DE102010032886A1 - Electrical power supply system for providing operating power to e.g. passenger car, has heat source connected with separation unit of refrigerating unit, and formed by waste heat from region of supply and/or removal of medium to/from cell - Google Patents

Abstract

The system (1) has an adsorption refrigerating unit i.e. refrigerant circuit (17), for cooling a fuel cell i.e. proton conducting membrane fuel cell (2), and an electrical energy storage device i.e. battery (3). Waste heat from a region of supply and/or removal of a medium to/from the fuel cell is formed as a heat source for the refrigerating unit. The heat source is indirectly connected with a separation unit (19) i.e. cylinder, of the refrigerating unit. The heat source is designed as an intercooler (10) for flowing of compressed air to the fuel cell.

Description

The invention relates to an electrical energy supply system, comprising at least one fuel cell and an electrical energy storage device according to the type defined in more detail in the preamble of claim 1.

Fuel cells, for example fuel cells based on proton-conducting membranes (PEM fuel cells), are frequently used for driving vehicles, in particular for driving passenger cars or commercial vehicles. In order to compensate for the comparatively low dynamics in the power supply of the fuel cell and to realize a highly dynamic driving operation as efficiently as possible, the electrical energy supply systems used in such "fuel cell vehicles" are very often designed as systems with fuel cells and electrical energy storage. Frequently, so-called high-voltage batteries or high-performance batteries, such as may be formed from single cells in lithium-ion technology, are used as electrical energy storage devices together with the fuel cell. In the case of such batteries, it is usual for them to generate a comparatively high waste heat during charging and discharging, that is to say during operation of the battery, and therefore they should be cooled. Ideally, an active cooling of the battery is provided, which ensures that the battery can always be operated below a certain temperature. This serves to increase the life of the battery. As an alternative to the design as a battery, the electrical energy store can also be designed as a high-performance capacitor or supercap. Even such capacitors can be cooled if necessary.

The cooling is therefore typically designed so that cooling air is actively conveyed through the region of the electrical energy storage device or that a liquid cooling medium is used for cooling the electrical energy storage device. In order to ensure sufficient cooling even at high ambient temperatures, a thermal coupling of the electrical energy storage or the cooling medium used for the electrical energy storage is often realized to the air conditioning of such a vehicle equipped. Since the air conditioning systems are typically designed as compression refrigeration systems, it requires for cooling the electrical energy storage so a certain drive power for the refrigerant compressor, which in turn must be provided directly or indirectly from the drive system available and thus reduces the overall efficiency of the drive system and increases the fuel or energy consumption ,

From the DE 103 46 975 A1 is proposed as an alternative for a vehicle air conditioning system, which is designed as a compression refrigeration system, an adsorption refrigeration system or adsorption refrigeration machine. This works in a manner known per se so that via a separation unit which is directly or indirectly coupled to a heat source, a separation of the refrigerant in gas phase and liquid phase takes place. The heat is provided in this structure via the cooling circuit of an internal combustion engine. However, such is not present in the case of the construction of an electrical energy supply system which has been considered here.

Of the Patent Abstract of Japan 06-036786 A describes a comparable structure for a fuel cell. However, there is the decisive disadvantage that the waste heat arising in the cooling circuit of a fuel cell, in particular when using a PEM fuel cell, is at a comparatively low temperature level of approximately 70 to 90 ° C. Although this waste heat is sufficient in principle to operate an adsorption refrigerator, it is extremely low for an efficient and compact design.

Specifically for the cooling of a battery in a vehicle, such as a hybrid vehicle or a fuel cell vehicle, describes the DE 10 2008 039 908 A1 an adsorption chiller, which is supplied with heat from a burner. This burner is directly or indirectly connected to a separation unit and can implement liquid, gaseous or solid fuels. As an alternative, an electrically operated heating element is set forth.

