means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system that obtains electric power through an electrochemical reaction.

  A fuel cell that obtains electric power by an electrochemical reaction between hydrogen gas and an oxidizing gas generates electric power and water generated by the electrochemical reaction. When the power generation of the fuel cell is stopped or when the outside air is at a low temperature, the water freezes and the fuel cell and the anode off gas passage may freeze.

  Therefore, there is a system that removes moisture in the anode offgas by providing a gas-liquid separator in the anode offgas passage. Furthermore, there is a system for cooling the anode off-gas before the gas-liquid separator in order to improve the water recovery efficiency (see, for example, Patent Document 1).

  Further, in a fuel cell system that recirculates anode off-gas discharged from the fuel cell to the fuel cell (hereinafter referred to as a circulation system), there is a possibility that the hydrogen pump that recirculates the anode male gas to the fuel cell may freeze, There is a fuel cell that drives the hydrogen pump when power generation of the fuel cell is stopped to discharge moisture in the hydrogen pump to the outside of the pump, thereby preventing the hydrogen pump from freezing (for example, see Patent Documents 2 and 3).

Further, in the circulation system, there is a system in which the gas-liquid separator is provided to remove moisture from the anode off gas (see, for example, Patent Document 4). Patent Document 5 describes a technique for cooling a gas-liquid separator in a circulation system to improve moisture removal efficiency.
JP 2002-170588 A JP 2005-158426 A Japanese Patent Laid-Open No. 2004-22198 JP 2004-327164 A JP 2003-317753 A JP 2005-276547 A

  According to the fuel cell system, moisture generated by the electrochemical reaction of the fuel cell can be removed. However, in the fuel cell system that recirculates the fuel cell, when the amount of water liquefied in the anode off-gas passage is very small, it may be difficult for water droplets to move with only the driving force of the hydrogen pump.

  Further, it is conceivable that the temperature of the anode off-gas passage is raised to vaporize the liquefied water to facilitate the movement of water as water vapor. However, if the temperature of the steam is increased, the recovery efficiency in the gas-liquid separator decreases.

  The present invention has been made in view of the above-mentioned various problems, and in a fuel cell system in which the anode off-gas discharged from the fuel cell is circulated again to the fuel cell, moisture contained in the anode off-gas discharged from the fuel cell. The purpose is to improve the recovery efficiency.

The present invention relates to a fuel cell system, a fuel cell that generates electric power by an electrochemical reaction between hydrogen gas and an oxidizing gas, and an off-gas circulation passage that guides anode off-gas discharged from the anode side of the fuel cell to the fuel cell And an off-gas supply means that is provided in the off-gas circulation passage and supplies anode off-gas from the off-gas circulation passage to the fuel cell, and at least a part of the off-gas circulation passage is cooled by a heat medium when the fuel cell is stopped. And gas-liquid separation means for separating moisture contained in the anode off-gas flowing through the off-gas circulation passage cooled by the passage cooling means.

  The present invention relates to a hydrogen gas circulation type fuel cell in which anode off-gas discharged from the anode side of the fuel cell is again supplied to the fuel cell as hydrogen gas. The circulation of the anode off gas is performed by an off gas supply means. As the off gas supply means, a pump for pumping the anode off gas to the fuel cell by a pumping action, an ejector, or the like can be used. Here, when the fuel cell is stopped from the operating state, the anode offgas was relatively high immediately after the stoppage, so that the moisture present in the gas in the anode offgas is liquefied with the cooling of the anode offgas, and flows in the offgas circulation passage. There is a risk of causing problems such as road blockage. In particular, the anode off-gas flowing through the off-gas circulation passage contains water generated by an electrochemical reaction in the fuel cell, and thus is liable to be defective.

  Therefore, in the fuel cell system according to the present invention, the cooling of the off-gas circulation passage by the passage cooling means is performed when the fuel cell is stopped. That is, the passage cooling means cools the off-gas circulation passage so that moisture contained in the anode off-gas can be liquefied in the off-gas circulation passage immediately after the fuel cell is stopped. Further, by cooling the off-gas circulation passage, the surface area of the water droplet liquefied therein is formed as large as possible. As a result, the water droplets are efficiently subjected to the anode offgas supply operation by the offgas supply means (for example, the pumping action by the pump as the offgas supply means), so that the waterdrops can be transported more reliably to the gas-liquid separation means. It becomes. Then, by separating the water from the anode off gas by the gas-liquid separating means, it is possible to more surely avoid problems such as channel blockage.

  In the present invention, the heat medium for cooling the off-gas circulation passage is not particularly limited as long as it can be cooled by exchanging heat with the off-gas circulation passage. For example, the cooling capacity of the air temperature adjusting device that adjusts the temperature of the air may be used for cooling the off-gas circulation passage through the heat medium.

