Cooling device for a fuel cell system

Abstract

The invention relates to a cooling device for a fuel cell system, comprising a first heat transfer unit and a second heat transfer unit, wherein a first metering device is configured to apply a cooling medium to the first heat transfer unit, wherein at least a second metering device is configured to apply the cooling medium to the second heat transfer unit, and wherein a control unit is configured to regulate or control the application of the cooling medium to the first heat transfer unit and / or the second heat transfer unit.

Description

[0001] The present invention relates to a cooling device for a fuel cell system, a fuel cell system for a fuel cell vehicle and a method for cooling a fuel cell system according to the independent claims.

[0002] From OE 102017209 35 A1 a metering device for applying a cooling medium to a cooler is known, wherein the metering device comprises a supply system with at least one supply line for transporting the cooling medium and a grid structure surrounding the cooler, and wherein the at least one supply line is integrated into the grid structure, and wherein the grid structure has at least one metering area for distributing the cooling medium to the cooler.

[0003] The cooling device according to the invention with the features of claim 1 has the advantage that the cooling medium is applied to heat transfer units in the fuel cell system as needed, thus ensuring optimal cooling over a wide operating range. The cooling device according to the invention is designed to apply the cooling medium not only to the main cooler, but also to the heat transfer units upstream of the main cooler as needed. This enables effective evaporative cooling both in the partial load range and in the full load range. Successive evaporation across two or more levels offers the advantage that effective evaporative cooling can be achieved even at lower outside temperatures and possibly high air humidity. Air humidity is understood to mean relative air humidity.Evaporation across multiple levels is particularly advantageous for reducing fan power requirements and saving fuel, as evaporative cooling can be operated with low energy consumption.

[0004] Therefore, a cooling device for a fuel cell system is proposed here, comprising a first heat transfer unit and a second heat transfer unit, wherein a first metering device is designed to apply a cooling medium to the first heat transfer unit, wherein at least one second metering device is designed to apply the cooling medium to the second heat transfer unit, and wherein the cooling device is designed to regulate or control the application of the cooling medium to the first heat transfer unit and / or the second heat transfer unit.

[0005] A heat transfer unit is understood to be a component of the cooling system of a fuel cell vehicle that is designed to cool the coolant of the coolant circuit and / or a fuel cell. A heat transfer unit within the meaning of the invention is understood to be a condenser, a low-temperature cooler, and / or a main cooler. The main cooler is designed to cool the fuel cell.

[0006] A dosing device is understood to be a device designed to apply the cooling medium to the first and / or at least the second heat transfer unit. The cooling medium can be applied by spraying, atomizing, sprinkling, and / or dripping. The cooling medium is preferably applied as a laminar jet. The dosing device can be a sprinkling grid, a wetting device, or a spray device.

[0007] A cooling medium is understood to be a liquid that is applied to the first and / or at least the second heat transfer unit in order to cool the heat transfer unit by evaporative cooling. According to the invention, the cooling medium is understood to be water, which is generated in the fuel cell. The water produced in the fuel cell is stored in a water tank or a reservoir and is available as a cooling medium. The cooling medium can be transported to the first and / or at least the second metering device via one or more pipes or hoses by means of one or more pumps.

[0008] A cooling device which is designed to regulate or control the application of the cooling medium to the first and / or heat transfer unit is understood to be a cooling device which is designed to increase or decrease the mass flow of cooling medium as required. The cooling device can comprise at least one control component or at least one control element. A control component or control element is understood to be a component which can control or regulate the transport of the cooling medium. The control component can be a valve and / or a pump. The valve is expediently designed to detect an electrical signal and, depending on the detection, to partially or completely open or close it. The pump is expediently designed to detect an electrical signal and, depending on the detection, to increase or reduce the delivery rate or to switch itself on or off.

[0009] The cooling device may further comprise a control unit. A control unit is understood to be a device designed to regulate or control the application of the cooling medium to the heat transfer unit. The control unit is designed to output an electrical signal to at least one control component or at least one control element of the cooling device.

