EP1203923A2 - Heat exchanger, in particular condensation laundry drier - Google Patents

Abstract

An automotive radiator or heat exchanger consists of a sandwich pack of layers of thin tubes (2) separated from the adjacent layer by a corrugated panel of especially semi-flexible material (5). The sandwich pack is held together by a clip or strap.

Description

The invention relates to a heat exchanger in the preamble of claim 1 specified genus.

Heat exchangers of this type are known in numerous embodiments. You serve when used on tumble dryers, the purpose of drying room to guide incoming, moist process air through process air channels and at the same time to cool with ambient or room air flowing through cooling air ducts. The Heat exchangers act as condensers for the process air, and from this condensing water drips into a collecting vessel. The process air thus dried is returned to the drying room after heating. The process air and cooling air channels are usually perpendicular to each other, so that the heat exchanger in cross flow is flowed through by the process air and the cooling air.

To achieve an effective heat exchange and to avoid contamination it is usually desirable to pass the process air through ducts with large, smooth ones Conduct surfaces, due to the improved heat transfer due to moisture is sufficient in view of the desired heat exchange. Against on the cooling air side preferably means in the form of fins or baffles provided that enlarge the heat-exchanging surfaces of the cooling air channels and should compensate for the poorer heat transfer due to the lack of condensation, that there are almost the same products on the process air and cooling air side Heat transfer coefficient and heat exchange surface result. In addition, such Heat exchangers to date, with the exception of the frame, either completely from one Metal such as B. aluminum or completely made of plastic.

Heat exchangers made entirely of metal of the type described at the beginning work perfectly with regard to the desired heat exchange. Are a disadvantage their comparatively large manufacturing costs, which are caused on the one hand by the application of Aluminum, on the other hand through the for connecting the pipes, frames, fins and Baffles, etc. required procedures. That applies essentially independently whether the heat exchanger by gluing, welding, soldering, clinching or otherwise manufactured and / or from individual tubes or from so-called Multi-tube or multi-chamber profiles are assembled (e.g. GB-PS 885 150, DE 30 27 900 A1, DE 195 05 641 A1, DE 197 19 258, DE 198 01 609 A1, DE 38 11 504 U1, DE 296 14 186 U1, DE 296 19 653 U1, EP 0 881 448 A2, US Pat. No. 4,570,700).

In contrast, heat exchangers made entirely of plastic can be used at the beginning designated genus are comparatively inexpensive to manufacture (e.g. EP 0 044 561 A2, EP 0 429 953 B1, DE 198 38 525 A1, DE 198 53 526 A1). With such heat exchangers however, interfere with the poor heat conduction of the plastics to be used or the resulting poor heat transfer, especially on the Cooling air side. Even common means in the form of webs, profiles, slats or the like. in or on the cooling air ducts hardly lead to the desired products Heat transfer coefficient and heat exchange area. This also applies if instead of individual tubes multi-tube or multi-chamber profiles are used (DE 39 29 004 A1).

Furthermore, it is known in refrigeration technology (DE 21 14 340 A1), flat or flat oval Metal pipes and between them, also made of metal fins by deforming the wide pipe sides to connect with each other that the finished stacked heat exchanger network with the help of tie rods between two outer plates is squeezed. This type of manufacture is a nuisance on the one hand like the others the above, the only heat exchangers made of metal Weight and the comparatively large material and manufacturing costs, on the other hand the high forces required to deform the metal pipes. Besides, they would have to Pipe ends if the pipes are not serpentine, as suggested there laid, bent in a circle or wound helically, additionally by Soldering, gluing or the like with frame or for connection to collection boxes Base plates or the like. Are connected, which further increases the manufacturing costs.

Finally, heat exchangers are known, the frames made of plastic and pipes have, optionally made of plastic or metal, the frame and Pipes can be connected to each other with a simple plug connection (DE 296 18 878 U1). However, such heat exchangers have no means for Increase in heat transfer so that it is not for everyone and especially not are usable for the above-mentioned purposes.

The invention is therefore based on the technical problem of the heat exchanger to initially form the genus so that it on the one hand good heat conduction and Has heat transfer properties, but on the other hand inexpensive and with a comparatively low total weight can be produced.