  More specifically, in the case where the fuel cell system further includes an air temperature adjusting device that adjusts an air temperature in a vehicle interior of the vehicle in which the fuel cell system is mounted, the passage cooling means is configured to cool the air temperature adjusting device. The heat medium may be cooled using the capacity, and at least a part of the off-gas circulation passage may be cooled by the cooled heat medium. The air temperature control device cools the passenger compartment in summer, etc., or heats the passenger compartment in winter, etc., and uses the ability to adjust the air temperature, especially the cooling ability, and the off-gas circulation passage Let's cool down.

  In the fuel cell system including the air temperature control device, further, a main cooling passage through which the heat medium flows and the off-gas circulation passage is cooled, and a first circulation cooling passage through which the heat medium flowing through the main cooling passage is circulated. And circulating the heat medium flowing through the main cooling passage, the second circulation cooling passage parallel to the first circulation cooling passage, and when the temperature inside the vehicle compartment is increased by the air temperature control device, A first heat exchanging device for exchanging heat between the heat medium flowing in one circulation passage and the air temperature adjusting device; and when the temperature drop in the vehicle interior is carried out by the air temperature adjusting device, the second circulation And a second heat exchange device that exchanges heat between the heat medium flowing through the passage and the air temperature control device, the passage cooling means is based on an operating state of the air temperature control device. Then, the heat medium flowing through the main cooling passage is passed through either the first circulation passage or the second circulation passage to cool the heat medium, and at least one of the off-gas circulation passages is cooled by the cooled heat medium. The part may be cooled.

  The cooling of the off-gas circulation passage is due to heat exchange occurring between the heat medium and the anode off-gas in the off-gas circulation passage when the heat medium flows through the main cooling passage. The heat medium flowing through the main cooling passage is circulated by either the first circulation cooling passage or the second circulation cooling passage, so that heat exchange between the heat medium and the anode off gas is continued. Then, the passage through which the heat medium is circulated is determined by the passage cooling means based on the operating state of the air temperature adjusting device so that the heat medium temperature becomes a temperature suitable for cooling the off-gas circulation passage.

  That is, when the temperature of the vehicle interior is increased (heating) by the air temperature adjusting device, the heat medium is circulated through the first circulation passage to cool the off-gas circulation passage. At this time, the temperature of the heat medium is adjusted to a temperature suitable for cooling the off-gas circulation passage by performing heat exchange with the air temperature adjusting device by the first heat exchanger. On the other hand, when the temperature drop (cooling) in the passenger compartment is performed by the air temperature adjusting device, the heat medium is circulated through the second circulation passage to cool the off-gas circulation passage. At this time, the temperature of the heat medium is adjusted to a temperature suitable for cooling the off-gas circulation passage by performing heat exchange with the air temperature adjusting device by the second heat exchanger. In this way, by properly using the two heat exchangers according to the operating state of the air temperature adjusting device, the temperature of the heat medium is adjusted to a temperature suitable for cooling the off-gas circulation passage regardless of the operating state of the air temperature adjusting device. It becomes possible.

  Here, in the fuel cell system, the passage cooling unit may cool at least a part of the off-gas circulation passage by using outside air of the fuel cell system as the heat medium. That is, if the outside air temperature is a temperature suitable for cooling the off-gas circulation passage, the outside air can be actively used for the cooling.

  In the fuel cell system, the passage cooling means further uses the outside air of the fuel cell system as the heat medium, and cools at least a part of the off-gas circulation passage. And a heat medium cooling control means for controlling cooling of the heat medium using either the air temperature adjusting device or the outside air based on the possible cooling temperature of the heat medium and the possible cooling temperature of the heat medium by the outside air. You may do it.

  Here, the possible cooling temperature is a temperature that serves as an index indicating how much the heat medium can be cooled by the air temperature adjusting device or the outside air. The lower the temperature, the more efficiently the cooling of the heat medium, and the more efficiently the off-gas circulation passage can be cooled. Therefore, it is preferable that the heat medium cooling control means cool the heat medium at a lower one of the possible cooling temperatures of the air temperature adjusting device and the outside air. Here, as the possible cooling temperature of the outside air, the temperature of the outside air itself can be used, and as the possible cooling temperature of the air temperature adjusting device, for example, the heat medium by the first heat exchange device or the second heat exchange device described above. The temperature at which the is placed can be utilized.

