EP1892491A2 - Unit with a gas cooler and inner heat exchanger and heat exchanger - Google Patents

Abstract

The heat exchanger unit has a heat exchanger (1) e.g. gas cooler, for transferring heat from a cooling medium to air or to another medium flowing through the heat exchanger. An internal heat exchanger (5) is formed as a structural unit and is arranged with the heat exchanger in a plane in a laterally shifted and spaced and/or thermally insulated manner. The internal heat exchanger is directly connected or soldered with the heat exchanger over a connecting cable (10) for formation of the structural unit.

Description

The invention relates to a unit comprising a gas cooler or condenser and an internal heat exchanger, as used for air conditioning systems, in particular for motor vehicles, according to the preamble of claim 1, and a heat exchanger, in particular an internal heat exchanger, according to the preamble of claim 17 ,

Insofar as a gas cooler is mentioned in the present documents, according to the invention it is also possible to use a condenser or another heat exchanger.

The use of internal heat exchangers for heat transfer between high and low pressure side of air conditioning systems is known, wherein the heat exchanger is usually in a refrigerant circuit, eg. With R744 as a refrigerant, arranged and operated in countercurrent operation. In this case, the heat exchanger is usually arranged on the high pressure side between a gas cooler and an expansion element and low pressure side between an accumulator and a compressor. Such an internal heat exchanger serves to increase the COP value of the air conditioner.

The EP 1 046 524 B1 discloses a generic unit. Here, a high-pressure gas cooler is provided for a coolant circuit of a motor vehicle air conditioner, wherein CO ₂ (R744) serves as a refrigerant. This gas cooler has an integrated internal heat exchanger, ie the gas cooler and the internal heat exchanger form a single unit that is soldered. The gas cooler here has a plurality of heat exchanger tubes, as well as the inner heat exchanger, and the inner heat exchanger is disposed above or below the gas cooler heat exchanger tubes. In the case of the heat exchanger tubes, both in the case of the gas cooler heat exchanger tubes and in the case of the heat exchanger tubes of the inner heat exchanger, they are flat tubes with a plurality of chambers arranged side by side, the profiles of all the heat exchanger tubes corresponding to one another and the heat exchanger tubes being different only for their length and exit areas differ. The flat tubes of the inner heat exchanger are arranged close to each other and alternately with respect to the refrigerant flowing through, so that a flat tube connected to the high pressure side is disposed directly adjacent to a flat tube connected to the low pressure side, and so on. However, in the region of the gas cooler, the flat tubes are arranged in a known manner at a distance from one another and with the interposition of corrugated ribs. The entire arrangement gas cooler and inner heat exchanger is soldered together in a single block.

Separately formed gas cooler and inner heat exchangers, which are connected in the context of the overall assembly after the separate soldering of the two heat exchanger mounted, usually flexible lines to each other, for example by flange, are known in principle.

An example of a use of a two-part Koaxialrohrsystems as an inner heat exchanger, consisting of an outer tube and an inserted into the outer tube inner tube for an air conditioner, in particular a motor vehicle air conditioning system, is from the DE 199 44 951 A1 known. Here are for the inner heat exchanger helical webs which separate the outer channels from each other, as well as the provision of turbulence elements on the webs disclosed.

From the EP 1 202 016 A2 is a one-piece heat exchanger tube with a multi-chamber profile known, according to which a plurality of outer channels are provided around a central channel. The outer channels are divided by intermediate walls which extend in the radial direction. On the wall of the central channel wave-like projections are provided, which extend slightly into the central channel. These projections serve to reduce the cross-sectional area and thus increase the flow velocity. The projections may also be helical, wherein constant, changing or changing slopes may be provided. The inner channel is used in this heat exchanger tube as the high pressure side, the outer channels as the low pressure side.

From the US 6,098,704 B2 a tube-in-tube arrangement is known, wherein both the outer tube and the inner tube has a plurality of equidistant spaced around the circumference, in the radial direction a short distance inwardly pointing ribs, which have a wedge-like shape. These ribs are used for corrosion protection, so that the pipe wall between the two media protected and extends the life of the tube-in-tube assembly.

Based on this prior art, in particular the EP 1 046 524 B1 it is an object of the invention to provide an improved unit comprising a gas cooler and an internal heat exchanger. Further an improved heat exchanger is to be made available, which is particularly suitable as an internal heat exchanger.

