EP2395296B1 - Heat exchanger - Google Patents

Description

The invention relates to a heat exchanger according to the preamble of claim 1. The invention also relates to an automotive air conditioning system with such a heat exchanger.

Automotive air conditioning systems serve to heat and / or to cool the air to be supplied to the interior of a motor vehicle. In automotive air conditioning systems, heat exchangers are used as electrical heaters to heat the air supplied to the interior. The electric heater includes PTC elements. Positive Temperature Coefficient (PTC) elements are current-carrying materials that have electrical resistance and can conduct electricity better at lower temperatures than at higher temperatures. Their electrical resistance thus increases with increasing temperature. The PTC element is generally made of ceramic and is a PTC thermistor. This raises regardless of the boundary conditions - such. For example, applied voltage, nominal resistance, or air quantity at the PTC element has a very uniform surface temperature at the PTC element. Overheating can be prevented as it z. B. could occur with a normal heat-emitting heating wire, since regardless of the boundary conditions always about the same resistance and thus a substantially identical electrical heating power is applied.

The heat exchanger comprises PTC elements, at least two electrical conductors through which electrical current is passed through the PTC element and heat conducting elements, in particular fins or corrugated fins, by means of which the surface is increased to heat the air. Increasingly, motor vehicles are produced which have an exclusive electric drive or a hybrid drive. Automotive air conditioning systems for these motor vehicles generally no longer have a heat exchanger for heating the air through which cooling fluid flows. The entire heating power of the automotive chimney system must therefore be applied by the electric heater or the PTC elements. For this reason, it is necessary, the PTC elements with high voltage, z. B. in the range of 50 to 600 volts instead of low voltage with 12 volts to operate. High voltage in an automotive air conditioning system, however, is a security problem because, for example, by a human touch of high voltage parts of the person from the high voltage health damage can be added.

The US 4,327,282 shows a heat exchanger with a PTC heating element. Current is passed through the PTC heating element by means of contact plates and an insulating layer is arranged on the contact plates. The components are held together by means of a U-shaped clip.

From the EP 1 768 458 A1 a heat generating element of a heater for air heating is known, comprising at least one PTC element and voltage applied to opposite side surfaces of the PTC element electrical conductor tracks, wherein the two electrical conductors are surrounded on the outside by a non-electrically conductive insulating layer.

The WO 03/088712 A2 discloses a heat exchanger with PTC elements arranged in a tube.

The EP 2 211 589 A1 discloses a heat exchanger with electrically heatable PTC elements.

The EP 2 151 639 A1 discloses a heat exchanger according to the preamble of claim 1.

The object of the present invention is therefore to provide a heat exchanger and a motor vehicle air conditioning system in which or in which a with electric current under high voltage, for example more than 50 V, operated heat exchanger without endangering the environment, in particular People, can be operated. The heat exchanger and the air conditioning should be inexpensive to manufacture and work reliably in operation.

This object is achieved with a heat exchanger according to claim 1.

An exemplary embodiment of the heat exchanger comprises at least one electrical resistance heating element, in particular at least one PTC element, at least two conductors electrically connected to the at least one electrical resistance heating element, in particular printed circuit boards, in order to conduct electrical current through the at least one electrical resistance heating element and thereby the electrical resistance heating element at least one heat conducting element for transmitting heat from the at least one electrical resistance heating element to a fluid to be heated, at least one electrical insulating element electrically isolating the at least two conductors, preferably from the at least one heat conducting element, wherein the at least two conductors and / or the at least one electrical resistance heating element is arranged in at least one cavity bounded by at least one cavity wall and the at least one electrical insulating belt t at least one molded seal is, wherein the at least one cavity wall is formed as at least one closed flat tube without joint in cross-section and the at least one molded seal in the cavity as a tube, in particular shrink tubing is formed. The tube is thus easy to manufacture and can only be produced by means of extrusion molding and already has a closed cross-section after production in cross-section. As a result, it is no longer necessary, the walls of the at least one tube to a closed tube with each other subsequently at a joint, z. B- a welding, soldering or splice to connect.

