AT520976A1 - Heat exchanger for a fuel cell system and method for operating a fuel cell system - Google Patents

Abstract

The invention relates to a heat exchanger (1) for a fuel cell system (100), in particular an operated with a liquid fuel SOFC system, with a plurality of heat transfer elements (2), wherein through the heat exchanger (1) thermal energy between a system exhaust line (3) and a Anode supply line (4) of a fuel cell system (100) is transferable, comprising an evaporation region (5), an overheating region (6) and a reforming region (7), which are flow-connected to each other, wherein the heat transfer elements (2) at least partially comprise a catalytic material. Furthermore, the invention relates to a use of such a heat exchanger (1) and a fuel cell system (100) with such a heat exchanger (1). Furthermore, the invention relates to a method for operating a fuel cell system (100), in particular a SOFC system, with such a heat exchanger (1).

Description

Summary

The invention relates to a heat exchanger (1) for a fuel cell system (100), in particular a SOFC system operated with a liquid fuel, with a plurality of heat transfer elements (2), thermal energy between a system exhaust pipe (3) and a through the heat exchanger (1) Anode supply line (4) of a fuel cell system (100) is transferable, comprising an evaporation area (5), an overheating area (6) and a reforming area (7) which are flow-connected to one another, the heat transfer elements (2) at least partially comprising a catalytic material.

The invention further relates to the use of such a heat exchanger (1) and a fuel cell system (100) with such a heat exchanger (1).

The invention further relates to a method for operating a fuel cell system (100), in particular an SOFC system, with such a heat exchanger (1).

Fig. 1/27

PP31901AT

AVL List GmbH

Heat exchanger for a fuel cell system and method for operating a fuel cell system

The invention relates to heat exchangers for a fuel cell system, in particular a SOFC system operated with a liquid fuel, with a plurality of heat transfer elements, thermal energy being transferable between a system exhaust line and an anode supply line of a fuel cell system, comprising an evaporation area, an overheating area and a reforming area, which are fluidly connected to each other.

The invention further relates to the use of such a heat exchanger.

Furthermore, the invention relates to a fuel cell system, in particular SOFC system, with such a heat exchanger, comprising a fuel cell stack with an anode section and a cathode section.

The invention further relates to a method for operating a fuel cell system, in particular an SOFC system.

Heat exchangers for fuel cell systems are known from the prior art. These are arranged at different locations in a fuel cell system, such as in an anode feed line. Fuel is conducted via the anode feed line to an anode section of the fuel cell system. If a liquid fuel such as diesel or ethanol is used, it must be evaporated and reformed beforehand so that the synthesis gas or hydrogen-rich gas required for the reaction in the fuel cell stack is generated. In order to be able to generate the necessary temperatures, it is known to use several heat exchangers through which heat from system exhaust gas can be transferred to the fuel.

In particular when using a fuel cell system in a vehicle, it is a goal to keep the number of components of the same as low as possible. Consequently, solutions known from the prior art attempt to combine individual components in a common component.

For example, it is known from DE ° 10 ° 2011 ° 088 ° 566 ° A1 that a reformer of a fuel cell system is at least heat-transferring with a heating jacket / 27

PP31901AT

To couple AVL List GmbH. Such a reformer is designed to carry out a partial catalytic reaction, which is why it also includes a mixing space for admixing air. Thus, such a fuel cell system does not achieve the goal of reducing the number of components while reducing a component size and effective operation of the fuel cell system.

This is where the invention comes in. The object of the invention is to provide a heat exchanger of the type mentioned at the outset, with which a fuel cell system with as few components as possible can be operated efficiently.

It is also an aim to indicate the use of such a heat exchanger.

It is also an aim to provide an improved fuel cell system.

Another aim is to specify a method of the type mentioned at the outset with which a fuel cell system can be operated with few components and efficiently.

The object is achieved in that the heat transfer elements of a heat exchanger of the type mentioned at least partially comprise a catalytic material.

An advantage achieved in this way can be seen in particular in the fact that, through the integral design of an evaporator, superheater and reformer as a heat exchanger according to the invention, in combination with the catalytic material, only a single element is required which combines the three elements mentioned. In addition, it is possible in the heat exchanger according to the invention to process liquid fuel directly in it, without the need for a separate evaporator and / or heat exchanger for this in the anode feed line upstream thereof. The catalytic material of the heat transfer elements allows a process of steam reforming with simultaneous heat transfer from a warm to a cold side of the heat exchanger. Furthermore, the solution according to the invention makes it possible to optimize the installation space optimization of the heat exchanger and consequently also of a fuel cell system with such a heat exchanger in such a way that the areas for heat exchange are still large enough to enable steam reforming or to be carried out efficiently. Steam reforming requires a high heat transfer and consequently a / 27

PP31901AT

AVL List GmbH large area for carrying out the chemical reaction. This is made possible by the design of the heat exchanger according to the invention in contrast to solutions known from the prior art.

