WO2005088219A1

WO2005088219A1 - Heat exchanger for a motor vehicle air conditioning system

Info

Publication number: WO2005088219A1
Application number: PCT/EP2005/002537
Authority: WO
Inventors: Frank Obrist; Norbert Tessendorf; Peter Kuhn; Martin Graz
Original assignee: Obrist Engineering Gmbh
Priority date: 2004-03-18
Filing date: 2005-03-10
Publication date: 2005-09-22
Also published as: US20070023172A1; DE112005000305A5; DE102004011608A1

Abstract

The heat exchanger (1) for a motor vehicle air conditioning system has mutually parallel and vertically arranged flat tubes (2), the ends of which join each of two headers (10, 18). The opposed and mutually spaced surfaces of adjacent flat tubes (2) define air flow channels (8, 9) allowing condensed moisture to flow away easily and preventing the accumulation of dirt. The heat exchanger (1) is compact and yet has a sufficiently large surface area on the air side because of the close spacing of the flat tubes (2). The correspondingly large number of flat tubes (2) produces a large flow cross-section on the working fluid side with correspondingly little pressure loss, so that the flat tubes (2) can be traversed more than once through the action of flow deflectors in the headers of the heat exchanger (1). The close spacing is achieved by bunching the tube ends (35) together at the connection point and incorporating a bend (36). Bead-like raised portions (11) of the flat tubes (2) running parallel to each other and obliquely to the longitudinal direction of the flat tubes (2) give both the air-side flow channels (8, 9) and the internal channels for the air conditioner working fluid within the flat tubes (2) an undulating form which promotes heat transfer. The smooth surface of the flat tubes (2) on the air side with its hydrophilic coating promotes the drainage of moisture from the heat exchanger (1) and thus makes it more effective for both cooling and heating a switchable air conditioning system without generating large quantities of steam when the system is switched to heating mode.

Description

Heat exchanger of a vehicle air conditioning system

The invention relates to an air / refrigerant heat exchanger, in particular for a motor vehicle air conditioning system, with a plurality of parallel, air-flowed flat tubes in which refrigerant is guided, opposing walls of adjacent flat tubes forming flow channels for air flow between them The flat end of the flat pipes jointly terminate in at least one connection distributor (10, 18), a connection distributor having a pipe connection for integration into a pipe system.

Heat exchangers of this type are known in numerous embodiments, e.g. show the US 5941303 and the prior art mentioned there. This literature, like DE 10306786, essentially deals with the configuration of the connection distributors and the flow guides that can be achieved by them for the medium flowing through the numerous pipes. What they have in common is that the pipes that open into the connection manifold to enlarge their outer, i.e. air-side surface, have corrugated ribs, since the air-side heat transfer is many times worse than that on the inside pipe surface in contact with the operating medium of the air conditioning system. In the drawings of US Pat. No. 5,941,303, these wavy ribs were not shown to simplify the drawing, but the second paragraph of the detailed description shows that they were considered necessary. Leaving them out would mean that, with the same compact construction required for vehicles, there is not a sufficiently large heat transfer area on the air side to achieve sufficient heat transfer for the air conditioning system.

The equipment of the tubes with fins, including their soldering to the tubes, is associated with a great deal of effort and is often faulty due to incompletely produced solder contacts along the soldering areas which run over relatively large distances. The numerous angular spaces formed between the tubes and their fins form collection points for airborne, partially organic ones

BESTÄTIGUΝGSKOPIE Dirt particles, with the consequence of hygienic loads and odors in the air flowing from the heat exchanger into the passenger compartment. The surfaces of the corrugated ribs and these angular spaces also form an extensive collecting space for moisture, which is formed by condensation from the cooled air during cooling operation of the air conditioning system and thus cannot flow downward. An optional operation of such a heat exchanger for heating by means of the air conditioning system would also lead to a sudden evaporation of the entire wetness and condensation on the windshield of the vehicle, so that instead a corresponding switch to a second heat exchanger connected in parallel has to be provided with corresponding effort.

The invention has for its object to provide a heat exchanger of the type mentioned, in which an improved heat transfer between the refrigerant and air is made possible. Furthermore, the heat exchanger in a compact design should have a reduced susceptibility to dirt and moisture, so that it can be used both in cooling mode and in heating mode, in particular in a CO ₂ air conditioning system.

