DE102008029529A1 - Fuel cell system operating method for motor vehicle, involves delivering exhaust gas carried along water, guiding cooling fluid, leading cooling fluid, separating water from gas, collecting water and partially spraying collected water - Google Patents

Abstract

The method involves delivering exhaust gas carried along water during operation and guiding a cooling fluid in a cooling circuit in a motor vehicle (10) to a heat source (12) for receiving heat. The cooling fluid is led to a cooling area (48) in which the cooling fluid discharges the received heat to the ambient air via walls. The water is separated from the exhaust gas and is collected in a container (28). The water collected in the container is partially sprayed on an outer side of the walls in the cooling area. An independent claim is also included for a fuel cell system comprising a container.

Description

The The invention relates to a method for operating a fuel cell system in a motor vehicle, a fuel cell system for performing of the method and a motor vehicle with such a fuel cell system.

To Fuel cell systems include at least one fuel cell. The fuel cell becomes a fuel and an oxidant fed, and the fuel is in the fuel cell implemented. This produces exhaust gas, which carries water, that arose during the reaction. The concentration of water is particularly high when hydrogen is used as fuel.

The Water should not be directly in liquid with the exhaust gas Form into the environment. For example, the water can on a road on which the motor vehicle is moving in cold Freezing ambient temperatures to ice and the icy road pose a danger to other motor vehicles. Farther can in the exhaust gas water in liquid form the inject subsequent vehicle onto the windshield and the Take a look.

It is well known in the art, the water from to collect the exhaust gas in a container. Partly collects the water from the exhaust anyway to the exhaust pipes, because These are at passage of the exhaust gas due to the heat exchange cooled with the ambient air, and at the cool Duct walls, the water can then precipitate, also condense when it is carried in vapor form. Partially is also provided that the water specifically in a separator is deposited. The container in which the water is collected can simultaneously act as a separator or a separator be downstream in the flow path of the exhaust gas.

In the US 2006/0240299 A1 is described that in a fuel cell system, water is collected in a container and is re-evaporated by a heater to be discharged in vapor form into the environment can. This system is laborious because not only does the heater have to be provided, it must also be operated, with much energy needed for evaporation.

From the DE 10 2006 048 187 A1 It is known to supply the water from a water separator in a fuel cell system to a radiator as cooling fluid, wherein the radiator is designed so that it emits the cooling fluid during operation. For this purpose, the cooler comprises a selectively permeable wall, so that liquid water or water vapor can selectively penetrate to the outside of the cooler. There, the water is evaporated and the cooling capability of the cooler is increased.

In the published after the filing date of the present application DE 10 2006 043 573 is described that the exhaust gas of a fuel cell system (ie, not collected in a container water) is heated prior to its release into the environment by means of a heated fuel cell by a cooling medium. In this case, it is described in particular that the cooling medium is used for cooling compressed air flowing to the fuel cell, thereby being heated and then finally giving off the heat energy to the moist exhaust gas again.

It Object of the invention, the possibilities as avoided can be that generated during operation of a fuel cell water on the traveled by a motor vehicle with the fuel cell system Roadway device to expand. The solution should be as cheap as possible, if possible both in terms of the production of the fuel cell system as well his business.

The Task is by a method according to claim 1 solved by a fuel cell system with the features according to claim 4 and by a motor vehicle with such a fuel cell system, that is according to claim 9.

The invention makes use of a refrigeration cycle system provided in the motor vehicle. A refrigeration cycle system is usually coupled to a heat source and has a cooling area. A cooling fluid is sent to the heat source in the refrigeration cycle system (usually through conduits) to receive heat there, then it is directed to the refrigeration area and releases the heat. In the present case, such a cooling region should be provided in the cooling circuit system in which the cooling fluid via walls (on a suitably shaped body, for example on a simple line) releases the absorbed heat to the ambient air. The method is based on the known measure that the water is collected from the exhaust gas in a container, for. B. after deposition or simultaneous deposition in the container. In order to dispose of the water again and thus to reduce the weight to be transported by the motor vehicle and to reduce the risk of icing of the container at cold ambient temperatures, the water collected in the container is at least partially exposed to the outside of the walls in the cooling area of the refrigeration cycle system applied. Due to the contact with the ambient air, promoted möglicherwei Also due to the heat contained in the cooling fluid and discharged to the walls, the water evaporates away from the outside of the walls and removes heat from the walls. The water thus does not reach the road on which the motor vehicle is traveling, and as a second positive effect, one obtains a particularly efficient cooling of the cooling fluid in the cooling region which is improved compared to previous systems. Among other things, the higher efficiency also makes possible a more compact construction of the cooling circuit system, in particular its cooling area, as a result of which it is even possible to achieve weight savings in the motor vehicle.

In Advantageously, the water is in fine droplets sprayed on the walls. Due to the fine distribution the water on the walls promotes the evaporation of the water.