In the context of the invention, the fact that the heat exchanger according to the invention comprises an evaporator, a superheater and a reformer means in particular that these are arranged within a common box or comprise a common shell or are closed off from the outside by a common jacket. In any case, these are sealed off from one environment. The heat transfer elements are arranged distributed over an entire volume of the heat exchanger. In the context of the invention, the fact that the heat exchanger can be arranged in a fuel cell system and / or can be flow-connected with lines thereof means that it is designed for arrangement in a fuel cell system and for the corresponding heat exchange.

It is also advantageous that all processes that can be carried out in the heat exchanger (evaporation, overheating, reforming) can be carried out or are carried out by steam reforming. Consequently, the heat exchanger is in particular free of and / or without a mixing chamber. It is not necessary to add air, especially oxygen. The evaporation area, the overheating area and the reforming area of the heat exchanger are directly fluidly connected to one another. It is favorable if each of the areas with the exception of the fluid connection are self-contained. The fuel can flow through the heat exchanger.

In the context of the invention, a heat exchanger is understood to mean a heat exchanger which can basically be operated in the cocurrent principle, countercurrent principle or cross-flow principle. In the context of the invention, the heat exchanger transfers thermal energy from a first fluid, in particular system exhaust gas, to a second fluid, in particular fuel or fuel, preferably a water-fuel mixture. In the context of the invention, the fluids can be gaseous or liquid or partly gaseous or partly liquid. The second fluid, in particular a water-containing fuel, is preferred / 27

PP31901AT

AVL List GmbH upstream of the heat exchanger liquid and the system exhaust gas. The anode supply line or the fuel and the system exhaust line or the system exhaust gas are therefore coupled to one another in a heat-transferring manner.

According to a first aspect of the present invention, a heat exchanger for a fuel cell system, in particular for an SOFC system (SOFC stands for “solid oxide fuel cell” or solid oxide fuel cell), is provided. Such a fuel cell system is operated in particular with liquid fuel, particularly preferably with a liquid fuel-water mixture such as an ethanol-water mixture. Nevertheless, it can also be favorable if the heat exchanger according to the invention is used in a motor arrangement of an internal combustion engine or is made available for this purpose. In particular, this can be provided for use in an EGR line and / or in an exhaust line or for heat transfer between an EGR line and an exhaust line.

In the case of a heat exchanger according to the invention, the heat transfer elements of the reforming area and / or of the superheating area in particular comprise a catalytic material, so that a catalytic reaction necessary for a reforming process can be carried out. The heat transfer elements are particularly preferably coated with a catalytic material. It is advantageous if the evaporation area is made smaller than the reforming area, that is to say the evaporation area also comprises fewer heat transfer elements than the reforming area. Its volume is preferably also smaller than the volume of the reforming area. The evaporation area is fluidly connected to the overheating area and the overheating area is fluidly connected to the reforming area.

It is expedient if the anode supply line is in flow connection with the evaporation region, fuel, in particular a fuel / water mixture, being able to be led to an anode section of the fuel cell system via the anode supply line connected to a cold side of the heat exchanger. Liquid fuel can be conducted via a part of the anode feed line forming a fuel feed line to the evaporation area, where it is converted into a gas. The fuel is therefore led over the cold side of the heat exchanger, / 27

PP31901AT

AVL List GmbH, which can be vaporized in particular by heat from system exhaust gas. The fuel flows in the flow direction in the anode feed line first into the evaporation area, then into the overheating area and finally into the reforming area before it can be conducted downstream of the heat exchanger in the direction of the anode gate.

It is advantageous if a system exhaust gas line is provided for supplying system exhaust gas of the fuel cell system to the overheating area and / or to the reforming area, wherein the system exhaust gas, which is completely burned in particular, can be conducted over the warm side of the heat exchanger. The catalytic material of the reforming area, in particular, can be brought to a predetermined operating temperature or activation temperature by means of warm or hot system exhaust gas. The catalytic material enables chemical reactions to convert the fuel from around 450 ° C in the reforming area of the heat exchanger. The heat of the system exhaust gas is transferred through the heat transfer elements to the gaseous fuel in the reforming area. Since the reforming area and / or the overheating area requires higher temperatures than the evaporation area, a downstream flow direction of the system exhaust gas is in particular as follows: reforming area, overheating area, evaporation area. In the context of the invention, system exhaust gas is understood to mean, in particular, anode exhaust gas and cathode exhaust gas. In a fuel cell system with a heat exchanger according to the invention, anode exhaust gas is, in particular, completely burned downstream of a fuel cell stack with the addition of cathode exhaust gas (air) in an afterburner. The system exhaust gas is then fed downstream of the afterburner to the heat exchanger according to the invention, the heat of which is used almost completely for the processes in the heat exchanger before cooled system exhaust gas is released to the environment downstream of the heat exchanger.