This object is achieved by a unit with the features of claim 1 and a heat exchanger with the features of claim 17. Advantageous embodiments are the subject of the dependent claims.

The term "pipe" - in particular in connection with the inner heat exchanger - is to be interpreted very broadly below and refers not only to round cross-sections, but in particular also oval, rounded rectangular or any other cross-sections. The pipe can also be two tubes arranged inside one another which have no direct connections (pipe-in-pipe arrangement). In this case, however, positioning elements for the inner tube may be provided in the outer tube, such as provided on the outer and / or inner tube, radially inwardly or outwardly projecting ribs to optionally ensure a coaxial arrangement. Furthermore, an integrally formed coaxial tube can be provided. The arrangement of the inner tube or of the inner region in the outer tube can be coaxial, but does not have to be so that, in particular, off-center arrangements are also possible. In particular, a plurality of inner tubes may be provided. The inner tube or tubes may also be brazed or otherwise connected to the outer tube in the contact regions. Furthermore, the division of the flow cross-section into individual open-ended chambers is possible, i. For example, the inner tube may be formed by one or more multi-chamber flat tubes, whereby the heat transfer area increases greatly.

According to the invention a unit is provided, comprising a first heat exchanger, in particular a gas cooler, which the Heat transfer from a refrigerant to air or another medium flowing through the first heat exchanger medium, and at least one second, in particular inner heat exchanger, which are formed as a structural unit, wherein the second, inner heat exchanger laterally offset and slightly spaced and / or thermally insulated in one Plain arranged with the first heat exchanger and connected via at least one connecting line directly to the first heat exchanger to form the structural unit, in particular soldered, is. The laterally offset arrangement allows due to the preferably provided gap between the two heat exchangers, in which optionally still an insulating material may be arranged, an improved decoupling with respect to the heat, which in the case of EP 1 046 524 B1 disclosed high-pressure gas cooler with integrated internal heat exchanger is not possible. Nevertheless, due to the structural unit - according to the EP 1 046 524 B1 - Soldering of the entire unit, ie the first heat exchanger and the second, in particular internal heat exchanger, possible in a single operation, however, the assembly can be quite simplified, since two separately prepositioned blocks and a somewhat flexible connection thereof instead of a single blocks are provided with significantly more components. Of course, it is also conceivable that, instead of an internal heat exchanger, another heat exchanger, in particular a fluid-fluid heat exchanger, preferably undergoes a phase transition in at least one, particularly preferably both fluids in at least a portion of the corresponding fluid flow.

The relative positions of the two heat exchangers to one another are preferably no longer changeable after soldering has taken place - if appropriate apart from slight corrections via the connection line, which interconnect the two heat exchangers preferably directly connects, in particular with regard to the bending of the same.

Furthermore, the choice of the inner heat exchanger is substantially independent of the shape of the first heat exchanger, so that the air conditioner can also be optimized with regard to the shape of the second, in particular inner heat exchanger.

The second, in particular inner heat exchanger is particularly preferably arranged parallel to a collector of the first heat exchanger and laterally offset thereto in a plane with the heat exchanger. According to another, likewise preferred embodiment, the second, in particular inner heat exchanger is arranged perpendicular to the collector, above or below the first heat exchanger and in a plane with the first heat exchanger, however, the first-mentioned embodiment is preferred.

The first heat exchanger is preferably a plate-type heat exchanger, ie the collector or collectors consist of a plurality of plate-like sheets soldered together, in particular a connecting plate, a distributor plate and a bottom plate. On the connecting plate, the connecting lines are attached, via which refrigerant is fed to the heat exchanger and discharged. The distributor plate has, for example, H-shaped and L-shaped openings, via which the refrigerant is distributed to the individual tubes. The bottom plate is used to connect the individual tubes, which are preferably flat tubes, which are soldered directly into slot-like openings in the floor panel. To increase the heat transfer surface, corrugated ribs or other structures which increase the heat transfer surface are preferably arranged between the tubes, in particular the flat tubes, wherein they are preferably soldered firmly to the tubes. The whole Heat exchanger is - preferably soldered together with the second heat exchanger - in a single operation.

The tubes of the first heat exchanger are - preferably in contrast to the tubes of the second internal heat exchanger - formed by flat tubes, more preferably by flat tubes with multiple flow channels. In this case, a plurality of flat tubes may be arranged in the depth of the heat exchanger, but preferably a relatively broad flat tube with a plurality of flow channels is provided, which is viewed in the width direction flows through two different refrigerant streams, particularly preferably in the opposite flow direction.