[0010] According to one embodiment, the cooling device is designed to regulate or control the application of the cooling medium depending on at least one parameter. A parameter is understood to be a physical measured variable, in particular a fuel cell temperature, a condenser inlet pressure, a fan power requirement, an ambient temperature, or an air humidity. At least one measuring device in the fuel cell vehicle is expediently designed to detect the at least one parameter, convert it into an electrical signal, and output the electrical signal. The at least one measuring device can be a sensor. The cooling device can comprise a control unit designed to detect the electrical signal and, depending on the detection, to control or regulate the application of the cooling medium. This has the advantage that the application of the cooling medium can be adapted to requirements.During partial load operation, the temperature of the low-temperature cooler may be too low at ambient temperatures of 20°C to 30°C to ensure effective evaporation of the cooling medium. Therefore, during partial load operation, it may be advantageous to apply the cooling medium only to the main cooler, as the main cooler has a sufficiently high temperature to ensure evaporation of the cooling medium. Furthermore, a smaller amount of cooling medium is available during partial load operation. The control unit ensures that the available amount of cooling medium is used efficiently. This has the advantage of achieving optimal cooling. Fan power consumption is reduced and fuel consumption is saved.

[0011] According to one embodiment, the cooling device has a first and at least a second dosing device, wherein the first and at least a second dosing device each have at least one supply line which has at least one perforated nozzle. A supply line is understood to be a hollow body through which a cooling medium flows. The supply line is designed to enable transport of a cooling medium. A supply line designed to enable transport of a cooling medium is understood to be a hollow body designed to receive and discharge the cooling medium. The supply line can be a pipe or a hose.

[0012] A perforated nozzle or nozzle is understood to be a component designed to distribute the cooling medium to one or more heat transfer units. A perforated nozzle has a hole or a recess. The hole or recess is designed to allow the cooling medium to escape from the supply lines or from the perforated nozzle. The hole or recess is designed to allow the cooling medium to be distributed to one or more heat transfer units. Distributing the cooling medium is understood to mean spraying, atomizing, sprinkling, dripping, and preferably applying a laminar jet. The at least one perforated nozzle is arranged at the output or outlet of the at least one supply line. A supply line can comprise one or more perforated nozzles. Several perforated nozzles can be spaced horizontally and / or vertically from one another.This has the advantage that double exposure of local areas to cooling medium from two superimposed perforated nozzles can be reliably avoided, thus ensuring optimized cooling with reduced cooling medium consumption. The hole or recess preferably has a circular cross-sectional area. A circular cross-sectional area has the advantage of optimizing the flow dynamics of the cooling medium and ensuring optimal distribution of the cooling medium across the heat transfer units.

[0013] According to one embodiment, the cooling device comprises at least one metering device with at least one perforated nozzle having a diameter of 0.20 to 0.35 mm. The diameter of the at least one perforated nozzle is understood to be an inner diameter of the hole or recess. The diameter of 0.20 to 0.35 mm results in a laminar jet of coolant emerging from the perforated nozzle. This has the advantage of optimal distribution of the coolant over the heat transfer unit and particularly efficient cooling.

[0014] According to one embodiment, the cooling device has at least two dosing devices, wherein the first and the at least second dosing device are identically designed. Identical design means that the first and the at least second dosing device have the same number of supply lines and the same number of perforated nozzles. Identical design can further be understood to mean that the perforated nozzles of the first and the at least second dosing device have the same diameter and / or the same vertical and / or horizontal spacing from one another. This has the advantage of simple and cost-effective manufacture of the cooling device. The first and the second dosing device each have 2 to 8 supply lines, preferably 3 to 5 supply lines, and particularly preferably 4 supply lines.A dosing device with 2 to 8 supply lines offers the advantage that the application of the cooling medium can be adapted particularly flexibly to requirements, achieving efficient cooling both at partial and full load. A dosing device with 3 to 5 dosing devices offers the advantage that double application of cooling medium to local areas from two perforated nozzles arranged one above the other can be reliably avoided, thus reducing cooling medium consumption. A dosing device with 4 supply lines offers the advantage of optimal distribution of the refrigerant over the heat transfer unit and particularly efficient cooling.

[0015] According to one embodiment, the first and second dosing devices have perforated nozzles with a diameter of 0.3 mm to 0.35 mm in one area and perforated nozzles with a diameter of 0.25 mm ± 0.05 mm in a further area. The first and second dosing devices have an overlap area. An overlap area is understood to be the area in which air flowing horizontally through the air path passes both the first and the second dosing devices. The first and second dosing devices have perforated nozzles with a diameter of 0.25 mm ± 0.05 mm in the overlap area and perforated nozzles with a diameter of 0.3 mm to 0.35 mm in an area outside the overlap area. The number of perforated nozzles can be smaller in the overlap area than outside the overlap area.A smaller diameter of the hole nozzles and / or a smaller number of hole nozzles in the overlap area has the advantage that an overdosage of cooling medium in the overlap area is avoided and the cooling efficiency is increased.