In principle, it can also be inexpensive via the system exhaust gas line for supplying system exhaust gas from the fuel cell system to the overheating area and / or system exhaust gas which has not completely burned over the warm side of the heat exchanger. That is, in a fuel cell system with the heat exchanger according to the invention, that downstream of a fuel cell stack is made up of anode exhaust gas and cathode exhaust gas / 27

PP31901AT

AVL List GmbH merged system exhaust gas in particular fed directly to the heat exchanger. There is therefore no need for a catalytic afterburner. The heat transfer elements thus have a catalytic material on the side through which the system exhaust gas flows or through which it can flow, or are coated with a catalytic material. All areas of the heat exchanger can be catalytically coated on one side through which the system exhaust gas flows, or only some of them. It is favorable if at least the heat transfer elements of the reforming area are catalytically coated both on the side through which the fuel flows and on the side through which the system exhaust gas flows. The catalytic material arranged on the system exhaust side of the heat transfer elements makes it possible for the system exhaust gas, which has not yet been completely burned in the fuel cell stack, to be completely catalytically combusted in the heat exchanger, and for another, enough heat is generated, which further improves heat transfer. Due to the possible saving of the afterburner in a fuel cell system with a heat exchanger according to the invention, the number of components is further reduced and the compactness of the fuel cell system is increased. A heat exchanger designed in this way thus comprises not only an evaporation area, an overheating area and a reforming area, but also an afterburner area.

It is advantageous if the overheating area and the reforming area are designed as a common area. This means that the fuel can be overheated and reformed in one step or at least very quickly in succession. The overheating area and the reforming area are not spatially separated from one another. In contrast, the evaporation area is separated from the overheating area and / or reforming area such that the fuel first passes the evaporation area in the direction of flow and then enters the overheating area and / or reforming area in gaseous form. In the overheating area, the gaseous fuel can be heated to a temperature of approximately 300 ° C. to approximately 400 ° C. or more by heat transfer from the system exhaust gas and can therefore be preconditioned for reforming. By forming the overheating area and the reforming area as a common / 27

PP31901AT

AVL List GmbH

In the area, the overheated and preconditioned gas can be used and reformed directly in the reformer.

Within the scope of the invention, the heat exchanger can be designed as desired, for example as a tube bundle heat exchanger. However, this is expediently designed as a plate heat exchanger. The heat transfer elements are thus designed as plates or bundles of plates, the plates or bundles of plates in the reforming area comprising a catalytic material or being coated with a catalytic material. A heat exchanger designed as a plate heat exchanger is particularly advantageous if the plates are designed with a small thickness in the range from approximately 1 mm to 2 mm, in particular approximately 1.2 mm to 1.5 mm, particularly preferably approximately 1.3 mm , Due to the thin wall thickness and a large area of the plates (in the range of approximately 200 mm by 80 mm), a large heat transfer is possible. The evaporation area may comprise, for example, approximately 24 plates, whereas a common area for overheating and reforming may comprise approximately 30 plates, these being at least partially catalytically coated or comprising a catalytic material. In principle, however, more or fewer plates can also be provided. The number of plates depends on a given installation space and / or pressure loss requirements. The plates of the plate-shaped heat exchanger are connected to one another in a force-locking or material-locking manner in such a way that the fuel and then the system exhaust gas flow or are guided in successive gaps between individual plates. The plates are advantageously each formed with a profile or profiled, so that an area for heat transfer is further increased. It is advantageous if the plates, which are arranged in the reforming area, are coated with a catalytic material. One side of each of the plates is coated catalytically, the coated side of two successive plates being aligned with one another, so that the gaseous and superheated fuel flows between these plates and is reformed. In principle, however, it can also be provided that only every second plate is coated catalytically. The plates of the plate heat exchanger can also be coated at least partially on both sides, so that those areas in which the system exhaust gas flows are also designed for catalytic reforming. This is particularly advantageous if the system exhaust gas / 27

PP31901AT

AVL List GmbH is fed directly downstream of a fuel cell stack to the heat exchanger via the system exhaust pipe without being completely burned in an afterburner. Such a heat exchanger then takes on the function of an afterburner or also contains this component.

It is advantageous if the catalytic coating is designed as a catalytic fabric or a catalytically coated, in particular metallic, grid.

It is particularly expedient if the heat transfer elements of the reforming area are coated with the catalytic fabric or the catalytically coated grid. The catalytic coating is designed to reform the vaporized and possibly overheated fuel. If the reforming area and the overheating area are integrally formed, the vaporized fuel is overheated and vaporized approximately simultaneously. The reforming is advantageously carried out by steam reforming without the addition of air or steam. In particular, when using a water-containing fuel such as an ethanol-water mixture, no separate supply of (water) steam is necessary. The amount of steam required for steam reforming is already provided by the vaporized fuel itself. In particular, it can be provided within the scope of the invention that the catalytic coating is designed as a catalytically coated metallic grid. This is inserted between two plate-shaped heat transfer elements, after which they are connected to one another in particular in a force-locking manner in such a way that the side of the plates which are arranged in relation to one another are coated with the grid. The fuel to be reformed is then passed between these two plates. The advantage of using a catalytically coated metallic grid is that it has a low thermal mass and consequently can be heated to the predetermined temperature required to activate the catalytic reactions in a short time. If, as an alternative or in addition, a catalytic coating is also provided on that side of the heat transfer elements which has the system exhaust gas flowing around it, this is designed accordingly as described above.