The connecting line, ie the direct connection of the two heat exchangers, is preferably designed to be short in comparison to the length of the second, in particular inner, heat exchanger, so that, inter alia, weight can be saved.

Particularly preferably, the second, parallel to a collector of the first heat exchanger and laterally offset in a plane arranged with the first heat exchanger, the second, in particular inner heat exchanger is shorter than the collector formed, in particular preferably so short that it fits between the terminals of the first heat exchanger and is protected to some extent by them. Furthermore, such a design allows a very compact, space-saving design. The space requirement for connecting lines can be minimized.

Particularly preferably, the second, in particular inner heat exchanger on a depth, which is at most as large as the overall depth of the first heat exchanger, but with sufficient space in the depth in the height of the second, in particular inner heat exchanger also deeper second, in particular internal heat exchanger possible.

According to the invention, the second, inner heat exchanger is directly and firmly connected to the first heat exchanger via at least one connecting line. This is preferably the outflow side of the first heat exchanger to the high-pressure side supply line of the refrigerant in the inner heat exchanger. Here, the connecting line is preferably designed to be short compared to the length of the second, in particular inner heat exchanger. Particularly preferably, the connecting line is formed by a curved piece, in particular preferably by a 90 ° bend piece. This allows a short distance to the second, in particular internal heat exchanger and the same can be arranged parallel to the collector, from which the refrigerant flows out.

The second, in particular internal, heat exchanger is preferably arranged directly adjacent to the first heat exchanger, but is preferably not directly attached to it, i.e., not directly adjacent to the first heat exchanger. between the two heat exchangers, a heat-decoupling gap is provided. Depending on the available installation space, advantages in terms of installation and optimum utilization of the installation space compared to a second, in particular internal, heat exchanger that is integrated into the first heat exchanger can result. The entire arrangement is more flexible and adaptable without labor-intensive, fluidic recalculations to other conditions, for example. By changing the length of the connecting lines and / or the angle between the two heat exchangers, so that the second, in particular internal heat exchanger in dependence of the available space relative to the first Heat exchanger can be positioned.

For the connection of one of the connection lines, at least one connection piece with a bottom is preferably provided, which part is the flow cross-section is concealed and designed to be open for another part of the flow cross-section. In this case, connection piece and bottom can also be formed in one piece. In order in particular to keep the pressure loss when flowing into the with respect to its flow cross-section usually smaller "inner tube" as low as possible, the inflow and outflow preferably takes place substantially coaxially, for which the connecting piece is designed accordingly.

The inflow of the refrigerant into the "outer tube" takes place - depending on the design of the connection piece either axially or radially, but it can also be introduced and discharged via a connection formed separately from the connector in the radial direction.

Preferably, at least one turbulence generator, for example corrugated fins or turbulence sheets, is arranged in a flow cross section, which is preferably the larger flow cross section of the "outer tube".

Preferably, a single continuous flow cross-section is provided for the first-pressure refrigerant and a plurality of smaller, non-connected and longitudinally-flowable chambers for the refrigerant under another pressure. In particular, in a case where the lower-pressure refrigerant flows in the outer region, it is not divided into individual chambers. However, it is also a divided into individual chambers embodiment of both flow areas, i. of the area in which the refrigerant coming from the high-pressure side and the area where the refrigerant coming from the low-pressure side flows.

The second, in particular inner heat exchanger preferably has an outer tube and a plurality of arranged in the same, possibly also in one piece with the same connected pipes with a multi-chamber profile, which may, for example, to flat tubes. In this case, flow paths for the refrigerant flowing in the outer tube are formed between the individual multi-chamber profile tubes or multi-chamber profile-like regions. These flow paths of the outer tube have a smallest flow cross section, which is preferably at least as large as the smallest flow cross section of the chambers of the inner tube or of the corresponding inner regions.

The heat exchanger is preferably flowed through in countercurrent operation, which improves the efficiency of heat transfer.

The free flow cross section of the high pressure side is preferably smaller than the free flow cross section of the low pressure side. In this case, the free flow cross sections differ such that the free flow cross section of the high pressure side is preferably at most half as large and preferably at least a quarter as large, more preferably about one third +/- 10% is as large as the free flow cross section of the low pressure side. These cross-sectional ratios result in a very good heat exchange between the two media.

The second, in particular inner, heat exchanger and / or the first heat exchanger preferably consists at least partially of aluminum or an aluminum alloy.

