EP1662199B1 - Evaporator and process for fabricating same - Google Patents

Description

The present invention relates to an evaporator arrangement, in particular for a vehicle heater or a reformer, comprising a shell-like support and in the shell-type support a porous evaporator medium and a method for producing the same.

Such evaporator arrangements are used, for example, in so-called evaporator burners to distribute this liquid fuel by introducing the initially liquid fuel into the porous evaporator medium due to the Kapillarförderwirkung in the volume range of the porous evaporator medium and can deliver over a relatively large surface area in the direction of a combustion chamber. In such known evaporator arrangements of the shell-like support is generally constructed of metal material, so for example made of sheet metal. The porous evaporator medium is also generally constructed of metal and made in a sintering process. Preformed bodies are therefore used here for the porous evaporator medium. These prefabricated bodies are inserted into the cup-like carrier and fixed at a plurality of discrete positions, for example by spot welding, or arrested by retaining rings at the edge region. Due to this only selective connection between the shell-like carrier and the porous evaporator medium received therein, there is the problem that, especially at the back of the porous evaporator medium, ie the side facing away from a combustion chamber, for example, gaps may be present in the adjoining area on the shell-like carrier or may arise. This may be due to the fact that deformations already occur during the bonding process in the porous evaporator medium, which lead to cracks. The thermal stress occurring during operation can also lead to deformations. In the area of this column, liquid fuel can accumulate and in an inappropriate place flow away. This can lead to uneven combustion, with the problem of increased pollutant emissions or an increased accumulation of combustion residues.

The DE 101 30 638 A1 discloses an evaporator assembly according to the preamble of claim 1. In this evaporator arrangement, a porous evaporator medium constructed with two layers is provided in a cup-like carrier. In a region in which liquid is introduced into this porous evaporator medium, a plate-like component providing a liquid deflection region lies between the two evaporator medium layers.

From the DE 101 64 225 A1 an evaporator arrangement for an evaporator burner is known, in which a two-layer constructed porous evaporator medium is sintered as a composite body in an evaporator housing. The two layers comprise an absorptive fiber layer serving for fuel evaporation and a fuel distribution view overlying the full area covering the same on its rear side facing away from a combustion chamber, which receives the fuel from a fuel supply line.

The DE 102 44 812 A1 discloses an evaporator arrangement for an evaporator burner with a single-layer porous evaporator body. The evaporator body has a circular segment-like region of lower porosity, which partially surrounds the junction region of a fuel supply line in the porous evaporator body.

It is the object of the present invention to provide an evaporator arrangement and a method for producing an evaporator arrangement, with which in a simple manner increased operational quality can be achieved.

According to a first aspect of the present invention, this object is achieved by an evaporator arrangement, in particular for a vehicle heater or a reformer according to claim 1.

This comprises a shell-like support and in the shell-like support a porous evaporator medium of multilayer construction, wherein the shell-like support has at least one Flüssigkeitseinleitöffnung and provided in a layer of the evaporator medium in a over the at least one Flüssigkeitseinleitöffnung extending portion of a liquid with respect to an inlet laterally dissipating Flüssigkeitsablenkbereich is.

It is further provided that the Flüssigkeitsablenkbereich comprises a portion of the porous evaporator medium with lower porosity, preceded by a liquid from a supply line receiving layer of higher porosity than the Flüssigkeitsablenkbereich, wherein the Flüssigkeitsablenkbereich providing layer in laterally adjacent to the Flüssigkeitsablenkbereich areas greater porosity than in the Flüssigkeitsablenkbereich and a smaller porosity than the liquid from the supply line receiving layer.

By such a configuration of the porous evaporator medium can be ensured that on the one hand reliably a fuel deflection can be achieved with a very simple structure, on the other hand, however, not facing, for example, a combustion chamber to be positioned areas of the porous evaporator medium covered by a separate deflection and thus not usable for the fuel evaporation.