It is particularly expedient if the reforming area is designed and assigned to carry out steam reforming. An endothermic reaction therefore takes place. According to the invention, the energy required for this is via / 27

PP31901AT

AVL List GmbH

System exhaust gas, which is coupled to the reforming area to transmit heat.

In addition, however, it can also be advantageous if a supply line of air to the evaporation area or superheating area is provided. In particular, air upstream of the evaporation area can be mixed with the fuel. Alternatively, it can also be provided that the fuel and the air are fed separately to the evaporation area of the heat exchanger. It can also be advantageous if the air is fed to the superheating area downstream of the evaporation area. In the context of the invention, air is understood to mean an oxygen-containing fluid, in particular an oxygen-containing gas, particularly preferably ambient air. This makes it possible to optionally carry out a catalytic partial oxidation in addition to or as an alternative to steam reforming. This is particularly advantageous in a starting phase of the fuel cell system, in which a fuel cell stack is still cold and has to be heated. By supplying air during, in particular exclusively, a starting phase of the fuel cell system, the fuel cell stack can thus be warmed up by catalytic partial oxidation. If this has reached a predetermined temperature, the supply of air is switched off again, in particular by means of a valve.

In addition, the air supply prevents or at least greatly reduces soot formation in the heat exchanger, in particular in the overheating area, during a starting phase of the fuel cell system in which the heat exchanger according to the invention can be arranged. It has been found that the supply of an oxygen-containing fluid to the evaporation process of the water-fuel mixture prevents soot formation during a, in particular exclusive, starting phase of a fuel cell system, or at least greatly reduces it. Since the formation of soot occurs in particular only when the water-fuel mixture overheats, for example from 200 ° C., in particular from 300 ° C. or more, the air is preferably fed to the heat exchanger only downstream of the evaporation area.

It is expedient to provide an electric heating device. This means that the heat exchanger comprises an electrical heating device. In principle, however, the heating device can also be non-electrical. This is designed in particular for heating the fuel or fuel / water mixture, / 27

PP31901AT

AVL List GmbH particularly preferably, the heating device is designed and arranged exclusively for heating, evaporating and / or reforming the fuel or fuel-water mixture during a warm-up phase of the fuel cell system. During a start-up phase or warm-up phase of the fuel cell system, there is still no or not enough or not enough warm system exhaust gas to transfer the required heat to the heat exchanger. In the case of a heating operation, the electrical heating device can be in operation for a period of approximately 2 minutes to 10 minutes, for example. It is expedient if the heating device is arranged in a section through the heat exchanger between the evaporation area and the reforming area and / or overheating area. The electrical support for evaporation and reforming can in principle be carried out in an external component, but integration of this function is desirable for reasons of space. As soon as the fuel cell system has reached an operating temperature, the heating device is switched off again.

The use of a heat exchanger according to the invention is advantageous for vaporizing, overheating and reforming a liquid fuel in a SOFC system.

According to a further aspect of the present invention, a fuel cell system with a heat exchanger as shown in detail above is provided. The fuel cell system also has a fuel stack with an anode section and a cathode section, as well as a starting burner, an afterburner and at least one further heat exchanger. It is also expedient if the fuel cell system has a plurality of valves for controlling various lines and a blower for conveying the cathode supply air to the cathode section. The at least one further heat exchanger is arranged with a cold side in a cathode supply line downstream of the fan in order to raise the air which is supplied to the cathode section to a temperature which is correspondingly necessary for this. The fuel cell system according to the invention is used in particular in a motor vehicle.

The further goal is achieved if a method of the type mentioned at the beginning comprises the following steps:

/ 27

PP31901AT

AVL List GmbH

Directing a liquid fuel, in particular a liquid fuel / water mixture, in the direction of a heat exchanger according to the invention arranged in an anode feed line,

Evaporation, overheating and reforming of the fuel in the heat exchanger, the heat exchanger being heated via, in particular completely burned, system exhaust gas, heat being transferred from the system exhaust gas carried in a system exhaust gas line to the fuel,

- Feeding the vaporized, superheated and reformed fuel to an anode section of the fuel cell system.

An advantage achieved in this way can be seen, in particular, in that the fuel is vaporized, superheated and completely reformed efficiently and in a single component by the steps of the method according to the invention, so that it can subsequently be passed as synthesis gas to the fuel cell stack, more precisely to the anode section , In the context of the invention, a reformed fuel is to be understood as meaning synthesis gas which can be used in the fuel cell stack. Due to the heat transfer from the system exhaust gas to an evaporation area, overheating area and reforming area, the entire waste heat of the system exhaust gas is used to heat a single component. The heat of the system exhaust gas is advantageously transferred in the following order to carry out the processes taking place in the heat exchanger: overheating and / or reforming of the vaporized fuel or vaporized water-fuel mixture and vaporization of the fuel or water-fuel mixture.

The other advantages and functions associated with the functioning of the heat exchanger are the same as those described in detail above with reference to the heat exchanger according to the invention and the fuel cell system according to the invention.

