DE102015015641A1 - A fuel cell system for a vehicle, fuel cell system, and method of operating a fuel cell system - Google Patents

Abstract

The invention relates to a fuel cell system (10) for a vehicle, comprising a fuel cell stack (12), a reservoir (32) for receiving product water of the fuel cell stack (12), and a battery (90) for providing electrical drive power to the vehicle. Here, the collecting container (32) in heat transferring manner with a cooling circuit (72) of the battery (90) is coupled, in which for cooling the battery (90), a coolant is conveyed. Furthermore, the invention relates to a vehicle with such a fuel cell system (10) and a method for operating such a fuel cell system (10).

Description

The invention relates to a fuel cell system for a vehicle comprising a fuel cell stack and a reservoir for receiving product water of the fuel cell stack. Furthermore, a battery is provided, which serves to provide electrical drive energy for the vehicle. The invention further relates to a vehicle having such a fuel cell system and a method for operating such a fuel cell system.

The WO 201462746 A1 describes a fuel cell system with a solid oxide fuel cell stack (SOFC fuel cell stack). Product water of the fuel cell stack is supplied to a storage unit. By means of the product water stored in the storage unit, the temperature of a battery is controlled. For this purpose, the product water of the battery is supplied as a tempering medium. Heat of the product water may be transferred to the battery, or the battery may be cooled by the product water.

In such a fuel cell system, the possibilities for cooling the battery are comparatively limited.

Battery-powered vehicles or electric vehicles, plug-in vehicles, or range extender vehicles will increasingly have the capability of fast charging or DC charging. When fast charging an AC / DC converter is not located in the vehicle, but a component of a charging station or charging station. By means of such a charging station can be a particularly high electrical power for charging the battery of the vehicle provide, so that the battery can be charged very quickly. Due to the high transferring power, however, this results in a relatively high waste heat output or an increase in the temperature of the battery during charging due to efficiency losses. In order to prevent high-temperature aging of the battery, it is therefore necessary to cool the battery during charging.

It is known from the prior art to transfer the relatively high waste heat output into a cooling circuit of the battery, in which a coolant is circulated or conveyed by means of a coolant pump. About a cooler arranged in the cooler then the waste heat of the battery can be discharged into the environment. It is known from the prior art to operate in the removal of the resulting waste heat power through the radiator a radiator fan to ensure good heat transfer to the environment. Because when charging the battery is the vehicle, so that the wind can not contribute to increase the heat transfer. The operation of the fan, however, leads to a not insignificant noise. This is generally undesirable, especially when multiple vehicles are being loaded in parallel or simultaneously.

On the other hand, if a corresponding increase in the temperature of the battery of the vehicle is permitted, in particular during rapid charging, this has a negative effect on the durability of the battery.

Object of the present invention is therefore to provide a fuel cell system of the type mentioned, a vehicle with a fuel cell system and a method for operating a fuel cell system, which allows improved cooling of the battery.

This object is achieved by a fuel cell system having the features of patent claim 1, a vehicle having the features of patent claim 9 and a method having the features of patent claim 10. Advantageous embodiments with expedient developments of the invention are specified in the dependent claims.

In the fuel cell system according to the invention, the collecting container for the product water is coupled in a heat-transferring manner with a cooling circuit of the battery. In the cooling circuit, a coolant can be conveyed to cool the battery. So on the one hand direct contact of the product water of the fuel cell stack is avoided with the battery. On the other hand, the cooling circuit, which contains the coolant, offers the possibility of dissipating heat from the battery, for example via a further cooler or heat exchanger arranged in the cooling circuit. Thus, an improved cooling of the battery is possible.

In particular, the waste heat of the battery is supplied to the sump or water sump, and the water or product water contained therein is heated. In this case, in particular a part of the product water can be made to evaporate. In this way, at least a portion of the resulting waste heat can be dissipated improved.

