Fuel cell device for vehicle and method for operating fuel cell device for vehicle

Abstract

The invention provides a fuel cell arrangement (10) for a vehicle (F), comprising: a fuel cell (BZ) having an anode side (A) and a cathode side (K); a hydrogen gas supply line (H) connected to the anode side (A) of the fuel cell (BZ); a recirculation line (RL) having a blower device (ARB), which is mounted on and connected to the anode side (A) of the fuel cell (BZ) and is designed to recirculate the remaining amount of hydrogen from the anode side to the anode side in a hydrogen return flow; a water separator (WA), which is connected to the recirculation line (RL) and which is designed to conduct water away from the hydrogen return on the anode side (A); a water reservoir (WR) connected to the water separator (WA) and arranged to receive water from the water separator (WA); a dosing device (DE), which is connected to the water reservoir (WR) and to the recirculation line (RL) and is designed to introduce a predetermined amount of water from the water reservoir (WR) into the recirculation line (RL) and to the blower device (ARB).

Description

Technical Field

[0001] The invention relates to a fuel cell system for a vehicle and a method for operating a fuel cell system for a vehicle. Background Art

[0002] In a fuel cell system, hydrogen is supplied from the medium-pressure region of the fuel cell in the anode circuit. Here, a regulating valve is typically used to meter the hydrogen as required and a blower is used.

[0003] A recirculation blower, also called ARB (anode recirculation blower), is used in fuel cell systems to return unconsumed hydrogen from the outlet of the fuel cell (reactor) back to the inlet. The recirculation blower is part of the anode subsystem, in which an upstream water separator is usually integrated. Since upstream water separators are usually not able to completely separate the process water, an ARB with an integrated water separator is used.

[0004] The amount of process water from fuel cells arises in particular during operation at high reactor powers or high reactor currents.

[0005] Thus, a low amount of water is produced at the ARB inlet when the fuel cell system is operating in a low load or partial load range, or a high amount of water is produced in the full load range. In a fuel cell system having a combination of an ARB and a suction jet pump in the recirculation path, the load on the ARB can be greatest at low reactor power / current.

[0006] If a high power of the fuel cell is required, sufficient hydrogen is taken from the tank system to serve as the operating volume of the suction jet pump and the suction jet pump then takes over the recirculation of the unconsumed hydrogen. In this operating range, the ARB applies no or almost no power.

[0007] When the ARB is in operation, waste heat is generated. Active cooling concepts are usually used to cool the ARB, in which, for example, a coolant flows through the housing. However, this type of cooling concept requires considerable additional costs in the form of additional cooling channels, sealing points and connecting stubs.

[0008] If free process water flows through the ARB or the ARB is separated by an integrated water separator, a cooling effect is achieved compared to the water-free gas mixture. Summary of the invention

[0009] The invention relates to a fuel cell system for a vehicle according to claim 1 and to a method for operating a fuel cell system for a vehicle according to claim 9 .

[0010] Preferred embodiments are the subject matter of the dependent claims.

[0011] Advantages of the invention

[0012] The invention is based on the idea of ​​specifying a fuel cell system for a vehicle and a method for operating a fuel cell system for a vehicle, wherein the cooling of a blower in the recirculation by process water from the fuel cell can be improved.

[0013] The fuel cell device for a vehicle according to the present invention comprises: a fuel cell having an anode side and a cathode side; a hydrogen supply pipeline, which is connected to the anode side of the fuel cell; a recirculation pipeline with a blowing device, which is installed on the anode side of the fuel cell and is connected to the anode side and is configured to recirculate the remaining amount of hydrogen from the anode side back to the anode side in the hydrogen reflux; a water separator, which is connected to the recirculation pipeline and is configured to guide water away from the hydrogen reflux on the anode side; a water reservoir, which is connected to the water separator and is configured to receive water from the water separator; a metering device, which is connected to the water reservoir and the recirculation pipeline and is configured to introduce a predetermined amount of water from the water reservoir into the recirculation pipeline and to the blowing device.

[0014] In any operating range of the fuel cell, it is advantageous to introduce a minimum flow of water into the recirculation line for cooling the fan, even if less water than that specified by the minimum flow can be separated in the current operation. Since the water reservoir always remains sufficiently filled, the minimum water flow can be provided even in the case of such a low separation amount.

[0015] By means of the metering device, a predetermined amount of water can flow in in the throughflow direction for a predetermined time or duration.

[0016] A passive cooling concept for the blower can thus be implemented by using free process water in a targeted manner for internal cooling of the blower. The overall temperature level of the blower should therefore be reduced by absorbing and discharging part of the waste heat via process water flowing through or separated in the blower.

[0017] The advantage here is that active cooling concepts or alternative measures can be dispensed with and costs and installation space can be saved. In situations with a high water separation potential, the separated process water from the water separator of the anode submodule is collected in a larger container / water reservoir (larger than is usually required) and thus an input water of, for example, 0.2 g / s (or another predetermined value range or value) can be introduced in a targeted manner into the inlet of the blower, so that the blower can be cooled in a targeted manner.