The Water does not have to be in the entire cooling area on the walls be applied. Rather, one can look to such places of the Concentrate application of the water to which the cooling fluid gives off a lot of heat. In addition or instead of which it is also possible, the water on such Position, ie an area that is only a partial area of the cooling area may be, muster, which flows through when driving the motor vehicle by wind is or is flowed around (which is typically at a Cooler, preferably a lamella cooler, or the individual pipe sections of the radiator the case is), and so evaporate the applied water promoted by the wind. You get too here a double effect: on the one hand, the amount of disposed of Water is particularly high, and the other is the cooling fluid cooled particularly well, because just a lot of water is evaporated. While it does in conventional radiator systems The task of the wind is to cool the walls directly, this happens at least partially in the present method on the detour over the water droplets on the Walls, and these water droplets are lighter off Airstream to achieve a cooling effect on the walls mitführbar than otherwise a cooling of the walls done by the wind. The invention Fuel cell system has a container in a conventional manner for carried by the exhaust gas water, and It also has a refrigeration cycle system, wherein in one Cooling area the cooling fluid in a body With walls is guided, the outside with the ambient air in contact. According to the invention the fuel cell system means for spilling water the container on the outside of the walls of the body in the cooling area. This will be the achieved advantageous effects, the above with respect to the inventive Procedures have been described.

The Means for spending can be a conventional Include (pipe) line. For a fine distribution of Water, it makes sense if this pipe in a nozzle ends. Basically it is possible to use the container to arrange for the water so high in the motor vehicle that the water by gravity to the walls of the body is brought. To be flexible in the arrangement of the container to be, for. For example, because of its high filling weight Rather be able to arrange further down, suitable Means provided for transporting the water through the conduit be preferred, which simultaneously serve to remove the water from the nozzle to urge, so the actual spraying out to effect the water. The means of transport can include a simple pump.

In A fuel cell system is usually already available a refrigeration cycle system, namely one, in which the heat source is at least one fuel cell is. Advantageously, the water from the means for Spend exactly on the cooling area of this cooling circulation system, it does not then have a separate cooling circuit system to be provided.

in the Fuel cell system can be of all the prior art known techniques, such as from the fuel cell generated water can be collected in a container. This can of suitable separators, ie means for depositing of water from a gas, use, said Gas can be both the actual exhaust and the fuel, So typically the hydrogen that go through the fuel cell unused Has.

to The invention also includes a motor vehicle with a fuel cell system.

The Cooling circuit system of the invention Fuel cell system has in a motor vehicle in itself known manner advantageous to a cooling area, the Is traversed by air in the operation of the motor vehicle. Typically, the cooling zone is then a cooler, preferably as a laminated radiator. Then promote the air, so the wind, the removal of water droplets. Here is the effect of eliminating the disturbing water already achieved when the wind is the water droplets just get carried away. But by the wind is especially also promoted the evaporation of water droplets and so a cooling of the radiator and thus the promotes cooling fluid in the cooler.

Hereinafter, a preferred embodiment of the invention will be described with reference to the drawing, wherein the figure in more schematic Representation illustrates an inventive fuel cell system in a motor vehicle.

An only schematically drawn and as a whole with 10 designated motor vehicle is operated by means of an electric motor, not shown in the figure, for the supply of electric current, a fuel cell system is provided, whose components are shown schematically in the figure. The exact location of the components is not shown in the figure, with the exception of the cooler described below.

At the heart of the fuel cell system is a fuel cell stack 12 (a so-called fuel cell stack). This consists of a plurality of fuel cells, in the present case, a single fuel cell would be sufficient. The fuel cell stack 12 gets out of a tank 14 over a line 16 Fuel, in the present case hydrogen, fed, wherein a valve 18 can regulate the amount of fuel supplied. The fuel is reacted with atmospheric oxygen. For this purpose, the fuel cell stack 12 from a compressor 20 compressed air via a pipe 22 fed. The reaction produces water. This is from the fuel cell stack 12 together with an exhaust gas, which in particular comprises the portion of the supplied air not consumed in the reaction, via a conduit 24 issued. Also in the exhaust pipe 24 is a valve 26 arranged. In known manner, the water, which is carried along with the exhaust gas, in a container 28 collected. The container 28 can be designed so that the water itself on the walls of the container 28 collects, z. B. condensed out of the vapor phase. Also in the field of management 24 in front of the container 28 can already accumulate water, which then, z. B. in training a suitable gradient to the container 28 down to the tank 28 flows. The exhaust gas from which the water at least partially into the container 28 is discharged, is below on the further line 24 ' to an outlet 30 led and released into the environment. Fuel cell stacks do not always consume exactly the total amount of fuel supplied. Excess fuel is supplied via a pipe 32 from the fuel cell stack 12 dissipated and at least partially by means of a suitable pump 34 (Means for recycling) via a line 32 back to the line 16 led to the fuel cell stack again 12 to be fed. The one by the line 32 Exhausted excess fuel can also carry water, especially in vapor. In the embodiment shown in the figure is preferably a separator 36 in the pipe 32 provided, which separates water from the excess fuel. From the separator 36 is over a line 38 with a valve 40 the water directly or via the pipe 24 the container 28 fed.