The design has the disadvantage that either additional fuel for the burner or additional electrical energy for the electric heating element must be provided. Thus, the problem mentioned above that the heat source for the adsorption chiller triggers an additional energy requirement, not or not efficiently reduced, so that there are still losses in the overall efficiency.

It is the object of the present invention to improve an electrical energy supply system with fuel cell and electrical energy storage to the effect that with sufficient cooling of the electrical energy storage the best possible overall efficiency is achieved.

According to the invention this object is achieved by the features mentioned in claim 1. Advantageous embodiments and further developments of the electrical energy supply system according to the invention result from the hereof dependent subclaims. A preferred use for the electrical power supply system according to the invention is specified in claim 9.

The solution according to the invention provides that, as in the last-mentioned prior art, an adsorption chiller is provided, which is used for cooling the fuel cell and / or the electric energy storage. The heat source for the adsorption chiller forms waste heat from the area of supply and / or discharge of media to / from the fuel cell. In the area of the fuel cell system, media are conducted to the fuel cell, typically hydrogen and compressed air as an oxygen source. After the fuel cell, the residual substances, ie oxygen depleted air and typically a certain amount of residual hydrogen, are removed from the area of the fuel cell and combusted in some fuel cell systems via a burner or catalytic burner to drive a turbine with the resulting hot exhaust gases, which mechanical power, for example, provides for the operation of the compressor for the supply air to the fuel cell.

In the area of the media flowing to the fuel cell and in the area of the media flowing away from the fuel cell, heat is generated at various points, which is thus not or not completely required. For example, the supply air supplied to the fuel cell heats up very strongly when it is compressed, so that it must be cooled accordingly in order not to unnecessarily dry out the membranes of the fuel cell when using a PEM fuel cell. This cooling of the compressed supply air typically takes on a charge air cooler, which is integrated, for example, in a cooling circuit of the fuel cell. This waste heat can now be used according to a first particularly advantageous embodiment of the present invention as a heat source for the adsorption chiller. The temperature level of the compressed air is typically at about 150 ° C to 250 ° C and thus significantly above the temperature level of the cooling circuit of the fuel cell. The compressed after the compressor supply air typically has a sufficiently high temperature to drive a simple and compact Adsorptionskältemaschine.

An alternative possibility is the use of heat generated in the region of the burner or catalytic burner, preferably after flowing through the turbine, since this heat can not be used elsewhere and is released to the environment. This heat could then be used to operate the adsorption chiller without the need for additional energy.

The Adsorptionskältemaschine can be shared directly or via a heat exchanger and a suitable cooling circuit indirectly for cooling the electric energy storage and alternatively or in addition to cooling the fuel cell itself or for supporting cooling of a cooling circuit of the fuel cell.

A preferred use of the described electrical energy supply system according to the invention is in the provision of drive energy for a vehicle. In particular, in vehicle applications in which fuel cells are combined with electrical energy storage in virtually all conceivable scenarios for reasons of dynamics plays as efficient as possible cooling of the electrical energy storage, but possibly also the support of the cooling circuit of the fuel cell, a crucial role for a long-lasting functionality of the electric power supply system. If this can be achieved without additional energy has to be used, then a correspondingly high overall efficiency of the electrical energy supply system can be realized. This is of decisive advantage for the energy consumption and range of the vehicle, so that the preferred use of the above-described electric power supply system according to the invention can be seen here.

Further advantageous embodiments of the electrical power supply system according to the invention will become apparent from the remaining dependent claims and will be apparent from the embodiment, which will be described in more detail with reference to the figures.

Showing:

1 an electric power supply system according to the invention in a first embodiment;

2 an electric power supply system according to the invention in a second embodiment; and

3 an electric power supply system according to the invention in a third embodiment.

In the presentation of the 1 is an electrical energy supply system 1 to recognize, which may be provided in particular for the provision of drive power for a vehicle, such as a passenger car. It essentially comprises a fuel cell 2 as well as a battery 3 as an electrical energy store, which are provided in a manner known per se for providing the electrical drive power, which is then fed via a drive motor to the region of the drive wheels directly or indirectly for propulsion of the vehicle.