This object is achieved in that elongated depressions and / or elevations are arranged in mutually opposing walls of adjacent flac tubes such that longitudinal axes of the depressions and / or elevations are oriented obliquely to a flow direction of the air flow and / or obliquely to a flow direction of the refrigerant flow , The object is further achieved in that an area ratio between the inner, refrigerant-side surface and the outer, air-side surface of the flat tubes (2) is set between 0.7 and 1.5, in particular approximately 1.

Advantageous embodiments of the invention are the subject of the dependent claims and the following description can be found with reference to the drawings. Show it

1 shows an overall view of a heat exchanger according to the invention in the direction of the air flow, FIG. 2 shows a side view of the heat exchanger according to FIG. 1, showing its tilted mounting position, 3 is a perspective view of a flat tube corrugated by stampings of a heat exchanger according to the invention,

4 is a partial perspective view against the air flow front side of the heat exchanger,

5 shows a partial cross section through a wave-shaped air duct,

6 shows a vertical longitudinal section through part of a bottom-side connection distributor with connected flat tubes bundled in pairs,

7 shows a side view of the connection distributor according to FIG. 6,

8 shows a vertical longitudinal section through the connection-side area of flat tubes bundled in a three-way arrangement,

9 is a vertical longitudinal section through the connection-side region of unbundled flat tubes,

10 is a horizontal section through the head-side connection distributor,

11 is a horizontal section through the bottom-side connection distributor,

12 shows a vertical cross section through a head-side connection distributor,

13 shows a vertical cross section through a bottom-side connection distributor,

14 shows a vertical cross section through a further embodiment of a head-side connection distributor,

15 shows a perspective illustration of a guide insert for the inflow channel of the connection distributor according to FIG. 13,

16 shows an overall view of a heat exchanger according to the invention in the direction of the air flow, with, to simplify the representation, only a partial, indicated representation of the profiling of its flat tubes,

17 shows a side view of the heat exchanger according to FIG. 16, without showing the profiling of its flat tubes,

18 shows a longitudinal section through the bottom wall of the bottom-side connection distributor of the heat exchanger according to FIG. 16,

19 is a plan view of the bottom wall of FIG. 18,

20 shows a vertical section through the bottom-side connection distributor of the heat exchanger according to FIGS. 16 and

21 shows a schematic representation of the flow distribution in a heat exchanger according to the invention, 22 is a schematic plan view of a portion of a comb-like spacer,

23 is a perspective view of another embodiment of a flat tube according to the invention,

24 shows a cross section through the flat tube according to FIG. 23 along the line Z-Z,

25 shows a schematic cross section through a further flat tube according to the invention along the line Y-Y in FIG. 26,

26 the further flat tube according to the invention according to FIG. 25,

Fig. 27 is a plan view of a further floor wall according to the invention similar to Fig. 19 and

28 shows a longitudinal section through the bottom wall according to FIG. 27 along the line X-X.

A heat exchanger 1 according to the invention is preferably provided for installation in the supply air flow of a CO ₂ vehicle air conditioning system and accordingly takes over the function of an evaporator in cooling operation. For this purpose, it is installed in an inflow housing, not shown, combined with a blower. This requires compact overall dimensions of the heat exchanger 1, for example corresponding to a width of 235 mm and a height of 250 mm. In order to ensure a heat exchange performance appropriate to the required performance of the air conditioning system, a relatively large heat exchange surface must be provided on the air side, since on this side the heat transfer is approximately five times worse than on the inner surface of the heat exchange tubes through which the operating medium of the air conditioning system, for example CO2, flows. In modified exemplary embodiments, other refrigerants, for example water, NH ₃ , R404A, R407C, R410A, R22, SF6 etc., are provided.

The heat exchange tubes are designed in a manner known per se as extruded flat tubes 2 made of an aluminum alloy and enclose inner channels 3 running parallel to one another. By dividing the flat tubes 2 into numerous inner channels 3 with a diameter of, for example, 0.6 mm and a thickness of the flat tubes 2 of, for example, 1.2 mm, the flat tubes 2 are suitable for absorbing a high internal pressure of substantially more than 100 bar, as is to be expected when a CO air conditioning system is operated in heating mode. In addition, the numerous narrow inner channels 3 result in a uniformly uniform flow distribution over the cross section of the flat tubes 2, which is advantageous for the heat exchange, with a relatively large one internal heat exchange surface. The diameter of the inner channels 3 is preferably chosen to be rather small, but can also be made larger than indicated, depending on the application and the refrigerant used.