It is furthermore advantageous if the fuel is steam-reformed in the heat exchanger, the heat exchanger comprising a catalytic material. In particular, no air supply is necessary or provided. Thermally conductive elements, for example plates, are particularly preferably coated with a catalytic material.

/ 27

PP31901AT

AVL List GmbH

Basically, the heat and system exhaust gas can flow through the heat exchanger in the direct current principle or in the cross flow principle. A particularly efficient heat transfer from the system exhaust gas to the fuel is achieved, however, if the fuel and the system exhaust gas flow through the heat exchanger in the counterflow principle. The fuel or vaporized or superheated fuel flows past the system exhaust gas as opposed to the respective area of the heat exchanger, heat being transferred from the system exhaust gas to the (vaporized and overheated) fuel and / or the catalytic material of the reforming area.

It is advantageous if the system exhaust flows through an evaporation region of the heat exchanger downstream of a reforming region of the heat exchanger, the system exhaust flowing through the reforming region downstream of an overheating region of the heat exchanger. With this arrangement of the elements or the order in which they flow through, heat is transferred particularly efficiently. This means that the necessary and predetermined temperatures which are required for the respective processes (evaporation, overheating, reforming) are reached in a short period of time.

It is particularly advantageous if the fuel flows through an evaporation area of the heat exchanger upstream of an overheating area of the heat exchanger, wherein the fuel flows through a reforming area of the heat exchanger downstream of the overheating area in order to further optimize the heat transfer.

It is expedient if air is conducted via a cathode supply line to a cathode section of the fuel cell system. In the context of the invention, air is understood to mean, in particular, ambient air, although air can also consist of a larger part of oxygen or pure oxygen. Downstream of the fuel cell stack, anode exhaust gas and cathode exhaust gas are mixed to form the system exhaust gas, by means of which the heat required for the evaporation process, overheating process and reforming process is made available.

Further advantages, features and effects result from the exemplary embodiments shown below. In the drawings, to which reference is made, show:

/ 27

PP31901AT

AVL List GmbH

1 shows a heat exchanger according to the invention;

2 shows a block diagram to illustrate a fuel cell system according to the invention in accordance with an embodiment according to the invention;

3 shows a block diagram to illustrate a further fuel cell system according to the invention in accordance with an embodiment according to the invention.

1 shows a heat exchanger 1 according to the invention. This comprises a plurality of heat transfer elements 2, an evaporation area 5, an overheating area 6 and a reforming area 7. Furthermore, the heat exchanger 1 designed as a plate heat exchanger has a cold side 8 and a warm side 9. The heat exchanger 1 is also included its cold side 8 can be arranged in an anode supply line 4 and heat can be transferred from system exhaust gas to an aqueous fuel carried in the anode supply line 4 via a system exhaust gas line 3. The heat exchanger 1 is designed as a plate heat exchanger and comprises a plurality of plate-shaped heat transfer elements 2, some of which comprise a catalytic material. Both the evaporation area 5, the overheating area 6 and the reforming area 7 comprise heat transfer element 2, these areas being flow-connected to one another. The heat exchanger 1 is designed to gradually evaporate, overheat and reform a fuel-water mixture, the thermal energy required for this being transmitted by the system exhaust gas. Since the heat exchanger 1 can be made compact due to the integral design of the three areas mentioned above, the size of an entire fuel cell system 100 is subsequently reduced. The heat exchanger 1 can in principle be designed for heat transfer in the cocurrent principle, countercurrent principle or cross-flow principle. The direction of flow of the fuel in the anode supply line 4 is always the same: in the direction of flow of the fuel first into the evaporation area 5, then into the overheating area 6 and finally into the reforming area 7. The heat exchanger 1 shown in FIG. 1 is operated in the counterflow principle. If this is to be operated according to the co-current principle or the cross-current principle, a guidance of the system exhaust gas line 3 or a flow sequence of the areas of the system exhaust gas are accordingly adapted.

/ 27

PP31901AT

AVL List GmbH

FIG. 2 shows a block diagram to illustrate a fuel cell system (100) according to the invention in accordance with an embodiment according to the invention. In addition to the heat exchanger 1, this further comprises a fuel cell stack 120 with an anode section 110 and a cathode section 130. In addition, there is a start burner 140, an afterburner 150, a further heat exchanger 160 and a fuel source 170 and an air source 180. The elements mentioned are via an anode feed line 4, a cathode supply line 12 and a system exhaust line 3 are connected to one another. Various valves 13 are provided for switching these lines 3, 4, 12. To supply air to the cathode section 130, a cathode fan 200 is provided, which is arranged in the cathode supply line 12 in the direction of flow of the air downstream of the air source 180 and upstream of the further heat exchanger 160. The further heat exchanger 160 is arranged with its cold side in the cathode supply line 12 and is designed to heat the air which is supplied to the cathode section 130. A warm side of the further heat exchanger 160 is flowed through by the system exhaust gas upstream of the heat exchanger 1.