Furthermore, the operation of a fan for applying a cooler arranged in the cooling circuit of the battery with cooling air can be delayed for a particularly long time and preferably even avoided. This results in a reduced noise emission by such a fan or radiator fan, especially during charging, preferably during fast charging of the battery of the vehicle.

The fact that a portion of the waste heat of the battery can be absorbed by the product water incurred reduces the waste heat output, which is to be dissipated from the cooling circuit by other means, in particular via the cooler. Accordingly, a power can be reduced, with which the fan is operated. Preferably, the operation of the fan can be dispensed with. Since the fan or radiator fan can be operated with reduced power or does not need to be operated at all, when the vehicle performs the charging process, in particular fast charging, the disturbing noise development is reduced. Furthermore, electrical energy is saved if the fan is not operated or with lower power. Since the maximum fan power typically ranges from 500 watts to 1 kilowatts, significant energy savings can be made.

Namely, a rapid charging or DC charging typically takes between 20 minutes and 45 minutes, depending on the capacity of the battery of the vehicle, the state of charge and the like. Accordingly, during this charging process, a non-negligible portion of electrical energy can be saved if fan operation can be reduced or completely avoided.

During operation of the fuel cell system, the product water preferably forms a free water surface in the collecting container. Thus, particularly good evaporation of the product water can be effected by supplying the waste heat of the battery to the product water. The evaporation of the product water is accompanied by a particularly good dissipation of the waste heat of the battery.

As further advantageous, it has been shown that the collecting container has a height which is less than a width and / or a length of the collecting container. The collecting container is thus preferably designed so that the largest possible evaporation surface is provided. For then the product water can evaporate well when supplying the waste heat of the battery, which is introduced via the cooling circuit into the collecting container. So much heat can be dissipated to the environment.

Preferably, the collecting container is further configured such that the product water, which is obtained during operation of the fuel cell system, cools particularly quickly from the operating temperature of the fuel cell stack and assumes the ambient temperature. This too can be realized by a correspondingly flat design of the collecting container, which leads to the formation of a particularly large free water surface during operation of the fuel cell system.

As further advantageous, it has been shown, when an inlet of the collecting container is coupled to an outlet of a water separator, which is arranged in an exhaust duct of the fuel cell stack. Via the water separator, the product water from the exhaust air of the fuel cell stack can be supplied to the collecting container particularly well.

Preferably, a charging plug for fast charging of the battery is provided. In particular, when fast charging or DC charging, in which very quickly a large electric power is introduced into the battery of the vehicle, namely, it comes to a particularly high waste heat capacity of the battery, which can be delivered to the product water in the reservoir.

Finally, it has proven to be advantageous if the fuel cell stack is designed as a polymer electrolyte membrane fuel cell stack. Namely, in such a fuel cell stack, the product water falls on a low temperature level as compared with an SOFC fuel cell. Accordingly, the product water can be cooled very quickly, for example, to ambient temperature, so that it is then particularly suitable for absorbing the waste heat of the battery.

The vehicle according to the invention comprises a fuel cell system according to the invention. The fuel cell system can be used in particular in a configuration of a drive train of a corresponding vehicle, in which the battery can be loaded either via the fuel cell system or by connecting to a charging station. In such a plug-in vehicle, it is possible, in particular, to supply an electric drive, which comprises at least one electric motor, first of all with electrical energy which originates from the rechargeable battery.

Furthermore, the fuel cell system can be used in a fuel cell vehicle in which the fuel cell stack of the fuel cell system is used as a range extender. In this case, therefore, the fuel cell system serves to increase the achievable with the battery or traction battery range in the electric driving mode of the vehicle.

In the method according to the invention for operating a fuel cell system for a vehicle is in a collecting container Added product water of a fuel cell stack of the fuel cell system. Waste heat from a battery designed to provide electrical power to the vehicle is dissipated to the product water. Here, the coolant is conveyed through a cooling circuit of the battery, wherein the product water is applied in the collecting container with the heat of the coolant. This dissipation of the heat of the battery to the product water can be made especially during charging of the battery, preferably during a fast charging of the battery.