  Here, in the fuel cell system described above, the fuel cell system further includes off gas temperature detection means for detecting the temperature of the anode off gas flowing through the off gas circulation passage, and the passage cooling means is the anode off gas detected by the off gas temperature detection means. You may make it cool at least one part of the said off-gas circulation path so that temperature may not become lower than predetermined temperature. That is, it is possible to avoid that the off-gas circulation passage is supercooled by the passage cooling means and the water in the passage is frozen. Therefore, the predetermined temperature is a threshold value that may cause moisture freezing in the off-gas circulation passage.

In the fuel cell system described above, when the off-gas circulation passage is cooled by the passage cooling means, a fuel cell cooling means for cooling the fuel cell at the same time may be further provided. The fuel cell cooling means can cool the fuel cell and cool the anode off-gas discharged from the fuel cell. That is, the off-gas circulation passage is indirectly cooled through the cooling of the fuel cell. The cooling by the fuel cell cooling means can be achieved by cooling the stack constituting the fuel cell with a heat medium or cooling the oxidizing gas supplied to the fuel cell.

  According to the fuel cell system of the present invention, the off-gas circulation passage can be cooled and water droplets can be enlarged at the position, so that the off-gas supply means can easily move the water drops to the gas-liquid separation means. Therefore, it is possible to improve the recovery efficiency of moisture contained in the anode off gas discharged from the fuel cell.

  Embodiments of a fuel cell system according to the present invention will be described in detail with reference to the drawings. The fuel cell system according to the present embodiment is an embodiment applied to a fuel cell vehicle using a fuel cell as a driving power source.

  FIG. 1 is a schematic configuration diagram of a fuel cell vehicle (hereinafter simply referred to as “vehicle”) 15 provided with a fuel cell system 10 according to the present embodiment. The space in the vehicle 15 can be broadly divided into an engine compartment 11 provided with a fuel cell system 10 as a drive source, and a passenger compartment 12 which is a user's boarding space. The passenger compartment 12 is supplied with air from an air temperature adjusting device 60 that adjusts the temperature in the passenger compartment. Details of the air temperature adjusting device 60 will be described later.

  The fuel cell system 10 according to the present embodiment includes an anode off-gas discharged from the anode side of the fuel cell, selectively using air in the passenger compartment 12, air in the engine compartment 11, and outside air as a heat medium. The anode off-gas passage itself passing through is cooled to remove moisture in the anode off-gas. The details will be described below.

  FIG. 2 shows a detailed configuration diagram of the fuel cell system 10. The fuel cell system 10 includes a fuel cell 1 that generates electric power through an electrochemical reaction between hydrogen gas and oxidizing gas, and the electric power generated there is a drive motor for the vehicle 10 via a battery (not shown) or the like. To be supplied. On the anode side of the fuel cell 1, hydrogen gas as fuel gas is stored and supplied to the fuel cell 1, and the hydrogen supply device 2 supplies the hydrogen gas to the anode side of the fuel cell 1. A hydrogen supply passage 31 through which hydrogen gas flows and an off-gas circulation passage 32 for circulating the anode off-gas discharged from the anode side of the fuel cell 1 to the hydrogen supply passage 31 are provided. Further, the off-gas circulation passage 32 is provided with an off-gas pump 3 for pumping anode off-gas, and the gas-liquid separator 4 is provided in the off-gas circulation passage 32 downstream of the off-gas pump 3.

  Further, on the cathode side of the fuel cell 1, an oxidizing gas supply passage 33 through which air as an oxidizing gas supplied to the cathode of the fuel cell 1 flows and an air compressor 5 that supplies compressed air to the oxidizing gas supply passage 33 are provided. It has been. Further, an intercooler 6 is provided in the oxidizing gas supply passage 33 for cooling the compressed air that has become hot due to the compression action of the air compressor 5. The intercooler 6 performs cooling by circulating a heat medium for cooling and exchanging heat with the compressed air by the air compressor 5. The cooling capacity of the intercooler 6 is used for a driving state of a cooling pump (not shown) for controlling the circulation flow rate of the cooling heat medium and a cooling radiator (not shown) for cooling the heat medium. It is controlled based on the number of rotations of the cooling fan.

The fuel cell 1 itself is also provided with a fuel cell cooling device 7 for cooling the stack. The fuel cell cooling device 7 removes heat generated by an electrochemical reaction or the like in the fuel cell 1, and circulates a heat medium for cooling to exchange heat with the stack of the fuel cell 1, thereby cooling the fuel cell. Do. The cooling capacity of the fuel cell cooling device 7 depends on the driving state of a cooling pump (not shown) that controls the circulation flow rate of the cooling heat medium and a cooling radiator (not shown) that cools the heat medium. It is controlled based on the number of rotations of the cooling fan used.