[0016] According to one embodiment, the first metering device is designed to apply the cooling medium to the low-temperature cooler. The first heat transfer unit is the low-temperature cooler. The second metering device is designed to apply the cooling medium to the main cooler. The main cooler is the second heat transfer unit. The first and second metering devices can be identical. This has the advantage that effective cooling of the cooling circuit and the fuel cell can be achieved even with small metering devices, space can be saved, and the manufacture of the cooling device is simplified.

[0017] According to one embodiment, the cooling device according to the invention comprises a first metering device with 2 to 4 supply lines and a second metering device with 6 to 8 supply lines. A higher number of supply lines enables the application of a higher total quantity or a higher volume flow of cooling medium to the heat transfer unit(s). The second metering device, which has 6 to 8 supply lines, enables rapid and strong cooling of the second heat transfer unit. The second heat transfer unit is cooled more intensely and faster than the first heat transfer unit. This has the advantage of preventing overheating of the second heat transfer unit and undercooling of the first heat transfer unit, and optimizing cooling.

[0018] According to one embodiment, the first dosing device is designed to apply the cooling medium to the condenser. The first heat transfer unit is the condenser. The second dosing device is designed to apply the cooling medium to the main cooler. The second heat transfer unit is the main cooler. A dosing device that cools the condenser is particularly advantageous in the partial load range, since in the partial load range the fan power or the fan power requirement is determined by the cooling air requirement of the condenser. The cooling medium is applied to the condenser with a mass flow of 2 g / s to 5 g / s (grams of cooling medium per second), preferably 3 g / s to 4 g / s. With this amount of cooling medium per second, a significant reduction in the fan power requirement can be achieved. In the full load range, a higher amount of cooling medium is available than in the partial load range.The total amount of cooling medium in the full-load range is 20 g / s to 30 g / s. In the full-load range, the amount of cooling medium required for the condenser is only a small proportion of the total amount of cooling medium available at full load. The remaining amount of cooling medium is available for cooling the main cooler. The at least second dosing device applies the cooling medium to the main cooler. The at least second dosing device preferably has 6 to 8 supply lines. This has the advantage that the main cooler can be optimally cooled and power curtailment of the fuel cell in the full-load range is avoided. The cooling device can comprise further dosing devices designed to apply the cooling medium to the main cooler. In the full-load range, the further dosing devices can be switched on.This has the advantage that the cooling medium is distributed more evenly over the main cooler, thus avoiding local overdosing and optimizing evaporative cooling.

[0019] According to one embodiment, the cooling device has a first dosing device and a second dosing device, wherein the first and the second dosing device each have at least two supply lines, and wherein the supply lines of the second dosing device are offset in the vertical direction relative to the supply lines of the first dosing device by half a supply line spacing. In addition to the offset in the vertical direction, the supply lines can be offset in the horizontal direction. The supply lines of the first dosing device are spaced apart from one another in the vertical direction. Furthermore, the supply lines of the second dosing device are spaced apart from one another in the vertical direction. A supply line spacing is understood to be the distance between a center point of a supply line and the center point of an adjacent supply line.The center point is understood to be the center point of the cross-sectional area of ​​the supply line in the vertical direction, for example the center point of a circular pipe cross-section. The supply line spacing of the first and second dosing devices is preferably identical. Half a supply line spacing is understood to be 50% ± 15% of the supply line spacing of two adjacent supply lines. Offsetting the supply lines of the second dosing device by half a supply line spacing enables the local evaporation zones behind the individual perforated nozzles to be separated and enables particularly efficient cooling. It prevents the air path behind the first dosing device, which is saturated with humid air, from hindering evaporation at the subsequent dosing device. This vertical offset of the dosing devices by half a distribution line spacing is therefore thermodynamically advantageous.

[0020] According to one embodiment, the cooling device has at least one third metering device. The cooling device can have further metering devices. The cooling device can have at least one third heat transfer unit. The third metering device and / or the further metering devices are designed to apply the cooling medium to the second heat transfer unit and / or the third heat transfer unit. This has the advantage that the cooling medium can be adapted particularly flexibly to the cooling requirements.

