Fuel cell system

Abstract

To sufficiently cool a fuel cell at the time of high output after suppressing power consumption.SOLUTION: The fuel cell system includes: a fuel cell; a circulation flow path in which a refrigerant for cooling a fuel cell circles around; a radiator for cooling the refrigerant flowing in the circulation flow path; a fan for sending air to the radiator; a collector for collecting water in cathode off-gas discharged from a cathode electrode of the fuel cell; and a water supply unit for supplying the water collected by the collector to the outer surface of the radiator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a fuel cell system. [Background technology]

[0002] A system for cooling a fuel cell using cooling water is known (see, for example, Patent Document 1). In the system described in Patent Document 1, abnormal conditions in the flow path are detected using a map based on the relationship between the estimated flow rate of the cooling water and the power consumption of the fuel cell. This system is equipped with a three-way valve to branch off into a bypass flow path on the way from the fuel cell stack flow path to the radiator flow path. By adjusting the opening degree of the three-way valve, the flow path where an abnormality is occurring can be identified. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 6802984 [Overview of the project] [Problems that the invention aims to solve]

[0004] The higher the power demands on the fuel cell, such as when driving uphill in a fuel cell vehicle, the higher the fuel cell temperature rises. If the heat generated by the fuel cell exceeds the cooling capacity and the fuel cell temperature exceeds the upper limit, the fuel cell output may be restricted, making it impossible to maintain a sufficient driving speed. When the fuel cell is at high output, the rotation speed of the radiator fan that blows air to the radiator increases. However, the power loss of auxiliary equipment, including the radiator fan, the pump for circulating the coolant, and the compressor that supplies compressed air to the fuel cell, is not insignificant. As the rotation speed of the radiator fan increases, the power consumption of the radiator fan also increases. Therefore, there was a need to ensure sufficient cooling capacity to cool the fuel cell while suppressing the power consumption of the entire system, including auxiliary equipment. The system described in Patent Document 1 does not address these improvements in cooling capacity.

[0005] This invention was made to solve at least some of the above-mentioned problems, and aims to sufficiently cool the fuel cell at high output while suppressing power consumption. [Means for solving the problem]

[0006] The present invention has been made to solve at least some of the above-mentioned problems and can be realized in the following forms. A fuel cell system comprising: a fuel cell; a circulation channel through which a refrigerant for cooling the fuel cell circulates; a radiator for cooling the refrigerant flowing through the circulation channel; a fan for blowing air onto the radiator; a recovery unit for recovering water from cathode-off gas discharged from the cathode electrode of the fuel cell; and a water supply unit for supplying the liquid water recovered by the recovery unit to the outer surface of the radiator, wherein the fan is a forced-air type positioned upstream of the radiator and comprises: a hollow shaft portion extending along a rotation axis and rotating around the rotation axis; a fan rotor connected to the shaft portion and rotating around the rotation axis to blow air onto the radiator; and a disc-shaped disk that rotates around the rotation axis and has a hollow portion formed radially connected to the interior of the hollow shaft portion, the hollow portion being open at the radially outer end of the disk, and the water supply unit supplying liquid water to the interior of the hollow shaft portion. In addition, the present invention can also be realized in the following forms.

[0007] (1) According to one embodiment of the present invention, a fuel cell system is provided. This fuel cell system comprises a fuel cell, a circulation channel through which a refrigerant for cooling the fuel cell circulates, a radiator for cooling the refrigerant flowing through the circulation channel, a fan for blowing air onto the radiator, a recovery unit for recovering water in the cathode-off gas discharged from the cathode electrode of the fuel cell, and a water supply unit for supplying the liquid water recovered by the recovery unit to the outer surface of the radiator.

[0008] In this configuration, water contained in the cathode-off gas is supplied to the outer surface of the radiator, and the heat of vaporization of the water cools the refrigerant flowing through the radiator tubes. This configuration improves the cooling capacity of the radiator by utilizing the heat of vaporization of water in the cathode-off gas, which was conventionally discharged into the outside air. As a result, it is possible to suppress the increase in fan speed necessary to cool the fuel cell at high output. Consequently, this configuration can sufficiently cool the fuel cell at high output while suppressing the overall power consumption of the system.

[0009] (2) In the fuel cell system according to the above embodiment, the fan is a forced-air type fan positioned upstream of the radiator and comprises a hollow shaft portion extending along the rotation axis and rotating around the rotation axis, a fan rotating body connected to the shaft portion and rotating around the rotation axis to send air to the radiator, and a disc-shaped disk that rotates around the rotation axis and is connected to the inside of the hollow of the shaft portion and has a hollow portion formed radially, the hollow portion being open at the radially outer end of the disk, and the water supply unit may supply liquid water to the inside of the hollow of the shaft portion. In this configuration, water supplied to the fan is sprayed onto the outer surface of the radiator using a so-called atomizer disc method, where water supplied to the fan is sprayed from the radially outer side of the disc using the centrifugal force of the disc. In the atomizer disc method, the state of the droplets sprayed from the disc can be controlled by adjusting the flow rate of water supplied to the fan, the fan speed, and the disc diameter. By controlling the state of the droplets, droplets of a suitable size can be sprayed from the disc to form a thin liquid film on the outer surface of the radiator. As a result, the cooling capacity of the radiator can be further improved.

[0010] (3) In the fuel cell system according to the above embodiment, the disk may include a first disk and a second disk which is located downstream of the first disk and has an outer diameter smaller than the outer diameter of the first disk. In this configuration, the fan has a first disc and a second disc with different outer diameters. The first disc, located upstream, has a larger outer diameter than the second disc, located downstream. Therefore, droplets sprayed from the radially outer side of the first disc and droplets sprayed from the radially outer side of the second disc are supplied to the outer surface of the radiator without interfering with each other. As a result, in this configuration, droplets are supplied to a wider area of ​​the outer surface of the radiator, improving the cooling capacity of the radiator through greater heat of vaporization.

[0011] (4) In the fuel cell system according to the above embodiment, a booster pump for compressing water is provided, which is located between the recovery unit and the water supply unit, the fan is of the suction vent type and is located downstream of the radiator, and the water supply unit is located upstream of the radiator and sprays water compressed by the booster pump onto the outer surface of the radiator. In this configuration, the fan is positioned downstream of the radiator, creating a suction-type airflow system. This uniformizes the flow field upstream of the radiator due to pressure loss as the air passes through the radiator. This suppresses the uneven distribution of small droplets on the outer surface of the radiator. Furthermore, the compression from the booster pump supplies fine droplets to the outer surface of the radiator, improving liquid dispersibility. This suppresses dripping of unvaporized droplets from the radiator, thereby improving liquid utilization.