The fuel cell 2 is intended as a so-called PEM fuel cell 2 be formed, which consists of a plurality of individual cells, each having an anode space 4 and a cathode compartment 5 feature. In addition, in the presentation of the 1 a heat exchanger 6 in the field of fuel cell 2 to recognize which via an indicated coolant circuit 7 the fuel cell 2 can be used for cooling the same. The anode compartment 4 the fuel cell 2 becomes fuel, for example hydrogen, from a pressurized gas tank 8th fed. The cathode compartment 5 the fuel cell 2 air is supplied as an oxygen supplier. This air is through a compressor 9 provided and flows through a charge air cooler 10 and an optional humidifier 11 in the area of the cathode compartment 5 , The battery 3 should be designed as a high-voltage battery or high-performance battery, for example in the form of a lithium-ion battery, which is formed of a plurality of electrically parallel and / or series-interconnected individual cells. The battery 3 is intended in a known manner via a cooling circuit 12 be cooled. This cooling circuit 12 consists of a coolant pump 13 , a three-way valve 14 through which the coolant either or by a division of the individual volume flows either by the battery 3 or the battery 3 is led around. In addition, the cooling circuit has a heat exchanger 15 in which the cooling medium flowing in the cooling circuit is cooled. Furthermore, a surge tank 16 for the cooling medium in the area of the cooling circuit 12 intended. The cooling circuit 12 for the battery 3 is over the heat exchanger 15 with a refrigerant circuit 17 coupled, which operates according to the principle of operation of an absorption chiller. In the refrigerant circuit 17 For example, it may be a separate one for cooling the fuel cell 2 and / or the battery 3 act refrigerant circuit provided. Additionally or alternatively, it is also conceivable that the refrigerant circuit 17 Part of a working according to the Adsorptionsprinzip vehicle air conditioner.

The refrigerant circuit 17 operates with a refrigerant solution K + L, which is formed from a refrigerant K on the one hand and a solvent L on the other hand. The refrigerant K may preferably be ammonia or water, with the solvent L preferably water or lithium bromide. For realizing the principle of operation of the adsorption refrigerating machine, the refrigerant circuit comprises 17 a refrigerant pump 18 , which is in particular a high-pressure pump, by means of which a separation unit 19 the coolant solution K + L can be supplied. The separation unit 19 , which is preferably a cylinder, is directly with the intercooler 10 connected as a heat source, so that in the intercooler 10 accumulating waste heat of the compressed to the fuel cell 2 flowing air, with its temperature level of about 150 ° C to 200 ° C, as a heat source for the separation unit 19 of the refrigerant circuit 17 serves. Due to the waste heat from the intercooler 10 the refrigerant solution K + L is heated. Due to the rather low boiling point of the refrigerant, this evaporation, while the solvent remains in the liquid state even after heating. The refrigerant K can thus be separated from the solvent L. Subsequently, the refrigerant K via a first supply line 20 a capacitor 21 , which is preferably an air-cooled condenser supplied. The refrigerant cools down accordingly in the region of this condenser with the release of heat and thus returns to the liquid state of aggregation. The refrigerant circuit 17 then includes downstream of the condenser 21 an evaporator 22 , in which under heat absorption, an expansion and evaporation of the refrigerant K takes place. The desired cooling effect is thus achieved in this component. The evaporator 22 is therefore in direct contact with the heat exchanger 15 or is formed together with this as a component. The cooling medium in the cooling circuit 12 the battery 3 is so by the in the area of the evaporator 22 Cooled expansion and evaporation accordingly cooled so that the cooling medium in the cooling circuit 12 Heat is removed and this again to cool the battery 3 can be used.