A region of lesser porosity is thus a region in which the pore volume fraction in the porous evaporator medium is lower than in other regions, for example those regions in which the distribution of the fuel is generally to take place. However, a lower porosity means a deteriorated fuel carrying capacity or the complete seal against the penetration of liquid, which of course will depend on the viscosity of this liquid. Here, for example, it may be provided that the porosity in this Flüssigkeitsablenkbereich is about 20%, while in other areas in which the liquid is to be distributed by utilizing the Kapillarförderwirkung, a porosity of 60% to 70% is present.

Furthermore, it is possible for at least part of the porous evaporator medium to be designed with pore-preferred orientation.

At least a portion of the porous evaporator medium may be provided as a preformed sintered body and sintered into the cup-like support by pressure and temperature application. Further, it is of course possible that at least a part of the porous evaporator medium is provided as particulate material, filled in the cup-like carrier and sintered into the cup-like carrier by pressure and temperature.

The invention further relates to a vehicle heater, comprising an evaporator burner with an evaporator arrangement according to the invention and a reformer comprising an evaporator arrangement according to the invention.

1. a) Bereitstellen eines schalenartigen Trägers mit wenigstens einer Flüssigkeitseinleitöffnung,
2. b) Einbringen des Materials für ein poröses Verdampfermedium in den schalenartigen Träger,
3. c) Ausüben von Druck und Temperatur zum Einsintern des Materials für das poröse Verdampfermedium in den schalenartigen Träger zum Erzeugen eines mehrschichtig aufgebauten Verdampfermediums und zum Erzeugen eines Flüssigkeitsablenkbereichs in dem porösen Verdampfermedium in einem über die wenigstens eine Flüssigkeitseinleitöffnung sich erstreckenden Bereich, wobei der Flüssigkeitsablenkbereich einen Bereich des porösen Verdampfermediums mit geringerer Porosität umfasst, dem eine Flüssigkeit von einer Zuführleitung aufnehmende Schicht höherer Porosität als der Flüssigkeitsablenkbereich vorangeht, wobei die den Flüssigkeitsablenkbereich bereitstellende Schicht in seitlich neben dem Flüssigkeitsablenkbereich liegenden Bereichen eine größere Porosität als im Flüssigkeitsablenkbereich und eine kleinere Porosität als die Flüssigkeit von der Zuführleitung aufnehmende Schicht aufweist.

The above-mentioned object is further achieved by a method for producing an evaporator arrangement according to claim 5. This comprises the steps:

1. a) providing a shell-like support with at least one liquid introduction opening,
2. b) introducing the material for a porous evaporator medium into the cup-like carrier,
3. c) applying pressure and temperature for sintering the material for the porous evaporator medium into the cup-like carrier to produce a multilayered evaporator medium and for generating a Flüssigkeitsablenkbereichs in the porous evaporator medium in an over the at least one Flüssigkeitseinleitöffnung extending region, wherein the Flüssigkeitsablenkbereich a region of the porous porosity porous evaporator medium preceded by a liquid from a supply line receiving layer of higher porosity than the liquid deflection region, the layer providing the liquid deflection region having greater porosity in regions laterally adjacent to the liquid deflection region than in the liquid deflection region and a smaller porosity than the liquid Having liquid from the supply line receiving layer.

In order to be able to obtain a stable connection between the porous evaporator medium or the starting material thereof and the shell-like support, it is proposed that step a) comprises providing the shell-like support of metal material, preferably as a sheet-metal part.

In the method according to the invention it can be provided that step b) comprises the introduction of at least part of the material for the porous evaporator medium as prefabricated body, preferably sintered body.

Furthermore, it is possible that step b) comprises introducing at least part of the material for the porous evaporator medium as particulate material.

