Fuel cell system

Abstract

A fuel cell system comprising at least a fuel cell (12), a cooling circuit (16) equipped with a cooling pump (18) and a heat exchanger (20), a water separator (34), and a ventilator (22) that generates a gaseous medium flow, particularly an air flow, in the direction of the heat exchanger (20), wherein the water separated in the water separator (34) by a cooling device having a transport device (46) reaches a discharge device (50), and the discharge device sprays the water into the surroundings by a spray nozzle (52), characterized in that the discharge device (50) sprays the water by the spray nozzle (52) in the direction opposite to the direction of the medium flow generated by the ventilator (22).

Description

Technical Field

[0001] The present invention relates to a fuel cell system, comprising at least - a fuel cell, - a cooling circuit provided with a cooling pump and a heat exchanger, - a water separation device, - a ventilator for generating a gaseous medium flow, specifically an air flow, passing through the heat exchanger, and it relates to a type in which water separated by a water separation device reaches a discharge device by means of a cooling device having a transport device, and the discharge device sprays the water to the surroundings by means of a spray nozzle.

Background Art

[0002] A fuel cell is a device for converting chemical energy into electrical energy from a gaseous energy carrier gas such as, for example, hydrogen and a gaseous oxidant in the form of, for example, ambient air. Typically, a plurality of fuel cells are combined with each other in one fuel cell stack so as to be able to produce an intended output. Stacks consisting of more than 200 individual cells are not uncommon. The fuel cell stack receives a cathode reaction gas, usually an air flow passing through the stack via a compressor. In this process, not all of the oxygen is consumed by the stack, and a part of the air is discharged as cathode exhaust gas. The cathode exhaust gas may contain liquid water and / or water vapor as stack by-products. The fuel cell stack also receives an anode hydrogen reaction gas flowing into the anode side of the stack, and further, a flow path for a cooling fluid passing through the fuel cell stack is provided so as to maintain a thermal balance. A proton exchange membrane is frequently used for fuel cells.

[0003] To achieve efficient stack operation and a long stack life, each fuel cell must be operated at an optimal relative humidity and within an optimal temperature range. Typical stack operating temperatures are usually between 60°C and 80°C. The stack temperature, in relation to a given stack pressure, provides the relative humidity within the fuel cells in the stack. Stack temperatures that are too high, exceeding the optimal temperature, damage fuel cell components, shortening the fuel cell's lifespan. Stack temperatures below the optimal operating temperature also degrade stack performance. Therefore, fuel cell systems utilize a thermal subsystem that can control the temperature within the fuel cell stack.

[0004] Such a thermal subsystem is shown in Patent Document 1. This known solution relates to a fuel cell system for a vehicle, the system comprising: a fuel cell stack that provides cathode exhaust to a cathode discharge line, wherein the cathode exhaust comprises gaseous and liquid water; a liquid water separator that receives the cathode exhaust from the cathode discharge line and separates the liquid water from the cathode exhaust; and a thermal subsystem comprising a pump, a cooling circuit, and a cooler, wherein the pump pumps a cooling fluid through the cooling circuit, the cooler, and the fuel cell stack, and the cooler comprises a selectively permeable wall portion, the wall portion allowing water in the cooling fluid flowing through the cooler to pass through and evaporate on the outer surface of the wall portion, the thermal subsystem further comprises a cooling fluid reservoir to which the liquid water separated from the cathode exhaust by the water separator is delivered, and the separated water is guided into the cooling circuit if necessary to maintain the water supply to the cooling circuit.

[0005] Known methods for selectively permeable wall portions include a polyethersulfone substrate coated with cross-linked polyvinyl alcohol, or a cross-linked chitosan film. These methods may become ineffective in rough daily operation, particularly in vehicle operation, due to clogging by contaminants. Furthermore, such selectively permeable substrates or films for heat exchangers are relatively expensive to implement.