3 shows a preferred embodiment of the fuel cell system 100, wherein the heat exchanger 1 is flowed through in the counterflow principle.

In a method according to the invention for operating a fuel cell system 100 according to FIG. 3, a liquid water-fuel mixture is routed from the fuel source 170 through the fuel pump 210 and a valve 190 in the open position in the anode supply line 4 in the direction of the heat exchanger 1 in regular operation. In the heat exchanger 1, the water-fuel mixture is completely evaporated in the evaporation area 5 in a first step, this having a temperature of over 100 ° C., preferably over 110 ° C., in particular about 120 ° C., when it emerges from the evaporation area 5 , In a second step, the temperature of the now gaseous water-fuel mixture step in the overheating area 6 is completely reformed to about 200 ° C. or 300 ° C. and in a third step in the reforming area 7. In the overheating area 6, the gaseous water-fuel mixture is thus preconditioned for use in the reforming area. The thermal energy required for these processes in the heat exchanger 1 is transferred via the heat transfer elements 2 from in / 27

PP31901AT

AVL List GmbH the system exhaust pipe 3 Transfer system exhaust. The water-fuel mixture now present as synthesis gas is conducted downstream of the heat exchanger 1 in the anode supply line 4 to the fuel cell stack 120, more precisely to the anode section 110.

Downstream of the fuel cell stack 120, the anode exhaust gas and the cathode exhaust gas are combined to form the system exhaust gas, the anode exhaust gas being burned in a catalytic afterburner 150 with admixture of the cathode exhaust gas. Downstream of the afterburner 150, the now completely burned system exhaust gas is conducted in the system exhaust gas line 3 in the direction of the further heat exchanger 160. Via the further heat exchanger 160, thermal energy is transferred from the system exhaust gas to the air, which is supplied to the cathode section 130 in the cathode supply line. Downstream of the further heat exchanger 160, it is arranged heat exchanger 1, to which the system exhaust gas is fed. The heat exchanger 1 is flowed through according to FIG. 3 in the counterflow principle, which is why heat is first transferred to the reforming area 7. 3, the reforming area 7 and the overheating area 6 are essentially designed as a common area. This means that the two steps of overheating and reforming in the heat exchanger 1 take place essentially simultaneously or with a very short time interval from one another. Downstream of the reforming area 7 or overheating area 6, the system exhaust gas is fed to the evaporation area 5 connected to the flow. The remaining heat from the system exhaust gas is used to evaporate the water-fuel mixture. The now cooled system exhaust gas is discharged downstream of the heat exchanger 1 into the environment 220.

Before the regular operation of the fuel cell system 100 described above, this and / or the elements arranged therein must generally be heated to a predetermined temperature. For this purpose, the fuel cell system 100 comprises a start burner 140. This is arranged in a partial line 14 of the fuel cell system 100. Fuel from the fuel source 170 and air from the air source 180 are fed to the starting burner 140 via two subsections 14a, 14b of the subsection 14. The first section 14a separates from the anode supply line 4 downstream of the fuel source 170, a valve 13b being arranged in the first section. The second subsection 14b separates / 27

PP31901AT

AVL List GmbH downstream of the air source 180 from the cathode supply line 12, the first section 14a and the second section 14b being brought upstream of the start burner 140. In the start burner 140, the fuel is consequently burned by supplying air to a hot gas. The gas is fed downstream of the starting burner 140 during a warm-up phase of the fuel cell system 100 in the flow direction first to the further heat exchanger 160 and then to the heat exchanger 1, the heat of the gas being transferred to the latter. As soon as the fuel cell system 100 or the individual elements thereof have reached the predetermined operating temperature, the heat transfer to the heat exchangers 1, 160 takes place via the system exhaust gas, as described above.

It is also expedient if a supply line 10 for air, evaporation area 5 or overheating area 6 is provided. 2 and 3, air or an oxygen-containing fluid can be fed to the evaporation region 5 via the feed line 10 in order to heat up the fuel cell stack 120 via catalytic partial oxidation when the fuel cell system 100 is in the heating mode. As soon as the fuel cell system 100 has reached an operating temperature, the air supply can be adjusted via a valve, not shown.

/ 27

PP31901AT

AVL List GmbH

claims

1. Heat exchanger (1) for a fuel cell system (100), in particular a SOFC system operated with a liquid fuel, with a plurality of heat transfer elements (2), thermal energy between a system exhaust gas line (3) and an anode supply line () through the heat exchanger (1) 4) of a fuel cell system (100) is transferable, comprising an evaporation area (5), an overheating area (6) and a reforming area (7) which are flow-connected to one another, characterized in that the heat transfer elements (2) at least partially comprise a catalytic material.

2. Heat exchanger (1) according to claim 1, characterized in that the anode supply line (4) is connected to the flow with the evaporation region (5), fuel via the anode supply line (4) connected to a cold side (8) of the heat exchanger (1), in particular a fuel-water mixture, which can be guided to an anode section (110) of the fuel cell system (100).