The advantages and preferred embodiments described for the fuel cell system according to the invention also apply to the vehicle according to the invention and to the method according to the invention and vice versa.

The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention. Thus, embodiments are also included and disclosed by the invention, which are not explicitly shown or explained in the figures, however, emerge and can be produced by separated combinations of features from the embodiments explained. Thus, embodiments and combinations of features are also to be regarded as disclosed which do not have all the features of an originally formulated independent claim.

Further advantages, features and details of the invention will become apparent from the claims, the following description of preferred embodiments and from the drawing.

This shows schematically a fuel cell system with a cooling circuit for cooling a fuel cell stack of the fuel cell system and a cooling circuit for a battery of the vehicle, via the cooling circuit waste heat of the battery can be transferred to product water of the fuel cell stack, which is collected in a sump.

From a fuel cell system 10 a vehicle is in 1 schematically a fuel cell stack 12 shown. The fuel cell stack 12 comprising a plurality of individual fuel cells is disposed within a stack housing (not shown). The stack housing has media connections in the form of a fuel supply line 16 , a fuel discharge 18 , an air supply line 20 and an exhaust duct 22 on. The exhaust duct 22 is part of an exhaust system of the fuel cell system 10 , Furthermore, a coolant supply line is connected to the stack housing 24 and an outlet conduit 26 connected for the coolant.

The powertrain or the vehicle, which is the fuel cell system 10 is preferably configured such that the fuel cell system 10 is used in a plug-in mode or a range extender mode. The fuel cell stack is preferred 12 only put into operation when it has reached a predetermined temperature. A freeze start of the fuel cell stack 12 or the fuel cell system 10 can thus be avoided. Rather, at a freeze start first, the fuel cell system 10 by means of an electric heating element 46 preheated before the fuel cell system 10 is started.

The electric heating element 46 or the electric heater is in a coolant circuit 48 arranged, in which a coolant pump 50 the coolant towards the fuel cell stack 12 promotes. The electric heating element 46 is in the coolant circuit 48 a heat exchanger 52 downstream, by means of which also an interior or passenger compartment of the vehicle can be heated.

In the present case, preference is first given by means of the electric heating element 46 the fuel cell stack 12 preheated and only then the fuel cell system 10 started. In the coolant circuit 48 is upstream of another heat exchanger in the form of a cooler 56 a valve 54 arranged. The valve 54 is preferably formed as a thermostatic valve which opens at a predetermined temperature and thus the supply of coolant to the radiator 56 allows. About the radiator 56 namely, during operation of the fuel cell system 10 Waste heat of the fuel cell stack 12 discharged into the environment. In this cooler 56 it is preferably the so-called main radiator, which is arranged in the region of a vehicle front of the vehicle.

According to 1 becomes a cathode 58 of the fuel cell stack 12 the supply air via the supply air line 20 by means of a compressor 60 which is supplied by a motor 62 is driven. Subsequently, the supply air flows through a charge air cooler 64 , In the supply air line 20 is further upstream of the fuel cell stack 12 a shut-off valve 66 arranged.

The hydrogen gets out of a tank 74 via a metering valve 76 a jet pump 78 fed. The hydrogen from the tank 74 forms a propulsion jet, which has the corresponding Suction hydrogen from an output of an anode 80 of the fuel cell stack 12 sucked in here. In the fuel drainage 18 coming from the outlet of the anode 80 coming into the exhaust air line 22 opens, is a purge valve 82 arranged.