[0006] In a known method for operating a fuel cell system in an automobile having at least one fuel cell, from which water-containing exhaust gas is emitted during operation, based on Patent Document 2, a cooling circuit system is provided inside the automobile, in which a cooling fluid is guided to a heat source where it absorbs heat, and then guided to a cooling region, in which the cooling fluid releases the absorbed heat to the surrounding air through a wall. This method collects water from the exhaust gas, particularly after separation, into a container, and the water collected in the container is at least partially deposited on the outer surface of the wall inside the cooling region. Typically, the cooling region is configured as a cooler, preferably a fin cooler, and during the operation of the automobile, the airflow helps to remove water droplets from the cooler, as the airflow entrains the water droplets in the airflow. However, in this known means, the airflow also promotes the evaporation of water droplets, thus enabling the cooling of the cooler and, consequently, the cooling fluid located inside the cooler. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] German Patent No. 102006048187 Specification [Patent Document 2] German Patent Application Publication No. 102008029529 Specification [Overview of the project] [Problems that the invention aims to solve]

[0008] Starting from such conventional technologies, the fundamental problem underlying the present invention is to provide an alternative solution that has low implementation costs, high functional reliability in use, and delivers improved cooling results. [Means for solving the problem]

[0009] These problems are solved as a whole by a fuel cell system having the features of claim 1. [Effects of the Invention]

[0010] According to the features of claim 1, the discharge device can eliminate technically complex selectively permeable wall portions, such as cross-linked chitosan membranes, by spraying water using a spray nozzle in the opposite direction to the media flow generated by the ventilator. This helps to lower manufacturing costs and improve the functional reliability of the fuel cell system in operation. In particular, the solution according to the present invention is less susceptible to the influence of contaminants from the surroundings. Since the electrical efficiency of a fuel cell is estimated to be about 50%, it is clear that most of the supplied energy must be released as heat. In particular, in low-temperature fuel cells, a large cooling device is required because the temperature difference between the ambient air and the fuel cell temperature to be maintained is only small. A fuel cell system including a cooling device according to the present invention can reliably control such small temperature differences in low-temperature fuel cells with minimal device technical effort. The configuration of spraying water using a spray nozzle in the opposite direction to the media flow generated by the ventilator enables an adiabatic cooling process in a particularly advantageous manner. In this manner, the water droplets released from the spray nozzle are directly atomized into a gaseous state. This adiabatic change in state from "liquid" to "gas" allows a large amount of heat to be released from the system, significantly improving cooling performance. There is no equivalent in conventional technology.

[0011] The process water generated during the operation of each fuel cell is used to adiabatically cool the airflow through a heat exchanger, which is used to cool the fuel cell, via a spray discharge device that takes reversal of direction into consideration. This results in a situation where the air impacting the heat exchanger has a lower temperature than the ambient air. As a result of this temperature reduction, higher cooling performance can be achieved using the same heat exchanger as in conventional technology. This expands the temperature range in which the fuel cell can operate, or conversely, reduces the size of the heat exchanger or the cooling circuit of the fuel cell system connected to the heat exchanger, which leads to cost reduction.

[0012] In particular, the solutions according to the present invention are important in thermal cooling of buildings. Furthermore, in the design of covers or housings for vehicles or stationary machinery, it is advantageous to design them in such a way as to minimize the potential impact of unwanted ambient airflow on the sprayed water.

[0013] The present invention further relates to a cooling device as a subsystem for the aforementioned fuel cell system, and to the use of such a cooling device for a fuel cell system.

[0014] In a preferred embodiment of the present invention, the spray nozzle of the discharge device is positioned between the ventilator and the heat exchanger, and the spray nozzle is positioned to spray into the ventilator wake (Ventilatornachlauf) on the outlet side of the ventilator. In this case, the spray nozzle sprays water into the space between the ventilator and the heat exchanger in the opposite direction to the airflow generated by the ventilator. Typically, a ventilator consisting of at least one axial fan draws in ambient air while forming a suction flow (Sog) on ​​the inlet side, and discharges the drawn-in air from the outlet side toward the heat exchanger in an accelerated state as a so-called wake (Nachlauf). In particular, the heat exchanger is passed through by the airflow in this case. Furthermore, the heat exchanger may be positioned between the spray discharge device and the ventilator. Preferably, the ventilator draws in ambient air through the heat exchanger, and the spray discharge device sprays water mist in the opposite direction to the airflow. This results in improved mist formation.

[0015] In yet another embodiment of the fuel cell system according to the present invention, the spray nozzle of the discharge device is positioned upstream of the ventilator, with respect to the flow direction of the medium flow generated by the ventilator, and a heat exchanger follows the ventilator such that the spray nozzle sprays into the ventilator suction flow on the inlet side of the ventilator. This provides a longer distance for the water droplets released by the spray nozzle. This helps to facilitate the adiabatic phase transition from "liquid" to "gaseous" for generating a misted cooling medium.