For a defined influencing of the distribution characteristic, it is proposed that steps b) and c) be carried out several times in succession to produce a multilayer porous evaporator medium. In a further embodiment, it is possible that in step b) a plurality of prefabricated bodies, preferably sintered bodies, are introduced into the dish-like carrier. In this case, a multi-layer structure is generated from the several prefabricated bodies in one operation.

Furthermore, it is particularly advantageous if, after step c) or each step c), a pressing step is carried out for at least partially compressing the porous evaporator medium generated in the preceding steps b) and c).

Fig. 1

eine Längsschnittansicht einer Brennkammerbaugruppe mit einer nicht erfindungsgemäßen Verdampferanordnung;

Fig. 2

eine Schnittansicht einer Ausgestaltungsart einer erfindungsgemäßen Verdampferanordnung;

Fig. 3

eine Schnittansicht einer alternativen Ausgestaltungsart einer erfindungsgemäßen Verdampferanordnung;

Fig. 4

eine weitere Schnittansicht einer alternativen Ausgestaltungsart einer erfindungsgemäßen Verdampferanordnung.

The present invention will be described below in detail with reference to the accompanying drawings. It shows:

Fig. 1

a longitudinal sectional view of a combustion chamber assembly with a non-inventive evaporator assembly;

Fig. 2

a sectional view of a Ausgestaltungsart an evaporator arrangement according to the invention;

Fig. 3

a sectional view of an alternative embodiment of an inventive evaporator assembly;

Fig. 4

a further sectional view of an alternative embodiment of an evaporator arrangement according to the invention.

In Fig. 1 is an evaporator assembly of a vehicle heater not constructed in accordance with the principles of the present invention or generally designated 10 for a reformer. This evaporator assembly comprises a combustion chamber housing 12, which forms an outer circumferential wall with a cylindrical region 14 and provides the axial termination with respect to a base region 16, which is firmly connected thereto or possibly integrally formed, axially relative to a longitudinal center axis A. In the housing 12 is a combustion chamber 18 (to be called in the case of use in a reformer as a mixing chamber) formed, in which, for example, over in the Fig. 1 recognizable openings 20 combustion stage is initiated. In order to provide the necessary for combustion fuel vapor, a generally designated 22 evaporator assembly is provided. This comprises a shell-like support 24 with an example cylindrical peripheral wall 26 and an adjoining bottom wall 28. Between the bottom wall 28 and the bottom portion 16 of the housing 12 is a designed for example as a heating coil 30 heater provided by excitation ensures that the evaporator assembly 22 and thus the liquid fuel contained therein can be heated. In this case, the arrangement is, for example, such that, by means of a securing ring 32, the bottom region 16 with the interposition of the heating spiral 30 clamps the shell-like carrier 24 against the peripheral region 14 of the housing 12 and thus locks it.

The bottom wall 28 of the carrier 24 has a funnel-like formation 34, which passes through an opening in the bottom region 16 of the housing 12 and into which a fuel supply line 36 opens. In this way, the fuel to be combusted together with combustion air can be introduced into the evaporator assembly 28. In the volume region enclosed by the carrier 24, a porous evaporator medium, indicated generally at 38, is provided. This is, as explained below, constructed of sintered material and has such a pore structure that the introduced via the fuel line 36 fuel can be distributed by Kapillarförderwirkung in the inner volume of the porous evaporator medium 38 and after distribution as evenly as possible over the combustion chamber 18 positioned side 40 of the porous evaporator medium 38 can be evaporated. For this purpose, for example, the porous evaporator medium 38 has a porosity ranging from 60% to 70%, i. 60% to 70% of the volume occupied by the entire porous evaporator medium 38 is actually provided by pores.

One recognizes in the Fig. 1 Furthermore, that the porous evaporator medium with two layers 42, 44 is constructed. The first layer 42 adjoins the bottom wall 28 and serves to directly receive the fuel from the fuel line 36 and to distribute it radially outward, radially here relative to the axis A again. The second layer 44 serves to further uniformize the fuel already pre-distributed in the layer 42 Direction way to the side 40 and thus evaporate down to the combustion chamber 18 out.