The characteristic features of claim 1 serve to solve this problem.

The invention is based on the idea of the advantages of plastic and metal materials to combine. According to the invention, where z. B. due to Condensation processes a good heat transfer is achieved due to operational conditions, usual Plastics such as B. Thermoplastics used while where the heat conduction magnifying agents must be provided from metals such. B. aluminum manufactured slats, baffles or the like. Are provided. The means to achieve good heat exchange properties by elastic bracing with the Plastic pipes kept in plant, making them easier, cheaper Assemble the different parts. By using pipes and frame made of plastic also has the advantage that inexpensive connection methods can be applied by the pipes and frames z. B. by Plastic welding processes are interconnected.

Further advantageous features of the invention emerge from the subclaims.

Fig. 1 und 2 je eine schematische, perspektivische Darstellung und eine Vorderansicht von Teilen eines ersten Ausführungsbeispiels eines erfindungsgemäßen Wärmeaustauschers;

Fig. 3 einen Längsschnitt etwa längs der Linie III - III der Fig. 1 durch einen fertigen, aus den Teilen nach Fig. 1 und 2 und zugehörigen Rahmen zusammengesetzten Wärmeaustauscher;

Fig. 4 eine schematische, perspektivische Darstellung von Teilen eines zweiten Ausführungsbeispiels eines erfindungsgemäßen Wärmeaustauschers;

Fig. 5 eine teilweise geschnittene perspektivische Darstellung eines fertigen, aus den Teilen nach Fig. 4 zusammengesetzten Wärmeaustauschers;

Fig. 6 zwei Varianten einer Verschiebesicherung für Lamellen des Wärmeaustauschers nach Fig. 4 und 5;

Fig. 7 eine teilweise geschnittene Seitenansicht von Teilen eines dritten Ausführungsbeispiels eines erfindungsgemäßen Wärmeaustauschers;

Fig. 8 eine teilweise geschnittene perspektivische Darstellung eines fertigen, aus den Teilen nach Fig. 7 zusammengesetzten Wärmeaustauschers;

Fig. 9 eine schematische Vorderansicht eines Teils eines vierten Ausführungsbeispiels eines erfindungsgemäßen Wärmeaustauschers; und

Fig. 10 einen vergrößerten Schnitt längs der Linie X - X der Fig. 9.

The invention is explained below in connection with the accompanying drawings of exemplary embodiments. Show it:

Figures 1 and 2 each a schematic, perspective view and a front view of parts of a first embodiment of a heat exchanger according to the invention.

3 shows a longitudinal section approximately along the line III - III of FIG. 1 through a finished heat exchanger composed of the parts according to FIGS. 1 and 2 and the associated frame;

4 shows a schematic, perspective illustration of parts of a second exemplary embodiment of a heat exchanger according to the invention;

5 shows a partially sectioned perspective view of a finished heat exchanger composed of the parts according to FIG. 4;

6 shows two variants of a displacement safety device for fins of the heat exchanger according to FIGS. 4 and 5;

7 is a partially sectioned side view of parts of a third embodiment of a heat exchanger according to the invention;

Fig. 8 is a partially sectioned perspective view of a finished heat exchanger composed of the parts of Fig. 7;

9 shows a schematic front view of part of a fourth exemplary embodiment of a heat exchanger according to the invention; and

10 is an enlarged section along the line X - X of FIG. 9th

1 and 2 schematically show a large number of individual tubes Pipes 1, which have oval cross sections and parallel in a plurality of planes one above the other and in each level in a plurality of columns in parallel next to each other are arranged. The tubes 1 have wide wall sections 2 and narrow wall sections 3 on and are arranged in the embodiment so that within each level each have their narrow wall sections 3 facing each other, whereas in superimposed levels each facing the wide wall sections 2 are. The tubes 1 are arranged at preselected intervals so that between them channels 4 (Fig. 1) are present.