In particular, the at least one flat tube is formed with two broad side walls and two narrow side walls, and the two narrow side walls are braced by means of a compressive force acting on the two wide side walls, in particular the two narrow side walls are braced at a bending edge or a bending circle. On the two broad side walls of the at least one tube thus acts a compressive force, so that thereby the two broad side walls are pressed onto a heating composite in a cavity enclosed by the at least one tube cavity, thus the heating system is non-positively, in particular by means of clamping or jamming, with the at least one Tube, in particular the Breitseitenwandungen connected.

In a further embodiment, the at least one heat-conducting element comprises the at least one tube and / or the at least one heat-conducting element comprises corrugated ribs which are arranged on the outside of the at least one tube, in particular by means of soldering or gluing.

In a supplementary embodiment, the at least one heat-conducting element, in particular the at least one tube and / or the corrugated ribs, at least partially, in particular completely, of metal, for example aluminum or steel, or plastic

Preferably, the at least one molded gasket is disposed between each of a wall of the at least one tube and a conductor, so that the at least two conductors are electrically insulated with respect to the at least one tube.

The tube, in particular as a shrink tube, which forms the molded seal encloses in the invention, the heating unit with the two circuit boards and the PTC elements. As a result, the heating unit is electrically insulated.

Suitably, the at least one molded seal is elastic and / or the at least one molded seal consists at least partially of silicone or plastic or rubber and / or the at least one molded seal is positively and / or positively and / or materially connected to the at least one tube and / or the at least one molded seal is a foil. On a heat exchanger with multiple heating registers, a compressive force is applied and the elastic molded seal can deform due to this compressive force.

In a further embodiment, the at least one molded seal comprises heat-transmitting or thermally conductive particles, for. For example, alumina and / or silicon carbide and / or boron nitride, and / or the at least one tube is from a first, z. B. upper, cover plate at a first end, in particular fluid-tight, closed and / or the at least one tube is of a second, z. B. lower, cover plate is closed at a second end, in particular fluid-tight. Heat-transferring or heat-conducting particles in the at least one molded seal ensure that the heat generated by the PTC elements can also be conducted outwards to the heat-conducting elements, in particular the at least one tube and / or the corrugated fins, in a sufficiently good thermal conductivity.

In particular, the at least one electrical resistance heating element, the at least two conductors and the at least one molded seal are connected to at least one heating composite, which is or are arranged within the at least one tube, and preferably a plurality of tubes each having a heating composite and arranged between the tubes corrugated fins form the heat exchanger, wherein in particular by means of a clamping frame or a spring on the walls of the at least one tube, in particular the broad side walls of the at least one flat tube, the compressive force is applied.

An automotive air conditioning system according to the invention comprises at least one heat exchanger described in this patent application.

The at least one molded seal consists of an electrically insulating and thermally conductive material. Due to the geometric arrangement of the at least one molded seal within the heat exchanger, the at least two conductors and the at least one electrical resistance heating element are electrically insulated. The molded gasket is in a solid state of aggregation, i. H. not liquid or gaseous, even at high temperatures, eg. 70 ° C or 100 ° C.

In a further embodiment, the at least one molded seal is a film or insulating film, for. Example, a polyimide film (Kapton film), (elastic) ceramic-filled film or a (elastic) ceramic-filled silicone film.

In an additional variant, the heat exchanger has an IP protection class of 67, so that a sufficient waterproofness and dust tightness is present.

A closed pipe is a pipe whose walls are completely closed in a cross section.

In a further embodiment, the corrugated fins and the at least one tube are connected to each other by means of gluing and / or soldering and / or non-positively under prestress.

In a further embodiment, the first and / or second sealing plate has a groove, in which one end of the at least one tube is arranged.