The essential parts of the second, in particular inner, heat exchanger, ie the parts which form the heat transfer surfaces or at least essential regions thereof, are preferably produced by extrusion, both as an integrally formed profile and as a component composed of two or more profiles. However, other types of profiles are possible, in particular bent and pressed or welded sheet metal profiles. Of course, this is also conceivable in the case of the first heat exchanger.

The second, inner heat exchanger can be formed both in one piece, particularly preferably as an extruded tube with a plurality of flow channels, as well as in several parts, in particular as a tube-in-tube arrangement.

The second, in particular inner, heat exchanger preferably has a circular cross section, but any other suitable cross section, for example also an oval or flat tube-like cross section, may be used.

The second heat exchanger - which can be used both alone and in the unit according to the invention as an internal heat exchanger - has at least one tubular flow channel, formed by an outer tube, for a first medium, and at least one in the at least one flow channel in the direction of Flow channel arranged line, formed by an inner tube, for a second medium, wherein the line is at least partially formed independently of the wall of the flow channel. In this case, the inner tube has a plurality of inner channels through which the second medium flows. The media may preferably be refrigerants of a single refrigerant circuit with different temperatures.

Preferably, a plurality of flat-tube-like, inner tubes or flat tube-like regions of the inner tube, each having a plurality of inner channels are provided, which are arranged in the outer tube.

Particularly preferably, the outer tube and the one or more inner tubes are firmly connected to each other at exactly one point. The connection can by means of Soldering or similar respectively. In particular, however, the tubes are configured in one piece, ie the connection is made via a connecting region in the region of the inner wall of the outer tube.

Particularly preferably, in at least one flow channel of the heat exchanger, in particular the second, inner heat exchanger, turbulence generators, for example. In the form of corrugated fins, provided to increase the efficiency of the heat exchanger.

An inventive unit of heat exchanger and inner heat exchanger can be used in particular for heat exchangers, preferably for motor vehicle air conditioning systems, particularly preferably for high-pressure air conditioning systems of motor vehicles, but other applications are possible. In particular, the internal heat exchanger described can also be used alone, i. especially not in the previously described, rigid orientation to another heat exchanger.

Fig. 1

eine ausschnittsweise Darstellung eines Gaskühlers mit benachbart angeordnetem inneren Wärmetauscher,

Fig. 2

eine schematische Darstellung des inneren Wärmeaustauschers von Fig. 1,

Fig.3

einen Längsschnitt durch einen Endbereich des inneren Wärmetauschers von Fig. 1 mit Anschlussstück,

Fig. 4a-k

Querschnitte durch verschiedene innere Wärmetauscher bzw. des Innenrohrs desselben,

Fig. 5

eine perspektivische, aufgerissene Darstellung eines inneren Wärmetauschers, welcher im Querschnitt im Wesentlichen dem inneren Wärmetauscher von Fig. 4i entspricht, in dem jedoch Umlenkbleche vorgesehen sind, und

Fig. 6

einen Querschnitt eines inneren Wärmetauschers mit Turbulenzblechen.

In the following, the present invention with reference to several embodiments and variants, partially explained with reference to the drawings. Show it:

Fig. 1

a fragmentary view of a gas cooler with adjacently arranged inner heat exchanger,

Fig. 2

1 is a schematic representation of the internal heat exchanger of FIG. 1,

Figure 3

a longitudinal section through an end portion of the inner heat exchanger of FIG. 1 with connector,

Fig. 4a-k

Cross sections through different inner heat exchanger or the inner tube thereof,

Fig. 5

a perspective, torn view of an internal heat exchanger, which corresponds in cross section substantially to the inner heat exchanger of Fig. 4i, but in which baffles are provided, and

Fig. 6

a cross section of an inner heat exchanger with turbulence plates.

A as a gas cooler for the same flowing through refrigerant CO ₂ (R744) serving heat exchanger 1 of a motor vehicle air conditioner, of which only a small part is shown in Fig. 1, has a known construction with side collectors 2, extending between the same heat exchanger tubes, in the present case formed by flat tubes 3, and arranged between the flat tubes 3 corrugated fins 4, wherein in the present case, the individual parts were soldered together in one operation.

In the refrigerant circuit of the air conditioner, an inner heat exchanger 5 is further arranged, which is flowed through by the refrigerant and serves to increase the COP value of the air conditioner. The inner heat exchanger 5 is arranged with its high pressure side H in the flow direction of the refrigerant behind the gas cooler and before an expansion element and with its low pressure side N behind a collector and in front of the compressor, wherein high and low pressure side of the inner heat exchanger 5 are flowed through in countercurrent operation.