In order to provide a sufficiently large heat exchange surface for the heat exchanger 1 on the outside of the flat tubes 2, around which the air flows, without adjacent disadvantages, adjacent flat tubes 2 according to the invention, without heat exchange ribs arranged in between, are closely spaced apart by less than 3 mm and preferably at least approximately 2 mm arranged so that the opposing surfaces 4, 5; 6, 7 or walls of adjacent flat tubes 2 preferably form largely non-contact flow channels 8, 9 between them for the air flow. As a preferred feature in this context, it should also be mentioned that the flat tubes 2 are oriented in the installation situation with their longitudinal axis essentially vertical or at an acute angle to the vertical, while the heat exchanger flows through essentially in the horizontal direction. Along the outer surfaces 4 to 7 of the flat tubes 2, water condensing on them can thus run down immediately, so that the heat transfer is not impaired by moisture. A smooth and non-angled design of the surfaces 4 to 7 prevents contamination from settling in the flow channels 8, 9 and thus an unsanitary air pollution, which could possibly have resulted in an unpleasant odor.

Surfaces 4 to 7 are preferably surface-treated or surface-structured in such a way that the natural surface tension of water on surfaces 4 to 7 is reduced. In particular, it is provided to provide the surfaces 4 to 7 with a hydrophilic surface layer. A hydrophilic surface layer can e.g. B. can be achieved by chemical surface treatment of the flat tubes formed from an aluminum alloy with chromic acid, as is known per se for the production of primers, for example in aircraft construction, as a chromic acid anodizing process. Alternatively, other chemical surface treatment methods such as silica anodizing processes etc. can also be used. As an alternative or in addition, mechanical surface treatments are conceivable which produce a hydrophilic surface structure on at least one of the surfaces 4 to 7. There are also various hydrophilic coatings can be provided, which can be applied to surfaces 4 to 7 in different thicknesses (if necessary in heat treatment processes). For example, coatings with chromium nitride (CrN), titanium dioxide (TiO ₂ ), zirconium-niobium compounds (Zr-2.5Nb) or similar compounds are suitable. In general, coatings with monodisperse nano and / or microparticles can also be used. Further alternatively or additionally, a polyvinylpyrrolidone coating can be provided.

With the help of the surface treatment and coating processes mentioned, hydrophilic surfaces can be produced on the flat tubes 2, which advantageously make it possible for condensed water to spread on the surfaces without the formation of drops and preferably to form a thin film. The water drains off correspondingly quickly or evaporates immediately, so that an accumulation of water is effectively avoided. In addition, the prevention of an accumulation of water enables the use of the heat exchanger 1 not only for cooling, but also for heating the passenger compartment of a vehicle, by preventing a substantial amount of evaporating moisture from entering the passenger compartment after switching to heating operation and there on the Windshield condenses in a dangerous manner.

A further improvement in the moisture repellency from the smooth surfaces 4 to 7 of the flat tubes 2 and an improved heat transfer to these surfaces 4 to 7 result from several, mutually parallel, bead-like features 11 which extend through the entire cross section of the flat tubes 2, so that they are wavy on both sides.

Preferably, the features 11 are so deep and the distance between the flat tubes 2 is so small that the concave side of the respective features 11 of a flacco tube 2 together with the convex side of the respective shape 11 of the adjacent flat tube 2 limit wavy air channels 12 in the flow direction. In other words, this means: In opposing walls 4, 5; 6, 7 of adjacent flat tubes 2, elongated depressions 11 are arranged in such a way that elongated elevations correspondingly dimensioned lie directly opposite the elongated depressions, so that there is no significant reduction in the flow cross-section on the air side. This is due to the Serte representation in Figure 5 illustrates. This illustration clarifies that with a distance “13” measured adjacent to the flat tubes 2 between adjacent flat tubes 2, the width of the flow channels 8, 9 changes periodically, with a minimum distance “14” and a maximum distance corresponding to said distance “13” Together with the waveform of such flow channels, this leads to eddies in the air flowing through, which improves the heat transfer and favors the separation of moisture with its downward conduction.

