EP1798506A2 - Heat exchanger, more particularly evaporator - Google Patents

Abstract

Heat exchanger has injecting pipe (4), several openings (9') and the injecting pipes are connected directly or indirectly over the several openings. The heat exchanger is formed such that the flow rate of the medium is increased in the injecting pipe in a range at least with a part of the openings. The free cross-section flow of the injecting pipe reduces in normal flow direction.

Description

The invention relates to a heat exchanger, in particular an evaporator, as used in particular for the air conditioning of a motor vehicle, according to the preamble of claim 1.

From the EP 1 065 453 B1 an evaporator is known, which has overhead collecting container and a bottom deflection and distribution box. The diverting and crushing box has plates provided with throttle openings for reducing the refrigerant passage cross section between the individual diverting and distributing tank sections. The throttle openings are provided here exclusively in the lower deflection and distribution box and serve to even out the refrigerant distribution to the individual multi-channel flat tubes of the evaporator. Such an evaporator still leaves something to be desired.

Further, in a two-phase refrigerant for equalizing the refrigerant distribution to four individual tubes arranged in parallel, it is known to reduce the diameter of the feeding tube continuously over the length (Patent Abstracts of Japan, Application No. 02055085).

Also is from the GB 2 392 233 A known to design the openings between a collecting container and flat tubes in such a way that the openings in the central region of the collecting container or distributor tube are larger than the openings on the two sides. In this case, turbulence generators in the form of slots can be provided in the distributor tube, the ridges projecting inward in the direction of the center of the collecting container being bent outward until they bear against the inner wall of the collecting container. Each of the slots is formed here by means of a cutting tool with a tapered blade, wherein the width of the slots varies.

Based on this prior art, it is an object of the invention to provide an improved heat exchanger available. This object is achieved by a heat exchanger with the features of claim 1. Advantageous embodiments are the subject of the dependent claims.

According to the invention, a heat exchanger is provided, in particular an evaporator, with at least one injection tube, a plurality of passage openings, a plurality of directly or indirectly connected via the passage openings with the injection tube, a heat transfer surface forming elements through which preferably a medium flows, which in the region Heat exchanger at least partially undergoes a phase change, and a suction pipe, wherein the heat exchanger is designed such that in at least a portion of the passage in at least a portion of the passage openings, the flow rate of the medium is increased in the injection tube. As a result of the increased flow rate of the medium, hereinafter referred to as refrigerant, there is a better mixing of the phases present. The refrigerant used here is preferably R744 (CO ₂ ) or R134a.

In order to increase the flow velocity, the free flow cross-section may be reduced, preferably in a region of the injection tube from shortly before the first passage opening to its end. In this area, the free flow cross-section is smaller than that of the supply line to the injection tube and / or the region of the injection tube in front of the first passage opening.

Preferably, the free flow cross section of the injection tube decreases in the normal flow direction, whereby the flow rate in the tube interior remains relatively constant over the entire length of the injection tube, i. is increased compared to the flow rate in a corresponding tube with a constant flow cross-section over the entire length, or even can be further increased, so that - especially in the case of an increase in speed - an improved mixing of the gaseous and liquid phase of the refrigerant.

The free flow cross-section of the suction tube preferably increases in the normal flow direction, so that the suction effect can be increased, which likewise leads to an increase in the flow velocity in the injection tube and thus to a better mixing of the refrigerant phases.

To increase the flow velocity, a sleeve may be provided in the injection tube. This is preferably formed slotted. The sleeve in this case preferably extends over a maximum of three quarters, in particular over half, of the inner circumference of the injection tube to which it bears or is firmly attached, in particular preferably by means of soldering, so that no special measures must be taken for keeping the through openings free. The slot may in this case also be of different widths, so that a reduction of the free flow cross-section over the length of the injection tube takes place through the sleeve can. It is also conceivable that the sleeve tapers seen in its longitudinal direction, in particular uniformly tapered. Preferably, the sleeve extends substantially over the entire length of the injection tube and / or has at least partially a smaller diameter than the connection cross-section.

If the evaporator is designed in such a way that an overflow pipe is provided through which refrigerant passes from one region of the evaporator to another region of the evaporator, the same advantages also apply to a corresponding design of the overflow pipe, at least in the region of its passage openings, through which the Refrigerant escapes again.