[0012] (5) In the fuel cell system according to the above embodiment, a heat exchanger may be provided to perform heat exchange between the air flowing into the cathode electrode and the cathode-off gas, and the recovery device may recover the water in the cathode-off gas after heat exchange. In this configuration, the temperature of the air flowing into the cathode electrode is lower than the temperature of the cathode off-gas. The cathode off-gas is cooled by the air flowing into the cathode electrode, which increases the amount of water recovered from the cathode off-gas.

[0013] (6) In the fuel cell system according to the above embodiment, further comprising: a temperature acquisition unit that acquires the temperature of the refrigerant discharged from the fuel cell; a control unit that operates the fan when the acquired temperature of the refrigerant is above a threshold and stops the fan when the temperature of the fuel cell is below the threshold; It may be provided. According to this configuration, when the temperature of the refrigerant discharged from the fuel cell is equal to or higher than the threshold value, that is, when the fuel cell is operating at high power and the radiator requires cooling capacity for the refrigerant, the fan operates. On the other hand, when the output of the fuel cell is not high, the fan does not operate, and the water recovered from the cathode off-gas is not supplied to the outer surface of the radiator. As a result, the fan operates only when cooling of the fuel cell is required, and the water stored in the recovery device is used. As a result, when the fuel cell is operating at high power, water can be supplied to the radiator without interruption.

[0014] (7) In the fuel cell system of the above aspect, further, a fluorine treatment unit may be provided which is disposed between the recovery device and the water supply unit and removes fluorine ions contained in the water sent from the recovery device to the water supply unit by reacting with rare earth oxides. According to this configuration, the fluorine ions contained in the water recovered from the cathode off-gas are removed by the fluorine treatment unit. The water recovered from the cathode off-gas may contain fluorine ions due to deterioration of the electrolyte membrane of the fuel cell. If water containing fluorine ions is sprayed on the outer surface of the radiator, the radiator may corrode. According to this configuration, the fluorine ions that cause corrosion of the radiator can be removed from the water sprayed on the outer surface of the radiator.

[0015] Note that the present invention can be realized in various aspects. For example, it can be realized in the form of a cooling device, a fuel cell system, a fuel cell cooling system, a cooling method, a fuel cell cooling method, and a system including these devices or realizing these methods, a computer program for executing these devices or methods, a server device for distributing this computer program, a non-temporary storage medium storing the computer program, and the like.

Brief Description of the Drawings

[0016] [Figure 1] It is a schematic block diagram of a fuel cell system as an embodiment of the present invention. [Figure 2]It is a schematic block diagram of a fuel cell system of a comparative example. [Figure 3] It is an explanatory diagram of power consumption and heat transfer rate that change according to the rotational speed of the fan. [Figure 4] It is an explanatory diagram of the relationship between the flow rate of water sprayed on the radiator and the heat transfer rate. [Figure 5] It is an explanatory diagram of the effect of the fuel cell system of the first embodiment. [Figure 6] It is an explanatory diagram of the effect of the fuel cell system of the first embodiment. [Figure 7] It is a schematic cross-sectional view of the fan and the water supply section of the second embodiment. [Figure 8] It is an explanatory diagram of the boundary between the film-like splitting region and the string-like splitting region and the boundary between the string-like splitting region and the droplet-like splitting region. [Figure 9] It is a schematic block diagram of a fuel cell system of the third embodiment. [Figure 10] It is an explanatory diagram of the power loss of the pump. [Figure 11] It is an explanatory diagram of the power loss of the pump. [Figure 12] It is a schematic block diagram of a fuel cell system of the fourth embodiment. [Figure 13] It is an explanatory diagram of the effect of the heat exchanger [Figure 14] It is an explanatory diagram of the mode of running. <了 [Figure 15] It is an explanatory diagram of the mode of running. [Figure 16] It is an explanatory diagram of the energy consumption of the fan of the fourth embodiment. [Figure 17] It is an explanatory diagram of the time-series change of the water storage amount. [Figure 18] It is an explanatory diagram of the energy consumption of the fan of the comparative example. [Figure 19] It is a schematic block diagram of a fuel cell system of the fifth embodiment.

Embodiments for Carrying Out the Invention

[0017] <First Embodiment> Figure 1 is a schematic block diagram of a fuel cell system 1 as one embodiment of the present invention. In the fuel cell system 1 of this embodiment, water contained in the cathode-off gas of the fuel cell 10 is sprayed toward the radiator 40. The sprayed droplets adhere to the outer surface of the radiator 40 and are vaporized by a fan 20 that sends air to the radiator 40. The refrigerant flowing through the radiator 40 is cooled by the heat of vaporization of the water. As a result, in the fuel cell system 1 of this embodiment, even if the fuel cell 10 generates heat at high output, the rotation speed of the fan 20 can be suppressed, that is, the power consumption required to operate the fan 20 can be suppressed, while still being able to cool the fuel cell 10.

[0018] The fuel cell system 1 of the first embodiment is installed as a power source for a fuel cell vehicle. As shown in Figure 1, the fuel cell system 1 includes a fuel cell 10, a compressor CP that supplies compressed air to the fuel cell 10, a hydrogen tank TK that stores hydrogen to be supplied to the fuel cell 10, a hydrogen circulator CC that circulates hydrogen, a circulation channel 60 through which a refrigerant that cools the fuel cell 10 flows, a pump P1 that circulates the refrigerant flowing in the circulation channel 60, a radiator 40 that cools the refrigerant, a fan 20 that blows air to the radiator 40, a recoverer 30 that recovers water from the cathode-off gas, a water supply unit 70 that sprays water, and a pump 50 that sends water to the water supply unit 70.

[0019] The fuel cell 10 comprises a membrane electrode assembly (MEA) 11, an anode-side gas diffusion layer (anode-side GDL (Gas Diffusion Layer)) 12 and a cathode-side gas diffusion layer (cathode-side GDL (Gas Diffusion Layer)) 13 formed on each surface of the MEA 11, and separators 14 and 15 in which a flow path for a refrigerant that cools the MEA 11 is formed.