The inner heat exchanger 5 is present, as shown in the section shown in Fig. 4a, formed by a round tube 6 and three arranged in the round tube 6, parallel, multi-chamber flat tubes 7, wherein two of the three flat tubes 7 have a cross section corresponding to each other and the third, arranged between the two flat tubes flat tube has a slightly wider cross section with a chamber more. The maximum outer diameter of the inner heat exchanger 5, which substantially corresponds to the outer diameter of the round tube 6, in this case has the same dimension as the overall depth of the gas cooler. The length of the inner heat exchanger is, as shown in FIG. 1, sufficiently smaller than the height of the gas cooler to have sufficient space for the connections of the heat exchanger. The connections of the inner heat exchanger 5 are in the present case designed such that in each case a connection 8 is provided in the axial direction and a connection 9 in the radial direction at each end thereof, the refrigerant being supplied to the chambers of the three flat tubes 7 via the connection 8 in the axial direction or is discharged from the same, and via the terminal 9 in the radial direction, the refrigerant is supplied to the free interior of the round tube 6 and discharged from the same. Here, the gas cooler, ie, the first heat exchanger 1, and the inner heat exchanger 5, the rigidly present to each other via one of the connecting lines 10, namely the connection line 10 shown in Fig. 1 below, which is soldered directly from the collector 2, form a structural Unit.

Alternatively to the representation of FIG. 1 with an arrangement thereof parallel to one of the collectors of the gas cooler, the inner heat exchanger can also be arranged parallel to the flat tubes of the gas cooler, in particular below or above the gas cooler. Likewise, the inner heat exchanger can also be arranged at another suitable location in the low and / or high pressure side of the refrigerant circuit. However, it is advantageous if at least one of the lines, with which the inner heat exchanger is connected directly to the gas cooler, is kept as short as possible and is soldered to the formation of the structural unit of the two heat exchangers 1 and 5 with the same.

As can be seen from the illustration of FIG. 3, the end of the high-pressure side, axial connecting line 10, which is connected to the inner heat exchanger 5, guided in a cover-like fitting 11, which on this side has an outer diameter of the connecting line 10 corresponding inner diameter.

Instead of a direct connection to the connection line 10, as provided herein, may also be a fixed connection pipe fixed to the connector 11, to which the actual connection line, for example, by means of a mechanical fastening device or by means of a forming process can be fastened. Alternatively, the connection piece can, for example, also be provided with a mechanical fastening device, so that the connection line does not have to be soldered to the connection piece or connected in a non-detachable manner in other ways. This is particularly useful on one side of the inner heat exchanger, which is not soldered to the gas cooler with the involvement of the corresponding connection line.

By forming a slight heel against which the end of the connecting line 10 rests, in the form of a stepped reduction of the connecting line-side inner diameter to a central inner diameter, a distributor chamber 12 is formed centrally in the connecting piece 11, which has a slightly larger inner diameter than the inner diameter of the connecting line 10, however has a smaller inner diameter than the outer diameter of the type of line 10.

On the opposite side, which is referred to below as the heat exchanger side, the connector 11 has a much larger inner diameter than the connection line side and as in the distribution chamber 12, wherein the transition again in the form of a step, the present significantly larger than the wall thickness of the round tube. 6 is done. At the step formed by the step is the round tube 6, whose outer diameter corresponds to the inner diameter of the connecting piece 11 in this area, at.

The end of the round tube 6 is provided with a bottom 13, which in the present case has three openings 14 whose cross-section corresponds to the outer dimensions of the flat tubes 7 arranged in the round tube 6. The connection piece-side ends of the round tube 6, the bottom 13 and the flat tubes 7 are presently arranged in a plane. The flat tubes 7 have such a dimension that all three flat tubes 7 with at least a small portion of their ends in contact with the connector 11, but as far as possible, none of the chambers in the interior of the flat tubes 7 is covered by the connector 11, so that the Flow cross-section of all chambers of the flat tubes 7 as completely as possible available.

The low-pressure-side connection 9 takes place, as shown in Fig. 2 - or FIG. 5, which does not differ from the present embodiment in terms of the design of the round tube and in particular the low-pressure side connection - in the radial direction of the round tube 6, for which a bore 14 and a tube 15 introduced therein and soldered to the round tube 6 is provided. The internal cross-sectional area of the tube 15 substantially corresponds to the free flow area in the round tube 6, i. the inner cross-sectional area minus the area of the flat tubes 7 arranged therein.