  The fuel cell 1 generates electricity by an electrochemical reaction between hydrogen gas and an oxidizing gas, and from the anode side of the fuel cell 1, an anode off-gas containing hydrogen gas that has not been used for power generation and water vapor generated by the electrochemical reaction. Is discharged. If the anode off-gas is discharged out of the system as it is, high-concentration hydrogen gas may be released. Therefore, the anode off-gas discharged from the fuel cell 1 is pumped by the off-gas pump 3, and the off-gas circulation passage 32 and the hydrogen supply passage 31 are discharged. Then, the fuel cell 1 is supplied again.

  Here, if a large amount of moisture is contained in the anode off gas, the off gas circulation passage 32 and the like may be frozen in a low temperature environment, and the fuel cell system 10 may be damaged. Therefore, it is necessary to provide the gas-liquid separator 4 in the off gas circulation passage 23 to remove moisture in the off gas. However, since the temperature of the anode offgas discharged from the fuel cell 1 is usually about 70 to 80 degrees and is relatively high, most of the moisture in the anode offgas exists in the form of water vapor. For this reason, the size of the water droplets formed in the off-gas circulation passage 23 is relatively small, and it is difficult to efficiently receive the pressure due to the pumping action of the off-gas pump 3, and the efficiency of removing the water is greatly reduced.

  Therefore, the fuel cell system 10 according to the present embodiment includes a passage cooling system 20 that cools the off-gas circulation passage 32 downstream of the off-gas pump 3 and upstream of the gas-liquid separator 4. The passage cooling system 20 cools the off gas circulation passage 32 and cools the anode off gas flowing through the portion. Due to this cooling, water droplets in the passage of the part become large. As the water droplets become larger, it becomes easier to receive the pressure-feeding action of the off-gas pump 3, and more water is guided to the gas-liquid separator 4. Therefore, the water removal efficiency from the anode off gas can be improved.

  Here, details of the passage cooling system 20 will be described. The passage cooling system 20 mainly includes a plurality of pipes through which air, which is a heat medium for cooling the off-gas circulation passage 32, a plurality of valves for controlling the flow, air flowing through the pipes, and the above-described air temperature control device. 60 is constituted by a plurality of heat exchangers that exchange heat with the heat medium used.

  First, a main cooling passage 22 that is a passage for directly cooling the off-gas circulation passage 32 with cooling air is provided along the longitudinal direction so as to cover the periphery of the off-gas circulation passage 32. A first cooling passage 21 into which air outside the vehicle 15 (hereinafter referred to as “outside air”) is taken is connected to the main cooling passage 22 via control valves 50 and 51. Further, the second cooling passage 24 is connected to the main cooling passage 22 via control valves 52 and 53 at both ends thereof, and the control valves 56 and 57 are connected to both ends of the second cooling passage 24. A third cooling passage 25 is connected via the second cooling passage 25. The main cooling passage 22, the second cooling passage 24, and the third cooling passage 25 form one circulation passage. Further, in this circulation passage, the fourth cooling passage 23 is connected from one second cooling passage 24 to the other second cooling passage 24 via control valves 54 and 55.

Here, the main cooling passage 22, the first cooling passage 21, the second cooling passage 24, and the fourth cooling passage 23 are provided on the engine compartment 11 side, and the third cooling passage 25 is provided from the engine compartment 11 side to the passenger compartment. It is provided over 12 sides. The main cooling passage 22 is provided with a cooling fan 26 for circulating or introducing cooling air for the off-gas circulation passage 32.

  Next, the air temperature adjusting device 60 will be described. The air temperature adjusting device 60 is a device that adjusts the temperature of air supplied into the passenger compartment 12, and includes a circulation passage 27 through which a heat medium for temperature adjustment circulates, an expansion valve 28 that expands the heat medium, And a compressor 29 for compressing the heat medium. The circulation passage 27 forms a circulation passage across the passenger compartment 12 and the engine compartment 11. And the heat exchanger 9a which performs heat exchange between the heat medium flowing through the circulation passage 27 on the passenger compartment 12 side and the air flowing through the third cooling passage 25, and the heat medium flowing through the circulation passage 27 on the engine compartment 11 side, A heat exchanger 9 b that performs heat exchange with the air flowing through the fourth cooling passage 23 is provided in the fuel cell system 10.