Should be from the tubes 1 z. B. a heat exchanger for a condensation heat exchanger are produced, then the tubes 1 are preferably used as flow channels for moist process air coming from a drying room, while channels 4 serve as flow channels for cooling air arranged perpendicular to the tubes 1 and with Thermally conductive elements in the form of fins 5 are provided, which, for. B. from meandering Shaped strips known per se in heat exchangers and the tubes 1 facing, with their wide wall sections 2 coming to the broad sides 5a exhibit. The fins 5 fill the channels 4 in a central part of the heat exchanger preferably completely out while in front in the outer sections and leave free pipe ends 1a (Fig. 1) at the rear. As in FIG. 3 shows when the heat exchanger is inserted into openings 6 of frame 7, which are attached to the front or rear end of the heat exchanger and the Keep pipes 1 at a distance.

According to the invention, the tubes 1 and frame 7 consist of a plastic, e.g. B. one Thermoplastic in the form of a polyolefin (PE, PP) or polyester (PET, PBT or ABS). You can therefore z. B. by extrusion, blow molding, injection molding or. The like. Can be produced inexpensively. Also the connection of the tubes 1 and Frame 7 can be inexpensive, d. H. without the use of adhesives or the like. B. by well-known plastic welding processes such as ultrasonic, vibration, friction, thermal contact, Induction, laser or heating element welding can be done as in Fig. 3 is indicated by blackened welds 8. The pipe ends 1a can be expanded slightly for this purpose. In contrast, the slats 5 according to the invention from good heat-conducting metals, and their production takes place, for. B. in that thin aluminum strips are folded in a meandering shape.

To make a good one between the plastic tubes 1 and the metal fins 5 to enable heat-conducting and, on the other hand, an inexpensive connection, the tubes 1 and fins 5 are elastically clamped together. This is in Fig. 3 shown on a heat exchanger, the tubes 1 to facilitate the Representation are arranged in only one plane and analogous to FIGS. 1 and 2 together with one in FIG. 3 lying above or below a slat 5 held together by the frame 7 Form a stack. This stack is from both sides by one Side part 9 (or an end plate) braced with its ends in a form-fitting manner corresponding recesses 10 of the frame 7 protrudes and with its upper or lower broad side on a broad side facing it of an associated lamella 5 is applied. An elastic bracing is achieved in that at least one Side part 9 in the relaxed state from a plate-shaped, but pre-bent Sheet metal part exists, the one facing the lamella 5 and coming into contact with it Broadside is convex, as shown schematically by a dash-dotted line in FIG. 3 side part 9a shown is indicated. The assembly of the different parts z. B. in that from the tubes 1, the fins 5 and the side parts 9a formed stack with a press or the like. Compressed so that the side parts 9a from the pre-bent shape into one shown in FIG. 3 with solid lines, be brought substantially plane-parallel shape 9. Then the front one and the rear frame 7 plugged on, the ends of which now act as leaf springs Side parts 9 enter the recesses 10 and are positively held in them while the pipe ends 1a enter the openings 6 with sufficient play, come into intimate contact with the slats 5 and then with the frame 7 under Formation of a stable heat exchanger block welded liquid or gas tight become. It is clear that the side parts 9 preferably over the entire width and depth of the heat exchanger block and are therefore in each case on the entire surface of the the broad sides 5a of the outermost slats 5 assigned to them act. The slats 5 are preferred in directions transverse to their broad sides comparatively rigid to ensure uniform power transmission.

The heat exchanger according to the invention preferably has an additional means for Improvement of the heat transfer caused by the elastic tension or thermally conductive contact. This agent contains e.g. B. the respective pipe shape adapted broad sides 5a of the slats 5, expediently at least those Broad sides 5a are adapted, which abut the tubes 1. In the embodiment this means that the fins 5 across the tubes 1 get a varying thickness (Fig. 1 and 2) by their broad sides 5a in the area of the tubes 1 with their length extending concave recesses 5b are provided. These take in the embodiment when forming the stacks, the wide wall sections 2 of the tubes 1 are open and have hence like this, an essentially oval or parabolic contour. Besides, that is Arrangement preferably made so that the radii of curvature of the recesses 5b are somewhat larger than that of the pipes 1 in the region of the wide wall sections 2 (FIG. 2, left half). The slats 5 are therefore through the side parts 9 with a certain Bias pressed against the tubes 1 (Fig. 2, right half), then these thereby pressed into a somewhat flatter shape and broadly into a good heat-conducting Brought into contact with the surfaces of the slats 5 forming the recesses 5b, such as can be clearly seen from a comparison of the left and right half of FIG. 2. It is clear that the distances from facing broad sides 5a of the slats 5 larger than the thickness of the tubes 1 measured across the broad sides 2 should be one sufficiently large elastic contact pressure can be exerted.