[0020] MEA11 comprises an electrolyte membrane, an anode catalyst layer formed on one side of the electrolyte membrane, and a cathode catalyst layer formed on the other side of the electrolyte membrane. The anode catalyst layer is formed on the side of the electrolyte membrane facing the anode-side GDL12. The cathode catalyst layer is formed on the side of the electrolyte membrane facing the cathode-side GDL13. The anode catalyst layer functions as the anode electrode. The cathode catalyst layer functions as the cathode electrode.

[0021] Hydrogen is supplied to the anode side GDL12 from the hydrogen tank TK. Compressed air, compressed by the compressor CP, is supplied to the cathode side GDL13. In MEA11, the hydrogen supplied from the anode side GDL12 becomes hydrogen ions in the anode catalyst layer and moves to the cathode catalyst layer. In the cathode catalyst layer, oxygen supplied from the electrolyte membrane cathode side GDL13 combines with hydrogen ions to produce water.

[0022] A cooling channel 14f through which the refrigerant flows is formed inside the separator 14 that is in contact with the anode-side GDL 12. Similarly, a cooling channel 15f through which the refrigerant flows is formed inside the separator 15 that is in contact with the cathode-side GDL 13. As shown in Figure 1, the cooling channels 14f and 15f are connected to the circulation channel 60.

[0023] Hydrogen supplied from hydrogen tank TK is delivered to the anode side GDL12 of fuel cell 10 via hydrogen circulator CC. A portion of the hydrogen supplied to the anode side GDL12 is discharged from the fuel cell without being used and is supplied back to the anode side GDL12 via hydrogen circulator CC.

[0024] Air compressed by the compressor CP is supplied to the cathode catalyst layer of the fuel cell 10, where the oxygen in the compressed air reacts with hydrogen ions supplied via the MEA 11 to generate water. The cathode-off gas, which includes a portion of the air supplied to the cathode-side GDL 13 and the water (H2O) generated in the cathode-side GDL 13, is supplied to the recovery unit 30. The recovery unit 30 is a gas-liquid separator that separates the moisture from the cathode-off gas. The liquid water separated by the recovery unit 30 is stored within the recovery unit 30. The separated gas is discharged into the atmosphere.

[0025] The circulation channel 60 connects the cooling channels 14f and 15f of the fuel cell 10, the radiator 40, and the pump P1. The refrigerant, which has been heated by passing through the cooling channels 14f and 15f via the circulation channel 60, is cooled by the radiator 40. The radiator 40 comprises multiple tubes through which the refrigerant passes, fins connecting the multiple tubes, an upper tank that distributes and supplies the refrigerant to each tube, and a lower tank that collects the refrigerant that has passed through each tube and supplies it to the circulation channel 60. The fan 20 blows air and droplets onto the tubes and fins (hereinafter, the tubes and fins are collectively referred to as the "radiator core"), thereby cooling the refrigerant passing through the tubes. The refrigerant cooled by the radiator 40 is sent to the pump P1 via the circulation channel 60. The pump P1 circulates the incoming refrigerant back into the cooling channels 14f and 15f of the fuel cell 10.

[0026] The water stored in the recovery unit 30 is sent to the water supply unit 70 by the pump 50. The water supply unit 70 is mounted on the rotation axis of the fan 20, opposite the radiator 40. The water supply unit 70 sprays the water sent by the pump 50 toward the radiator core. The fan 20 in this embodiment is a so-called forced-air fan that blows air from the upstream side of where water is sprayed toward the radiator 40. The water (droplets) sprayed from the water supply unit 70 adheres to the outer surface of the radiator core. The droplets adhering to the outer surface of the radiator core vaporize. The refrigerant passing through the tube is cooled by the heat of vaporization of the droplets.

[0027] Figure 2 is a schematic block diagram of comparative fuel cell system 1x. Compared to fuel cell system 1 shown in Figure 1, comparative fuel cell system 1x does not include a recovery unit 30, a pump 50, and a water supply unit 70. Therefore, in comparative fuel cell system 1x, when the power output requirement for fuel cell 10 increases and the temperature of fuel cell 10 rises, the rotation speed of fan 20 is increased to cool the refrigerant in radiator 40 and suppress the temperature rise of fuel cell 10.

[0028] Figure 3 is an explanatory diagram illustrating the changes in power consumption and heat transfer coefficient according to the rotational speed of fan 20. Figure 3 shows the rate of change in power consumption (kW) of fan 20 and the heat transfer coefficient (W / (m) of radiator 40, with the rotational speed (rpm) of fan 20 on the horizontal axis. 2 The rate of change of (K) is shown. In Figure 3, the power consumption of the fan 20 is shown by a black circle, and the heat transfer coefficient of the radiator 40 is shown by a white circle. As shown in Figure 3, as the rotational speed of the fan 20 increases, the power consumption of the fan 20 also increases. In addition, as the rotational speed of the fan 20 increases, the heat transfer coefficient of the radiator 40 also increases, that is, the ability of the radiator 40 to cool the refrigerant improves.

[0029] The combined power consumption of the auxiliary equipment in the fuel cell system 1x, including the compressor CP, the pump P1 for circulating the refrigerant, and the fan 20, reduces the power generation efficiency of the fuel cell system 1x by approximately 3-4%. Therefore, the power consumption of the auxiliary equipment has a significant impact on power generation efficiency. In particular, the power consumption of the fan 20 has a significant impact when driving uphill in heavy vehicles where the required output to the fuel cell 10 is high. To address this impact, the fuel cell system 1 of this embodiment suppresses the increase in the rotational speed of the fan 20 by utilizing the heat of vaporization of the droplets sprayed onto the radiator 40, thereby suppressing the increase in power consumption of the auxiliary equipment.

[0030] Figure 4 is an explanatory diagram illustrating the relationship between the flow rate of water sprayed onto the radiator 40 and the heat transfer coefficient. Figure 4 shows the flow rate of the spray liquid (m³) sprayed onto the radiator 40. 3The heat transfer coefficient (W / (m 2 ·K)) due to the latent heat of vaporization of the outer surface of the radiator 40, which changes according to / s), and the film Reynolds number Re,f are shown. In FIG. 4, the heat transfer coefficient is shown by white circles, and the film Reynolds number Re,f is shown by black circles. The film Reynolds number Re,f is calculated using the following formula (1).

[0031]

Equation

[0032] Using the film Reynolds number Re,f calculated by the above formula (1), the Nusselt number Nu is expressed as in the following formula (2). Also, the Nusselt number Nu can be expressed as in the following formula (3) using the gravitational acceleration g (m 2 / s) and the thermal conductivity λ L (W / (m·K)).