[0016] In an advantageous embodiment of the fuel cell system according to the present invention, a collection container is connected to the conduit of a discharge device between a water separator and a feedwater pump. If each fuel cell produces an excessive amount of water, the water can be stored in the collection container. If there is an excessive amount of water, the collection container can supply it to the spray nozzle of the discharge device. In this case, the collection container preferably has a distributor for hydrogen. Due to the operation of the fuel cell, due to leakage, hydrogen may unintentionally enter the cooling fluid passage, where it may dissolve in the cooling fluid in the form of water or mix into the cooling fluid as hydrogen bubbles. Such accumulation of hydrogen in the cooling water can be gasified in proportion to the amount in the collection container and advantageously supplied for some use. If there is no use, the hydrogen gas accumulated around the collection container may be incinerated. Particularly preferably, the discharge device is part of a closed, adiabatic cooling circuit connected to the inlet and outlet sides of the collection container, which helps to avoid cooling losses.

[0017] In this regard, the ventilator is a turbomachine driven externally by a motor, for example, in the form of an electric motor. This turbomachine transports air as a gaseous medium from the inlet side of the ventilator (fan suction flow) to its outlet side (fan wake), which is advantageously located on the opposite side of the heat exchanger, preferably in the form of a plate heat exchanger. This allows the ventilator to force the air drawn in from the surroundings through the gaps secured between the thin layers of the heat exchanger. In particular, an axial flow ventilator is used, in which the fan blades of the ventilator generate a laminar axial flow with a correspondingly high cooling input into the heat exchanger, at least on the outlet side of the ventilator.

[0018] The water, which is released from each spray nozzle of the discharge device and exists in a misted form, can be intensively collected especially in stationary applications and returned, for example, into a water circulation circuit as part of the building water supply. In mobile applications, the water can be captured and collected in a similar manner, but the discharged water can also be easily released into the surroundings in a pure form, for example, like the condensate water generated in a vehicle air conditioner.

[0019] In a further preferred embodiment of the fuel cell system according to the invention, the water separation device has a distribution device for the cathode exhaust gas. In particular, the cathode exhausts having ambient air can thus be separated from the liquid water on the fuel cell system side, thereby reducing the entrainment of air bubbles in the spray water supplied to the discharge device.

[0020] The cooling device, as a subsystem for such a fuel cell system, at least - a water separation device, - a cooling pump, - a heat exchanger, - a cooling circuit connected to the heat exchanger, - a ventilator for generating a gaseous media flow, in particular an air flow, through the heat exchanger, and is provided with The feed pump of the conveying device conveys the fluid from the water separation device to the discharge device, and the discharge device sprays the fluid into the surroundings by means of spray nozzles, and the discharge device sprays the water in a direction opposite to the direction of the media flow generated by the ventilator by means of the spray nozzles.

[0021] The fuel cell system according to the invention and the associated cooling device will be described in detail below based on the embodiments shown in the drawings. Here, it is illustrated in the form of a fluid recirculation system.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1 is a diagram showing a first embodiment of the cooling solution means according to the invention. [Figure 2]Figure 2 shows a modified embodiment of the solution shown in Figure 1. [Figure 3] Figure 3 is an exploded view showing the main components of the cooling device used in Figures 1 and 2. [Modes for carrying out the invention]

[0023] The fuel cell system shown in its entirety in Figure 1 has a fuel cell stack 10 comprising a plurality of interconnected individual fuel cells 12. The fuel cell stack 10 has a proton exchange membrane (not shown). Furthermore, the system has a cooling circuit 16 comprising a cooling pump 18 and a heat exchanger 20 in the form of a cross-flow heat exchanger with individual cooling thin layers 23, for example, as shown in Figure 3. The individual components of such a cooling circuit 16 are common for fuel cell systems and will not be described in further detail here. The cooling fluid used for the cooling circuit 16 is typically a mixture of ethylene glycol and water at various concentrations in composition and is supplied or discharged through distribution pipes 25 and 27 adjacent to the individual flow channels. The flow channels are in a general form and are fluid guided to the distribution pipes 25 and 27 to guide the fluid to be temperature controlled, in particular the fluid to be cooled. The individual flow channels are held apart from each other in a plate-like manner via thin layers 23. These thin layers, as part of the plate structure, form an air-side rib pattern and in this respect serve as surface extensions for the heat exchanger that guide the airflow of the ventilator 22. In all cases, the glycol acts to prevent the water from freezing even at extremely low temperatures. To improve the cooling performance of the heat exchanger 20, ventilators 22 in the form of three axial fans 29 having identical structures are advantageously positioned upstream of the heat exchanger 20.