The recesses 5b have, as shown in particular in FIG. 1, in the assembled state furthermore the effect of securing the slats 5 against displacement across the tube axes, which means that even with thin walls of the various parts an overall stable block formation is achieved. Alternatively or additionally, the Pipes 1 are provided with different wall thicknesses for this purpose. Moreover can the tube outer walls and / or the facing broad sides 5a of the fins 5 for Improvement of the heat transfer can be covered with a thermal paste.

3, the block consists of tubes 1 arranged in several planes, then in each case both opposite broad sides 5a of the slats 5 with the depressions 5b provided. It goes without saying that in the exemplary embodiment like the Broad sides 5a are not continuously continuous (FIG. 1), but from them bordering sections of the meandering aluminum strips are formed.

When using individual tubes 1, those that can be achieved with the frame 7 according to FIG. 3 are obtained Packing densities are not optimal. On the one hand, the curves on the narrow sides of the Pipes 1 inevitably result in dead spaces, on the other hand, the distance between the pipes 1 in the frame 7 should not be arbitrarily small, since there is sufficient space for the sealing or Welding process must be available. According to a particularly preferred Exemplary embodiment of the invention (FIGS. 4 to 6) is therefore instead of the individual tubes 1 at least one multi-tube or multi-chamber profile, preferably produced in one piece 14 provided, which as a whole forms a plane of the heat exchanger block. The Multi-chamber profile 14 contains a plurality of parallel and without dead spaces next to each other lying tubes 15, the top and bottom in Fig. 4 by wide side walls 16 and right and left are limited by narrow webs 17 and one self-contained Form chamber or a channel. Each have two adjacent tubes 15 a web 17 arranged between them in common. The broad ones, between two Wall sections 16 arranged in webs are oval or similar to the tubes 1 (FIG. 1) or convex outwards. Are more pipes 15 required than one of the chambers Corresponds to multi-chamber profile 14, several multi-chamber profiles 14 are side by side or according to FIGS. 5 and 6 arranged in several planes one above the other. The Multi-chamber profiles 14 are made of plastic according to the invention and can be inexpensive z. B. can be produced by extrusion.

In a further analogy to FIGS. 1 and 3 there are 14 between the individual multi-chamber profiles or on their two sides forming the wide wall sections 16 each made of metal existing slats 18 arranged, the z. B. from the slats 5 of FIGS. 1 to 3 meandering folded aluminum strips are made, but across the axes of the Pipes 15 have a consistently constant thickness in the manner of a plane-parallel plate. In addition, the multi-chamber profiles 15 are at the ends left free by the slats 18 14a (FIG. 4) held in plastic frame 19 (FIG. 5), which frame 7 according to FIG. 3 to the same in the difference that they have openings 20 with a width of the multi-chamber profiles 14 have the appropriate length.

5 shows, one of at least one multi-chamber profile 14 and one associated slat formed stack on the top and possibly also the bottom by one Side part 21 elastically clamped to a stable heat exchanger block. At least For this purpose, one of the side parts 21 is relaxed like the side part 9a according to FIG. 3 Condition pre-curved convex, in the assembled condition, however, with its ends shaped like a leaf spring into a substantially plane-parallel plate by its ends are positively received in corresponding recesses 22 of the frame 19 are. Otherwise, the side parts 21 extend between the frames 19 the entire width and depth of the heat exchanger (Fig. 5).

When using the heat exchanger according to FIGS. 4 and 5 flows on clothes dryer the process air z. B. in the direction of an arrow PL through the pipes 15, the cooling air in the direction of an arrow KL through the fins 18.