The bead-like, for example rectilinear shapes 11 are preferably directed obliquely to the longitudinal axis (main axis) of the flat tubes 2, as can be seen in the illustrations in FIGS. 2, 3 and 4. In this way it is achieved that the inner channels 3 running in the longitudinal direction of the flat tubes 2 are curved in a wave shape and that there is also an improved heat transfer on the inside of the flat tubes 2 with the prevention of the formation of larger drops. In other words, this means: In opposing walls 4, 5; 6, 7 of adjacent flat tubes 2, elongated, bead-shaped depressions 11 are arranged such that the longitudinal axes of the depressions are inclined to the direction of flow of the air flow (which is oriented approximately horizontally and parallel to the surfaces 4 to 7) and obliquely to a direction of flow of the refrigerant flow (which in is aligned approximately in the direction of the main or longitudinal axes of the flat tubes). Correspondingly dimensioned elongated elevations lie directly opposite the elongated depressions, so that there is no significant reduction in the flow cross-section on the air side.

To improve the inflow angle of the horizontally flowing air to the sloping, bead-like features 11 and to improve the discharge of condensed water, the heat exchanger 1 is arranged according to the illustration in FIG. 2 at an angle of 5 °, for example, slightly tilted forward.

The free end regions of the flat tubes 2 each end in secondary chambers 15, 16, 17 of the two connection distributors 10 and 18, which are provided on the heat exchanger 1 on the bottom and on the head side. They are tightly integrated there by soldering. The secondary walls 15, 16, 17 mutually delimiting, parallel to the flat tubes 2 web walls 19, 20, 21 and connecting them together, longitudinal web walls 22, 23, 24 according to the representations in Fig. 10 and Fig. 11 give the Flat tubes facing the side of the manifold 10, 18 a strength appropriate to the maximum internal pressure. In addition, they serve to divide the operating medium of the air conditioning system that flows in and out via primary channels 25 to 29 of the two connection distributors 10, 18, in order to flow through the flat tubes 2 and the heat exchanger 1 in a plurality of deflected partial streams in a manner known per se, so that this flows through it a largely uniform temperature distribution and consequently a maximum average temperature gradient of the heat transfer results. An example of such a flow distribution is shown in the schematic illustration in FIG. 21 using the connection distributor 53 shown there.

For an improved distribution of the operating medium flowing in at the bottom in this exemplary embodiment into the regions of the flat tubes 2 divided by web walls 21, 23, 24, a guide insert 34 is provided in the inflow channel 33, which, due to its twisted, screw-like shape, causes the flow f stops and thus contributes to a mixing of the operating medium of the air conditioning system.

In order to be able to integrate the flat tubes 2, despite a predetermined distance between the web walls 20, 21 delimiting the secondary chambers 16, 17, at a small distance 13 from one another into the connection manifolds 10, 18 and accordingly one in comparison to the exemplary embodiment of the invention according to FIG. 9 6 and 8, two or three flat tubes 2 are bundled together in a preferred embodiment of the invention, in that the end region of at least one of the bundled flat tubes 2 is offset laterally via an offset 36 to the remaining flat tube surface and lies tightly against the end region 37 of the adjacent flat tube. The mutual soldering at the end regions 35, 37 lying against one another and with the wall 38 of the connection distributor 10, 18 surrounding the bundling takes place, for example, by previously applying soldering material in the immersion process and heating to the soldering temperature after its assembly. As shown in FIG. 14, the connection distributors 10, 18 can preferably be produced from an extruded profile 40 with a row of inner channels 41, the intermediate walls 42 of which increase the pressure resistance of the connection distributors 10, 18 and contribute to the flow guidance. For flow connection to the open end regions 35, 36 of the flat tubes 2, these inner channels 41 are opened by two circular-arc-shaped cutouts 43, 44, which form receiving slots for the flat tubes 2 or bundles of flat tubes 2. A web part 22 'between these cutouts 43, 44 corresponds to the web part 22 of FIG. 10 and thus serves to divide the flow into two cross-sectional areas 45, 46 of the flat tubes 2.