In the refrigerant circuit 17 can be found downstream of the evaporator 22 an adsorber 23 to which the refrigerant K and the solvent L are supplied. This is between the separation unit 19 and the adsorber 23 another supply line 24 arranged, by means of which the adsorber 23 that in the separation unit 19 from the refrigerant solution K + L separated solvent L can be supplied. In the representation of the refrigerant circuit selected here 17 is the supply line 24 in this case designed so that these in the region of a jacket tube 25 with the line containing the refrigerant K is brought together, so that in the region of the jacket tube, the solvent L before entering the adsorber 23 is cooled. The cooled solvent L and the refrigerant K become the adsorber 23 then fed together. The cooled solvent L has a tendency to absorb the refrigerant K to saturation, so after the adsorber 23 again the refrigerant solution K + L is present, which by means of the refrigerant pump 18 again the separation unit 19 can be supplied.

The structure has two decisive advantages. In the pure use of an adsorption chiller with the refrigerant circuit 17 for cooling the battery 3 The decisive advantage arises from the fact that in the intercooler 10 accumulating waste heat directly as a heat source for the separation unit 19 can be used. Additional energy is thus used to heat the separation unit 19 unnecessary. In addition, the heat from the compressed air in the area of the intercooler 10 so not in the coolant circuit 7 the fuel cell 2 registered, as is common in other constructions. Because of the comparatively low temperature level of the fuel cell 2 the removal of waste heat through the coolant circuit 7 the fuel cell 2 is difficult anyway, this represents a decisive advantage because of the in the intercooler 10 accumulating waste heat of this already sensitive coolant circuit 7 the fuel cell 2 will not be charged further.

In addition or as an alternative to the embodiment shown here, it would of course also be conceivable, in addition to the cooling circuit 12 for the battery 3 also heat from the coolant circuit 7 the fuel cell 2 over the refrigerant circuit 17 dissipate.

In the presentation of the 2 is a comparable construction of the electric power supply system 1 to recognize in an alternative embodiment. The same components are provided with the same reference numerals and work analogously to the above description of 1 , It is therefore intended only to the differences between the two electrical power systems 1 be discussed in more detail. As a heat source for the separation unit 19 of the refrigerant circuit 17 is used in the embodiment shown here, the exhaust gas to a turbine 26 in the electric power supply system 1 , This turbine 26 drives together with an electric motor 27 the compressor 9 for the compression of the supply air to the fuel cell 2 at. This construction known from the prior art is also referred to as an electric turbocharger or ETC (Electric Turbo Charger). The structure is designed so that the engine 27 and the turbine 26 the compressor 9 drive together. Located in the area of the turbine 26 a sufficient amount of energy or power, so the turbine 26 the compressor 9 also driving alone and in case of that, in the area of the turbine 26 there is an excess of power, the engine can 27 be powered as a generator to generate electrical energy.

To drive the turbine 26 Hot exhaust gases are used, which come from a burner 28 , typically a catalytic burner, a pore burner or the like. The burner 28 the exhaust gases from the cathode compartment 5 and the anode compartment 4 fed to the fuel cell, which have radicals of oxygen and hydrogen radicals. Optional and not shown here is the burner 28 also fuel or hydrogen, for example, from the area of the compressed gas tank 8th be supplied as needed. In the area of the burner 28 become the residues in the exhaust gases of the fuel cell 2 then burned accordingly. The hot exhaust gases that are under pressure from the environment then drive the turbine 26 , They also point to the turbine 26 typically still a comparatively high temperature level and are in the embodiment shown here via a heat exchanger 29 with the separation unit 19 of the refrigerant circuit 17 connected to as a heat source for this separation unit 19 to serve. The refrigerant circuit 17 then works as above.

Another difference in the structure shown here is that the intercooler 10 after the compressor 9 in a manner known per se in a coolant circuit, for example, the coolant circuit 7 the fuel cell 2 , is integrated, as shown in the illustration of 2 indicated.