There is a means of improving the heat transfer or heat-conducting contact in this embodiment in that each multi-chamber profile 14 a plurality of contains tubes 15 arranged next to one another, the convex curvature of the individual Broad sides or wall sections 16 is selected so that it is due to the assembly of the elastic pressure are pressed into a substantially flat shape (FIG. 6), whereby there is an intimate contact between the wide wall sections 16 and Broad sides of the fins 18 and good heat transfer between the process air side (Tubes 15) and the cooling air side (fins 18). Because of the small width that each individual pipe section 15 without significantly affecting the desired Function can be given, there is no risk that the broadsides bend concavely when pressing the fins 18, as is the case when using a single tube 1 the size of a multi-chamber profile 14 inevitably the case would.

The heat exchanger according to FIGS. 4 and 5 is assembled analogously to that according to FIG. 1 to 3. The connection of the multi-chamber profiles 14 and the frame 19 takes place as in 1 to 3 expediently by welding.

In order to avoid that the slats 18 unintentionally crosswise during or after assembly move the tubes 15, according to the invention are additional locking devices intended. For this purpose, the multi-chamber profiles 14 have their in FIGS. 4 and 5 right and left side surfaces z. B. each have a retaining web 23 projecting above their height, as indicated in the left part of FIG. 6. This holding webs 23 lay in the assembled State from the outside to the lamellae 18 lying between the multi-chamber profiles 14 and thereby prevent their lateral displacement. Alternatively, as in 6, the right and left side surfaces of the slats 18 with their height-superior retaining webs 24, which are mounted in the State from the outside to the multi-chamber profiles 14 lying between the slats 18 create and thereby prevent lateral displacements of the slats 18.

Otherwise, the same applies to the heat exchanger according to FIGS. 4 to 6 as for the 1 to 3.

The exemplary embodiment according to FIGS. 7 and 8 is distinguished from those according to FIGS. 1 to 6 characterized in that first and second tubes 26, 27 in the form of multi-chamber profiles and first and second frames 28, 29 each form structural units made from one piece Plastic injection molded parts are made. To simplify production, the Heat exchanger composed of three parts, namely the first, z. B. front frame 28 and the attached first tubes 26, the second, for. B. rear frame 29 and the attached second tubes 27 and between the Pipes 26, 27 to be arranged, here wavy or also corresponding to FIGS. 4 to 6 trained slats 30 with the same thickness throughout. Here are in the embodiment the tubes 26 of the front frame 28 vertically backwards and the tubes 27 of the rear frame 29 each vertically from the front, each coaxially Passages 31 are aligned, which pass through the frames 28, 29 to the tubes 26, 27 analogous to FIGS. 3 and 5 with to be arranged on the outer sides of the frames 28, 29 To be able to connect collecting boxes or the like.

7 and 8, the first and second tubes 26 and 27 alternately arranged in different planes, the frame 28 three in FIG. 7 first and the frame 29 forms two second tube levels and each a level of Tubes 27 is arranged between two levels of tubes 26. Alternatively, it would be also possible to attach the tubes 26, 27 to the frame 28, 29 so that in each Level both first tubes 26 of one frame 28 and second tubes 27 of the other Frame are arranged.

As shown in FIG. 7 in particular, the tubes 26 and 27 have tapering cross sections on, which are largest in the area of the associated frame 28, 29 and in the direction their free ends gradually decrease. Among other things, this facilitates demolding of the units 26, 28 and 27, 29 in their manufacture by injection molding Plastic.

The frames 28, 29 have further passages 32 between the passages 31. These are dimensioned and shaped so that they can accommodate the free ends of those tubes 26, 27 which are attached to the other frame 28, 29. Therefore, the two units consisting of the frame 28 and the tubes 26 or of the frame 29 and the tubes 27, each made in one piece, are moved towards one another in the direction shown by FIG. 7 in the direction of arrows v , w until the free ones The ends of the tubes 26, 27 each enter the associated passages 32 of the frames 28, 29, a block is obtained analogously to FIGS. 1 to 3, in which the free ends of the individual tubes 26, 27 and the frames 28, 29 are preferably through Welding can be connected.

The cross-sectional tapering of the tubes 26, 27 are preferably uniform throughout. This results in between the assembly of the two units the tubes 26, 27 channels with a substantially constant height throughout, which the Arrangement and uniform contact of slats 30 with the same thickness throughout enables and facilitates. It is also clear that the passages 31, 32 in the manner of a Grid are distributed in the frame 28, 29, as is the arrangement of the the frame 28, 29 attached pipes corresponds.