[0021] According to one embodiment, the cooling device has a first, a second, and a third metering device. The first metering device is designed to apply the cooling medium to the condenser. The condenser is the first heat transfer unit. The second metering device is designed to apply the cooling medium to the low-temperature cooler. The low-temperature cooler is the second heat transfer unit. The third metering device is designed to apply the cooling medium to the main cooler. The main cooler is the third heat transfer unit. The control unit is designed to regulate or control the application of the cooling medium to the condenser, the low-temperature cooler, and the main cooler. The application of the cooling medium to the condenser is regulated or controlled depending on the fan power requirement.The cooling medium is applied to the condenser as soon as the fan power requirement exceeds a predefined threshold. The cooling medium is preferably applied at a mass flow of 2 g / s to 5 g / s, more preferably 3 g / s to 4 g / s. This has the advantage that in the partial load range the fan power requirement is reduced even with small quantities of cooling medium. At higher partial loads, an increased quantity of cooling medium is available. The application of the cooling medium to the main cooler is controlled or regulated depending on the level of the cooling medium in the storage tank. The cooling medium is applied to the main cooler as soon as the level exceeds a predefined threshold. This has the advantage that at high ambient temperatures above 30°C effective cooling of the fuel cell is ensured and power curtailment is prevented. The maximum quantity of cooling medium is available during full load operation.The application of the cooling medium to the low-temperature cooler is controlled or regulated depending on the level of the cooling medium in the storage tank. The cooling medium is applied to the low-temperature cooler as soon as the level of the cooling medium in the storage tank exceeds a predefined threshold. This has the advantage that the cooling can be adapted particularly flexibly to demand, i.e., to different load ranges.

[0022] The invention also relates to a fuel cell system for a fuel cell vehicle having a fuel cell and a cooling device according to the invention. The first and at least one second heat transfer unit are suitable for installation in an air path. In other words, the first and at least one second heat exchanger unit are designed to be arranged in an air path. The fuel cell system can comprise one or more fans designed to set air in flow. The fan is expediently switched on as soon as a predefined coolant temperature is exceeded. An air path is understood to be a region in which the air is set in flow by means of at least one fan. The air path has an upstream end and a downstream end. The air flows from the upstream end to the downstream end.The first dosing device is arranged upstream of the second dosing device. In other words, the first and second dosing devices are designed to be arranged in an air path such that air flows through and / or around the first dosing device first and then the second dosing device. Furthermore, the first dosing unit is arranged upstream of the first heat transfer unit, and the at least second dosing unit is arranged upstream of the at least second heat transfer unit. This arrangement has the advantage of achieving effective and demand-based cooling and reducing the fan's power consumption.

[0023] According to one embodiment, the first dosing device is designed to apply the cooling medium to an upper third of the first heat transfer unit, and the second dosing device is designed to apply the cooling medium to an upper third of the second heat transfer unit. The upper third of a heat transfer unit is understood to mean the upper third of the height of the respective heat transfer unit. The upper third is understood to mean the upper 20% to 40%, preferably the upper 30% to 35%, of the heat transfer unit. The first and second heat transfer units are arranged vertically in an air path. Applying the coolant to the upper third of the respective heat transfer unit has the advantage that the coolant is applied to an area of ​​particularly high temperature, thereby ensuring particularly effective evaporative cooling.

[0024] According to one embodiment, the first dosing device and the second dosing device are arranged downstream of a condenser. An arrangement downstream of a condenser means that the first dosing device and the second dosing device are arranged in an air path downstream of the condenser. An arrangement downstream of the condenser further means that the first and second dosing devices are arranged at the level of the condenser. In other words, the first and second dosing devices are arranged in a horizontal plane with the condenser. The arrangement of the first and second dosing devices downstream of the condenser has the advantage that evaporative cooling takes place in an air path that has an elevated air temperature, whereby effective evaporative cooling takes place.

[0025] The invention also relates to a method for cooling a fuel cell system according to the invention. The method comprises the following steps: a) Recording at least one parameter, b) converting the at least one parameter into an electrical signal, c) forwarding the at least one electrical signal to the control unit, d) detecting the level of the cooling medium in a storage tank, e) converting the water level into an electrical signal, f) Forwarding the electrical signal to the control unit, g) regulating or controlling the transport of the cooling medium to the first dosing device and / or the at least second dosing device, and h) Applying the cooling medium to the first and / or at least the second dosing device.

[0026] Detecting at least one parameter means measuring or determining a physical variable that characterizes the cooling system in a fuel cell vehicle and / or the ambient conditions. Detecting a parameter can be the fuel cell temperature, the condenser inlet pressure, the fan power requirement, the ambient temperature, and / or the air humidity. One or more parameters can be detected. The detection can be carried out using at least one sensor. The detected at least one parameter is converted into at least one electrical signal and forwarded to at least one control unit. Detecting a level of the cooling medium in a storage container means measuring or determining the weight and / or volume of the cooling medium in a coolant reservoir or cooling medium tank.The weight and / or volume of the cooling medium can be detected using a sensor. The detection is converted into an electrical signal and forwarded to a control unit. Steps d) to f) can be carried out before / after or simultaneously with steps a) to c). The control unit controls or regulates the application of the cooling medium to the heat transfer units depending on the detection, i.e. depending on the fuel cell temperature, the condenser inlet pressure, the fan power requirement, the ambient temperature and / or the air humidity. The application of the cooling medium can be regulated or controlled by partially or completely opening or blocking one or more valves. Alternatively or additionally, the application of the cooling medium can be regulated or controlled by increasing or reducing the flow rate of one or more pumps and / or switching one or more pumps on and off.This has the advantage that the application of the cooling medium can be flexibly adjusted to meet demand. Optimal cooling of the cooling system can be achieved and overheating of the fuel cell can be reliably prevented.