To further improve the air-side heat transfer on the smooth surfaces 4, 5; 6, 7 of the flat tubes 2, the inflowing air is already swirled on the exposed front edge 47 of the flat tubes 2 by their sawtooth-like profiling. 4 shows an embodiment of a suitable edge profile. Additionally or alternatively, one or more comb-like spacers 70 are provided on the front edges 47 of the flat tubes 2, one of which is shown schematically in sections in FIG. 22. A spacer engages with a plurality of teeth 71 in some or all of the spaces between the individual flat tubes 2 (not shown in more detail). For this purpose, the spacer 70 is aligned approximately horizontally and transversely to the main axes of parallel flat tubes 2, placed on the edges 47 and soldered to the flat tubes 2. With a view to ease of manufacture, a spacer 70 is produced from a solder-plated sheet and in particular from the same material as the solder-plated sheets in the connection distributors 50, 53.

The heat exchanger 1 'of the exemplary embodiment in FIGS. 16 to 20 has connection pipes 51, 52 provided on a head-side connection distributor 50 for the inflow and outflow of the operating medium of the air conditioning system, which are connected to the grid-like distribution system of the connection distributor 50, similar to the illustration in FIG. 11 , are connected in order to distribute the operating medium of the air conditioning system to the individual flat tubes 2 or a cross-sectional part thereof and to derive them again. In this exemplary embodiment, each flat tube 2 is flowed through in four opposite directions and, in addition, by means of a central transverse separation 49 of the connection distributors 50, 53, there is an overflow in the transversely adjacent part of the heat exchanger 1 'in accordance with a cross-counterflow guide. In this way, disadvantages due to an uneven distribution of the liquid phase on the overall cross section of the heat exchanger 1 'of the air conditioning system can be counteracted. Internal connection of the heat exchanger in cross-countercurrent is particularly preferred when the flat tubes of the heat exchanger are divided into two blocks of four rows according to FIG. 21. In order to intensify this effect, refrigerants can be fed into individual flat tubes in different amounts.

The possibility of dividing the flow of the air conditioning equipment into a relatively large number of partial flows with a plurality of deflections and correspondingly longer flow paths arises as a further, essential advantage of the invention, because given the size of the air-side outer heat transfer surface is due to the larger number of flat tubes 2, the heat transfer surface on the equipment side is many times and approximately four times larger than that of a heat exchanger of known design, so that a correspondingly larger flow cross section is also available, by means of which an increase in the flow resistance on the equipment side is avoided. Because of this larger, inner or operating-side surface of a heat exchanger according to the invention, there is a size ratio between the air-side and operating-side heat transfer surface in the range from 0.7 to 1.5, in particular in a range from 0.9 to 1.1. In the case of motor vehicle air conditioning systems, 1.5-2.5 m ^{2 of} surface on the air side are customary, a correspondingly large surface on the refrigerant side being provided according to the invention.

Since the operating medium flowing in cooling mode, depending on the load on the air conditioning system, consists of a different proportion of the liquid and vapor phases, there is a tendency towards an uneven distribution of the proportion of liquid phase, influenced by gravity or inertial forces, over the inflow and outflow width of the heat exchanger 1 'and an uneven temperature distribution across the heat exchanger 1', with correspondingly poor utilization of its theoretical performance. To one To counteract uneven distribution on the width of the heat exchanger 1 ', according to a further exemplary embodiment of the invention, the bottom-side connection distributor 53 has a bottom wall 54, for example four longitudinal channels 55 to 58 which run parallel to one another and are each laterally delimited by a web wall 22 " increasingly deepen towards the central area of its longitudinal extent and then flatten it again towards its end, preferably continuously, ie in the manner of a flat trough, optionally in steps, so that there is an upward step surface 59 to 62 on each upstream direction opposing the direction of flow Flow build-up or a flow swirl occurs, by means of whose component directed upwards towards the flat tubes 2, a part of the liquid phase is directed into the latter instead of being conveyed into a side region of the heat exchanger 1 '.

A step-like course of the bottom surface of the longitudinal channels 55, 58 can be achieved by milling into a light metal plate, e.g. be produced with a milling tool rotating about a vertical axis, so that the upwardly directed step surfaces 59 to 62 have a semicircular cross section, through which there results an upward directed flow guide centering towards the flow axis.

23 shows a further embodiment of a flat tube 2 according to the invention in a perspective view. It has alternating V-shaped depressions 80 and V-shaped elevations 81, which are arranged one behind the other in the longitudinal direction of the flat tube. Since both the stiffeners 80 and the elevations 81 continuously flatten towards the edge of the tube, a largely non-corrugated side edge 82 of the flat tube results. Numerous inner channels 3 with corresponding openings end on the narrow end face 83 of the flat tube.