In a further variant, the at least one tube in the groove with a seal, z. B. a, preferably elastic, seal, or an adhesive, sealed.

In a further embodiment, the at least one heat-conducting element and / or the at least one molded seal has a thermal conductivity of at least 1 W / mK, in particular at least 15 W / mK.

In a further embodiment, the at least one molded seal has an electrical insulation of at least 1 kV / mm, in particular at least 25 kV / mm.

In a variant, the at least one molded seal, preferably in cross section, has a dielectric strength of at least 1 kV.

In a further embodiment, the at least one molded seal has a thermal conductivity of at least 1 W / mK, in particular at least 15 W / mK. On the one hand, the at least one molded seal can thus insulate well electrically and, on the other hand, can sufficiently conduct the heat from the electrical resistance heating element to the heat-conducting element or the heat-conducting elements.

Fig. 1

einen Querschnitt einer Kraftfahrzeugklimaanlage,

Fig. 2

eine perspektivische Ansicht eines Wärmeübertragers ohne Deckplatten,

Fig. 3

eine Seitenansicht des Wärmeübertragers gemäß Fig. 2,

Fig. 4

eine Draufsicht des Wärmeübertragers gemäß Fig. 2.

Fig. 5

eine perspektivische Ansicht des Wärmeübertragers gemäß Fig. 2 mit Deckplatten ohne Heizverbund,

Fig. 6

eine Explosionsdarstellung des Wärmeübertragers gemäß Fig. 5,

Fig. 7

einen Querschnitt eines Heizregisters in einem ersten Beispiel gemäß Fig. 2,

Fig. 8

einen weiteren Querschnitt des Heizregisters gemäß Fig. 7,

Fig. 9

eine Explosionsdarstellung des Wärmeübertagers der Erfindung,

Fig. 10

eine perspektivische Ansicht des Wärmeübertragers ohne Deckplatten in einem ersten Beispiel,

Fig. 11

eine perspektivische Ansicht des Wärmeübertragers ohne Deckplatten in einem zweiten Beispiel,

Fig. 12

einen Querschnitt eines Rohres mit einer Einlage,

Fig. 13

einen Querschnitt des Rohres gemäß Fig. 12 mit dem Heizverbund,

Fig. 14

einen Querschnitt des Rohres gemäß Fig. 12 nach einem Zusammendrücken von Breitseitenwandungen,

Fig. 15

einen Querschnitt des Rohres ohne der Einlage in einem weiteren Beispiel und

Fig. 16

einen Längsschnitt des Heizregisters.

Hereinafter, examples that do not fall under the scope of the claims, as well as an embodiment (see Figure 9 ) of the invention with reference to the accompanying drawings. It shows:

Fig. 1

a cross section of an automotive air conditioning system,

Fig. 2

a perspective view of a heat exchanger without cover plates,

Fig. 3

a side view of the heat exchanger according to Fig. 2 .

Fig. 4

a plan view of the heat exchanger according to Fig. 2 ,

Fig. 5

a perspective view of the heat exchanger according to Fig. 2 with cover plates without heating compound,

Fig. 6

an exploded view of the heat exchanger according to Fig. 5 .

Fig. 7

a cross section of a heater in a first example according to Fig. 2 .

Fig. 8

a further cross section of the heater according to Fig. 7 .

Fig. 9

an exploded view of the heat exchanger of the invention,

Fig. 10

a perspective view of the heat exchanger without cover plates in a first example,

Fig. 11

a perspective view of the heat exchanger without cover plates in a second example,

Fig. 12

a cross section of a pipe with an insert,

Fig. 13

a cross-section of the pipe according to Fig. 12 with the Heizverbund,

Fig. 14

a cross-section of the pipe according to Fig. 12 after compression of broad side walls,

Fig. 15

a cross section of the tube without the insert in another example and

Fig. 16

a longitudinal section of the heater.