In order to ensure that the introduced via the line 36 into the carrier 24 liquid fuel is not directly in the area in which this introduction takes place reinforced in the direction of the page 40, a deflector 46 is provided. This is in the region in which the fuel line 36 introduces the fuel into the carrier 24, disposed in the adjoining region of the two layers 42, 44 and deflects the fuel, relative to its direction of introduction, which corresponds approximately to the axial direction A, radially outward and thus into the further volume regions of the layer 42.

For the production of in Fig. 1 Evaporator assembly 22 shown can be operated so that first the carrier 24 is provided with the desired shape. This can be done for example by forming a disc-like sheet metal blank, but can of course also be done by machining or material removal. If the carrier is provided with the desired shape and of the desired material, generally metal material, it may be positioned so that the bottom wall 28 is at the bottom and thus the cup-like carrier 24 is open towards the top. The particle-like or fibrous material intended to build up the first layer 42 of the porous evaporator medium 38 can then be scattered into the carrier 24 and distributed uniformly over the bottom wall 28. In this case, of course, that region which is provided for the opening of the fuel line 36, to be completed by a plug or the like. The thus prepared assembly is then compressed and sintered from above at a temperature of up to 1300 ° C. and by applying pressure to the particle material, so that essentially the first layer 42 with the desired material properties, ie approximately the desired porosity and the desired shape is obtained. In this sintering process, the individual particles of the particulate material, which are also generally made of metal, but for example, as well Contain shares of ceramic material, interconnected in their surface areas. At the same time, a connection to the surface of the shell-like carrier 24 takes place, so that the first layer 42 is also connected to it over substantially its entire surface area contacting the shell-like carrier 24.

In a next manufacturing step, by pressing the material of the first layer 42, it can then be brought to the desired final shape and desired density in order, if necessary, to be able to provide the required porosity in adaptation to the viscosity of the liquid to be conveyed. In this pressing operation, which can also be referred to as leveling, the deflecting element 46 can also be pressed into the material of the first layer 42 at the same time so that it lies flush with the remaining surface of this material of the second layer after the pressing process.

In a further working step, the second layer 44 is then formed. This can, as well as the first layer 42, by applying particulate material and subsequent sintering, so exerting pressure and temperature, are formed. However, it is also possible here to make available a prefabricated body of this second layer 44 with the desired circumferential dimensions, to apply it to the already produced layer 42 and then in a further sintering process, ie likewise by applying pressure and temperature, to the first layer 42 on the one hand and the deflector 46 and the peripheral wall 26 of the cup-like carrier 24 on the other hand by sintering to connect. Also, the second layer 44 is thus stable and without the possibility of gap formation on the carrier 24 on the one hand and the first layer 42 on the other hand connected.

In particular, when using a prefabricated body for the layer 44, which of course also in the layer 42 can be realized in the same way, it becomes possible to design this already with defined conveying capacity by making in the preparation of this prefabricated body preferred orientation of the particle or fiber material, in order to obtain a further improved distribution behavior in this way. By orienting the fibers in a particular preferred direction, a better capillary flow behavior is achieved in that direction than across it. Here it is also possible to provide a plurality of layers of differently oriented particles or fibers in such a body.

A major advantage in the foregoing with respect to the Fig. 1 described embodiment of an evaporator arrangement, that in addition to the previously mentioned stable and full-surface connection between the porous evaporator medium 38 and the carrier 24 and thus prevented gap formation, the material and the structure of the layers 42, 44 can be optimally adapted to the requirements occurring. For example, the layer 42 can be provided with greater porosity than the layer 44, so that although a faster, but nevertheless more uneven distribution in the layer 42 is obtained, while in the layer 44 then takes place a very uniformly extending fine distribution. Furthermore, such a stepped configuration of the porosity ensures better heat decoupling of that region in which, for example, liquid fuel is introduced, from the region in which very high temperatures prevail. Thus, the problem of a fuel outgassing can be counteracted especially in low-boiling fuels in this fuel inlet region. Also, the layer 42, in cooperation with the cup-like carrier 24, may be configured optimally for absorbing heat from the heating coil 30.