In the container 28 is gradually accumulating more and more water. The water should not be released directly into the environment, but on the other hand be disposed of. In the present case, the water is used in its disposal at the same time meaningful, namely by the cooling circuit system (or short cooling system) is supplied, which for cooling the fuel cell stack 12 serves. In the cooling system, a pump moves 42 a cooling fluid through pipes 44 and 46 in a circle. The cooling fluid passes through the fuel cell stack 12 and heats up. There is a cooling area, namely the usually front in the vehicle 10 arranged cooler area 48 , This is designed as a cooler, preferably as a finned cooler, so as a branched piping system. The individual pipelines are small so that the total surface area is increased and a high cooling capacity is achieved. The cooler 48 is when driving the motor vehicle 10 flows through the wind or cooled at low speed through the radiator fan, so that the cooling fluid is cooled particularly well.

Now the water gets out of the container 28 by means of a pump 50 through a pipe 51 to the cooler area 48 transported, namely to nozzles, which cause the water is sprayed finely distributed on the radiator body, as shown by the dashed lines 52 indicated. In a real embodiment, the spraying may also take place from the side or preferably also from the rear, differently than shown in the figure.

By spraying the water from the container 28 on the radiator area 48 Not only is the water disposed of, but it also has the positive effect of increasing the radiator performance: the water evaporates away from the walls of the radiator, draining heat from the walls, and thus the cooling fluid can re-heat the walls and, in turn, heat the environment, namely to the water and the ambient air. Because of the increased compared to conventional radiator systems cooling capacity per area, the total effective area can be reduced, so that the size of the radiator, z. As well as the thickness, and thus the weight.

It does not have all the water from the container 28 be disposed of in the manner described. Part of the water may also be disposed of via other disposal facilities known in the art or in the container 28 remain until emptying at a stop of the motor vehicle.

The present invention may also find application to Auxiliary Power Units (APUs), which as Power source, z. As for stationary air conditioning or stand-alone power supply, act and thus be used in vehicles with internal combustion engine or fuel cells as a drive. The cooler necessary for the cooling of the APU is then preferably cooled by a radiator fan.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• US 2006/0240299 A1 [0005]
• - DE 102006048187 A1 [0006]
• - DE 102006043573 [0007]

Claims (10)

Method for operating a fuel cell system in a motor vehicle ( 10 ), which has at least one fuel cell, is discharged from the water carrying along in operation exhaust, and wherein in the motor vehicle ( 10 ) a refrigeration cycle system ( 42 . 44 . 46 . 48 ) is provided in which a cooling fluid to a heat source ( 12 ) is passed to receive heat there, and wherein the cooling fluid to a cooling area ( 48 ), in which the cooling fluid via walls discharges the absorbed heat into the ambient air, wherein the method comprises the step that water from the exhaust gas, in particular after a separation, in a container ( 28 ), characterized in that in the container ( 28 ) collected water at least partially on the outside of the walls in the cooling area ( 48 ) is applied. Process according to claim 1, characterized in that the water ( 52 ) is sprayed onto the walls. Process according to claim 1 or 2, characterized in that the water ( 52 ) is applied to such a location, which is traversed by the wind during travel of the motor vehicle, so that evaporation of the applied water is promoted. Fuel cell system with at least one fuel cell from which an exhaust pipe ( 24 ) leads away over the accumulating during operation of the fuel cell exhaust gas is discharged, wherein in the exhaust pipe ( 24 ) a container ( 28 ) is arranged for carried by the exhaust gas water, and wherein in the fuel cell system, a refrigeration cycle system ( 42 . 44 . 46 . 48 ), in which, in its operation, a cooling fluid between a heat source ( 12 ) and a cooling area ( 48 ), wherein in the cooling zone ( 48 ) the cooling fluid is passed into a body having walls whose outside is in contact with the ambient air, characterized by means ( 50 . 51 ) for the removal of water from the container ( 28 ) on the outside of the walls of the body in the cooling area ( 48 ). Fuel cell system according to claim 4, characterized in that the means for transporting a conduit ( 51 ) leading to a nozzle. Fuel cell system according to claim 5, characterized by means ( 50 ) for transporting the water through the conduit ( 51 ) and to urge the water from the nozzle. Fuel cell system according to one of the claims 4 to 6, characterized in that the heat source at least includes a fuel cell. Fuel cell system according to one of claims 4 to 7, characterized by means ( 36 ) for separating water from a gas and a conduit ( 38 ), the separated water to the container ( 28 ) leads. Motor vehicle ( 10 ) with a fuel cell system according to one of claims 4 to 8. Motor vehicle ( 10 ) according to claim 9, in which the body is in the cooling zone ( 48 ) during operation of the motor vehicle ( 10 ) is traversed by air.