24 shows a cross section through the flat tube 2 according to FIG. 23 along the line Z-Z. The points A and B belong to a single elevation 81 and the points C and D to a common depression 80 adjoining the elevation. A center line of the flat tube wall runs at “M”. It can be seen from the cross-sectional view that both the the outer area L of the flat tube forming the air side and the inner channels 3 forming the refrigerant side have a wave-shaped course. In its installed position, tube 2 is preferably arranged in such a way that the tips of the V-shaped recesses 80 and elevations 81 point approximately upward in the vertical direction, that is to say there is an inverted V-shaped profile of a correspondingly designed heat exchanger. This ensures that condensate can drain downward in the area of the air side L and does not collect anywhere.

The flat tube explained with reference to FIGS. 23 and 24 can be inserted into a heat exchanger shown above, so that all the features and advantages described above apply accordingly. In particular, all possible combinations with the aforementioned features are to be used. As an additional advantage, when using the flat tube 2 explained with reference to FIGS. 23 and 24, there is an increased stiffness both in the longitudinal direction and in the transverse direction of the flat tube and thus an overall improved stiffness of a correspondingly designed heat exchanger. With such a stiffening, a very high dimensional stability of the flat tubes can be achieved and the distance between flat tubes 2 may be reduced to less than 1 mm. When installing a plurality of flat tubes 2 explained with reference to FIGS. 23 and 24, it is preferably provided to combine two flat tubes with opposite cranked ends 84 to form a pair (cf. FIG. 6). The offset areas 84 each have an approximately rectangular end cross section; Elevations 81 and depressions 80 flatten to zero in these areas.

Finally, FIG. 25 shows a schematic cross section along a line YY and in FIG. 26 a perspective view of a further flat tube 2 according to the invention. In this case, an extruded profile is used, which has offset, channel-like indentations 90 on the outside relative to the inner channels 3. This results, for example, in comparison with the flat tube produced in FIGS. 23 and 24, on the one hand in a reduced material requirement and thus in a reduced component weight. There is also an enlarged surface on the air side, which enables better heat transfer. 25 and 26, the flat tube 2 has a wave shape oriented transversely to the longitudinal axis of the flat tube with a plurality (preferably three to ten) of depressions 91 and elevations 92, which forces a correspondingly wave-shaped air flow. In this case, the indentations 90, which result in an overall rib-like surface structure of the flat tube, run exactly at right angles to the air flow. The wavy shape of the flat tube is preferably converted into a flat shape at the end (ie on the narrow end faces S), for example by a rolling process, in order to obtain a rectangular cross section. This process is preferably carried out with a continuous rolling tool in the refrigerant flow direction or in the direction of the main axis of the flacro tube 2. The rolling tool preferably uses the indentations (ribbing) as a guide and brings the flat tube 2 to the desired width and height at the end. The cutting edges for cutting the flat tube to length are integrated in such a rolling tool. According to the rectangular cross-sectional shape generated at the end, the flat tube can be fitted into a rectangular slot in a connection distributor and soldered there.

In a modified exemplary embodiment, the depressions 91 and elevations 92 have a V-shaped configuration (corresponding to the variant according to FIGS. 23 and 24), while the indentations 90 continue to run parallel to the inner channels 3. The depressions and elevations are to be produced, for example, by an embossing process, which is to be applied to a flat flat profile provided with the indentations. Further modifications and combinations are also possible in accordance with the exemplary embodiments described above.