The injection tube and / or the suction tube and / or an overflow tube, which is arranged between two rows of tubes, preferably has a D-shaped cross-section. Here, the distances between the passage openings to the upper region of the tube, in which usually accumulates the gaseous phase, low, so that - as required - already with relatively simple measures an increased suction of the gaseous phase or a uniform suction of the gas phase in the most or all holes can be realized.

Preferably, the inner diameter of the injection tube at least in a region in which passage openings are provided, between 2.0 and 3.0 mm, in particular between 2.2 and 2.6 mm, wherein in the case of non-circular cross-sections of the hydraulically equivalent inner diameter in place of the inner diameter occurs. These dimensions allow a sufficiently high flow rate of the refrigerant. The values mentioned apply in particular when the cross-section of the tubes is constant. In the case of pipes whose cross-section (if necessary) even in sections), the numbers mentioned can be used as average cross-sectional diameter.

The inner diameter of the suction tube is preferably between 4.0 and 6.6 mm, in particular between 4.5 and 6.0 mm, wherein in the case of non-circular cross sections of the hydraulically equivalent inner diameter occurs in place of the inner diameter. Again, the values mentioned apply in particular when the cross-section of the tubes is constant. In the case of pipes whose cross-section changes (possibly only in sections), the figures mentioned can also be used in connection with suction pipes as the average cross-sectional diameter.

If an overflow pipe is provided, then the inner diameter of the injection pipe is preferably 2.0 to 3.0 mm, in particular between 2.2 and 2.6 mm, the inner diameter of an overflow pipe 2.0 to 4.5 mm, in particular between 3.0 and 4.0 mm, and the inner diameter of the suction pipe between 4.0 and 6.6 mm, in particular between 4.5 and 6.0 mm, wherein in the case of non-circular cross-sections of the hydraulically equivalent inner diameter occurs in place of the inner diameter.

However, it is also conceivable that the inner diameter of the injection pipe and / or the inner diameter of an overflow pipe and / or the inner diameter of the suction pipe is each formed substantially equal in size. This may prove to be advantageous in terms of standardization of the components used, especially in the case D-shaped tubes. The diameters may in particular be between 2.5 and 4.0 mm, preferably between 2.8 and 3.7 mm, more preferably between 3.0 and 3.4 mm, wherein in the case of non-circular cross sections of the hydraulically equivalent inner diameter in place of the inner diameter occurs.

In the injection tube, in the free flow cross sections, at least in the region of the passage openings under normal operating conditions of the heat exchanger, a constant mass flow density with a fluctuation range of at most +/- 20%, in particular +/- 10%, particularly preferably +/- 5%, between the individual Cross sections before. To achieve this, the free flow cross sections are designed accordingly.

The heat exchanger is preferably an evaporator, particularly preferably a plate-type or serpentine-type evaporator.

Preferably, the injection tube is attached to the lower side of the heat exchanger.

The inlet of at least one passage opening is preferably arranged above the lowest point of the injection tube. This allows a targeted suction of the gaseous phase, as it accumulates in the upper area. This is particularly useful in an arrangement of the injection tube on the underside of the heat exchanger, possibly also in combination with other measures that increase the flow rate.

Benefits may continue to arise when the injection tube is mounted on the upper side of the heat exchanger, in principle, also other types of attachment are possible.

In particular, in the case of an arrangement of the injection pipe on the upper side (or optionally in the case of transfer pipes on the upper side), liquid phase can be sucked in through an inlet, which lies below the highest point of the injection pipes (or of the transfer pipe).

Preferably, the entry is formed by a projecting into the interior of the injection tube passage or by a pipe arranged in the passage opening.

It proves to be advantageous if the height of the protruding into the interior of the injection tube passage or disposed in the passage opening tube 20% to 70%, preferably 30% to 60%, particularly preferably 40% to 55%.

The evaporator is particularly preferably a plate-type evaporator which has a distributor plate which preferably provides an at least simple diversion into the depth and an at least simple, preferably two-fold deflection in the width. In this case, sections can be formed the same or mirror-image. In particular, in a mirror image design of adjacent sections, the inlet and outlet of the refrigerant can be merged, so that the structure is somewhat simplified.