[0024] Overall, the fuel cell stack 10, as shown in the schematic block diagram, has an anode side and a cathode side, as in a typical configuration. The anode side receives hydrogen inflow gas via supply line 28. Furthermore, the cathode side receives airflow via supply line 30. Cathode discharge of water occurs at the outlet side of the fuel cell stack 10 via discharge line 32. The discharge line is connected to a water separator 34 of a common structural form. This water separator 34 separates water from the cathode discharge and discharges the liquid water to discharge line 36. The water separator may consist of a common water separator used to mechanically separate water droplets from the gas flow. Preferably, the physical separation of water from the gas flow is caused by condensation. The cathode exhaust gas is discharged from the water separator 34 via line 38. If the fluid pressure in discharge line 36 is sufficient, the fluid reaches into a collection container 42. On the discharge side of the collection container 42, a transport device 46, for example in the form of a pressure pump 48, is connected within the associated discharge line 44. The pressure pump has a discharge pressure of 5 to 15 bar for a fluid such as water. In this regard, the discharge line 44 forms a fluid guide connection between the pressure pump 48 and the discharge device, collectively indicated by reference numeral 50. In the illustrated embodiment, the discharge device has three individual spray nozzles 52 arranged vertically to one another. Multiple such spray nozzles 52 can also be arranged in rows or grouped together, and the arrangement is preferably selected so that the spray jet from the discharge device 50 substantially reaches the free end face of the heat exchanger 20. A relevant embodiment is detailed in Figure 3. Individual spray cones 54 produced by the nozzles 52 are indicated by dotted lines in the figure. The direction of fluid flow in the relevant lines is indicated by arrows.

[0025] During operation of the fuel cell stack 10, heat is generated. This heat is released to the heat exchanger 20 through a closed cooling circuit 16. For this purpose, a cooling pump 18 removes the heated cooling fluid from the fuel cell stack 10, and after cooling through the heat exchanger 20, the cooled cooling fluid is released back into the fuel cell stack 10 for new cooling fluid circulation.

[0026] In addition, process water, which is inevitably generated during fuel cell operation, is sent from the discharge line 44 to the discharge device 50 via the water separator 34 and collection container 42, using a pump 48. Subsequently, under the action of the pump 48, spray discharge is carried out towards the ventilator 22 via the spray nozzle 52. At this time, the water-spray discharge, usually in the form of water mist, is mixed with the ambient air drawn in by the ventilator 22. As a result, the air is cooled on the discharge side of the ventilator 22, that is, before it flows through the cooling thin layer of the heat exchanger 20. The air thus adiabatically cooled by the water mist enhances the cooling performance of the heat exchanger 20, and overall, this improves the cooling performance of the cooling circuit 16. In addition to adiabatic cooling based on spray water discharge in the form of mist into the air, there is also a convective cooling process using the ventilator 22. The cooling device according to the present invention, which can be retrofitted to existing fuel cell systems as shown in the illustration, is particularly suitable for use in low-temperature fuel cells. This is because the temperature difference between the ambient air and the fuel cell temperature to be maintained is small, and effective cooling can be easily achieved technically with the cooling device according to the present invention, thus eliminating the need for a large-capacity cooling device. A reasonably good cooling performance can be achieved if a closed insulated circuit 56 is implemented by an inlet line 58 extending from the collection container 42 to the discharge device 50 via a conveying device 46 or pressure pump 48, and a return line 60 returning from there to the collection container 42. In this respect, the circuit 56 is closed except for discharge through individual nozzles 52. A shut-off cock 62 can be used to shut off such a circuit 56. The shut-off cock is connected into the return line 60 downstream of the spray nozzle 52 when viewed in the direction of fluid flow. Instead of the illustrated circuit 56, there may be only one inlet line 58 to the spray nozzle 52, and any excess fluid not sprayed by the spray nozzle 52 may be discharged into the surroundings or into a collection pan located below the discharge device 50, which is not shown in detail.