In the free flow cross-section of the round tube 6 is thus present in a lower pressure than in the chambers of the flat tubes arranged therein. The operating pressure on the low pressure side is according to the present embodiment about 130 bar, the corresponding bursting pressure 264 bar, and the operating pressure on the high pressure side is about 160 bar, the corresponding Bursting pressure 352 bar. The stated pressure values relate in particular to the use of CO ₂ as refrigerant.

Because the high-pressure side is arranged on the inside, an improved, defined flow of the high-pressure refrigerant can be realized via the corresponding connection piece 11; in particular, as shown in FIG. 2, a relatively deflection-free flow of the high-pressure refrigerant in the direction of the longitudinal axis of the flat tubes 7 is provided , whereby the pressure loss can be reduced and thereby the cooling capacity can be improved. The flow of the low-pressure refrigerant takes place in the radial direction with respect to the longitudinal axis of the round tube. 6

The round tube, as well as the flat tubes 7 in the interior of the round tube 6, in the present case are extruded tubes made of aluminum. The same are with the bottoms 13, the fittings 11 and the radial connections 9 forming tubes soldered, which is advantageously carried out in one operation. The soldering of the parts can also - with a corresponding arrangement of the inner heat exchanger 5 on at least one refrigerant-carrying and directly connected to the guest pipe - done in a single operation with the soldering of the gas cooler.

As an alternative to the described embodiment of the connecting piece 11, the same can also be designed as a stamped and bent part, so that in particular the region extending in the direction of the adjoining tube can be made larger so that, if necessary, a short, short, soldered pipe section or the direct soldering of the connection line omitted and can be provided directly to the edge of the fitting a corresponding attachment for the pipe to be connected.

In particular, in the case of a formation of the connection piece as a stamped and bent part, the same can also with ribs or the like. be formed stiffening structures. Furthermore, the provision of extended regions, ribs or other guide structures also makes it possible to optimize the shape of the distributor space with regard to the inflow and outflow of the refrigerant into the chambers of the flat tubes or corresponding refrigerant-carrying structures.

Furthermore, the inlet and / or outlet direction of the refrigerant into and out of the connection piece does not necessarily have to be in the axial direction to the inner heat exchanger, although this direction is the most favorable with regard to the refrigerant flow. Rather, a radial flow direction, for example. Parallel to the flow direction of the radial port or an oblique flow direction is possible, which may be particularly advantageous in view of the required space for the connecting lines. Likewise, high and low pressure side can be arranged reversed compared to the first embodiment.

The floor described above may also be formed integrally with the connector. Although production is more difficult to manufacture, the number of individual parts and the number of points to be sealed in the course of manufacture are thereby reduced. Furthermore, the distributor space can be made more pressure- and flow-compatible. The one-piece design further allows a slight increase in the heat-transmitting length of the inner heat exchanger.

In the following, with reference to the figures 5a to 5k different embodiments with respect to the cross section of the inner heat exchanger 5 will be explained in more detail. In the present case, these are exclusively extruded profiles - partly in one piece and partly in several pieces.

In the round tube 6, four flat tubes 7 are arranged parallel to each other and slightly spaced from each other according to the second, shown in Fig. 4b embodiment, each of the widths of the outer flat tubes 7 and the central flat tubes 7 corresponds to each other, so that the flat tubes 7 relatively evenly in the interior of the round tube 6 are arranged distributed. The configuration of the terminals corresponds to that of the first embodiment, i. The flat tubes end in a bottom, which is accommodated in a connection piece.

Likewise, the number of flat tubes can be increased, also in principle round tubes or tubes can be used with other cross-sections instead of the flat blanks.

Fig. 4c shows a third embodiment with a single, € -like design tube 7, which is arranged in the round tube 6 to form an annular gap with the same. In the tube 7 a plurality of longitudinally continuous, adjacently arranged chambers are formed whose function corresponds to that of the chambers of the multi-chambered flat tubes.

According to the fourth embodiment shown in FIG. 4d; of which only the tube arranged in the inner tube 7 is shown, the same is formed by a plurality of centrally interconnected flat tubes of different widths. Here, the longitudinally continuous chambers are also provided in the connection area.