[0027] Further advantages and features of the invention will become apparent from the following description of preferred embodiments of the subject matter according to the invention with reference to the accompanying figures.

[0028] They show, schematically, Fig. 1 a side view of a cooling device according to the invention with two identically designed dosing devices and a temperature profile, Fig. 2 a side view of a cooling device according to the invention with two dosing devices and a temperature profile, Fig. 3 a side view of a cooling device according to the invention with three dosing devices and a temperature profile, Fig. 4 a circuit diagram of a fuel cell system according to the invention, and Fig. 5 a diagram of a method according to the invention for cooling a fuel cell system according to the invention.

[0029] Fig. 1 shows a side view of a cooling device KV according to the invention with the air paths L1 and L2. The direction of the arrow indicates the flow direction of the air L in the air paths L1 and L2 with a fan LÜ. The cooling device KV has a condenser W3, a low-temperature cooler W1 and a main cooler W2. The condenser W3 is arranged upstream of the low-temperature cooler W1. The low-temperature cooler W1 is arranged upstream of the main cooler W2. The low-temperature cooler and the main cooler are arranged behind the condenser, i.e. they are arranged downstream of the condenser in a horizontal plane with the condenser. Upstream of the low-temperature cooler W1 is arranged a first dosing device D1. The first dosing device D1 comprises four tubes R. Each tube R has at least one perforated nozzle LD. The tubes R of the first dosing device D1 are arranged at a distance from one another.The pipe spacing A is defined as the distance from a pipe center point to the pipe center point of the adjacent pipe. A second dosing device D2 is arranged upstream of the main cooler W2. The second dosing device D2 has four pipes R, each with at least one perforated nozzle LD. The pipes R of the second dosing device D2 are spaced apart by a pipe spacing A. The first dosing device D1 and the second dosing device D2 are identical. The pipes R of the second dosing device D2 are offset relative to the pipes R of the first dosing device by half a pipe spacing A in the vertical direction downwards, i.e. towards the vehicle floor. The second dosing device D2 is offset relative to the first dosing device D1 by half a pipe spacing A in the vertical direction.

[0030] The temperature profile shows the air temperature TL of the air L in the air path L1 at various points in the cooling device KV. Upstream of the condenser W3, the air L in the air path L1 has an initial temperature. The initial temperature of the air L is lower than the temperature of the condenser W3. The air L absorbs heat from the condenser W3 and cools the condenser W3 in the process. The air temperature TL rises at the condenser W3. Downstream of the condenser W3, the air L hits the low-temperature cooler W1. The air L cools the low-temperature cooler W1, causing the air L to heat up further. The air L has a higher temperature TL at the low-temperature cooler W1 than at the condenser W3. Downstream of the low-temperature cooler W2, the air L hits the main cooler W3 and cools the main cooler W3, causing the air temperature TL to rise further.The first dosing device D1 applies cooling water K to the low-temperature cooler W1 to cool it by evaporative cooling. The second dosing device D2 applies cooling water K to the main cooler W2 to cool it by evaporative cooling. Part of the heat from the low-temperature cooler W1 and the main cooler W2 is absorbed by the cooling water K, which evaporates. For this reason, the air temperature with evaporative cooling TMV (dashed line in the temperature profile) at the low-temperature cooler W1 and the main cooler W2 increases less than the air temperature without evaporative cooling TOV (solid line in the temperature profile) and is overall lower downstream of the first dosing device D1 than without evaporative cooling. The fan power requirement LS is reduced when evaporative cooling is activated. The control unit SG (not shown) switches the first dosing device D1 and / or second dosing device D2 on and / or off as required.Cooling is optimized and fan power consumption LS is reduced.

[0031] Fig. Figure 2 shows a side view of a cooling device KV according to the invention with a first metering device D1 and a second metering device D2. The cooling device KV is arranged in an air path L1. The direction of the arrow indicates the flow direction of the air L in the air path L1. The cooling device KV has a condenser W1, a low-temperature cooler W3, and a main cooler W2.