According to a further exemplary embodiment of the invention, the bottom-side connection distributor of a heat exchanger according to the invention is provided, analogously to FIGS. 18/19, with a bottom wall 54 ′ according to FIGS. 27 and 28. The bottom wall 54 'preferably enables a favorable passage of refrigerant through different areas of the heat exchanger in accordance with the basic distribution mode according to FIG. 21. The distribution mode according to the invention includes in particular a division of the heat exchanger into a total of eight groups of 20 to 80 flat tubes, two of which Groups connected in series each form a row Rl to R4 and the rows Rl to R4 are laterally delimited by web walls 22 ". In addition, the heat exchanger is divided in the center into two blocks Bl, B2. Refrigerant is introduced into a heat exchanger provided with the bottom wall 54 ', for example in section E from above in the area of the row R1. After the introduction, the refrigerant flows through the flat tubes of row 1 in area E in the vertical direction from top to bottom. Arrived at the bottom, the refrigerant hits the bottom wall 54 'and is divided into four longitudinal channels 101 to 104 which run parallel to one another and belong to the R 1 series and are delimited from one another by three narrow walls 100. The refrigerant flows from the first block B1 to the second block B2 along the bottom wall 54 '. In the second block B2, the longitudinal channels 101 to 104 of the row R1 end in different areas, as can be seen from FIG. 27. In particular, the last third of the second block B2 in the area of the row R1 is only supplied via the longitudinal channel 104 (some associated flat tubes 2 are indicated schematically). The second half of the block B2, in which the end regions of the longitudinal channels 103 and 104 lie, is supplied in the region of the row R1 only via the longitudinal channels 103 and 104. In a modified exemplary embodiment, a central part of the block B2 in the area of the row R1 is supplied exclusively via the longitudinal channel 103. After a U-shaped flow through the first row R1 (see also FIG. 21), the refrigerant in the second block B2 reaches the second row R2 from above in an upper reversal area U1, which is also flowed through again in a U-shape the design of the bottom wall 54 'for a new division of the refrigerant flow. The rows R3 and R4 are then flowed through in the same way, so that the refrigerant in section A in block B1 can exit the heat exchanger.

The longitudinal channels, as can be seen in FIG. 28, flow out towards their ends in a radius 59, which builds up the refrigerant flow and thus forces it into the flat tubes. By dividing the refrigerant flow into several individual flows 101 to 104 (corresponding to the number of longitudinal channels), a targeted distribution into the block downstream in the flow direction can take place. The individual streams are supplied with different numbers of flat tubes. This means that the refrigerant is redistributed each time it is redirected to a different block.

The longitudinal channels 101 to 104 in the form of slot-shaped recesses can be produced by milling in with a disk milling cutter or a grinding disk, so that the upward radii 59 result from the tool radius.

Claims

claims

1. Air / refrigerant heat exchanger, especially for a vehicle air conditioning system, with

- Melireren, parallel to each other, air-flowed flat tubes (2), in which refrigerant is guided, wherein

- Opposing walls (4, 5; 6, 7) of adjacent flat tubes (2) form flow channels (8, 9) between them for an air flow and wherein

- Several flat tubes (2) end together in at least one connection distributor (10, 18), wherein

- At least one connection distributor has at least one pipe connection (33, 51, 52) for integration into a pipe system, characterized in that

- In mutually opposing walls (4, 5; 6, 7) of adjacent flat tubes (2) elongated depressions (11, 80) and / or elevations (81) are arranged such that

- Longitudinal axes of the depressions and / or elevations are oriented obliquely to a flow direction of the air flow and / or obliquely to a flow direction of the refrigerant flow, in particular obliquely to a main axis of the flat tubes (2).

2. Heat exchanger according to claim 1, characterized in that

- In opposing walls (4, 5; 6, 7) of adjacent flat tubes (2) V-shaped depressions (11) and / or elevations are arranged such that

- The axes of the depressions and / or elevations forming the V-shape are oriented obliquely to a direction of flow of the air flow and or obliquely to a direction of flow of the refrigerant flow, in particular obliquely to a main axis of the flat tubes.

3. Heat exchanger according to claim 2, characterized in that the axes of the depressions and / or elevations forming the V-shape open downwards with respect to the vertical.

4. Heat exchanger according to one of claims 1 to 3, characterized in that depressions (11) in a flat tube (2) are formed such that they extend through the entire tube cross-section and on the opposite side of the flat tube (2) a corresponding Form elevation so that the flat tube (2) is profiled on both sides.

5. Heat exchanger according to one of claims 1 to 4, characterized in that a flat tube (2) has an end region (35, 37) with a rectangular cross-sectional shape constant in the direction of the main axis of the flacco tube (2) and a central section with itself in the direction of the main axis of the Flat tube (2) has a continuously changing cross-sectional shape.

6. Heat exchanger according to one of claims 1 to 5, characterized in that opposing surfaces (4, 5; 6, 7) of two adjacent flat tubes (2) are arranged such that one or more (concave) depressions of a flat tube (2) with one or more (convex) elevations of the adjacent flat tube (2) in the direction of the air flow guided between the adjacent flat tubes jointly limit undulating air channels (8, 9).