[0033]

Equation

Equation

[0034] The heat transfer coefficient α f calculated by the above formula (3) is shown by white circles in FIG. 4. As shown in FIG. 4, when the liquid flow rate sprayed onto the fan 20 increases, the heat transfer coefficient in the latent heat of vaporization of the outer surface of the radiator 40 decreases. This indicates that the thinner the liquid film formed by the liquid droplets adhering to the outer surface of the radiator 40, the better the cooling ability due to the latent heat of vaporization of the liquid film.

[0035] Figures 5 and 6 are explanatory diagrams illustrating the effects of the fuel cell system 1 of the first embodiment. Figure 5 shows the change in the rotational speed of the fan 20 and the change in the auxiliary power (kW) used to operate the auxiliary equipment, which vary according to the output power (kW) of the fuel cell 10. Specifically, Figure 5 shows the fan rotational speed and auxiliary power for the first embodiment and the comparative example when the cooling capacity for cooling the fuel cell 10 is the same. In Figure 5, the fan rotational speed of the first embodiment is indicated by a white circle, and the fan rotational speed of the comparative example is indicated by a black circle. Also, the auxiliary power for the first embodiment is indicated by an open white triangle, and the auxiliary power for the comparative example is indicated by a filled black triangle. As shown in Figure 5, in the first embodiment, in which droplets are sprayed onto the outer surface of the radiator 40, the increase in fan rotational speed and auxiliary power accompanying the increase in the output of the fuel cell 10 is suppressed compared to the comparative example.

[0036] Figure 6 shows the change in droplet spray volume (kg / s) in the first embodiment, which varies according to the output power of the fuel cell 10, and the change in the percentage improvement in power efficiency of the first embodiment compared to the comparative example. In Figure 6, the spray volume is shown by black circles, and the percentage improvement is shown by white circles. As shown in Figure 6, the spray volume increases almost proportionally with the increase in the output power of the fuel cell 10. On the other hand, the percentage improvement increases more rapidly when the output power of the fuel cell 10 exceeds 60 kW. From this, it can be seen that spraying droplets onto the outer surface of the radiator 40 in the first embodiment is more effective when the output of the fuel cell 10 is high.

[0037] As described above, in the fuel cell system 1 of this embodiment, the recovery unit 30 recovers water from the cathode-off gas. The water supply unit 70 sprays the supplied water toward the radiator 40, and the sprayed water adheres to the outer surface of the radiator 40. In this embodiment, the water contained in the cathode-off gas is supplied to the outer surface of the radiator 40, and the heat of vaporization of the water cools the refrigerant flowing through the tubes of the radiator 40. In this embodiment, the cooling capacity of the radiator 40 is improved by utilizing the heat of vaporization of water in the cathode-off gas, which was conventionally discharged into the outside air. This makes it possible to suppress the increase in the rotation speed of the fan 20 in order to cool the fuel cell 10 at high output. As a result, the power consumption of the entire fuel cell system 1 can be suppressed while the fuel cell 10 at high output can be sufficiently cooled.

[0038] <Second Embodiment> In the second embodiment, the configuration of the water supply unit 70a differs from that of the first embodiment. In the second embodiment, the fan 20a sprays droplets onto the radiator 40 using a so-called atomizer disc method.

[0039] Figure 7 is a schematic cross-sectional view of the fan 20a and water supply unit 70a of the second embodiment. Figure 7 shows a longitudinal cross-section of the fan 20a and water supply unit 70a along the rotation axis OL1. As shown in Figure 7, the fan 20a comprises a shaft portion 25 that extends along the rotation axis OL1 and rotates around the rotation axis OL1, a rotating fan 21 that rotates together with the shaft portion 25, and three disc-shaped disks 22-24 that are connected to the shaft portion 25 and rotate together with the shaft portion 25 around the rotation axis OL1. In Figure 7, the radiator 40 is positioned along the rotation axis OL1 in the direction from the water supply unit 70a towards the fan 20a (to the left in the figure). That is, in Figure 7, the left side is the downstream side and the right side is the upstream side.

[0040] The shaft portion 25 has a hollow interior. The rotating fan 21 rotates around the central axis OL1 and blows air to the radiator 40 located downstream. The three discs 22-24 have a disc shape that extends radially outward from the rotating axis OL1 and are arranged at equal intervals along the rotating axis OL1 in order from upstream. The three discs 22-24 consist of a first disc 22 with the largest outer diameter, a second disc 23 with a smaller outer diameter than the first disc 22, and a third disc 24 with an even smaller outer diameter than the second disc 23, in order from upstream. Inside each of the discs 22-24, hollow portions SP1-SP3 are formed along the radial direction and connected to the hollow interior of the shaft portion 25. As shown in Figure 7, the hollow portions SP1-SP3 are open at the radially outer ends of each disc 22-24.

[0041] The water supply unit 70a supplies water to the hollow interior of the shaft portion 25 of the fan 20a. As a result, the water supplied to the interior of the shaft portion 25 flows into the hollow portions SP1 to SP3 formed in each disc 22 to 24. Since the discs 22 to 24 rotate together with the shaft portion 25, the water that flows into the hollow portions SP1 to SP3 is sprayed as droplets DR from the radially outer ends by centrifugal force. The sprayed droplets DR are carried to and adhere to the outer surface of the radiator 40 by the wind generated by the rotation of the rotating fan 21.

[0042] As described in the first embodiment, the thinner the liquid film formed by droplets DR adhering to the outer surface of the radiator 40, the better the cooling capacity. In this embodiment, the water supply unit 70a controls the flow rate of water supplied to the shaft unit 25 using the rotational angular velocity ω (rad / s) of the fan 20a, so that the water sprayed from the disks 22-24 is in the shape of string-like splitting regions (microdroplets).

[0043] Here, the dimensionless number of the flow rate, Γ², is expressed as shown in equation (4) below. Also, the Reynolds number Re is expressed as shown in equation (5) below. The ratio We, obtained by dividing the inertial force by the surface tension, is expressed as shown in equation (6) below.

number

number

number

[0044] Here, if the inertial force is greater than that of the filamentous splitting region, the droplet DR is sprayed from disks 22-24 in the shape of a film-like splitting region. Also, if the surface tension is greater than that of the filamentous splitting region, the droplet DR is sprayed in the shape of a drop-like splitting region. The dimensionless number Γ² representing the boundary between the film-like splitting region and the filamentous splitting region is expressed as shown in equation (7) below. Also, the dimensionless number Γ² representing the boundary between the filamentous splitting region and the drop-like splitting region is expressed as shown in equation (8) below.