[0032] The condenser W1 is arranged upstream of the low-temperature cooler W3. The low-temperature cooler W3 is arranged upstream of the main cooler W2. A first metering device D1 is arranged upstream of the condenser W1. The first metering device D1 has two tubes R, each with at least one perforated nozzle LD. A second metering device D2 is arranged upstream of the main cooler W2. The second metering device D2 has six tubes R, each with at least one perforated nozzle LD. No metering device is arranged upstream of the low-temperature cooler W3.

[0033] The temperature profile shows the air temperature TL at various points on the cooling device KV. The first dosing device D1 applies cooling water K to the condenser W1 to cool it by evaporative cooling. The second dosing device D2 applies cooling water K to the main cooler W2 to cool it by evaporative cooling. Part of the heat from the condenser W1 and the main cooler W2 is absorbed by the cooling water K, causing the cooling water K to evaporate. For this reason, the air temperature with evaporative cooling TMV (dashed line in the temperature profile) at the condenser W1 and the main cooler W2 increases less than the air temperature without evaporative cooling TOV (solid line in the temperature profile).

[0034] Fig. 3 shows a side view of a cooling device KV according to the invention with a first dosing device D1, a second dosing device D2 and a third dosing device D3. The cooling device KV is arranged in an air path L1. The cooling device KV has a condenser W1, a low-temperature cooler W2 and a main cooler W3. The first dosing device D1 is arranged upstream of the condenser W1. The first dosing device D1 has two tubes R, each with at least one perforated nozzle LD. The second dosing device D2 is arranged upstream of the low-temperature cooler W2 and has four tubes, each with at least one perforated nozzle. The third dosing device D3 is arranged upstream of the main cooler W3 and has four tubes, each with at least one perforated nozzle.The first dosing device D1, the second dosing device D2, and the third dosing device D3 are arranged such that the cooling water K is applied to an area of ​​maximum surface temperature of the respective heat transfer unit. The first dosing device D1, which cools the condenser W1, is arranged in the inlet area of ​​the air path L1. The second dosing device D2 is arranged in the upper area of ​​the low-temperature cooler W2 behind the condenser W1 in order to compensate for the heat load of the condenser W1 and ensure a homogeneous temperature distribution in the air path L2. This arrangement also reduces the entry of contaminants into the evaporation area of ​​the downstream heat transfer units. The third dosing device D3 is offset vertically downwards relative to the first dosing device D1 and relative to the second dosing device D2.The third dosing device D3 is offset relative to the second dosing device D2 by at least half a pipe spacing A.

[0035] The maximum height offset between the height HO of the topmost pipe R of the second dosing device D2 and the height HU of the bottommost pipe R of the third dosing device D3 corresponds to the height of 6 rows of pipes with a pipe spacing A of 45-80 mm each. The maximum height offset between the height HO of the topmost pipe R of the second dosing device D2 and the height HU of the bottommost pipe R of the third dosing device D3 is 400 to 450 mm. This maximum height offset ensures particularly uniform humidification of the air in the exposed air path L1 and effective cooling.

[0036] The temperature profile shows the air temperature TL of the air L at various points of the cooling device KV. The first dosing device D1 supplies cooling water K to the condenser W1, the second dosing device D2 to the low-temperature cooler W2, and the third dosing device D3 to the main cooler W3. For this reason, the air temperature TL in the air path L1 with evaporative cooling TMV (dashed line in the temperature profile) at the condenser W1, the low-temperature cooler W2, and the main cooler W3 rises less than the air temperature would rise without evaporative cooling TOV (solid line in the temperature profile), and is overall lower downstream of the first dosing device D1 than it would be without evaporative cooling.

[0037] Fig. 4 shows a circuit diagram of a fuel cell system BS according to the invention with a cooling device KV according to the invention and a fuel cell B. The cooling device KV is arranged in the air paths L1 and L2. The cooling device KV has a condenser W1, a low-temperature cooler W3 and a main cooler W2. Upstream of the condenser W1, a first metering device D1 is arranged, which has two tubes R, each with at least one perforated nozzle LD. Upstream of the main cooler W2, a second metering device D2 is arranged, which has six tubes, each with at least one perforated nozzle LD. The tubes R of the first metering device D1 are offset downwards in the vertical direction by half a tube spacing A relative to the tubes R of the second metering device D2. Water K is generated in the fuel cell B. A water tank VB is designed to collect and store water K from the fuel cell B.A water level sensor PSS is designed to detect the water level PS of the water K in the water tank VB, convert it into an electrical signal, and transmit it to a control unit SG. The control unit SG is designed to detect further parameters P. The control unit SG is designed to...