[0027] The ventilator 22 has a suction direction 64 for ambient air. The suction direction is axially conveyed by the fan blades of the ventilator 22 toward the spray nozzles 52 of the discharge device 50. Three such individual spray nozzles 52 then spray water toward the axial fan direction of the ventilator 22, i.e., in the opposite direction to the suction direction 64, forming individual spray cones 54. The thus cooled airflow then reaches from the side of the ventilator 22 into the gaps between the thin layers 23 of the heat exchanger 20. Advantageously, the ventilator 22, together with its axial fan 29, heat exchanger 20, and spray nozzle-discharge device 50, are assembled as a single component unit 66 within a common housing 68. However, in one embodiment not shown in detail, the ventilator 22 could instead be located on the other side, opposite to the heat exchanger 20, such that the heat exchanger 20 is positioned between the ventilator 22 and the spray discharge device 50. In this case, the ventilator 22 draws in ambient air through the heat exchanger 20, resulting in a flow characteristic that also has a suction direction 64. In this respect, the spray discharge containing water mist also persists in the direction opposite to the suction direction 64.

[0028] A further modified embodiment shown in Figure 2 relates to the lower right portion of the diagram shown in Figure 1 and includes a heat exchanger 20, a ventilator 22, and a discharge device 50. Otherwise, the solution shown in Figure 1 relating to the fuel cell stack 10 is retained, as are the illustrated connection lines for the heat exchanger 20 and the discharge device 50.

[0029] This differs from the solution shown in Figure 1 in that here, individual spray nozzles in the form of two spray nozzles 52 protrude in the direction of the suction direction 64 of the ventilator 22, and the discharge of the spray cone 54 is again in the opposite direction to the suction direction 64. However, the water droplets are deflected by approximately 180°, are caught in the suction flow of the ventilator 22, pass through the ventilator 22 parallel to the suction direction, are thus atomized, and then collide with the individual thin layers 23 of the heat exchanger 20. In this way, the path for the water droplets after discharge is longer compared to the solution shown in Figure 1. This helps to facilitate the adiabatic conversion process from "liquid" to "gaseous". In this respect, the configuration shown in Figure 2 can achieve even better cooling performance than the solution shown in Figure 1, if necessary. Furthermore, Figure 2 shows an open recirculation system without a return line 60. In this respect as well, the ventilator 22 can be positioned on the opposite side of the spray nozzles 52 of the heat exchanger 20.

[0030] The cooling system for the fuel cell stack 10 used in Figures 1 and 2 is described below in detail based on feasibility. Figure 3 shows a plate heat exchanger as a so-called cross-flow heat exchanger (Kreuzstrom-Waermetauscher) in exploded view as a heat exchanger 20. Between two distribution pipes 25 and 27 (one serving as the inlet for a cooling fluid such as a water-glycol mixture, and the other as the outlet), flow paths are provided that run parallel to each other, guiding the fluid to be cooled, such as the hydraulic medium from the hydraulic system. A thin layer 23 is provided between the flow paths, and the thin layer 23 maintains equally spaced free space for guiding air in the usual manner. Since this structure of the heat exchanger 20 is common, it will not be described in further detail here.

[0031] On the opposite side of Figure 3, that is, the side facing the observer, are shown three axial fans 29 of the ventilator 22, which can be housed within a housing 68. Facing the housing 68, each axial fan 29 has a grid of through-holes that allow it to draw air from the surroundings. Although not shown in detail, such wire structures, otherwise forming a common means within axial fan structures, prevent damage to the fan blades of each axial fan 29 (not shown in detail) and protect the operator from injury during operation. Furthermore, each axial fan 29 has an electric motor 70 in a common form at its center to drive its fan blades. The electric motor obtains its supply current via electrical connection lines 72 in a similarly common form. The free end of each of these electrical connection lines has a kind of terminal strip (Luesterklemme) to connect the ventilator 22 to an electrical supply network (not shown in detail). Individual axial fans 29 are fixed within the housing 68, and during operation, air flows through the axial fans 29 through a circular fan opening 73 within the housing 68, from left to right in the suction direction 64 as viewed in the line of sight in Figure 3. The air supplied axially is then blown through the gaps between the individual thin layers 23 of the heat exchanger 20. After passing through the heat exchanger 20, the cooling air is discharged again to the right side of the perimeter 20. In this way, the fluid to be cooled, guided into the thin layers 23, is cooled through the airflow. High-temperature cooling fluid is supplied via a first distribution pipe 25 and then, after being adequately cooled, is discharged from the heat exchanger 20 via a second distribution pipe 27 for further use.

[0032] As further shown in Figure 3, a discharge device 50 for discharging water is located between the heat exchanger 20 and the ventilator 22. The discharge device 50 has parallel pipe lines 74 within this area as part of a pipe connection section (Rohrgestaenge) 75. As shown in Figure 1, at each end of these pipe lines 74, one is connected to the inlet line 58 and the other to the return line 60. In Figure 3, these lines 58, 60 are shown only in cross-section. Furthermore, for positioning, the linearly extending pipe lines 74 are screw-fastened to corresponding notches 76 provided in the housing 68.