From an exit of the cathode 58 leads the exhaust air line 22 to the intercooler 64 , Here, by means of the heat released by the compressed charge air in the exhaust air existing liquid water is evaporated, so that comparatively little liquid water can escape into the environment. Then the exhaust air flows through another shut-off valve 68 , which is in the exhaust pipe 22 is arranged. Thereafter, the exhaust air flows through a water separator 70 , By means of which liquid water or product water is separated from the exhaust gas. From the water separator 70 the product water enters a collection container 32 , There is an inlet for this 34 of the collection container 32 with an outlet 36 of the water separator 70 coupled via a line. About a coolant, which through a cooling circuit 72 a battery 90 If the vehicle is flowing, it can waste the battery 90 be introduced into the product water, which is in the sump 32 located.

In the cooling circuit 72 can the coolant by means of another coolant pump 84 to the battery 90 and to a high voltage component 88 such as an on-board loader (OBL, charger) are performed. Downstream of the battery 90 and the high voltage component 88 is in the cooling circuit 72 another valve 86 arranged. From the valve 86 From the coolant flows in the cooling circuit 72 optionally to a chiller 94 which another valve 96 upstream, or to a heat exchanger 28 over which heat of the coolant from the cooling circuit 72 on the product water in the sump 32 can be transferred.

About the chiller 94 Heat may be transferred to a (not shown) refrigerant circuit of the vehicle. Depending on the position of the valve 96 This can be done through the cooling circuit 72 flowing coolant also another cooler 98 be supplied.

The other cooler 98 which prefers as well as the radiator 56 is arranged in the region of a vehicle front of the vehicle is by means of a fan 30 subjected to cooling air. So while charging the battery 90 accumulating waste heat to be dissipated via the coolant.

In the present case, however, in particular, the operation of the fuel cell stack 12 accumulating product water used to dissipate waste heat, which when charging the battery 90 accrues. This is done by the battery 90 coming coolant the heat exchanger 28 fed. The coolant, which when fast-charging the battery 90 dissipates waste heat transfers this heat through the heat exchanger 28 on the product water, which in the operation of the fuel cell stack 12 incurred and which present in the sump 32 saved or collected. The resulting product water is thus in the sump 32 collected. When charging, especially fast charging or DC charging the battery 90 or high-voltage battery is due to the high charging power and a significant waste heat performance of the battery 90 , To the durability of the battery 90 not to reduce, the resulting high waste heat output must be dissipated.

In the present case is when charging the battery 90 the coolant pump 84 operated and the coolant in the cooling circuit 72 the battery 90 circulated. That by the battery 90 flowing coolant is heated in this case and then through the heat exchanger 28 passed, which preferably in the sump 32 is arranged. For example, the heated coolant may flow through a plurality of tubes that are in the sump 32 are arranged and thus the heat exchanger 28 provide. By material separation, however, is a contact of the product water in the sump 32 avoided with the coolant, which by means of the coolant pump 84 through the cooling circuit 72 is encouraged.

The heat energy from the cooling circuit 72 the battery 90 So it is transferred to the product water, which is in the sump 32 or water collection tank is located. By raising the temperature of the product water in the sump 32 the evaporation is promoted. As a result, a relatively high heat transfer performance can be realized. As a result, the fan 30 does not need to be operated or can be operated at reduced power.

After cooling the coolant in the reservoir 32 the coolant is either the radiator 98 and / or the chiller 94 supplied to achieve a further reduction in the temperature of the coolant.

The fuel cell system 10 , which can be used in particular in a fuel cell plug-in vehicle or a fuel cell range extender vehicle can, in principle, also be configured differently than shown here by way of example. The decisive factor is the fuel cell system 10 in that the accumulated product water in the collecting container 32 is caught.

For example, it is conceivable that the order of the media guide is changed by the individual heat exchanger. Accordingly, that of the battery 90 Coming coolant also first the chiller 94 and / or the radiator 98 be supplied. Subsequently, the coolant can the heat exchanger 28 be supplied to heat the product water in the sump 32 transferred to. Such a media guide can be provided in particular at the beginning of the charging process. Subsequently, in particular as a function of the temperature of the coolant, which through the cooling circuit 72 flows, the coolant through the reservoir 32 be guided.