  Further, in the fuel cell system 10, the temperature of the air flowing through the first cooling passage 21, that is, the outside air temperature sensor 41 for detecting the temperature of the outside air, and the temperature of the air flowing through the third cooling passage 25 heat-exchanged by the heat exchanger 9a. A first temperature sensor 42 for detecting the temperature, a second temperature sensor 43 for detecting the temperature of the air flowing through the fourth cooling passage 23 heat-exchanged by the heat exchanger 9b, and an off-gas circulation passage cooled by the main cooling passage 22 And a third temperature sensor 43 for detecting the temperature of the anode off-gas flowing through 32, and these sensors are electronic control units (hereinafter referred to as “ECUs”) 8 for controlling each element of the fuel cell system. Is electrically connected. The control valves 50 to 57 are also electrically connected to the ECU 8 to control opening / closing thereof, and the cooling fan 26 is also electrically connected to the ECU 8 to control driving thereof. The ECU 8 includes a CPU, a ROM, a RAM, and the like that store various programs and maps to be described later, and is a unit that controls the operating conditions of the fuel cell 1 for driving the vehicle 15.

  Here, the mode of cooling of the off-gas circulation passage 32 by the passage cooling system 20 will be described with reference to FIGS. In each of FIGS. 3, 4 and 5, the first to third cooling modes are shown. The cooling mode shown in FIG. 3 is the cooling of the off-gas circulation passage 32 using the air in the fourth cooling passage 23 cooled by the heat exchanger 9b. At this time, the control valves 50 and 51 and the control valves 56 and 57 are closed, and the control valves 52 and 53 and the control valves 54 and 55 are opened, and then the cooling fan 26 is driven. The operation of the air temperature adjusting device 60 at this time will be described. The heat medium whose temperature has been lowered by the expansion action of the expansion valve 28 is sent to the heat exchanger 9b to cool the air in the fourth cooling passage 23. Thereafter, the heat medium in the circulation passage 27 is compressed by the compressor 29 and rises in temperature. Based on the heat, high-temperature air is provided into the passenger compartment 12 to heat the passenger compartment 12. As described above, in the cooling mode shown in FIG. 3, the off-gas circulation passage 32 is cooled by the flow of air cooled by the heat exchanger 9b (the flow indicated by the solid line arrow in the figure), and the moisture in the anode off-gas It is possible to promote the cooling of. The flow of air for cooling by the cooling mode shown in FIG. 3 is hereinafter referred to as “cooling line 1”.

Next, the cooling mode shown in FIG. 4 is the cooling of the off-gas circulation passage 32 using the air in the third cooling passage 25 cooled by the heat exchanger 9a. At this time, the control valves 50 and 51 and the control valves 54 and 55 are closed, and the control valves 52 and 53 and the control valves 56 and 57 are opened, and then the cooling fan 26 is driven. The operation of the air temperature adjusting device 60 at this time will be described. The heat medium whose temperature has been lowered by the expansion action of the expansion valve 28 is sent to the heat exchanger 9a to cool the air in the third cooling passage 25. Thereafter, the heat medium in the circulation passage 27 is compressed by the compressor 29 and the temperature rises. The low-temperature heat medium generated by the expansion valve 28 is also used for providing low-temperature air into the passenger compartment 12, that is, for cooling the passenger compartment 12. As described above, in the cooling mode shown in FIG. 4, the off-gas circulation passage 32 is cooled by the flow of air cooled by the heat exchanger 9a (the flow indicated by the solid line arrow in the figure), and the moisture in the anode off-gas It is possible to promote the cooling of. The flow of air for cooling by the cooling mode shown in FIG. 4 is hereinafter referred to as “cooling line 2”.

  Next, the cooling mode shown in FIG. 5 is cooling of the off-gas circulation passage 32 using outside air. At this time, the cooling fan 26 is driven after the control valves 52 and 53 are closed and the control valves 50 and 51 are opened. As a result, the off-gas circulation passage 32 is cooled by the flow of the outside air (the flow indicated by the solid arrow in the figure), and the cooling of the moisture in the anode off-gas can be promoted. Further, the flow of air for cooling by the cooling mode shown in FIG. 5 is hereinafter referred to as “cooling line 3”.

  As described above, the cooling mode shown in FIGS. 3 to 5 can be appropriately used for cooling the off-gas circulation passage 32. However, which cooling mode is most suitable for cooling the off-gas circulation passage 32 is determined by the temperature of the air supplied to the main cooling passage 22 in each cooling mode. Therefore, control for optimally cooling the off-gas circulation passage 32 (hereinafter referred to as “circulation hydrogen cooling control”) will be described with reference to FIG. Note that the circulating hydrogen cooling control in this embodiment is a routine executed by the ECU 8.

  First, in S201, the stop process of the fuel cell 1 is started. Specifically, the supply of hydrogen gas from the hydrogen supply device 2 and the supply of compressed air by the air compressor 5 are stopped. At this time, the off-gas pump 3 is maintained in an operating state, and the anode off-gas is continuously introduced into the gas-liquid separator 4. When the process of S201 ends, the process proceeds to S202.