Fig. 1 shows an automotive air conditioning 24. In an air conditioning case 26 having a bottom wall 27 and an outlet portion 29, a fan 25, an air filter 30, a refrigerant evaporator 31 and a heat exchanger 1 is arranged as an electric heater. The air conditioning housing 26 thus forms a channel 35 for passing the air. Housing walls 28 of the air conditioning housing 26 have on the inside a surface 36 which define the channel 35. The air for the interior of a motor vehicle is passed by means of the blower 25 through the air filter 30, the refrigerant evaporator 31 and the heat exchanger 1.

The automotive air conditioning system 24 is thus not provided with a heat exchanger through which coolant flows for heating the air conducted through the motor vehicle installation 24. The air conducted by the motor vehicle air conditioning system 24 is electrically heated exclusively by means of the heat exchanger 1. The motor vehicle air conditioning system 24 is preferably used in a motor vehicle with exclusively electric drive or with a hybrid drive (not shown). In order to achieve the necessary electrical heating power by means of the heat exchanger 1, the heat exchanger with high voltage, eg. B. with more than 50 volts, for example, 60 V or 600 V, operated to not too large Amperages and thus too thick power lines (not shown) to get.

In the Fig. 2 to 16 Examples of the heat exchanger 1 for the motor vehicle air conditioning system 24 are shown. An aluminum tube 18 designed as a flat tube 13 has two broad side walls 20 and two narrow side walls 21 (FIG. Fig. 8 . 12, 13, 14 and 15 ) on. The width and narrow side walls 20, 21 thereby represent cavity walls 17, which enclose a cavity 19 within the tube 18. The width and Schmalseitenwandungen 20, 21 of the tube 18 are thus walls 16 of the tube 18. In this case, the walls 18 in cross-section no joint, z. As a tongue and groove connection, a welding or soldering, on. The tube 18 is made in one piece as a closed wall 18 with extrusions, so that no joints are required in cross section on the tube 18.

Within the flat tube 13, two molded seals 23 are arranged as electrical insulating elements 22. The two form seals 23 are made of elastic silicone. On the two rectangular shaped seals 23 ( Fig. 7, 8 . 13 and 14 ) are two conductors 4, namely a first circuit board 6 and a second circuit board 7, on. Between the two circuit boards 6, 7 three PTC elements 3 designed as electrical resistance heating elements 2 are arranged. The PTC elements 3 are connected to each other with the two printed circuit boards 6, 7 with adhesive. At the two conductors 4, an electrical contact plate 5 is formed in each case ( Fig. 3 and 9 ). The cavity 19 enclosed by the cavity walls 17 of the flat tube 13 is a void 32 in the region of the narrow side walls 21, ie in the void 32 only air ( Fig. 8 ).

As a result, the two circuit boards 6, 7 with the interposed three PTC elements 3 due to the electrical insulation of the molded gaskets 23 electrically isolated. The electrical contacting of the two circuit boards 6, 7 takes place by means of not shown electrical lines to the contact plates 5. The two circuit boards 6, 7 with the three PTC elements 3 thereby constitute a heating unit 10. After arranging the two form seals 23 on the heating unit After forming the heating system 8 into the flat tubes 13 with the corrugated fins 12, a heating coil 9 or the heat exchanger 1 is present. Several heater 9 as shown in FIG Fig. 2 . 10 and 11 can also be connected to a heat exchanger 1 with a larger number of heating registers 9 to each other.

The net height H _{N of} the heat exchanger 1 as shown in FIG Fig. 3 is about 50 to 300 mm, preferably 100 to 200 mm and the mesh width B _N is about 50 to 300 mm, preferably 100 to 200 mm. The transverse division Q, ie the distance between the flat tubes 13 as shown in FIG Fig. 4 , is in this case between 5 and 30 mm, preferably 9 to 18 mm and the overall depth T _N as shown in FIG Fig. 8 is 6 to 50 mm, preferably 10 to 40 mm. The overall depth T _R is 10 to 50 mm, preferably 10 to 40 mm. The thickness D _{E of} the printed circuit boards 6, 7 is 0.2 to 1.5 mm, the thickness D _{I of} the molded seals 23 0.1 to 1.5 mm and the width B _{R of} the tube 18 is 2 to 10 mm. The thickness D _{stone of} the PTC elements 3 is in the range between 0.8 to 3 mm.