7. Heat exchanger according to one of claims 1 to 6, characterized in that the main axes of a plurality of flat tubes (2) each include an acute angle with the vertical in an installed position of the heat exchanger (1).

8. Heat exchanger according to one of claims 1 to 7, characterized in that mutually opposing surfaces (4, 5; 6, 7) of adjacent flat tubes (2) have hydrophilic coatings and / or a surface property reducing the surface tension of water.

9. Heat exchanger according to one of claims 1 to 8, characterized in that the narrow end faces of a plurality of adjacent flat tubes (2) are connected to at least one common spacer.

10. Heat exchanger according to one of claims 1 to 8, characterized in that a plurality of flat tubes (2) are connected to one another by means of a comb-like spacer, the spacer in spaces between opposing surfaces (4, 5; 6, 7) of adjacent flat tubes (2) intervenes.

11. Air / refrigerant heat exchanger, in particular according to one of claims 1 to 10, with

- Several, parallel to each other, air-flowed flat tubes (2), in which refrigerant is guided, wherein

- At least one connection distributor has at least one pipe connection (33, 51, 52) for integration into a pipe system, characterized in that an area ratio between the inner, refrigerant-side surface and the outer, air-side surface of the flat pipes (2) is between 0.7 and 1.5, in particular approximately 1.

12. Heat exchanger according to claim 11, characterized in that elongated depressions (11, 80, 91) and / or elevations (81, 92) are arranged in mutually opposing walls (4, 5; 6, 7) of adjacent flat tubes (2) that

13. Heat exchanger according to one of claims 1 to 12, characterized in that two or more flat tubes (2) are bundled together, the end regions (35) of at least one of the bundled flat tubes (2) via an offset (36) to the remaining flat Pipe surface is laterally offset and abuts the end region (37) of the adjacent flat tube (2).

14. Heat exchanger according to one of claims 1 ^' to 13, characterized in that the connection distributors (10, 18) have numerous, secondary chambers (15, 16, 17) separated from one another by web walls (19, 20, 21), in which in each case the end region (35, 37) of a flat tube (2) or the end regions (35, 37) of a bundle of flat tubes (2) end openly, in each case a plurality of secondary chambers (15, 16, 17) with a common primary chamber (25 to 29) of the connection distributor (10, 18) are connected, via which the inflow or outflow of the flat tubes (2) runs.

15. The heat exchanger according to claim 14, characterized in that the connection distributors (10, 18) with their primary chambers (25 to 29) formed by channels (25 ', 26') consist of an extruded profile (40) having inner channels (41).

16. Heat exchanger according to one of claims 1 to 15, characterized in that at least one primary chamber (25 ', 26') as the longitudinal channel of the connection distributor (10, 18) has a flat circular arc cross-section (43, 44) formed by a milling tool.

17. Heat exchanger according to claim 16, characterized in that a guide insert (34) is arranged in an inflow channel (33) of a bottom-side connection distributor (10) for the flow distribution, which orders from a ribbed extruded profile twisted about its longitudinal axis.

18. Heat exchanger according to Anspmch 14, characterized in that the pipe connections (51, 52) are provided on a head-side connection distributor (51) and a bottom plate (54) of the bottom-side connection distributor (53) has at least one longitudinal channel (55-58) with its inside. forms, which deepens increasingly to the central area of its longitudinal extent and then flattens again towards the end.

19. Heat exchanger according to Anspmch 17 or 18, characterized in that at least the decrease in the depression present in the flow direction of the respective longitudinal channel (55-58) takes place in a step-like manner via vertical step surfaces (59-62).

20. The heat exchanger according to spoke 14, characterized in that the pipe connections (51, 52) are provided on a head-side connection distributor (51) and a bottom plate (54 ') of the bottom-side connection distributor (53) has at least two longitudinal channels (101 to 104) on the inside which enables the refrigerant flow to be divided into at least two refrigerant flows, the refrigerant flows being able to be fed at least partially to different flat tubes (2) and / or to a different number of flat tubes (2).

21. Heat exchanger according to claim 20, characterized in that at least the radius (59) present in the flow direction of the respective longitudinal channel (101-104) is generated by a radius of the machining tool.