[0018] According to a preferred embodiment of the fuel cell device, the hydrogen supply line and the recirculation line are connected.

[0019] According to a preferred embodiment of the fuel cell device, the water separator is integrated into the blower device.

[0020] The water separator can be situated upstream of the blower device, or the water separator or a further water separator can be integrated into the blower device.

[0021] The blower device can also have an internal (additional) water separator.

[0022] According to a preferred embodiment of the fuel cell device, the water reservoir contains a predetermined minimum volume of water.

[0023] The water reservoir can be a larger water reservoir compared to the known hydrogen return channel, which can be filled with a predetermined amount of water, in particular water from a water separator (from an upstream water separator of the blower device and / or from an internal water separator).

[0024] According to a preferred embodiment of the fuel cell device, the metering device is arranged at the inlet of the blower device in order to add a predetermined amount of water per unit time to the hydrogen return flow in the recirculation line.

[0025] According to a preferred embodiment of the fuel cell device, the metering device comprises a Venturi nozzle or a metering pump or a trickle nozzle.

[0026] According to a preferred embodiment of the fuel cell device, the predetermined amount of water is at least less than or equal to 0.2 g / s and is constantly available during operation of the fuel cell.

[0027] In this case, the expression "constant" is acceptable and possible within a predetermined tolerance range of value fluctuations.

[0028] According to a preferred embodiment of the fuel cell device, the metering device is connected via a first supply line to the water reservoir and via a second supply line to the water separator.

[0029] According to the present invention, in a method for operating a fuel cell device for a vehicle, a fuel cell device according to the present invention is provided S1; a load range for operation of the fuel cell is determined S2 and a predetermined amount of water in a recirculation line is inferred S3 for a predetermined cooling effect on a blower device according to the determined load range; the predetermined amount of water is introduced S4 into the recirculation line by a metering device and a predetermined cooling effect on the blower device is produced S5.

[0030] According to a preferred embodiment of the method, the water reservoir is filled under high power conditions of the fuel cell and a predetermined amount of water is removed from the water reservoir under low power conditions of the fuel cell, wherein the high power conditions and the low power conditions can be determined based on predetermined boundary values.

[0031] The fuel cell arrangement can also be distinguished by the features and advantages mentioned in connection with the method, and vice versa.

[0032] Other features and advantages of the embodiments of the present invention are apparent from the following description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The invention is explained in greater detail below with reference to an exemplary embodiment shown in the schematic drawings of the accompanying drawings.

[0034] The accompanying drawings show:

[0035] Figure 1 : A schematic graph depicting the relationship between fuel cell power and blower power demand;

[0036] Figure 2 : A schematic description of a dosing device according to an embodiment of the present invention;

[0037] Figure 3 : A block diagram of method steps of a method for operating a dosing device of a hydrogen circuit of a fuel cell device according to an embodiment of the present invention;

[0038] In the figures, the same reference signs denote identical or functionally identical elements. DETAILED DESCRIPTION

[0039] Figure 1 A schematic diagram is shown which depicts the relationship between the fuel cell power (b) and the blower power requirement (a). Due to the suction jet pump in the fuel cell system, the maximum power requirement of the blower is in the partial load range.

[0040] Figure 1 A comparison of the operation of a fuel cell with a jet pump (suction jet pump) (a) and without a jet pump (b) in the recirculation loop is shown. In this case, the power of the blower is shown relative to the power of the fuel cell.

[0041] Figure 2 A schematic depiction of a dosing device according to an embodiment of the invention is shown.

[0042] The fuel cell device 10 for a vehicle includes: a fuel cell BZ having an anode side A; a hydrogen supply line H, which is connected to the anode side A of the fuel cell BZ; a recirculation line RL having a blower ARB, which is installed on the anode side A of the fuel cell BZ and is connected to the anode side A and is configured to recirculate the remaining amount of hydrogen from the anode side back to the anode side in the hydrogen reflux; a water separator WA, which is connected to the recirculation line RL and is configured to guide water away from the hydrogen reflux of the anode side A; a water reservoir WR, which is connected to the water separator WA and is configured to receive water from the water separator WA; a metering device DE, which is connected to the water reservoir WR and the recirculation line RL and is configured to introduce a predetermined amount of water from the water reservoir WR into the recirculation line RL and to the blower ARB.

[0043] The hydrogen supply line H can be connected to the recirculation line RL. In addition, an internal water separator iWA can be integrated in the blower ARB. Advantageously, the two water separators can discharge water from the process gas to the water reservoir and release the excess to the discharge valve. The water reservoir WR can advantageously contain a predetermined minimum volume of water and can be filled to this minimum volume or to a minimum filling level during operation, whereby the minimum filling level can provide a predetermined minimum water flow. The metering device DE can be arranged at the inlet of the blower ARB so that a predetermined amount of water is loaded into the hydrogen reflux in the recirculation line per unit time. Water can therefore be mixed with the recirculated gas at the inlet of the blower. The blower with an integrated water separator iWA can achieve the requirement for free water (amount) at the fuel cell inlet connection pipe.

[0044] Thus, over a wide operating range of the fuel cell, but especially in the low to medium load range, a substantially constant low water supply to the blower device ARB can be produced in order to cool the blower device thereby.