Between the flat tubes 13 corrugated fins 12 are arranged as Wärmeleitelemente 11 ( Fig. 2 . 3 . 5 . 10 and 11 ). The corrugated fins 12 serve to enlarge the surface of the heat exchanger 1, in order to better release the heat emitted by the PTC elements 3 to the air, which flows through the heat exchanger 1. The heating coil 8, consisting of the two printed circuit boards 6, 7, the PTC elements 3 and the molded seal 23 is thereby only after the manufacture of the flat tube 13 in the Flat tube 13 inserted. The relevant manufacturing steps are in the Fig. 12 to 14 shown. The corrugated fins 12 can be connected to the corrugated fins 12 either before or after the heating composite 8 is introduced into the flat tube 13. The corrugated fins 12 can be connected to the flat tubes 13, for example, by gluing, welding or soldering. In addition, it is also possible to frictionally connect the world fins 12 with the flat tubes 13, because a pressure force 33 is applied to a heat exchanger 1 with a plurality of flat tubes 13 or heating coil 9 and due to this pressure force 33 (FIG. 10 and 11 ), the corrugated fins 12 between the flat tubes 13 can be held non-positively.

In Fig. 12 is a flat tube 13 with attached corrugated fins 12 shown in a cross section. Within the cavity 12 enclosed by the flat tube 13 there is a liner 38 or inlay 38. During the joining of the corrugated fins 12 with the flat tubes 13, low pressure forces in the region of the broad side walls 20 of the flat tube 13 may occur. In order to prevent resulting deformations and a reduction of the cavity 19, the insert 38 is arranged in the cavity 19. The insert 38 is not required if the flat tube 13 has a sufficiently high rigidity in order to be able to counteract these forces during the assembly of the corrugated fins 12 with the flat tube 13, without any deformation occurring on the flat tube 13. After joining, z. B. by means of soldering, the corrugated fins 12 to the flat tube 13, the insert 38 is removed from the flat tube 13 and then the heating composite 8 with the PTC elements 3 the two circuit boards 6, 7 and two molded seals 23 inserted into the flat tube 13 ( Fig. 13 ). The two form seals 23 have a substantially rectangular cross-sectional shape. These are thus two separate molded seals 23. According to the invention, the molded seal 23 is in the form of a hose 34 (FIG. Fig. 9 ), The hose 34 can In this case, be attached to the heating unit 10 with the two circuit boards 6, 7 and the PTC elements 3 as a shrink tube by shrinking under heating. During the insertion of the heating system 8 in the flat tube 13 ( Fig. 13 ), the distance between the two broad side walls 20 of the flat tube 13 is greater than the thickness of the heating composite 8, ie the distance between the two form seals 23. There is thus a distance between the two form seals 23 and the two wide side walls 20 before. As a result, the heating composite 8, the flat tube 13 can be easily inserted. After inserting the heating composite 8 into the flat tube 13, a compressive force 33 is applied to the two wide side walls 20 or to the corrugated fins 12 ( Fig. 14 ), so that the narrow side walls 21 deform or bend substantially at a bending edge 39 and thereby the distance between the two broad side walls 20 is reduced, so that the two wide side walls 20 are pressed onto the two form seals 23 of the heating system 8. In this in Fig. 14 illustrated state of the heating register 9 are thus the two narrow side walls 21 braced and the heating system 8 kraftschloßig, in particular by means of clamping, clamped between the two broad side walls 20. The pressure force 33 is, for example, by means of a not in Fig. 10 shown tension spring applied to the heat exchanger 1 with a plurality of heating registers 9 or by means of an in Fig. 11 shown tenter 37.