In Fig. 2 One embodiment of an evaporator arrangement 22 according to the invention is shown. The carrier 24 with its circumferential wall 26 and the bottom wall 28 and the region 34 for connecting the fuel line 36 can again be seen. Here, too, the porous evaporator medium 38 is basically composed of two layers 42, 44. However, the layer 42 extends only over that area in which fuel is taken up by connecting the fuel line 36. This layer 42 can be used again as a prefabricated sintered body in the carrier 24 and by pressure and Temperaturbeaufschlagung with be firmly connected to this.

The layer 44 is then produced on this layer 42, for example by placing a prefabricated sintered material body in the carrier 24 and pressurizing it. Due to the presence of the layer 42, the layer 44 will be compressed more strongly in a region 48 which lies above the layer 42 than in those regions in which the bottom wall 28 of the carrier 24 is not covered with the layer 42. The sintered body prefabricated for forming the layer 44 can then be sintered back into the carrier 24 by applying pressure and temperature and thus be connected to it in a planar manner and at the same time be connected to the layer 42 in the region 48. Due to the greater compression of the layer 44 in the region 48, which can be enhanced in a subsequent grading process, ie further pressing the sintered already in the carrier 24 layer 44, here is an area with significantly lower porosity compared to the side next the layer 42 lying areas available. The porosity in this region 48 may be about 20%, while it may be about 60% to 70% in the radially outer, ie less densified regions. The consequence of this is that the liquid fuel introduced into the layer 42 is very easily distributed in this layer 42, since it also has a greater porosity than the region 48. The porosity in the layer 42 is chosen to be higher than is in the region of the layer 44 outside the more densely compressed region 48. However, the liquid fuel received and predistributed in the layer 42 will preferably flow out radially outward, since the region 48, due to its lower porosity, represents a flow barrier for the capillary flow. However, a comparatively small proportion of the liquid fuel can also pass through this region 48 of lesser porosity and thus be discharged on the side 40 in the direction of the combustion chamber. Even with this arrangement, therefore, for a very uniform distribution of the liquid fuel, initially radially outward, and then for a uniform delivery, essentially over the entire surface of the side 40, is provided towards the combustion chamber. It can be the use of a additional deflecting be avoided, which makes the structure easier and cheaper. Furthermore, by selecting the composition or porosity and the material of the layer 42, the distribution behavior can be further improved. Here, for example, a ceramic tile can be used. In particular, this layer 42 can also serve to trap the pulsations occurring during fuel delivery in the pressure.

It should be noted here that, of course, also in this embodiment, for example, the second layer 44 can be generated by initially unbound fiber or particulate material is input into the shell-like carrier 24 and sintered into this. For deflecting the fuel in the region of its introduction then, for example, a separate deflection element could again be present.

In Fig. 3 In one embodiment, the first layer 42 is not only locally present in the region where the fuel is introduced into the cup-like carrier 24, but covers substantially the entire bottom wall 28. However, in the area where fuel is introduced, the second layer 42 is made slightly thicker. This can be done, for example, by using a corresponding punch in performing the sintering of this layer 42. Regardless of whether this is entered as a prefabricated body or as a particulate material, this form can also be produced in the subsequent leveling by using a correspondingly shaped stamp, with the result that a slightly lower porosity in the sections lying outside the thickened area layer 42 would be present.

Subsequently, the second layer 44 is then provided again, for example, again by inserting a prefabricated body and subsequent Einsintern the same. Due to the thickened region of the first layer 42, the area 48 with lower porosity and thus increased in this Einsintern or also in the subsequent leveling again Flow resistance generated for the required fuel deflection radially outward on the one hand, however, however, can provide a slight fuel passage in the direction of the combustion chamber on the other hand. Again, of course, it is again possible to use a body made for example of longer fibers to be able to pretend in this way again a preferred direction for the capillary.