As a means of improving the heat transfer in this exemplary embodiment, such a dimensioning of the cross-sectional tapering of the tubes 26, 27 is preferably provided that when the frames 28, 29 approach in the direction of the arrows v and w, the previously inserted fins 30 analogously to the exemplary embodiments according to FIG. 1 to 6 elastically biased transversely to the tubes 26, 27 and thereby brought into good heat-conducting contact therewith. As an alternative and in addition, the means could consist of providing the tubes 26, 27 with trapezoidal or oval cross sections, analogously to FIGS. 1 to 6, in order to additionally elastically deform their wide wall sections and / or to provide pre-bent side parts 33 which fit in recesses 34 of the frames 28, 29 are inserted and brace the entire block elastically. Provision can furthermore be made to use the side parts 33 only as customary end plates and, if necessary, for bracing the two outermost fins (for example 30a in FIG. 7), the other fins 30 on the other hand solely via the conical or other shape of the tubes 26 To clamp 27 with these. Finally, it is possible to replace the multi-chamber profiles or tubes 26, 27 by means of individual tubes analogously to FIGS. 1 to 3.

Otherwise, the same applies to the embodiment according to FIGS. 7 and 8 as for the Embodiments according to FIGS. 1 to 6, in particular additional displacement locks can be provided.

9 and 10, in which only parts of a heat exchanger are shown, the elastic bracing takes place in that heat-conducting elements in the form of baffles 36 which have openings 37 with these z. B. on Flat oval tubes 38 are pulled up, the guide plates 36 according to the invention a metal such as B. aluminum and the tubes 37 made of plastic such. B. one Thermoplastic exist. As a means of improving the heat transfer between the Baffles 36 and tubes 38 have the openings 37 by a bending process manufactured, upstanding collar 39 which in the relaxed state by the angle are smaller than 90 °, protrude from the guide plates 36 and therefore obliquely into the openings 37 protrude. In contrast, the outer cross sections of the tubes 38 with a certain Excess manufactured with regard to the inner cross sections of the collar 39 so that the Collar 39 elastically spread when the tubes 38 are inserted into the openings 37 and be resiliently applied to the outer walls of the tubes 38, which ensures good heat transfer is ensured. The collar 39 can be continuous in the circumferential direction trained or only partially, e.g. B. in the area of the wide wall sections the tubes 38 may be provided.

Plastic frames, not shown in FIGS. 9 and 10, can be analogous to FIGS. 1 to 8 be formed and connected to the tubes 38 by welding. Moreover 4 to 6, the tubes 38 can be realized by multi-chamber profiles.

An advantage of the embodiment of FIGS. 9 and 10 is that the biased Side parts can be omitted.

The invention has the advantage that on the side of the pipes (e.g. process air side) smooth and therefore insensitive to dirt on the side of the In contrast, fins or baffles (e.g. cooling air side) have large heat exchange surfaces high heat conduction can be obtained in the individual surface sections, as z. B. at the application of the heat exchanger described in tumble dryers is desired.

The invention is not restricted to the exemplary embodiments described, which are based on can be modified in many ways. That applies e.g. B. for those used in individual cases Pipe shapes, since the pipes are especially different from those shown Arches and cross sections can be provided. The tubes can also be used Required inside with known webs or the like which increase their surface area. be provided, which are of little use in terms of their heat conduction, but one can give increased stability. Also the combination of single pipes and Multi-chamber tubes possible within one and the same heat exchanger. Further depend on the number of pipes and fins or guide plates used and the number of pipe levels provided for each heat exchanger entirely depending on the needs of the individual case from. Instead of the meandering (rectangular) slats shown wavy (rounded), triangular and other lamellas as well as mixed forms of which are used. In addition, the heat exchangers described can be provided other than the shown protection against displacement and in addition not shown drip edges, collecting channels or the like. for dripping condensate exhibit. Finally, it goes without saying that the different features also exist in other than the combinations shown and described can be applied.