The flat tube 13 can next to the in the Fig. 12 to 14 illustrated example with the narrow side wall 21 with a bending edge 9 as a flat tube 13 with narrow side walls 21 in the geometric shape of a bending circle as shown in FIG Fig. 14 be educated. The manufacturing steps for connecting the heating composite 8 with the flat tube 13 according to Fig. 15 correspond in an analogous manner to the example of the flat tube 13 according to the first example, which in the Fig. 12 to 14 is shown.

After inserting the Heizverbünde 8 in the flat tubes 13 and the application of the compressive force 33 to the heat exchanger 1, an upper first cover plate 14 is applied to the upper ends of the flat tubes 13 and applied to the lower second ends of the flat tubes 13, a second lower cover plate 15 ( Fig. 5, 6 and 16 ). The first and second cover plate 14, 15 in this case has a plurality of substantially rectangular grooves into which the ends of the flat tubes 13 are inserted. In the grooves at the lower end of the grooves in each case a cutout 40 ( Fig. 16 ) available. In the cutout 40, for example, an adhesive is introduced as a seal 41. After insertion of the flat tubes 13 in the grooves of the first and second cover plate 14, 15, the ends of the flat tubes 13 are glued to this adhesive and thereby a liquid and dust-tight connection and sealing between the flat tubes 13 and the first and second cover plate 14, 15 produced. As a seal 41, for example, silicone can be used in addition to adhesive. The first and second cover plate 14, 15 consists of metal or plastic. As a result, all the flat tubes 13 of the heat exchanger 1 are dust-tight and sealed against the environment of the heat exchanger 1. Thus, to the circuit boards 6, 7 or the PTC elements 3 within the cavity 19 no liquid and no dust penetrate.

An upper side of the first upper cover plate 14 is connected dust-tight and liquid-tight with the air conditioning housing 26, so that no dust and no liquid can penetrate into the cavity 19 at the upper ends of the flat tubes 13. Notwithstanding this may be on the top of the first upper cover plate 14 also dust and liquid-tight an electronic housing attached (not shown).

The arranged within the channel 35 of the motor vehicle air conditioner 24 heat exchanger 1 is thus sealed dust and liquid-tight. dust or liquid within the channel 35 can thus not penetrate into the cavity 19 within the flat tubes 13.

Overall, significant benefits are associated with the heat exchanger 1 and the automotive air conditioning system 24. The heating assembly 8 is arranged dust and liquid-tight within the flat tubes 13, so that in the air duct 35 existing dust particles or liquid can cause no damage to the heat exchanger 1. The molded seal 23 is a commercially available insulating film and can thus be made available inexpensively in the production.

LIST OF REFERENCE NUMBERS

1

Heat exchanger

2

Electric resistance heating element

3

PTC element

4

ladder

5

Electric contact plate

6

First circuit board

7

Second circuit board

8th

Heizverbund

9

heater

10

heating unit

11

thermally conductive element

12

corrugated fins

13

flat tube

14

First cover plate

15

Second cover plate

16

Walls of the pipe

17

cavity wall

18

pipe

19

cavity

20

Breitseitenwandung

21

narrow side

22

Electrical insulating element

23

shaped seal

24

Automotive air conditioning system

25

fan

26

Air conditioning case

27

bottom wall

28

housing

29

exit section

30

filter

31

Refrigerant evaporator

32

White space within the flat tube

33

thrust

34

tube

35

channel

36

surface

37

tenter

38

inlay

39

bending edge

40

cutout

41

seal

H _N

net height

B _N

net width

Q

transverse pitch

T _N

overall depth

T _R

overall depth

D _E

Thickness of the printed circuit board

D _I

Thickness of the molded gasket

B _R

Width of the flat tube

D _Stain

Thickness of the PTC stone

Claims (9)