In principle, it would of course also conceivable, the hot exhaust gases of the burner 28 entirely or at least partially for direct heating of the separation unit 19 to use, without, that the hot exhaust gases before through the turbine 26 have been conducted. The remaining waste heat could then still be in the turbine 26 to be implemented with. However, this structure would be the energy yield in the turbine 26 adversely affect, so this would be a slight reduction in the overall efficiency compared to the ideal case described above to be feared.

In the presentation of the 3 is now another alternative embodiment of the electrical power system 1 shown. This also essentially corresponds to the structure already described. In addition to the refrigerant circuit 17 , which analogously to in 2 is arranged in the electrical power supply system 1 according to 3 also a second refrigerant circuit 17 ' , which operates on the same principle of operation and which after in the context of 1 described principle is constructed. The refrigerant circuit 17 thus uses the heat exchanger 29 in the hot exhaust after the turbine 26 as a heat source, while the refrigerant circuit 17 ' the intercooler 10 as a heat source uses. In the in 3 illustrated embodiment, the refrigerant circuit is used 17 while cooling the battery 3 while the refrigerant circuit 17 ' is shown without a specific cooling application. About this refrigerant circuit 17 ' For example, a passenger compartment could be one with the electrical power system 1 equipped vehicle and / or the coolant circuit 7 the fuel cell 1 be cooled cooled or supportive.

About at least one of the refrigerant circuits 17 . 17 ' , here the refrigerant circuit 17 ' , so can only or in parallel to the cooling of the fuel cell, for example 2 a cooling of a region take place, which is outside of the power supply system 1 is arranged. Such an external area or even an external component, for example a power electronics, an electric drive motor or the like, can thus additionally or exclusively via the refrigerant circuit 17 ' be cooled.

In addition to the direct heating of the separation unit shown here 19 either via the hot exhaust gases or the hot compressed supply air of the fuel cell 2 , it would of course also conceivable, these two heat sources for heating a single separation unit in a single refrigerant circuit 17 to use accordingly. For that would be a combination of in 1 and 2 shown structures necessary, the heat transfer either directly, via heat conduction or a heat cycle, which the separation unit 19 , the heat exchanger 29 and the intercooler 10 together.

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

• DE 10346975 A1 [0004]
• JP 06-036786A [0005]
• DE 102008039908 A1 [0006]

Claims (9)

Electric power supply system ( 1 ) comprising at least one fuel cell ( 2 ) and an electrical energy store ( 3 ), wherein for cooling the fuel cell ( 2 ) and / or the electrical energy store ( 3 ) at least one Adsorptionskältemaschine (refrigerant circuit 17 . 17 ' ) is provided, wherein waste heat from the area of supply and / or discharge of media to / from the fuel cell ( 2 ) forms the heat source for the Adsorptionskältemaschine, and wherein the heat source, at least indirectly with a separation unit ( 19 ) of the adsorption chiller is connected. Electrical power supply system according to claim 1, characterized in that the heat source is a charge air cooler ( 10 ) for the fuel cell ( 2 ) is flowing compressed air. Electrical power supply system according to claim 1 or 2, characterized in that the heat source combustion exhaust gases of an afterburning of exhaust gases of the fuel cell ( 2 ) uses. Electrical power supply system according to claim 3, characterized in that the heat source, the waste heat in the combustion exhaust gases before or after a turbine ( 26 ) uses. Electrical power supply system according to claim 3 or 4, characterized in that the afterburning in a catalytic burner ( 28 ) he follows. Electrical energy supply system according to one of claims 1 to 5, characterized in that the at least one adsorption chiller for cooling the electrical energy storage ( 3 ) via a cooling circuit cooled by the adsorption chiller ( 12 ) is used. Electrical energy supply system according to one of claims 1 to 6, characterized in that two Adsorptionskältemaschinen are provided, which use different heat sources. Electrical energy supply system according to claim 7, characterized in that at least one of the adsorption chillers is used for cooling an external area and / or external components. Use of the electrical energy supply system ( 1 ) according to one of claims 1 to 8, for providing drive energy for a vehicle.

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