[0033] Each pipe line 74 has a total of four tubular openings 78. These openings are grouped together at different intervals. A so-called hollow cone nozzle (Hohlkegelduese), not shown in detail, is inserted into each cylindrical opening 78. The hollow cone nozzle acts as a precision nozzle, enabling the atomization of droplets. The atomized droplets are drawn into the airflow of the ventilator 22 in the opposite direction to the airflow direction of the ventilator. This results in further cooling of the cooling airflow and, consequently, improves the cooling results of the heat exchanger 20. There is no equivalent in the prior art.

Claims

1. A fuel cell system, and at least, - Fuel cell (12) and, - A cooling circuit (16) equipped with a cooling pump (18) and a heat exchanger (20), - Water separator (34), - A ventilator (22) that generates a gaseous medium flow, specifically an airflow, through the heat exchanger (20), In a cooling device equipped with a conveying device (46), the water separated in the water separator (34) reaches a discharge device (50), and the discharge device sprays the water into the surroundings using a spray nozzle (52), The fuel cell system is characterized in that the discharge device (50) sprays the water by the spray nozzle (52) in the opposite direction to the direction of the medium flow generated by the ventilator (22).

2. The fuel cell system according to claim 1, characterized in that the spray nozzle (52) of the discharge device (50) is positioned between the ventilator (22) and the heat exchanger (20) such that the spray nozzle (52) sprays into the downstream flow of the ventilator at the outlet side of the ventilator (22).

3. The fuel cell system according to claim 1 or 2, characterized in that the spray nozzle (52) of the discharge device (50) is positioned upstream of the ventilator (22) when viewed in the flow direction of the medium flow generated by the ventilator (22), and the heat exchanger (20) follows the ventilator such that the spray nozzle (52) sprays into the ventilator suction flow on the inlet side of the ventilator (22).

4. The fuel cell system according to any one of claims 1 to 3, characterized in that the collection container (42) is connected to the conduit (44) of the discharge device (50) between the water separation device (34) and the transport device (46).

5. The fuel cell system according to any one of claims 1 to 4, characterized in that the discharge device (50) is part of a closed adiabatic cooling circuit, and the adiabatic cooling circuit is connected to the collection container (42) at the inlet and outlet sides.

6. The fuel cell system according to any one of claims 1 to 5, characterized in that the collection container (42) has a distribution device for hydrogen.

7. A fuel cell system according to any one of claims 1 to 6, characterized in that a plurality of fuel cells (12) each have an inlet (28) for hydrogen and, preferably, an inlet (30) for oxygen derived from ambient air, and are assembled into a single stack (10).

8. A cooling device for a fuel cell system according to any one of claims 1 to 7, comprising at least - The water separator (34) and, - The cooling pump (18) and, - The heat exchanger (20) and, - The cooling circuit (16) connected to the heat exchanger, - The ventilator (22) generates the gaseous medium flow, specifically the airflow, through the heat exchanger (20), Equipped with, The water supply pump (48) of the conveying device (46) conveys fluid from the water separator (34) to the discharge device (50), and the discharge device (50) sprays the fluid into the surroundings using the spray nozzle (52), The cooling device is characterized in that the discharge device (50) sprays the water using the spray nozzle (52) in a direction opposite to the direction of the medium flow generated by the ventilator (22).

9. The cooling device according to claim 8, characterized in that the heat exchanger (20) is formed from a cross-flow heat exchanger, the ventilator (22) comprises a plurality of axial fans (29), and the discharge device (50) has at least one fluid guide tube rod (73), and individual hollow conical nozzles as spray nozzles (52) are inserted into the fluid guide tube rod to adiabatically generate a mist of cooling gas from liquid water.

10. A use of the cooling device according to claim 8 or claim 9 for a fuel cell system according to any one of claims 1 to 7, wherein the water obtained during the operation of each fuel cell (12) is sent to the discharge device (50) by the transport device (46), and the discharge device (50) sprays the water by the spray nozzle (52) into the air transported by the ventilator (22) of the heat exchanger (20) in the opposite direction to the airflow direction in order to produce adiabatic cooling for the purpose of cooling the cooling fluid inside the cooling circuit (16) of each fuel cell (12).

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