Fig. 4e shows the inner tube 7 according to the fifth embodiment, which in turn is arranged in a round tube (not shown). This inner tube 7 has a meandering cross section with a plurality of longitudinally continuous chambers.

The sixth embodiment shown in Fig. 4f substantially corresponds to the embodiment of Fig. 4c, but the inner tube 7 and the round tube are connected to each other via a web, which forms a transitional area, i. integrally formed. The production of this tube is done by means of extrusion in a single operation.

Due to the function is hereinafter - despite an optionally one-piece design - occasionally referred to the outer part of the tube as the outer tube and the inner part of the tube with its plurality of smaller flow channels as inner tube reference.

According to the seventh exemplary embodiment illustrated in FIG. 4g, fork-like, flat tube-like regions 7 are formed integrally with the circular tube 6 with chambers extending in the longitudinal direction. The outer flat tube-like regions 7 are, in order to obtain as uniformly wide flow cross sections as possible, curved slightly in the direction of one another in the region of their free ends, and the middle flat tube-like region 7 is shorter.

Fig. 4h shows the eighth embodiment, which substantially corresponds to the seventh embodiment, but the individual, inner flat tubes, which are connected to one side with the outer round tube, straight and have different widths to fill the interior of the round tube as evenly as possible ,

The ninth exemplary embodiment illustrated in FIG. 4i has wedge-shaped regions with chambers extending in the longitudinal direction, in addition to chambers arranged at an angle to one another, integrally connected to one side with the outer circular tube, inner flat tubes the channels between the wedges and flat tubes present have a constant width.

According to the tenth embodiment shown in FIG. 4j, three inner flat tubes 7 arranged parallel to one another and at a distance from each other are provided, which are connected in one piece with the outer round tube 6 on one side. However, the side connected to the round tube alternates, so that, in contrast to the embodiment of FIG. 4h, no fork-shaped regions but a meandering region remains between the individual flat tubes.

The eleventh embodiment shown in FIG. 4k differs from the tenth embodiment shown in FIG. 4j only in that, instead of three flat tubes, four flat tubes 7 are integrally and mutually connected to the round tube 6.

Instead of an outer round tube, as described according to the present embodiments, also an outer tube can be used with a different cross section, in particular preferably with an oval cross section. The same applies, of course, to the tubes, in which the longitudinally continuous chambers are formed in the cross-section of the (outer) tube, i. a single tube provides the channels for high and low pressure side.

The outer tube can also with ribs or similar. be formed, as well as have changing wall thicknesses. The longitudinal extent does not necessarily have to be straight; on the contrary, a curved, for example U-shaped, or a helical configuration of the tube, as well as a corresponding configuration of the inner tube or chambers, is possible.

Fig. 5 shows a part of an inner heat exchanger 5, which corresponds in cross section substantially to the inner heat exchanger of Fig. 4i, in which, however, in the channels around the flat tubes 7 baffles 15 are provided. These baffles 15 are each arranged only in a partial region of the cross section and each offset from one another, so that the refrigerant flowing in the channel is constantly deflected. This prevents the formation of a laminar flow and mixes the refrigerant flowing outside and in the middle of the flow channel with each other, so that a very uniform temperature profile is formed and the heat transfer of the counterflowing refrigerant flows is optimized.

Furthermore, in FIG. 5, in the upper, left-hand region, the opening 14 for the connection 9 in the radial direction can be seen, through which the low-pressure-side refrigerant is introduced into the inner heat exchanger 5. As can be seen in FIG. 5, the refrigerant is conveyed through the first deflecting plate 15, in particular into the width of the inner heat exchanger 5, i. distributed to the rearmost channel, so that even this inflow area is flowed through evenly by refrigerant. The design of the discharge area is designed accordingly, so that the entire length of the inner heat exchanger 5 is used optimally.

The baffles 15 are presently arranged at equidistant intervals from each other and soldered to the flat tubes 7 and the inner wall of the round tube 6. However, other embodiments are also possible, in particular, the baffles can also be integrally connected to one another and loosely inserted into the inner heat exchanger.