  In S202, it is determined whether or not an air conditioner (that is, the air temperature adjusting device 60) is used in the passenger compartment 12 of the vehicle 15. If it is determined that the air conditioner is used, the process proceeds to S203, and if it is determined that the air conditioner is not used, the process proceeds to S209.

  In S203, it is determined whether or not the air temperature adjustment mode by the used air conditioner is cooling. If it is determined that it is cooling, the process proceeds to S204, and if it is determined that it is not cooling, the process proceeds to S206.

  In S204, whether or not the outside air temperature TA detected by the outside air temperature sensor 41 is equal to or higher than the air temperature T1 in the third cooling passage 25 cooled by the heat exchanger 9a detected by the first temperature sensor 42. Determined. That is, when cooling is performed in the passenger compartment 12, it is preferable to cool the off-gas circulation passage 32 using air used for cooling, or cooling the off-gas circulation passage 32 using low-temperature outside air. It is determined whether it is good to perform. Therefore, if it is determined that the outside air temperature TA is equal to or higher than the air temperature T1, the process proceeds to S205 to supply cooler air to the main cooling passage 22, and each control valve is set to the cooling line 2 shown in FIG. Is controlled. If it is determined that the outside air temperature TA is not equal to or higher than the air temperature T1, the process proceeds to S207 to supply cooler outside air to the main cooling passage 22, and the cooling line 3 shown in FIG. The opening is controlled.

Next, in S206, is the outside air temperature TA detected by the outside air temperature sensor 41 equal to or higher than the air temperature T2 in the fourth cooling passage 23 cooled by the heat exchanger 9b detected by the second temperature sensor 43? It is determined whether or not. That is, when heating is performed in the passenger compartment 12, it is preferable to cool the off-gas circulation passage 32 using low-temperature air generated during the heating, or the off-gas circulation passage 32 using low-temperature outside air. It is determined whether or not to cool the air. Therefore, if it is determined that the outside air temperature TA is equal to or higher than the air temperature T2, the process proceeds to S208 in order to supply cooler air to the main cooling passage 22, and each control valve is provided in the cooling line 1 shown in FIG. Is controlled. Further, when it is determined that the outside air temperature TA is not equal to or higher than the air temperature T2, the process proceeds to S207 to supply cooler outside air to the main cooling passage 22, and the cooling valve 3 shown in FIG. The opening is controlled.

  Here, in S202, when it is determined that the air conditioner is not used and the process proceeds to S209, the air conditioner (air temperature adjusting device 60) is started in S209, and the above-described heating operation is performed. However, the high-temperature air generated by heating at this time is not supplied into the passenger compartment 12. This is because the air conditioner is not started by a request from the user in the vehicle 15. Since the air conditioner is started in the heating mode, as described above, low-temperature air is generated in the fourth cooling passage 23 by the heat exchanger 9b. Therefore, when the processing of S209 ends, the process proceeds to S210, and the same determination as in S206 described above is performed.

  In S210, whether or not the outside air temperature TA detected by the outside air temperature sensor 41 is equal to or higher than the air temperature T2 in the fourth cooling passage 23 cooled by the heat exchanger 9b detected by the second temperature sensor 43. Is determined. If it is determined that the outside air temperature TA is equal to or higher than the air temperature T2, the process proceeds to S208 in order to supply cooler air to the main cooling passage 22, and each control valve is opened as much as possible in the cooling line 1 shown in FIG. The degree is controlled. If it is determined that the outside air temperature TA is not equal to or higher than the air temperature T2, first, the process proceeds to step S211 to stop the air conditioner started in step S209 in order to supply cooler outside air to the main cooling passage 22. It progresses to a process and the opening degree of each control valve is controlled as much as possible to the cooling line 3 shown in FIG.

  When the processes of S205, S207, and S208 are completed, the process proceeds to S212. In S212, the operation of the cooling fan 26 is started. Thereby, a low-temperature air flow is formed in each cooling line formed by the processes of S205, S207, and S208. As a result, low temperature air is supplied around the off gas circulation passage 32, and larger water droplets are formed in the off gas circulation passage 32. When the process of S212 is completed, the process proceeds to S213, and the moisture in the anode offgas formed into droplets in the offgas circulation passage 32 is efficiently removed. When the process of S213 ends, the process proceeds to S214.