[0045]

number

number

[0046] Figure 8 is an explanatory diagram of the boundary BD1 between the membrane-like fission region and the filament-like fission region, and the boundary BD2 between the filament-like fission region and the drop-like fission region. In Figure 8, the boundaries BD1 and BD2 are shown on a graph when the rotation speed of the fan 20a is 250 rpm, the output power of the fuel cell 10 is 40 to 90 kW, the water flow rate F is 40 to 90 kW, and the diameters of the disks 22 to 24 are φ100 (white square), 75 (white triangle), and 50 (white circle) (mm). Multiple plots exist for each disk 22 to 24 because multiple plots were created for each 10 kW increase in output power. In this embodiment, the value of the multiplier m on the horizontal axis of Figure 8 is "-0.94" calculated from the above formula (7). The value of the multiplier n on the vertical axis is "0.25" calculated from the above formula (8). Figure 8 also shows conceptual diagrams of the filament-like fission region (microdroplets), the membrane-like fission region, and the drop-like fission region (coarse).

[0047] As described above, the fan 20a of the second embodiment has disc-shaped disks 22-24 that extend radially outward from the rotation axis OL1. Inside each of the disks 22-23, hollow sections SP1-SP3 are formed along the radial direction and connected to the hollow interior of the shaft section 25. As shown in Figure 7, the hollow sections SP1-SP3 open at the radially outward ends of each disk 22-24. The water supply unit 70a supplies water to the hollow interior of the shaft section 25 of the fan 20a. In this embodiment, the water supplied to the inside of the fan 20a is sprayed from the radially outward side of the disks 22-24 using the centrifugal force of the disks 22-24, and the water is supplied to the outer surface of the radiator 40 by a so-called atomizer disk method. In the atomizer disk method, the state of the droplets DR sprayed from the disks 22-24 can be controlled according to the adjustment of the flow rate of water supplied to the fan 20a, the rotation speed of the fan 20a, and the diameter of the disks 22-24. By controlling the state of the liquid droplets DR, liquid droplets DR of a suitable size for forming a thin liquid film on the outer surface of the radiator 40 can be sprayed from discs 22-24. As a result, the cooling capacity of the radiator 40 can be further improved.

[0048] In the second embodiment, the three disks 22-24 are composed of a first disk 22 with the largest outer diameter, a second disk 23 with a smaller outer diameter than the first disk 22, and a third disk 24 with an even smaller outer diameter than the second disk 23, in order from the upstream side. In other words, the fan 20a of this embodiment has disks 22-24 with different outer diameters. For example, the first disk 22, located furthest upstream, has a larger outer diameter than the second disk 23 and third disk 24, which are located downstream. Therefore, the droplets DR sprayed from the radially outside of the first disk 22 and the droplets DR sprayed from the radially outside of the second disk 23 and third disk 24 are supplied to the outer surface of the radiator 40 without interfering with each other. As a result, in this embodiment, droplets DR are supplied to a wider area of ​​the outer surface of the radiator 40, improving the cooling capacity of the radiator 40 due to greater heat of vaporization.

[0049] <Third Embodiment> Figure 9 is a schematic block diagram of the fuel cell system 1b of the third embodiment. The fuel cell system 1b of the third embodiment differs from the fuel cell system 1 of the first embodiment in that the fan 20b is a suction-ventilation type located downstream of the radiator 40, and the pump 50b functions as a booster pump that supplies pressurized water to the water supply unit 70b. Therefore, in the third embodiment, the differences from the first embodiment will be explained, and the same configurations as in the first embodiment will be omitted from the explanation.

[0050] In the third embodiment, the pump (boost pump) 50b pressurizes the water supplied to the water supply unit 70b, so that finer droplets DR (e.g., φ1 to 100 μm) than those of the atomizer disc method in the second embodiment are sprayed onto the outer surface of the radiator 40. The water supply unit 70b in this embodiment is a single-component nozzle. The water supply unit 70b forms a wide-angle (120°) spray pattern.

[0051] Here, as pump 50b pressurizes the water, the power loss of the auxiliary equipment of the fuel cell system 1b increases. Figures 10 and 11 are explanatory diagrams of the power loss of pump 50b. Figure 10 shows the power consumed by pump 50b and the discharge pressure (MPa) of the pressurized water supplied by pump 50b, depending on the discharge flow rate (L / min) of the water supplied from pump 50b to the water supply unit 70b. The points plotted in Figure 10 are the points when the output power of the fuel cell 10 is changed in 10kW increments from 40kW to 90kW. In Figure 10, the power of pump 50b is shown by white circles, and the discharge pressure is shown by white triangles. As shown in Figure 10, as the discharge flow rate of pump 50b increases, the power of pump 50b increases proportionally. On the other hand, the discharge pressure of pump 50b is approximately constant at 2MPa, independent of the discharge flow rate.

[0052] Figure 11 shows how the power consumed by the auxiliary equipment—the boosting pump 50b, the fan 20b, and the pump P1—changes in response to the output power of the fuel cell 10. In Figure 11, the power of the water boosting pump 50b is shown by a white triangle, the power of the fan 20b is shown by a white square, and the power of the pump P1 is shown by a white circle. As shown in Figure 11, the power of each auxiliary equipment increases as the output power of the fuel cell 10 increases. Comparing the power of the pump 50b and the fan 20b, the rate of increase and the magnitude of the increase in power of the pump 50b are small. In other words, even if the power of the pump 50b increases, the power of the fan 20b can be reduced by an even greater amount.

[0053] As described above, the pump 50b of the third embodiment pressurizes the water supplied to the water supply unit 70b. As a result, the water supply unit 70b sprays fine droplets DR (for example, φ1 to 100 μm) onto the outer surface of the radiator 40. In this embodiment, since the fan 20b is a suction-type fan located downstream of the radiator 40, the pressure loss as the water passes through the radiator 40 uniformizes the flow field upstream of the radiator 40. This suppresses the uneven distribution of small droplets DR on the outer surface of the radiator 40. In addition, since fine droplets DR are supplied to the outer surface of the radiator 40 by the compression of the pump 50b, liquid dispersibility is improved. This suppresses the dripping of unvaporized droplets DR from the radiator and improves the liquid utilization rate.