FIG. 6 shows a further embodiment of the outer tube as a round tube 6. In the present case four flat tubes 7 arranged parallel to one another are arranged, wherein corrugated ribs 16 are respectively arranged between the flat tubes 7 for enlarging the heat transfer surface. The ribs 16 lie with a portion each on the outside of the flat tubes 7 and here take heat from the same (or possibly also give heat to the same from). This heat is conducted into the oblique connection areas, which are surrounded by the refrigerant, which absorbs the heat. Further, the corrugated fins 16 are used for turbulence generation, ie prevent the formation of a laminar flow and thus ensure equalization of the temperature profile over the entire flow cross-section. Such corrugated ribs can of course also be provided in connection with other types of flat tube geometries 7, in particular in conjunction with the above-mentioned embodiments of the flat tubes. 7

In addition to being used in a CO ₂ refrigerant cycle, the described air conditioning system may also be used in an R134a refrigerant circuit or in a circuit with another suitable refrigerant.

Claims (19)

A unit comprising a first heat exchanger (1), in particular a gas cooler or condenser, which serves for the heat transfer from a refrigerant to air or another medium flowing through the first heat exchanger (1), and at least one second, in particular internal heat exchanger (5), which are designed as a structural unit,
characterized in that
the second, in particular inner heat exchanger (5) laterally offset and slightly spaced and / or thermally insulated in a plane with the first heat exchanger (1) and at least one connecting line (10) directly to the first heat exchanger (1) for forming the structural unit connected, in particular soldered, is. Unit according to claim 1, characterized in that the second, in particular internal heat exchanger (5) parallel to a collector (2) of the first heat exchanger (1) and laterally offset in a plane with the heat exchanger (1) is arranged, or perpendicular to the collector (2) and above or below the first heat exchanger (1) and in a plane with the first heat exchanger (1) is arranged. Unit according to claim 1 or 2, characterized in that the connection line (10) is short compared to the length of the second, in particular inner heat exchanger (5). Unit according to one of the preceding claims, characterized in that the second, in parallel to a collector (2) of the first heat exchanger (1) and laterally offset in a plane with the first heat exchanger (1) arranged, in particular second internal heat exchanger (5) shorter as the collector (2) is formed. Unit according to one of the preceding claims, characterized in that between the first and the second heat exchanger (1 and 5), a gap is provided. Unit according to one of the preceding claims, characterized in that the first and the second heat exchanger (1 and 5) are designed as a rigid, structural unit. Unit according to one of the preceding claims, characterized in that the first heat exchanger (1) is a plate-type heat exchanger. Unit according to one of the preceding claims, characterized in that the first heat exchanger (1) by a plurality of flat tubes (3), which are arranged between one or two collectors (2) extending, is formed. Unit according to one of the preceding claims, characterized in that the first heat exchanger (1) by a plurality of flat tubes (3) and between the flat tubes (3) arranged corrugated fins (4) is formed. Unit according to one of the preceding claims, characterized in that at least one connecting piece (11) is provided with a bottom (13), which covers a part of the flow cross section and is open to another part of the flow cross section. Unit according to claim 10, characterized in that the connecting piece (11) and the bottom (13) are integrally formed. Unit according to one of the preceding claims, characterized in that at least one turbulence generator in a flow cross-section, in particular in a flow cross-section of the second, inner heat exchanger (5) is arranged. Unit according to one of the preceding claims, characterized in that in the region of the inner heat exchanger (5) has a single continuous flow cross-section for the under a first pressure refrigerant and a plurality of smaller, non-interconnected and longitudinally permeable chambers for the under another Compressed refrigerants are provided. Unit according to claim 12 and 13, characterized in that the turbulence generator, in particular formed by corrugated fins (16) and / or baffles, in the single, continuous flow cross-section is arranged. Unit according to one of the preceding claims, characterized in that the second, in particular inner heat exchanger (5) can be flowed through in countercurrent operation. Air conditioning system, in particular motor vehicle air conditioning system, with a refrigerant circuit, characterized by a unit according to one of claims 1 to 15. Heat exchanger, in particular inner heat exchanger of an automotive air conditioning system, comprising at least one tubular flow channel formed by an outer tube (6) for a first medium, and at least one arranged in the at least one flow channel in the direction of the flow channel line formed by an inner tube ( 7), for a second medium, wherein the line is at least partially formed independently of the wall of the flow channel, characterized in that the inner tube (7) has a plurality of inner channels. Heat exchanger according to claim 17, characterized in that a plurality of flat tube-like, inner tubes (7) or flat tube-like portions of the inner tube (7) is provided with a plurality of inner channels, which are arranged in the outer tube (6). Heat exchanger according to claim 18, characterized in that the outer tube (6) and the one or more inner tubes (7) are firmly connected to each other at exactly one point in the region of the inner wall of the outer tube (6).

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