  In S214, it is determined whether the temperature T3 of the anode offgas in the offgas circulation passage 32 detected by the third temperature sensor 44 is 0 degrees or less. That is, it is determined whether the off-gas circulation passage 32 is supercooled by the passage cooling system 20. Therefore, when it is determined that the temperature T3 is 0 degrees or less, the operation of the cooling fan 26 is stopped, all the control valves are closed, and the cooling capacity of the passage cooling system 20 is stopped. As a result, overcooling of the off-gas circulation passage 32 is prevented. If it is determined that the temperature T3 is not less than 0 degrees, the operation of the cooling fan 26 is continued, the cooling of the offgas circulation passage 32 is continued, and the moisture in the anode offgas is efficiently removed. After the process of S215 or S216, this control is terminated.

  According to this control, it is possible to efficiently cool the off-gas circulation passage 32, and thus it is possible to efficiently remove water in the anode off-gas.

  A second embodiment of the exhaust gas purification system for the internal combustion engine 1 according to the present invention will be described below. In the present embodiment, control for cooling the off-gas circulation passage 32 (hereinafter referred to as “circulation hydrogen cooling control”) will be described with reference to FIG. In addition, the circulating hydrogen cooling control in the present embodiment is a routine executed by the ECU 8. In addition, about the process same as the process content of the circulating hydrogen control shown in FIG. 6, the same reference number is attached | subjected and the description is abbreviate | omitted.

In this control, after the fuel cell stop process is performed in S201, the process proceeds to S301. In S301, the cooling capacity of the fuel cell cooling device 7 that cools the stack of the fuel cell 1 is increased. Specifically, the fuel cell cooling is performed by increasing the circulation flow rate of the heat medium by the above-described cooling pump constituting the fuel cell cooling device 7 or by increasing the rotational speed of the cooling fan for cooling the heat medium. The cooling capacity by the device 7 is increased. When the process of S301 ends, the process proceeds to S302.

  In S302, the fuel cell 1 is further cooled by the process of S301. As a result, the anode off gas discharged from the fuel cell 1 is also indirectly cooled. After the process of S302, the processes of S213 and S214 are performed.

  In this control, if it is determined in S214 that the temperature T3 is 0 degrees or less, the process proceeds to S303, and the cooling capacity of the fuel cell cooling device 7 is reduced. As a result, overcooling of the off-gas circulation passage 32 is prevented. If it is determined that the temperature T3 is not less than 0 degrees, the process proceeds to S304, the cooling capacity of the fuel cell cooling device 7 is maintained, the cooling of the offgas circulation passage 32 is continued, and the removal of moisture in the anode offgas is efficiently performed. Do it. Thereafter, this control is terminated.

  A third embodiment of the exhaust gas purification system for the internal combustion engine 1 according to the present invention will be described below. In the present embodiment, control for cooling the off-gas circulation passage 32 (hereinafter referred to as “circulation hydrogen cooling control”) will be described with reference to FIG. In addition, the circulating hydrogen cooling control in the present embodiment is a routine executed by the ECU 8. In addition, about the process same as the process content of the circulating hydrogen control shown to FIG. 6, 7, the same reference number is attached | subjected and the description is abbreviate | omitted.

  In this control, after the fuel cell stop process is performed in S201, the process proceeds to S401. In this embodiment, during the fuel cell stop process, the operation of the air compressor 5 is continued, and the supply of compressed air to the fuel cell 1 is continued. In S401, the cooling capacity by the intercooler 6 is increased. Specifically, the cooling by the intercooler 6 is performed by increasing the circulation flow rate of the heat medium by the above-described cooling pump constituting the intercooler 6 or by increasing the rotation speed of the cooling fan for cooling the heat medium. Increase ability. When the process of S401 ends, the process proceeds to S402.

  In S402, further cooling of the compressed air supplied to the fuel cell 1 is performed by the process of S401. As a result, the anode offgas discharged from the fuel cell 1 is also indirectly cooled through the fuel cell 1. After the process of S402, the processes of S213 and S214 are performed.

  In this control, if it is determined in S214 that the temperature T3 is 0 degrees or less, the process proceeds to S403, and the cooling capacity of the intercooler 6 is reduced. As a result, overcooling of the off-gas circulation passage 32 is prevented. If it is determined that the temperature T3 is not less than 0 degrees, the process proceeds to S404, the cooling capacity of the intercooler 6 is maintained, the cooling of the offgas circulation passage 32 is continued, and the moisture in the anode offgas is efficiently removed. Do. Thereafter, this control is terminated.