3. Heat exchanger (1) according to claim 1 or 2, characterized in that the system exhaust line (3) for supplying system exhaust gas from the fuel cell system (100) to the overheating area (6) and / or to the reforming area (7) is provided, in particular completely burned system exhaust gas can be conducted over a warm side (9) of the heat exchanger (1).

4. Heat exchanger (1) according to one of claims 1 to 3, characterized in that the overheating area (6) and the reforming area (7) are designed as a common area.

5. Heat exchanger (1) according to one of claims 1 to 4, characterized in that the heat exchanger (1) is designed as a plate heat exchanger.

6. Heat exchanger (1) according to one of claims 1 to 5, characterized in that the catalytic coating is designed as a catalytic fabric or catalytically coated, in particular metallic, grid.

/ 27

PP31901AT

AVL List GmbH

7. Heat exchanger (1) according to one of claims 1 to 6, characterized in that the reforming area (7) is designed and arranged to carry out steam reforming.

8. Heat exchanger (1) according to one of claims 1 to 7, characterized in that a supply line (10) of air to the evaporation area (5) or overheating area (6) is provided.

9. Heat exchanger (1) according to one of claims 1 to 8, characterized in that an electrical heating device is provided.

10. Use of a heat exchanger (1) according to one of claims 1 to 9 for evaporating, overheating and reforming a liquid fuel in a SOFC system.

11. Fuel cell system, in particular SOFC system, with a heat exchanger (1) according to one of claims 1 to 9, comprising a fuel cell stack (120) with an anode section (110) and a cathode section (130), characterized in that a starting burner ( 140), an afterburner (150) and at least one further heat exchanger (160) are provided.

12. A method for operating a fuel cell system, in particular an SOFC system, comprising the steps:

Directing a liquid fuel, in particular a liquid fuel / water mixture, in the direction of a heat exchanger (1) arranged in an anode supply line (4) according to one of claims 1 to 10,

- Evaporation, overheating and reforming of the fuel in the heat exchanger (1), the heat exchanger (1) being heated via, in particular completely burned, system exhaust gas, heat being transferred from the system exhaust gas carried in a system exhaust gas line (3) to the fuel,

- Feeding the vaporized, superheated and reformed fuel to an anode section (110) of the fuel cell system (100).

13. The method according to claim 12, characterized in that the fuel in the heat exchanger (1) is steam-reformed, the heat exchanger (1) comprising a catalytic material.

/ 27

PP31901AT

AVL List GmbH

14. The method according to claim 12 or 13, characterized in that the heat exchanger (1) is flowed through by the fuel and the system exhaust gas in the countercurrent principle.

15. The method according to any one of claims 12 to 14, characterized in that an evaporation area (5) of the heat exchanger (1) downstream of a reforming area (7) of the heat exchanger (1) is flowed through by the system exhaust gas, the reforming area (7) downstream of an overheating area (6) of the heat exchanger (1) is flowed through by the system exhaust gas.

16. The method according to any one of claims 12 to 15, characterized in that an evaporation area (5) of the heat exchanger (1) upstream of an overheating area (6) of the heat exchanger (1) is flowed through by the fuel, wherein a reforming area (7) of the heat exchanger ( 1) is flowed through by the fuel downstream of the overheating region (6).

17. The method according to any one of claims 12 to 16, characterized in that air is passed via a cathode supply line (12) to a cathode section (130) of the fuel cell system (110).

/ 27

PP31901AT

AVL List GmbH

1.3

Fig. 1

21/27

PP31901AT

AVL List GmbH

2.3

22/27

PP31901AT

AVL List GmbH

3.3

AOC,

Fig. 3

23/27

Search report for A 50153/2018 Austrian Patent Office

Classification of the subject of the application according to IPC: H01M 8/04014 (2016.01); H01M 8/0612 (2016.01); F28D9 / 00 (2006.01); H01M 8/124 (2016.01) Classification of the application according to CPC: H01M 8/04014 (2016.02); H01M 8/0618 (2016.02); F28D 9/0093 (2013.01); H01M 2008/1293 (2016.02) Researched test substance (classification): H01M, F28D Consulted online database: EPODOC, WPIAP, full-text patent databases EN and DE This search report was compiled on claims 1-17 filed on February 16, 2018. Category*) Title of the publication: Country code, publication number, document type (applicant), publication date, text or figure if necessary Concerning claim X X A A DE 102007018264 Al (EBZ DEVELOPMENT AND SALES COMPANY FUEL CELL MBH [DE]) October 16, 2008 (October 16, 2008) The whole document WO 02085777 A2 (PRECHTL PETER [DE] et al.) October 31, 2002 (October 31, 2002) Pages 11, 17-21, claims 22-28; Figure 1 DE 102008005839 Al (BORIT LEICHTBAU-TECHNIK GMBH [DE] et al.) July 30, 2009 (July 30, 2009) The whole document EP 0861802 A2 (MITSUBISHI ELECTRIC CORP. [JP] et al.) September 02, 1998 (September 2, 1998) Claims 1-13; Figure 1 1-7, 10-17 1, 5-9 1-17 1-17 Date of completion of the search: "... , Auditors (in): 14.12.2018 be ite from Ί ENGLISH Julia *> Categories of the listed documents: A publication that defines the general state of the art. X Publication of special importance: the application P document that is of importance (categories X or Y), but after object cannot be published as new or published on the priority date of the registration solely due to this publication, inventive activity can be considered based. E Document of particular importance (Category X) from which Y Publication of importance: the subject of the application may not result in an "older right" (earlier filing date, however novelty would be considered as based on inventive step, if the republished, protection is possible in Austria Make publication with one or more other publications), is associated with this category and this connection for & publication which is a member of the same patent family. is obvious to a specialist.