[0054] <Fourth Embodiment> Figure 12 is a schematic block diagram of the fuel cell system 1c of the fourth embodiment. The fuel cell system 1c of the fourth embodiment differs from the fuel cell system 1 of the first embodiment in that it includes a heat exchanger 80, a water storage tank 90, a temperature sensor 65, and a control unit 29. Therefore, in the fourth embodiment, the differences from the first embodiment will be explained, and explanations of the same configuration and control as the first embodiment will be omitted.

[0055] As shown in Figure 12, the heat exchanger 80 in the fuel cell system 1c is located between the compressor CP and the fuel cell 10, and between the fuel cell 10 and the recovery unit 30. The heat exchanger 80 performs heat exchange between the air compressed by the compressor CP and the cathode-off gas discharged from the cathode-side GDL 13 of the fuel cell 10. Through heat exchange, the air compressed by the compressor CP flows into the heated cathode-side GDL 13. Meanwhile, the cathode-off gas is cooled and supplied to the recovery unit 30. Figure 12 shows an example of the temperature of the compressed air flowing into the heat exchanger 80 and an example of the temperature of the cathode-off gas discharged from the heat exchanger 80. The cathode-off gas supplied to the recovery unit 30 is cooled to approximately 30°C to recover the water contained in the cathode-off gas. As shown in Figure 12, the water storage tank 90 of the fuel cell system 1c is located between the recovery unit 30 and the pump 50, and stores the water recovered by the recovery unit 30.

[0056] Figure 13 is an explanatory diagram of the effect of the heat exchanger 80. Figure 13 shows the liquid flow rate (kg / s) recovered by the recovery unit 30 from the cathode-off gas, which changes according to the output power of the fuel cell 10. In Figure 13, the liquid flow rate at which the recovery unit 30 condenses is plotted for each case where the temperature of the cathode-off gas supplied to the recovery unit 30 is 40°C, 50°C, and 60°C. 40°C is indicated by a white circle, 50°C by a white triangle, and 60°C by a white square. As shown at each plot point in Figure 13, the lower the temperature of the cathode-off gas supplied to the recovery unit 30, the more water is recovered from the cathode-off gas. Also, the higher the output power of the fuel cell 10, the more water is recovered from the cathode-off gas.

[0057] The temperature sensor (temperature acquisition unit) 65 in the fuel cell system 1c is a thermocouple that detects the outlet temperature of the refrigerant discharged from the fuel cell 10. The control unit 29 controls the rotation speed of the fan 20 according to the temperature of the fuel cell 10 detected by the temperature sensor 65. Specifically, the control unit 29 operates the fan 20 when the outlet temperature of the refrigerant detected by the temperature sensor 65 is above a preset threshold. On the other hand, the control unit 29 stops the fan 20 without operating it when the outlet temperature of the refrigerant is below the threshold. The water supply unit 70 sprays water when the fan 20 is operating and stops spraying water when the fan 20 is stopped. Therefore, when the outlet temperature of the refrigerant is below the threshold, i.e., when the output power of the fuel cell 10 is not high, the amount of water recovered by the recovery unit 30 gradually increases in the water storage tank 90.

[0058] Here, we consider the mode driving of a vehicle equipped with a fuel cell system 1c and driven by the output power of the fuel cell 10. Figures 14 and 15 are explanatory diagrams of mode driving. Figure 14 shows the changes in the output power of the fuel cell 10 and the heat generation amount (kW) of the fuel cell 10 as the elapsed time during mode driving is taken on the horizontal axis. In Figure 14, the output power is shown by black circles and the heat generation amount is shown by white circles. In the mode driving shown in Figure 14, the output power and heat generation amount increase particularly after 250 seconds (sec) and 1700 seconds after the start of mode driving. Note that the state shown in Figures 14 and 15 is during mode driving when water is not being sprayed onto the radiator 40 by the water supply unit 70.

[0059] Figure 15 shows the changes in the temperature of the fuel cell 10 (°C), the inlet temperature of the refrigerant flowing into the radiator 40 (°C), and the outlet temperature of the refrigerant flowing out of the radiator 40 (°C) as the horizontal axis represents the elapsed time during mode driving. In Figure 15, the temperature of the fuel cell 10 is shown as a white circle, the inlet temperature of the refrigerant flowing into the radiator 40 is shown as an open white square, and the outlet temperature of the refrigerant flowing out of the radiator 40 is shown as a filled black square. In addition, in Figure 15, the ambient temperature and the target temperature (Target), which is the control target for the temperature of the fuel cell 10, are shown as straight lines. As shown in Figure 15, the temperature of the fuel cell 10 exceeds the target temperature around 250 seconds and 1700 seconds after the elapsed time of mode driving, where the output power and heat generation are particularly high in Figure 14.

[0060] Figures 16 to 18 are explanatory diagrams illustrating the effects of the fuel cell system 1c of the fourth embodiment. Figure 16 shows the time-series changes in fan output and cumulative energy consumption (kJ) of the fan 20 when the control unit 29 of the fourth embodiment controls the rotation of the fan 20 for a vehicle during mode driving. In Figure 16, the output of the fan 20 is shown by a solid line, and the cumulative energy consumption of the fan is shown by a dashed line. In the example shown in Figure 16, the cumulative energy consumption of the fan 20 during one cycle of mode driving was 7.4 kJ / cyc. In the examples shown in Figures 16 and 17, the rotation speed of the fan 20 is controlled to a constant 250 rpm, the initial amount of water stored in the water storage tank 90 is 1 kg, and the temperature of the water recovered from the cathode-off gas by the recovery unit 30 is 40°C. The control unit 29 operates the fan 20 when the heat output of the fuel cell 10 is 10 kW or more, and the water supply unit 70 sprays water onto the outer surface of the radiator 40.

[0061] Figure 17 shows the time-series changes in the amount of water stored in the water storage tank 90 (kg) and the amount of water sprayed by the fan 20 (kg / s) during mode driving. In Figure 17, the amount of water stored is shown by a dashed line, and the amount of water sprayed is shown by a solid line. As shown in Figure 17, the amount of water stored is always greater than zero, so when the fan 20 is operating, water is always sprayed from the water supply unit 70 onto the outer surface of the radiator 40. On the other hand, the amount of water stored around 300 seconds after the start of mode driving is less than the initial amount of water stored (1 kg), so it can be seen that if there is no water storage tank 90, a situation will occur where water cannot be sprayed from the water supply unit 70.