It is a figure showing the schematic structure of the vehicle carrying the fuel cell system which concerns on the Example of this invention. It is a figure which shows the structure of the fuel cell system which concerns on the Example of this invention, especially the structure of the channel | path cooling system which cools the off gas circulation channel which circulates anode off gas. It is a figure showing the 1st cooling mode at the time of cooling an off-gas circulation channel with a channel cooling system in a fuel cell system concerning an example of the present invention. In the fuel cell system according to the embodiment of the present invention, it is a diagram showing a second cooling mode when the off-gas circulation passage is cooled by the passage cooling system. In the fuel cell system according to the embodiment of the present invention, it is a diagram showing a third cooling mode when the off-gas circulation passage is cooled by the passage cooling system. It is a 1st flowchart regarding the circulation hydrogen cooling control performed in the fuel cell system which concerns on the Example of this invention for cooling an off-gas circulation path efficiently. It is a 2nd flowchart regarding the circulating hydrogen cooling control performed in the fuel cell system which concerns on the Example of this invention for cooling an off-gas circulation path efficiently. It is a 3rd flowchart regarding the circulation hydrogen cooling control performed in the fuel cell system which concerns on the Example of this invention for cooling an off-gas circulation path efficiently.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell 2 ... Hydrogen supply device 3 ... Off gas pump 5 ... Air-conditioner press 6 ... Intercooler 7 ... Fuel cell cooling device 9a, 9b ... Heat exchanger 10 ... Fuel cell system 11 ... Engine compartment 12 ... Passenger compartment 15 ... Vehicle 20 ... Passage cooling system 21 ... First cooling Passage 22 ... Main cooling passage 23 ... Fourth cooling passage 24 ... Second cooling passage 25 ... Third cooling passage 26 ... Cooling fan 31 ... Hydrogen supply Passage 32 ... Off gas circulation passage 41 ... Outside air temperature sensor 42 ... First temperature sensor 43 ... Second temperature sensor 44 ... Third temperature sensor 50-57 ... .Control valve 60 ... Air temperature control device

Claims (7)

A fuel cell that generates electricity by an electrochemical reaction between hydrogen gas and oxidizing gas;
An off-gas circulation passage for guiding the anode off-gas discharged from the anode side of the fuel cell to the fuel cell;
Off gas supply means provided in the off gas circulation passage, for supplying anode off gas of the off gas circulation passage to the fuel cell;
Passage cooling means for cooling at least a part of the off-gas circulation passage with a heat medium when the fuel cell is stopped;
Gas-liquid separation means for separating moisture contained in the anode off-gas flowing through the off-gas circulation passage cooled by the passage cooling means;
A fuel cell system comprising: An air temperature adjusting device for adjusting an air temperature in a passenger compartment of a vehicle on which the fuel cell system is mounted;
The passage cooling means cools the heat medium using a cooling capacity of the air temperature adjusting device, and cools at least a part of the off-gas circulation passage by the cooled heat medium. 2. The fuel cell system according to 1. A main cooling passage through which the heat medium flows and the off-gas circulation passage is cooled;
A first circulation cooling passage for circulating a heat medium flowing through the main cooling passage;
Circulating a heat medium flowing through the main cooling passage, a second circulation cooling passage parallel to the first circulation cooling passage;
A first heat exchanging device that exchanges heat between the heat medium flowing through the first circulation passage and the air temperature adjusting device when the temperature of the vehicle interior is increased by the air temperature adjusting device;
A second heat exchanging device for exchanging heat between the heat medium flowing through the second circulation passage and the air temperature adjusting device when the temperature drop in the vehicle interior is carried out by the air temperature adjusting device; Prepared,
The passage cooling means cools the heat medium by flowing the heat medium flowing through the main cooling passage to either the first circulation passage or the second circulation passage based on the operating state of the air temperature control device. The fuel cell system according to claim 2, wherein at least a part of the off-gas circulation passage is cooled by the cooled heat medium.   The fuel according to any one of claims 1 to 3, wherein the passage cooling means cools at least a part of the off-gas circulation passage by using outside air of the fuel cell system as the heat medium. Battery system. The passage cooling means further uses the outside air of the fuel cell system as the heat medium, cools at least a part of the off-gas circulation passage,
Heat for controlling cooling of the heat medium using either the air temperature adjusting device or the outside air based on the possible cooling temperature of the heat medium by the air temperature adjusting device and the possible cooling temperature of the heat medium by the outside air The fuel cell system according to claim 2, further comprising medium cooling control means. An offgas temperature detecting means for detecting the temperature of the anode offgas flowing through the offgas circulation passage;
The said passage cooling means cools at least a part of the offgas circulation passage so that the anode offgas temperature detected by the offgas temperature detection means does not become lower than a predetermined temperature. The fuel cell system according to any one of the above.   7. The fuel cell cooling unit according to claim 1, further comprising a fuel cell cooling unit that cools the fuel cell at the same time when the off-gas circulation passage is cooled by the passage cooling unit. Fuel cell system.

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