24/27

PP31901AT

Claims (17)

1. Heat exchanger (1) for a fuel cell system (100), in particular a SOFC system operated with a liquid fuel, with a plurality of heat transfer elements (2), thermal energy between a system exhaust gas line (3) and an anode supply line (1) through the heat exchanger (1). 4) of a fuel cell system (100) is transferable, comprising an evaporation area (5), an overheating area (6) and a reforming area (7) which are flow-connected to one another, the heat transfer elements (2) at least partially comprising a catalytic material, characterized in that that the heat transfer elements (2) have a catalytic material on the side through which system exhaust gas can flow. 2. Heat exchanger (1) according to claim 1, characterized in that the anode supply line (4) is connected to the flow with the evaporation region (5), fuel via the anode supply line (4) connected to a cold side (8) of the heat exchanger (1), in particular a fuel-water mixture, which can be guided to an anode section (110) of the fuel cell system (100). 3. Heat exchanger (1) according to claim 1 or 2, characterized in that the system exhaust line (3) for supplying system exhaust gas from the fuel cell system (100) to the overheating area (6) and / or to the reforming area (7) is provided, in particular completely burned system exhaust gas can be conducted over a warm side (9) of the heat exchanger (1). 4. Heat exchanger (1) according to one of claims 1 to 3, characterized in that the overheating area (6) and the reforming area (7) are designed as a common area. 5. Heat exchanger (1) according to one of claims 1 to 4, characterized in that the heat exchanger (1) is designed as a plate heat exchanger. 6. Heat exchanger (1) according to one of claims 1 to 5, characterized in that the catalytic coating is designed as a catalytic fabric or catalytically coated, in particular metallic, grid. 25/27 [LAST CLAIMS] PP31901AT AVL List GmbH 7. Heat exchanger (1) according to one of claims 1 to 6, characterized in that the reforming area (7) is designed and arranged to carry out steam reforming. 8. Heat exchanger (1) according to one of claims 1 to 7, characterized in that a supply line (10) of air to the evaporation area (5) or overheating area (6) is provided. 9. Heat exchanger (1) according to one of claims 1 to 8, characterized in that an electrical heating device is provided. 10. Use of a heat exchanger (1) according to one of claims 1 to 9 for evaporating, overheating and reforming a liquid fuel in a SOFC system. 11. Fuel cell system, in particular SOFC system, with a heat exchanger (1) according to one of claims 1 to 9, comprising a fuel cell stack (120) with an anode section (110) and a cathode section (130), characterized in that a starting burner ( 140), an afterburner (150) and at least one further heat exchanger (160) are provided. 12. A method for operating a fuel cell system, in particular an SOFC system, comprising the steps: Directing a liquid fuel, in particular a liquid fuel / water mixture, in the direction of a heat exchanger (1) arranged in an anode supply line (4) according to one of claims 1 to 10, - Evaporation, overheating and reforming of the fuel in the heat exchanger (1), the heat exchanger (1) being heated via, in particular completely burned, system exhaust gas, heat being transferred from the system exhaust gas conducted in a system exhaust gas line (3) to the fuel, system exhaust gas via heat transfer elements (2) having catalytic material is guided, - Feeding the vaporized, superheated and reformed fuel to an anode section (110) of the fuel cell system (100). ^26/27 [LAST CLAIM SUBMITTED ^ PP31901AT AVL List GmbH 13. The method according to claim 12, characterized in that the fuel in the heat exchanger (1) is steam-reformed, the heat exchanger (1) comprising a catalytic material. 14. The method according to claim 12 or 13, characterized in that the heat exchanger (1) is flowed through by the fuel and the system exhaust gas in the countercurrent principle. 15. The method according to any one of claims 12 to 14, characterized in that an evaporation area (5) of the heat exchanger (1) downstream of a reforming area (7) of the heat exchanger (1) is flowed through by the system exhaust gas, wherein the reforming area (7) upstream of an overheating area (6) of the heat exchanger (1) is flowed through by the system exhaust gas. 16. The method according to any one of claims 12 to 15, characterized in that an evaporation area (5) of the heat exchanger (1) upstream of an overheating area (6) of the heat exchanger (1) is flowed through by the fuel, wherein a reforming area (7) of the heat exchanger ( 1) is flowed through by the fuel downstream of the overheating region (6). 17. The method according to any one of claims 12 to 16, characterized in that air is passed via a cathode supply line (12) to a cathode section (130) of the fuel cell system (110).