[0062] Figure 18 shows the time-series changes in fan output and cumulative energy consumption of fan 20 during driving of a vehicle equipped with a comparative example fuel cell system that does not spray water from the water supply unit 70. The control unit 29 operates fan 20 when the heat generated by the fuel cell 10 is 10kW or more, just as in the mode driving shown in Figure 16. In the comparative example shown in Figure 18, instead of spraying water onto the radiator 40, the refrigerant in the radiator 40 is cooled by increasing the rotation speed of fan 20. As shown in Figure 18, unlike the embodiment shown in Figure 16, the rotation speed of fan 20 increases significantly above 250 rpm around 300 seconds and 1700 seconds after the start of mode driving. As a result, the cumulative energy consumption of fan 20 also increases, and the cumulative energy consumption of fan 20 during one cycle of mode driving was 46.5kJ / cyc. In other words, it can be seen that the fuel cell system 1c of the fourth embodiment can cool the refrigerant with less energy consumption compared to the fuel cell system of the comparative example. Note that the vertical axis scale representing the cumulative energy consumption of fan 20 in Figure 18 is larger than the scale in Figure 16.

[0063] As described above, the heat exchanger 80 of the fourth embodiment performs heat exchange between air compressed by the compressor CP and cathode-off gas discharged from the cathode-side GDL 13 of the fuel cell 10. In this embodiment, the temperature of the air flowing into the cathode-side GDL 13 is lower than the temperature of the cathode-off gas. By cooling the cathode-off gas with the air flowing into the cathode-side GDL 13, the amount of water recovered from the cathode-off gas can be increased.

[0064] Furthermore, in the fourth embodiment, the control unit 29 activates the fan 20 when the outlet temperature of the refrigerant discharged from the fuel cell 10, as detected by the temperature sensor 65, is above a preset threshold. In this embodiment, the fan 20 activates when the temperature of the refrigerant discharged from the fuel cell 10 is above the threshold, i.e., when the fuel cell 10 is at high output and the radiator 40 needs to cool the refrigerant. On the other hand, when the output of the fuel cell 10 is not high, the fan 20 does not activate, and the water recovered from the cathode-off gas is not supplied to the outer surface of the radiator 40. As a result, the fan 20 activates and the water stored in the water storage tank 90 is used only when the fuel cell 10 needs to be cooled. As a result, water can be supplied to the radiator 40 without interruption when the fuel cell 10 is at high output.

[0065] <Fifth Embodiment> Figure 19 is a schematic block diagram of the fuel cell system 1d of the fifth embodiment. The fuel cell system 1d of the fifth embodiment differs from the fuel cell system 1 of the first embodiment in that it includes the heat exchanger 80 and the fluorine treatment unit 95 of the fourth embodiment. Therefore, in the fifth embodiment, the fluorine treatment unit 95, which differs from the first embodiment, will be described, and the same configuration as the first embodiment and the description of the heat exchanger 80 will be omitted.

[0066] As shown in Figure 19, the fluorine treatment unit 95 of the fuel cell system 1d is located between the recovery unit 30 and the pump 50. Water is supplied to the fluorine treatment unit 95 from the recovery unit 30. In addition, slaked lime (Ca(OH)2) is supplied to the fluorine treatment unit 95 in this embodiment as a coagulant. The water in the cathode-off gas may contain trace amounts of fluoride ions from fluorine compounds contained in the electrolyte membrane of the MEA 11 of the fuel cell 10. If the concentration of fluoride ions in the water recovered by the recovery unit 30 reaches a certain level, it may corrode the radiator 40 to which the water is sprayed. Therefore, in this embodiment, slaked lime, which condenses and precipitates fluoride ions as sparingly soluble calcium fluoride (CaF2), is supplied to the fluorine treatment unit 95. The calcium fluoride precipitated in the fluorine treatment unit 95 is separated and removed. Furthermore, by separating and removing the calcium fluoride from the fluorine treatment unit 95, it is possible to prevent sparingly soluble calcium fluoride from being supplied to the water supply unit 70 and clogging the nozzles of the spray nozzle.

[0067] <Modified examples of embodiments> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit. For example, the following modifications are possible. Furthermore, in the above embodiments, some of the configurations implemented by hardware may be replaced with software, and conversely, some of the configurations implemented by software may be replaced with hardware.

[0068] In the first to fifth embodiments described above, an example of a fuel cell system was explained. However, the fuel cell system can be modified to include a fuel cell 10, a radiator 40, a fan 20, a recovery unit 30 for recovering water from the cathode-off gas, and a water supply unit 70 for spraying water onto the outer surface of the radiator 40. The fan 20 in the first embodiment may be a so-called suction-ventilation type, located downstream of the radiator 40. In the embodiments described above, an example in which the fuel cell system 1 is mounted on a vehicle was explained, but the use of the fuel cell system 1 is applicable within the scope of well-known technology.

[0069] The number of discs on the fan 20a of the second embodiment may be less than three or four or more. Also, the diameter of the upstream disc 22 may be smaller than or the same as the diameters of the downstream discs 23 and 24. Furthermore, the fan 20a of the second embodiment and the rotating body comprising discs 22 to 24 may be separate components. In this case, the fan 20a may be an intake-type fan positioned downstream of the radiator 40, and the rotating body comprising discs 22 to 24 may be positioned upstream of the radiator 40. Also, the fan may be positioned on either the upstream or downstream side of the radiator 40.

[0070] The fuel cell system of the second embodiment may also include the control unit 29 provided in the fourth embodiment. In this case, the control unit 29 may control the rotational angular velocity ω of the fan 20a and the flow rate F of the water supplied by the water supply unit 70 by calculating equations (4) to (8) above using the disk radii r of disks 22 to 24, thereby controlling the shape of the droplets DR sprayed on the outer surface of the radiator 40 to become a string-like splitting region. In this modified example, a liquid film that is easily vaporized by the droplets DR is formed on the surface of the tubes and fins of the radiator 40, thereby improving the radiator 40's ability to cool the refrigerant.

[0071] In the fourth embodiment described above, the control unit 29 controlled the rotation speed of the fan 20 according to the outlet temperature of the refrigerant discharged from the fuel cell 10. However, the temperature used for control may be other than the outlet temperature of the refrigerant. For example, the control unit 29 may control the fan 20 according to the temperature of the refrigerant after it has been cooled by the radiator 40, or it may control the fan 20 according to the temperature of the fuel cell 10. Furthermore, the control unit 29 may control the rotation speed of the fan 20 by increasing or decreasing it according to the temperature, rather than by switching it on and off a fixed number of times.