[0038] Fuel cell temperature BT, condenser inlet pressure KD, fan power requirement LS, ambient temperature UT and relative air humidity LF. The control unit SG is designed to regulate the application of cooling water K to the first metering device D1 and the second metering device D2 as a function of the parameters P and the water level PS. The control unit SG is designed to output an electrical signal to the valve V and to the water pump WP as a function of the parameters P and the water level PS. The valve V is designed to detect the electrical signal and to open or close it partially or completely depending on the detection. The pump WP is designed to detect the electrical signal and to increase or reduce the delivery rate or to switch itself on or off as a function of the detection.

[0039] Fig.Figure 5 shows a schematic diagram of a method according to the invention for cooling a fuel cell system BS according to the invention. The method comprises the following steps: a) Measuring at least one fuel cell temperature BT, one condenser inlet pressure KD, one ambient temperature UT, one air humidity LF and one fan power requirement LS by means of sensors, b) Converting the measured values ​​into electrical signals, c) Forwarding the electrical signals to a control unit SG, d) Measuring a level PS of the cooling water K in a water tank VB by means of a level sensor PSS, e) converting the measured value into an electrical signal, f) Forwarding the electrical signal to the control unit SG, g) regulating or controlling the transport of the cooling water K to the first dosing device D1 and to the second dosing device D2, and h) Spraying the condenser W1 and the main cooler W2 with cooling water K.

[0040] In step a), the fuel cell temperature BT, the condenser inlet pressure KD, the ambient temperature UT, the air humidity LF, and the fan power requirement LS are recorded using sensors in the fuel cell vehicle. In step b), the measured values ​​or numerical values ​​for the fuel cell temperature BT, the condenser inlet pressure KD, the ambient temperature UT, the air humidity LF, and the fan power requirement LS are each converted into an electrical signal by the respective sensors. In step c), the electrical signals from the sensors are forwarded to a control unit SG. In step d), the level PS of the cooling water K in the water tank VB is measured using a level sensor PSS. In step e), the measured value or numerical value for the level PS of the cooling water K is converted into an electrical signal by the level sensor PSS. In step f), the electrical signal from the level sensor PSS is forwarded to the control unit SG.In step g), the control unit SG regulates the transport of the cooling water K to the first dosing device D1 and to the second dosing device D2 depending on the fuel cell temperature BT, the condenser inlet pressure KD, the ambient temperature UT, the air humidity LF, the fan power requirement LS, and the level PS of the cooling water K in the water tank VB. The control unit SG outputs an electrical signal to the valve V and to the water pump WP. The valve V detects the electrical signal and opens or closes depending on the detection. The water pump WP detects the electrical signal and switches on or off depending on the detection. If the fuel cell temperature BT, the condenser inlet pressure KD, the ambient temperature UT, the air humidity LF, the fan power requirement LS, and the level PS are above predefined threshold values, the valve V is opened and the water pump WP is switched on.The cooling water K can be transported to the first dosing device D1 and / or the second dosing device D2. In step h), the condenser W1 and the main cooler W2 are sprayed with cooling water K. Depending on requirements, evaporative cooling can be applied to the main cooler W2 and the condenser W1, or only to the main cooler W2. Due to evaporative cooling, sufficient cooling is achieved even at lower fan power than without evaporative cooling. The fan power is reduced accordingly to lower the fan power requirement LS.

[0041] Steps d) to f) can be performed before, after, or simultaneously with steps a) to c). After step h), the process can be repeated. After step h), steps a) to h) can be repeated one or more times. Preferably, steps a) to h) are repeated continuously throughout the entire operation of the fuel cell vehicle. List of reference symbols: A pipe spacing AL exhaust air duct B Fuel cell BF humidifier BM fuel cell monitor BS fuel cell system BT fuel cell temperature D1 first dosing device D2 second dosing device D3 third dosing device DS pressure sensor EK electric compressor with turbine F Air filter HO Height of the top pipe of the dosing device HU Height of the lowest pipe of the dosing device iCAC* indirect charge air cooling system K Cooling water KD condenser inlet pressure KV cooling device L Air LD hole nozzle LF Humidity LFS humidity sensor L1 air path with evaporative cooling L2 Air path without evaporative cooling LS fan power requirement LÜ fan P parameters PS water level PSS water level sensor R pipe RS Resonator SG control unit TS temperature sensor TL Temperature of the air in the air path TOV Temperature of the air in the air path without evaporative cooling TMV Temperature of the air in the air path with evaporative cooling U environment UT ambient temperature V valve VB storage container VKS evaporative cooling system VL supply line W1 first heat transfer unit W2 second heat transfer unit W3 third heat transfer unit WP water pump WSK water separator / water collector WZ hydrogen supply