Another embodiment is in Fig. 4 shown. It can be seen here first that the shell-like and shaped, for example, sheet metal carrier 24 is stepped here, so that two axially successive Umfangswandungsbereiche 26 and 26 'are provided with radial staggering and correspondingly also two Bodenwandungsbereiche 28, 28' with corresponding axial displacement available are. The porous evaporator medium 38 is again constructed in two layers from the two layers 42, 44. These, as already described above, can be provided from prefabricated sintered nonwoven bodies. These sintered nonwoven bodies or prefabricated bodies can be generated by punching out mat material. The prefabricated body provided to obtain the layer 42 is dimensioned such that it fits into the spatial region formed by the circumferential wall region 26 'and the bottom wall region 28', for example but initially has a greater axial extent than the peripheral wall region 26 'and thus the depth this room area. In a first Einsintervorgang can then by pressure and temperature exercise of the prefabricated body for the layer 42 with the carrier 24 in both the bottom wall portion 28 'and in the peripheral wall portion 26' are connected. Possibly. If necessary, a compression step, that is to say a pressing step, can then be carried out in order to bring the thus generated layer 42 to the desired thickness or porosity, wherein, for example, the surface of the layer 42 exposed to the front can lie flush with the bottom wall region 28. In an alternative, very advantageous procedure can be provided that after performing this first sintering or-Einpressvorgangs the Layer 42 still protrudes beyond the bottom wall region 28, so that it can be ensured that in the second sintering process, a stable sintered bond between the two layers 42 and 44 is generated. In a second machining operation, the prefabricated body for the layer 44 can then be introduced into the volume region bounded by the peripheral wall region 26, the bottom wall region 28 and the exposed side of the layer 42. In a subsequent sintering process, the layer 42 may be connected to the peripheral wall portion 26, the bottom wall portion 28 and the layer 42 by sintering. Again, the desired thickness or porosity of the layer 44 can be adjusted by a subsequent pressing operation.

It should be noted that the above-described multi-stage manufacturing process can also be carried out in one stage. Thus, the two prefabricated bodies for the layers 42 and 44 can be inserted into the carrier 24 in one operation and then joined in a common sintering process with this and with each other in their abutting surface regions.

With the in Fig. 4 As can be seen, the same advantages as described above can be obtained. Again, the layer 42 is configured with greater porosity, as the layer 44. Thus, the layer 42 can very quickly receive liquid fuel from a corresponding feed, pre-distribute this and in the layer 44, in which then due to the finer porosity and a very uniform fine distribution takes place. Furthermore, it is ensured by such a construction that the heat transfer from the combustion chamber facing side of the layer 44 is reduced towards the region in which the liquid fuel is fed from a line. Significantly contributes to this, the relatively low porosity of the layer 42. Of course, it is possible to use suitable adapted to the temperature conditions materials. Thus, for example, for the layer 42, a material can be used which withstand the high temperatures in the region of a combustion chamber very well can. In particular, ceramic material or a combination of such materials can be used here for the construction of this layer 42 in addition to metal material. Of course, the prefabricated bodies for the layers 42, 44 may be constructed of fibrous material, and in the manufacture of these bodies, the fibers may be selected according to the desired requirements. It is of course also possible to build up the layers 42, 44 to use materials or combinations of materials with different sintering or melting temperatures in order to obtain the desired deformation properties.