[0045] In most cases, a sufficiently high water mass flow rate is only available for higher reactor powers (the reactor is designed as a fuel cell stack if it is designed in this manner) (0.2 g / s from about 100 amperes, which corresponds to a reactor power of about 35 kW at a cell voltage of 0.8 V and 419 cells). The blower operating point with the maximum power demand (high thermal load) corresponds to a reactor power of about 40 kW.

[0046] The water reservoir WR can be used for this purpose as a water storage tank, which is filled at higher reactor powers and from which water is taken out in the low reactor load range to cool the blower ARB. The water is fed from the water reservoir to the inlet of the blower ARB for internal cooling, for example, via a Venturi nozzle (jet pump) using recirculated gas as driving flow, and / or via a trickle nozzle in the ARB inlet, if the water reservoir is located above the ARB inlet nozzle, and / or via a small metering pump.

[0047] In the hydrogen inlet H there may be a hydrogen injector HGI and a suction jet pump SSG.

[0048] In other words, the water produced by the fuel cell can be separated via the water separator of the anode submodule and collected in a water reservoir. Ideally, the separation degree of the water separator is very high, so that the gas contains almost no water and can then be charged with the amount of water required for cooling the ARB in a targeted manner.

[0049] Via a metering device (e.g. in the form of a venturi nozzle), a small or at least predetermined amount of water can be supplied to the gas in the ARB inlet for cooling. The water can then receive part of the waste heat in the ARB and be discharged through the outlet or separated by a water separator integrated in the ARB.

[0050] Figure 3 The block diagram shows method steps of a method for operating a fuel cell system according to an exemplary embodiment of the present invention.

[0051] In the method, S1 a fuel cell device according to the invention is provided; S2 a load range for the operation of the fuel cell is determined and S3 a predetermined water quantity in the recirculation line is inferred for a predetermined cooling effect on the blower device according to the determined load range; the predetermined water quantity is introduced S4 into the recirculation line by means of a metering device and S5 a predetermined cooling effect on the blower device is generated.

[0052] Although the invention has been completely described above with reference to preferred exemplary embodiments, it is not restricted thereto but can be modified in many different ways and methods.

Claims

1. A fuel cell device (10) for a vehicle (F), comprising: - a fuel cell (BZ) having an anode side (A) and a cathode side (K); a hydrogen supply line (H) connected to the anode side (A) of the fuel cell (BZ); a recirculation line (RL) with a blower (ARB), which is arranged on the anode side (A) of the fuel cell (BZ) and is connected to the anode side (A) and is designed to recirculate a surplus amount of hydrogen from the anode side back to the anode side in a hydrogen return flow; a water separator (WA) which is connected to the recirculation line (RL) and is designed to conduct water away from the hydrogen return flow on the anode side (A); a water reservoir (WR) connected to the water separator (WA) and arranged to receive water from the water separator (WA); a metering device (DE) which is connected to the water reservoir (WR) and to the recirculation line (RL) and is designed to introduce a predetermined amount of water from the water reservoir (WR) into the recirculation line (RL) and to the blower device (ARB).

2. The fuel cell device (10) according to claim 1, wherein the hydrogen supply line (H) is connected to the recirculation line (RL).

3. The fuel cell system (10) according to claim 1 or 2, in which the water separator (WA) is integrated in the blower device (ARB).

4. The fuel cell device (10) according to any one of claims 1 to 3, in which the water reservoir (WR) contains a predetermined minimum volume of water.

5. A fuel cell device (10) according to any one of claims 1 to 4, in which the metering device (DE) is installed at the inlet of the blower (ARB) so as to load the hydrogen return flow in the recirculation line (RL) with a predetermined amount of water per unit time.

6. The fuel cell device (10) according to claim 1, wherein the metering device (DE) comprises a Venturi nozzle or a metering pump or a trickle nozzle.

7. The fuel cell device (10) according to claim 1, wherein the predetermined amount of water is at least less than or equal to 0.2 g / s and can be provided constantly during operation of the fuel cell (BZ).

8. The fuel cell device (10) according to claim 1, wherein the metering device (DE) is connected to the water reservoir (WR) via a first supply line and to the water separator (WA) via a second supply line.

9. A method for operating a fuel cell device (10) for a vehicle (F), comprising the following steps: - providing (S1) a fuel cell device (10) according to any one of claims 1 to 8; - determining (S2) a load range for the operation of the fuel cell (BZ) and inferring (S3) a predetermined water quantity in the recirculation line (RL) for a predetermined cooling effect on the blower (ARB) according to the determined load range; The predetermined amount of water is introduced ( S4 ) into the recirculation line (RL) by means of the metering device (DE) and produces ( S5 ) a predetermined cooling effect on the blower device (ARB).

10. The method according to claim 9, wherein the water reservoir (WR) is filled in a high power condition of the fuel cell (Z) and a predetermined amount of water is removed from the water reservoir (WR) in a low power condition of the fuel cell (Z), wherein: The high power condition and the low power condition can be determined according to predetermined boundary values.

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