Claims

[1] Cooling device (KV) for a fuel cell system (BS), comprising a first heat transfer unit (W1) and a second heat transfer unit (W2), wherein a first metering device (D1) is designed to apply a cooling medium (K) to the first heat transfer unit (W1), wherein at least one second metering device (D2) is designed to apply the cooling medium (K) to the second heat transfer unit (W2), and wherein the cooling device (KV) is designed to regulate or control the application of the cooling medium (K) to the first heat transfer unit (W1) and / or the second heat transfer unit (W2). [2] Cooling device (KV) for a fuel cell system (BS) according to claim 1, characterized byin that the cooling device (KV) is designed to regulate or control the application of the cooling medium (K) to the first heat transfer unit (W1) and / or the second heat transfer unit (W2) as a function of at least one parameter (P), wherein the at least one parameter (P) is a fuel cell temperature (BT), a condenser inlet pressure (KD), a fan current requirement (LS), an ambient temperature (UT) and / or an air humidity (LF). [3] Cooling device (KV) for a fuel cell system (BS) according to one of the preceding claims, characterized bythat the first dosing device (D1) and the at least second dosing device (D2) each comprise at least one supply line (VL) for transporting the cooling medium (K), wherein the at least one supply line (VL) has at least one perforated nozzle (LD), and wherein the at least one perforated nozzle (LD) is designed to distribute the cooling medium (K) to the first heat transfer unit (W1) and / or the second heat transfer unit (W2). [4] Cooling device (KV) for a fuel cell system (BS) according to claim 3, characterized by that the at least one hole nozzle (LD) has a diameter of 0.20 to 0.35 mm. [5] Cooling device (KV) for a fuel cell system (BS) according to claim 3 or 4, characterized bythat the first dosing device (D1) and the at least second dosing device (D2) are identically designed and each have 2 to 8 supply lines (VL), preferably 3 to 5 supply lines (VL), and particularly preferably 4 supply lines (VL). [6] Cooling device (KV) for a fuel cell system (BS) according to claim 3 or 4, characterized by that the first dosing device (D1) has 2 to 4 supply lines (VL) and the second dosing device (D2) has 6 to 8 supply lines (VL). [7] Cooling device (KV) for a fuel cell system (BS) according to one of claims 3 to 6, characterized by that the supply lines (VL) of the second dosing device (D2) are arranged offset in the vertical direction relative to the supply lines (VL) of the first dosing device (D1) by one third to one half of the supply line distance (A). [8] Cooling device (KV) for a fuel cell system (BS) according to one of the preceding claims, characterized by that at least one third dosing device (D3) is designed to apply the cooling medium (K) to the second heat transfer unit (W2) and / or at least one third heat transfer unit (W3). [9] Fuel cell system (BS) for a fuel cell vehicle comprising a cooling device (KV) according to one of the preceding claims and a fuel cell (B), characterized by that the first heat transfer unit (W1) and the second heat transfer unit (W2) are suitable for installation in an air path (L1), wherein the first dosing device (D1) is arranged upstream of the first heat transfer unit (W1) and the second dosing device (D2) is arranged upstream of the second heat transfer unit (W2). [10] Fuel cell system (BS) for a fuel cell vehicle according to claim 9, characterized bythat the first dosing device (D1) is designed to apply the cooling medium (K) to an upper third of the first heat transfer unit (W1) and the second dosing device (D2) is designed to apply the cooling medium (K) to an upper third of the second heat transfer unit (W2). [11] Fuel cell system (BS) for a fuel cell vehicle according to claim 9 or 10, characterized by that the first dosing device (D1) and the second dosing device (D2) are arranged behind a capacitor (W3). [12] A method for cooling a fuel cell system according to any one of claims 9 to 11, comprising the steps: a) recording at least one parameter (P), b) converting the at least one parameter (P) into at least one electrical signal, c) forwarding the at least one electrical signal to a control unit (SG), d) detecting a level (PS) of the cooling medium (K) in a storage tank (VB), e) converting the water level (PS) into an electrical signal, f) Forwarding the electrical signal to the control unit (SG), g) regulating or controlling the transport of the cooling medium (K) to the first metering device (D1) and / or the at least second metering device (D2), and h) applying the cooling medium (K) to the first heat transfer unit (W1) and / or the at least second heat transfer unit (W2).

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