Claims (22)

Heat exchanger, in particular for condensation tumble dryers, with a plurality of tubes (1, 15, 26, 27, 38) and attached at their ends sealed in openings (6, 20, 32) of frames (7, 19, 28, 29) a plurality of channels (4) arranged between the tubes (1, 15, 26, 27, 38), in which heat-conducting elements (5, 18, 30, 36) are arranged, characterized in that the frames (7, 19, 28 , 29) and pipes (1, 15, 26, 27, 38) are made of plastic, while the heat-conducting elements (5, 18, 30, 36) are made of metal and are thermally conductive to the pipes (1, 15, 26, 27, 38) are connected. Heat exchanger according to claim 1, characterized in that the means consist of folded fins (5, 18, 30) made of metal, the broad sides (e.g. 5a.) Coming into contact with the tubes (1, 15, 26, 27) ) exhibit. Heat exchanger according to claim 2, characterized in that the tubes (1) consist of individual tubes having oval cross sections. Heat exchanger according to one of claims 1 to 3, characterized in that it has a means for improving the heat transfer between the tubes (1, 15, 26, 27, 38) and the heat-conducting elements (5, 18, 30, 36). Heat exchanger according to Claim 4, characterized in that the means contains depressions (5b) in the broad sides (5a) of the fins (5) which are adapted to the tubular shape. Heat exchanger according to claim 5, characterized in that the depressions (5b) are formed with larger radii of curvature than the broad sides (5a). Heat exchanger in succession Claims 3 to 6, characterized in that fins (5) stacked one above the other and tubes (1) arranged between their broad sides form a stack which is elastically braced by two side parts (9, 9a) arranged on opposite sides. Heat exchanger according to claim 2, characterized in that the tubes (15) are formed by multi-chamber profiles (14) which have a plurality of parallel chambers lying next to one another. Heat exchanger according to claim 8, characterized in that the agent contains outwardly curved wall sections (16) of the tubes (15) facing the fins (18). Heat exchanger according to claim 8 or 9, characterized in that the fins (18) have a substantially constant thickness. Heat exchanger according to one of Claims 8 to 10, characterized in that a plurality of fins (18) stacked alternately one above the other and multi-chamber profiles (14) arranged between them form a stack and the stack is elastically clamped by two side parts (21) arranged at opposite ends. Heat exchanger according to one of claims 7 to 11, characterized in that the side parts (9, 9a, 21) consist of pre-bent plates held in the frame (7, 19) by positive locking. Heat exchanger according to claim 4, characterized in that the agent contains tubes (26, 27) with cross sections tapering in opposite directions and the fins (30) are each arranged between two tube levels and have essentially constant thicknesses. Heat exchanger according to Claim 13, characterized in that the tubes (26) tapered in one direction with their ends having the largest cross section at a first frame (28) and the tubes tapered in the opposite direction with their ends having the largest cross section a second frame (29) is fastened and the frames (28, 29) have passages (32) for receiving the free ends of the tubes (26, 27) fastened to the other frame (28, 29). Heat exchanger according to claim 14, characterized in that the elastic bracing of the fins (30) takes place by inserting and fastening the free ends of the tubes (26, 27) into the passages (32) of the frames (28, 29). Heat exchanger according to one of claims 13 to 15, characterized in that the tubes (26, 27) consist of single tubes or multi-chamber profiles. Heat exchanger according to one of Claims 13 to 16, characterized in that the tubes (26, 27) and the frames (28, 29) are combined to form two injection-molded plastic parts. Heat exchanger according to one of claims 1 to 17, characterized in that the tubes (1, 15, 26, 27) are connected to the frames (7, 19, 28, 29) by welding. Heat exchanger according to one of claims 2 to 17, characterized in that it has displacements (5b, 23, 24) which prevent displacements between the tubes (1, 15) and fins (5, 18). Heat exchanger according to Claim 1, characterized in that the heat-conducting elements consist of baffles (36) which are elastically drawn onto the tubes (38) and which have openings (37) penetrated by the tubes (38) and collars (39) surrounding them , Heat exchanger according to claim 20, characterized in that the means contains elastically biased collars (39) which can be expanded by the tubes (38). Heat exchanger according to one of claims 2 to 21, characterized in that the fins (5, 18, 30) and / or baffles (36) are made of aluminum.

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