Furthermore, a chiller or a heat pump 100 with the collection container 32 and the heat exchanger 28 be thermally coupled. That is in 2 shown. The thermal coupling is carried out so that the condenser of the refrigerator or the heat pump 100 with the collection container 32 and the evaporator of the refrigerator or heat pump 100 with the heat exchanger 28 thermally coupled. This can be in the container 32 The collected product water, the waste heat even then supply, if the product water already has a relatively high temperature. As a result, the product water can be brought to boiling, which can dissipate a particularly large waste heat output.

LIST OF REFERENCE NUMBERS

10

The fuel cell system

12

fuel cell stack

16

fuel supply

18

fuel derivative

20

air supply

22

exhaust duct

24

coolant supply line

26

outlet pipe

28

Heat exchanger

30

Fan

32

Clippings

34

inlet

36

outlet

46

heating element

48

Coolant circuit

50

Coolant pump

52

Heat exchanger

54

Valve

56

cooler

58

cathode

60

compressor

62

engine

64

Intercooler

66

shut-off valve

68

shut-off valve

70

water

72

Cooling circuit

74

tank

76

metering valve

78

jet pump

80

anode

82

flush valve

84

Coolant pump

86

Valve

88

High-voltage component

90

battery

94

Chiller

96

Valve

98

cooler

100

Chiller or heat pump

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 201462746 A1 [0002]

Claims (10)

Fuel cell system for a vehicle, with a fuel cell stack ( 12 ), a collecting container ( 32 ) for receiving product water of the fuel cell stack ( 12 ), and with a battery ( 90 ) for providing electrical drive energy for the vehicle, characterized in that the collecting container ( 32 ) in heat transferring manner with a cooling circuit ( 72 ) of the battery ( 90 ), in which for cooling the battery ( 90 ) A coolant is conveyed. Fuel cell system according to claim 1, characterized in that the product water during operation of the fuel cell system ( 10 ) in the collecting container ( 32 ) forms a free water surface. Fuel cell system according to claim 1 or 2, characterized in that the collecting container ( 32 ) has a height which is less than a width and / or a length of the collecting container ( 32 ). Fuel cell system according to one of claims 1 to 3, characterized in that an inlet ( 34 ) of the collecting container ( 32 ) with an outlet ( 36 ) of a water separator ( 70 ), which in an exhaust duct ( 22 ) of the fuel cell stack ( 12 ) is arranged. Fuel cell system according to one of claims 1 to 4, characterized by a charging plug for fast charging of the battery ( 90 ). Fuel cell system according to one of claims 1 to 5, characterized in that in the cooling circuit ( 72 ) of the battery ( 90 ) a cooler ( 98 ), which by means of a fan ( 30 ) can be acted upon with cooling air. Fuel cell system according to one of claims 1 to 6, characterized in that in the cooling circuit ( 72 ) of the battery ( 90 ) a heat exchanger ( 94 ) is arranged, via which heat of the coolant is transferable to a refrigerant circuit of the vehicle. Fuel cell system according to one of claims 1 to 7, characterized in that the fuel cell stack ( 12 ) is formed as a polymer electrolyte membrane fuel cell stack. Vehicle with a fuel cell system ( 10 ) according to one of claims 1 to 8. Method for operating a fuel cell system ( 10 ) for a vehicle in which in a collecting container ( 32 ) Product water of a fuel cell stack ( 12 ) of the fuel cell system ( 10 ) and in which waste heat of a battery designed to provide electric drive energy for the vehicle ( 90 ) is delivered to the product water, characterized in that a coolant through a cooling circuit ( 72 ) of the battery ( 90 ), in particular during charging of the battery ( 90 ), the product water in the collecting container ( 32 ) is acted upon by the heat of the coolant.

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