The present invention thus provides, in a simple manner, an evaporator arrangement for an evaporator burner or else also a reformer in which a very stable connection leading to high quality of operation is obtained between the porous evaporator medium and a dish-like carrier. For the porous evaporator medium as well as the shell-like support suitable materials with suitable dimensions can be provided in each case. This means that, for example, the shell-like carrier is constructed of metal material, in which case the use of a sheet-metal shaped part is preferred on account of its ease of manufacture. In the case of the porous evaporator medium, the use of metal particles or metal fibers has also proven to be particularly advantageous. Of course, here also ceramic materials, possibly mixed with metal materials are used. Of course, the layer structure can also be chosen as it is suitable for operation. Thus, of course, for the first layer as well as for the second layer in each case the suitable layer thickness or a suitable ratio of the layer thicknesses can be selected. Of course, more than two layers can of course be provided in the porous evaporator medium.

Claims (11)

1. Evaporator arrangement, in particular for a vehicle heating device or a reformer, comprising a shell-like carrier (24) and in said shell-like carrier (24) a multilayer porous evaporator medium (38), said shell-like carrier (24) comprising at least one liquid insertion opening and in a layer (44) of said evaporator medium (38) in a region extending across said at least one liquid insertion opening a liquid redirection region (48) draining off liquid to the sides in relation to an insertion direction,
   characterized in that said liquid redirection region (48) comprises a region of said porous evaporator medium (38) with a lower porosity, preceded by a layer (42) receiving liquid from a supply line (36) and having a higher porosity than the liquid redirection region (48), said layer (44) forming the liquid redirection region (48) having a higher porosity in regions laterally adjacent to the liquid redirection region (48) than in said liquid redirection region (48) itself and having a lower porosity than the layer (42) receiving liquid from the supply line (36).
2. Evaporator arrangement according to claim 1,
   characterized by at least part of the porous evaporator medium (38) being provided as a prefabricated sintered body and being integrated into said shell-like carrier (24) by sintering using pressure and temperature.
3. Vehicle heating device, comprising an evaporation burner with an evaporator arrangement (22) according to one of the preceding claims.
4. Reformer, comprising an evaporator arrangement (22) according to one of claims 1 or 2.
5. Method for manufacturing an evaporator arrangement (22) according to one of claims 1 or 2, comprising the following steps:

   a) providing a shell-like carrier (24) with at least one liquid insertion opening,

   b) integrating the material for a porous evaporator medium (38) into the shell-like carrier (24),

   c) applying pressure and temperature for integrating the material for the porous evaporator medium (38) by sintering into the shell-like carrier (24) for realizing a multi-layer evaporator medium (38) and for realizing a liquid redirection region (48) in said porous evaporator medium (38) in a region extending across said at least one liquid insertion opening, said liquid redirection region (48) comprising a region of said porous evaporator medium (38) with a lower porosity, preceded by a layer (42) receiving liquid from a supply line (36) and having a higher porosity than the liquid redirection region (48), said layer (44) forming the liquid redirection region (48) having a higher porosity in regions laterally adjacent to the liquid redirection region (48) than in said liquid redirection region (48) itself and having a lower porosity than the layer (42) receiving liquid from the supply line (36).
6. Method according to claim 5,
   characterized in that step a) comprises the realization of said shell-like carrier (24) by a metal material, preferably as a sheet metal part.
7. Method according to claim 5 or 6,
   characterized in that step b) comprises the insertion of at least part of the material for said porous evaporator medium (38) as a prefabricated body, preferably a sintered body.
8. Method according to one of claims 5 to 7,
   characterized in that step b) comprises the insertion of at least part of the material for said porous evaporator medium (38) as a particle material.
9. Method according to one of claims 5 to 8,
   characterized in that steps b) and c) are repeated several times in sequence for realizing a multilayer porous evaporator medium (38).
10. Method according to one of claims 5 to 8,
    characterized in that in step b) several prefabricated bodies, preferably sintered bodies, are integrated into said shell-like carrier (24).
11. Method according to one of claims 5 to 10,
    characterized in that after step c) or after each realization of step c) a compression step is carried out for at least partly compressing said porous evaporator medium (38) produced in the preceding steps b) and c).

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