[0072] The fluorine treatment unit 95 of the fifth embodiment described above can be modified to remove fluoride ions contained in the water supplied from the recovery unit 30. For example, the compound supplied to the fluorine treatment unit 95 may be a calcium salt, such as calcium chloride.

[0073] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate.

[0074] The present invention can also be realized in the following forms. [Application Example 1] A fuel cell system, Fuel cells and A circulation channel through which the refrigerant used to cool the fuel cell circulates, A radiator for cooling the refrigerant flowing through the aforementioned circulation path, A fan that blows air onto the aforementioned radiator, A recovery device for recovering water in the cathode off-gas discharged from the cathode electrode of the fuel cell, A water supply unit that supplies the liquid water recovered by the recovery unit to the outer surface of the radiator, A fuel cell system equipped with the following features. [Application Example 2] The fuel cell system described in Application Example 1, The aforementioned fan said, It is a forced-air type located upstream of the radiator, A hollow shaft portion extending along the axis of rotation and rotating around the axis of rotation, A fan rotating body connected to the aforementioned shaft and rotating around the aforementioned rotation axis to blow air to the radiator, A disc-shaped disk that rotates around the aforementioned rotation axis and has a hollow portion formed radially along the shaft, connected to the hollow interior of the shaft portion, It has, The hollow portion is open at the radially outer end of the disk, The water supply unit is a fuel cell system that supplies liquid water into the hollow interior of the shaft. [Application Example 3] A fuel cell system as described in Application Example 1 or Application Example 2, The aforementioned disk is The first disc and A second disk is positioned downstream of the first disk and has an outer diameter smaller than the outer diameter of the first disk, A fuel cell system having the following features. [Application Example 4] A fuel cell system described in any one of Application Examples 1 to 3, further, Displaced between the recovery unit and the water supply unit, and equipped with a booster pump for compressing water, The aforementioned fan is an intake-type fan positioned downstream of the radiator, The water supply unit is located upstream of the radiator and sprays compressed water, supplied by the booster pump, onto the outer surface of the radiator in a fuel cell system. [Application Example 5] A fuel cell system described in any one of Application Examples 1 to 4, further, The system includes a heat exchanger that performs heat exchange between the air flowing into the cathode electrode and the cathode off-gas. The recovery device is a fuel cell system that recovers water from the cathode-off gas after heat exchange. [Application Example 6] A fuel cell system described in any one of Application Examples 1 to 5, further, A temperature acquisition unit that acquires the temperature of the refrigerant discharged from the fuel cell, A control unit that activates the fan when the acquired refrigerant temperature is above a threshold and stops the fan when the fuel cell temperature is below the threshold, A fuel cell system equipped with the following features. [Application Example 7] A fuel cell system described in any one of the application examples 1 to 6, further, A fuel cell system comprising a fluorine treatment unit disposed between the recovery unit and the water supply unit, which removes fluorine ions contained in the water sent from the recovery unit to the water supply unit by reacting them with rare earth oxides. [Explanation of Symbols]

[0075] 1, 1b, 1c, 1d, 1x… Fuel cell systems 10…fuel cell 11…MEA 12... Anode-side GDL 13… Cathode-side GDL 14, 15… Separator 14f, 15f… Cooling channel 20, 20a, 20b... Fan 21…Rotating fan 22…Disc 1 23…Second Disc 24…Disc 3 25... Shaft 29... Control Unit 30...Collection device 40...Radiator 50... Pump 50b... Pump (boost pump) 60…Circulation channel 65…Temperature sensor (temperature acquisition unit) 70,70a,70b…Water supply section 80...Heat exchanger 90...Water storage tank 95...Fluorine treatment CC…Hydrogen circulator CP... Compressor DR…droplet OL1... Fan rotation axis P1... Pump SP1,SP2,SP3…Hollow part TK... Hydrogen tank

Claims

1. A fuel cell system, Fuel cells and A circulation channel through which the refrigerant used to cool the fuel cell circulates, A radiator for cooling the refrigerant flowing through the aforementioned circulation path, A fan that blows air onto the aforementioned radiator, A recovery device for recovering water in the cathode off-gas discharged from the cathode electrode of the fuel cell, A water supply unit that supplies the liquid water recovered by the recovery unit to the outer surface of the radiator, Equipped with, The aforementioned fan said, It is a forced-air type located upstream of the radiator, A hollow shaft portion extending along the axis of rotation and rotating around the axis of rotation, A fan rotating body connected to the shaft portion and rotating around the rotation axis to send air to the radiator, A disc-shaped disk that rotates around the aforementioned rotation axis and has a hollow portion formed radially along the shaft, connected to the hollow interior of the shaft portion, It has, The hollow portion is open at the radially outer end of the disk, The water supply unit is a fuel cell system that supplies liquid water into the hollow interior of the shaft.

2. A fuel cell system according to claim 1, The aforementioned disk is The first disc and A second disk is positioned downstream of the first disk and has an outer diameter smaller than the outer diameter of the first disk, A fuel cell system having the following features.

3. A fuel cell system according to claim 1, further, A booster pump for compressing water is positioned between the recovery unit and the water supply unit, A suction-type ventilation fan is positioned downstream of the radiator, Equipped with, The water supply unit is located upstream of the radiator and sprays compressed water, supplied by the booster pump, onto the outer surface of the radiator in a fuel cell system.

4. A fuel cell system according to claim 3, further, The system includes a heat exchanger that performs heat exchange between the air flowing into the cathode electrode and the cathode off-gas. The recovery device is a fuel cell system that recovers water from the cathode-off gas after heat exchange.

5. A fuel cell system according to claim 4, further, A temperature acquisition unit that acquires the temperature of the refrigerant discharged from the fuel cell, A control unit that operates the fan and the intake ventilation fan when the acquired refrigerant temperature is above a threshold, and stops the fan and the intake ventilation fan when the fuel cell temperature is below the threshold, A fuel cell system equipped with the following features.

6. A fuel cell system according to any one of claims 1 to 5, further comprising: A fuel cell system comprising a fluorine treatment unit disposed between the recovery unit and the water supply unit, which removes fluorine ions contained in the water sent from the recovery unit to the water supply unit by reacting them with rare earth oxides.

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