1. A heat exchanger (1), comprising

   - at least one electrical resistance heating element (2), in particular at least one PTC element (3),

   - at least two flat conductors (4) which are connected to the at least one electrical resistance heating element (2) in an electrically conductive manner, in particular conductor plates (6, 7), wherein the conductors are arranged on both sides of the resistance heating elements in order to guide electric current through the at least one electrical resistance heating element (2) and thereby heat the electrical resistance heating element (2),

   - at least one heat-conducting element (11) for the transfer of heat from the at least one electrical resistance heating element (2) to a fluid to be heated,

   - at least one electrically insulating element (22) which electrically insulates the at least two conductors (4), preferably from the at least one heat-conducting element (11), wherein

   - the at least two conductors (4) and the at least one electrical resistance heating element (2) are arranged in at least one hollow space (19) limited by at least one wall of the hollow space (17) and the at least one electrically insulating element (22) is at least one moulded seal (23), wherein

   the at least one wall of the hollow space (17) is formed as at least one closed flat tube (18), characterised in that the closed flat tube (18) is formed without a joint in the cross section and the at least one moulded seal (23) in the hollow space (19) is formed as a hose (34), in particular a shrinking hose (34).
2. The heat exchanger according to claim 1, characterised in that the at least one flat tube (13) is formed with two broadside walls (20) and two narrow side walls (21) and the two narrow side walls (21) are braced by means of a compressive force acting on the two broadside walls (20), in particular that the two narrow side walls (21) are braced on a bending edge (39) or a bending circle.
3. The heat exchanger according to claim 1 or 2, characterised in that the at least one heat-conducting element (11) comprises the at least one tube (18) and/or the at least one heat-conducting element (11) comprises corrugated ribs (12) which are arranged on the outside of the at least one tube (18), in particular by means of soldering or bonding.
4. The heat exchanger according to one or more of the preceding claims, characterised in that the at least one heat-conducting element (11), in particular the at least one tube (18) and/or the corrugated ribs (12), consist at least partially, in particular completely, of metal, for example aluminium or steel, or of plastic material.
5. The heat exchanger according to one or more of the preceding claims, characterised in that the at least one moulded seal (23) is arranged between one wall (16, 17) each of the at least one tube (18) and a conductor (4), so that the at least two conductors (4) are electrically insulated with regard to the at least one tube (18).
6. The heat exchanger according to one or more of the preceding claims, characterised in that the at least one moulded seal (23) is elastic and/or the at least one moulded seal (23) consists at least partially of silicon or plastic material or rubber and/or the at least one moulded seal (23) is connected to the at least one tube (18) in a non-positive and/or positive and/or firmly bonded manner and/or the at least one moulded seal (23) is a film.
7. The heat exchanger according to one or more of the preceding claims, characterised in that the at least one moulded seal (23) comprises heat exchanging or heat conducting particles, e.g. aluminium oxide and/or silicon carbide and/or boron nitride and/or the at least one tube (18) is closed, in particular in a fluid-tight manner, by a first, e.g. upper, cover plate (14) on a first end and/or the at least one tube (18) is closed, in particular in a fluid-tight manner, by a second, e.g. lower, cover plate (15) on a second end.
8. The heat exchanger according to one or more of the preceding claims, characterised in that the at least one electrical resistance heating element (2), the at least two conductors (4) and the at least one moulded seal (23) are connected to form at least one heating combination (8) which is or are arranged within the at least one tube (18) and preferably several tubes (18) having one heating combination (8) each and having corrugated ribs (12) arranged between the tubes (18) form the heat exchanger (1), wherein the compressive force is applied to the walls (16, 17) of the at least one tube (18), in particular the broadside walls (20) of the at least one flat tube (13), in particular by means of a tenter frame (37) or a spring.
9. A motor vehicle air conditioning system (24), characterised in that the motor vehicle air conditioning system (24) comprises at least one heat exchanger (1) according to one or more of the preceding claims.

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