Particularly preferably, the evaporator has an overflow pipe, which has the same inventive features as the injection pipe.

Fig. 1

einen Ausschnitt eines Schnitts in Längsrichtung eines Verdampfers gemäß dem ersten Ausführungsbeispiel,

Fig. 2

eine Draufsicht auf einen Teil des Verdampfers von Fig.1,

Fig. 3

einen Schnitt durch den oberen Teil eines Verdampfers gemäß dem zweiten Ausführungsbeispiel,

Fig. 4

einen Schnitt durch den oberen Teil eines Verdampfers gemäß dem dritten Ausführungsbeispiel,

Fig. 5

einen Schnitt durch den oberen Teil eines Verdampfers gemäß einer Variante des dritten Ausführungsbeispiels,

Fig. 6

einen Schnitt durch den oberen Teil eines Verdampfers gemäß einer weiteren Variante des dritten Ausführungsbeispiels,

Fig. 7

eine Draufsicht auf den oberen Teil eines Verdampfers gemäß dem vierten Ausführungsbeispiel,

Fig. 8

eine Draufsicht auf den oberen Teil eines Verdampfers gemäß einer Kombination des ersten und vierten Ausführungsbeispiels,

Fig. 9

einen Verdampfer mit U-förmig gebogenen Flachrohren,

Fig. 10

einen Schnitt X-X durch den Verdampfer von Fig. 9,

Fig. 11

einen Schnitt XI-XI durch den Verdampfer von Fig. 9,

Fig. 12

einen Verdampfer mit hintereinander geschalteten U-förmigen Rohren (Umlenkung in der Breite),

Fig. 13

einen Wärmetauscher in einer Teilansicht,

Fig. 14

einen Wärmetauscher in einer Teilansicht,

Fig. 15

eine Vorderansicht eines Wärmetauschers,

Fig. 16

eine Drausicht auf den Wärmetauscher von Fig. 15,

Fig. 17

eine Seitenansicht des Wärmetauschers von Fig. 15,

Fig. 18

eine Teilansicht einer Schnittdarstellung des Wärmetauschers von Fig. 15 in Längsrichtung des Einspritzrohres,

Fig. 19

eine Teilansicht einer anderen Schnittdarstellung des Wärmetauschers von Fig. 15 in Längsrichtung des Saugrohres,

Fig. 20

eine Teilansicht einer weiteren Schnittdarstellung des Wärmetauschers von Fig. 15 in Längsrichtung des Übertrittrohres,

Fig. 21

eine Draufsicht auf die Verteilerplatte des Wärmetauschers von Fig. 15,

Fig. 22

eine Schnittdarstellung der Einspritzplatte des Wärmetauschers von Fig. 15,

Fig. 23

eine Draufsicht auf die Einspritzplatte von Fig. 22,

Fig. 24

eine Draufsicht auf die Bodenplatte des Wärmetauschers von Fig. 15,

Fig. 25

eine Schnittdarstellung eines Flachrohres des Wärmetauschers von Fig. 15,

Fig. 26

eine Draufsicht auf eine Verteilerplatte gemäß einer Variante des Wärmetauschers von Fig. 15, und

Fig. 27 von Fig. 26.

eine Draufsicht auf die Einspritzplatte des Wärmetauschers

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

Fig. 1

a section of a section in the longitudinal direction of an evaporator according to the first embodiment,

Fig. 2

a plan view of a part of the evaporator of Figure 1,

Fig. 3

a section through the upper part of an evaporator according to the second embodiment,

Fig. 4

a section through the upper part of an evaporator according to the third embodiment,

Fig. 5

a section through the upper part of an evaporator according to a variant of the third embodiment,

Fig. 6

a section through the upper part of an evaporator according to another variant of the third embodiment,

Fig. 7

a plan view of the upper part of an evaporator according to the fourth embodiment,

Fig. 8

a plan view of the upper part of an evaporator according to a combination of the first and fourth embodiment,

Fig. 9

an evaporator with U-shaped flat tubes,

Fig. 10

a section XX through the evaporator of Fig. 9,

Fig. 11

a section XI-XI through the evaporator of Fig. 9,

Fig. 12

an evaporator with U-shaped tubes connected in series (deflection in width),

Fig. 13

a heat exchanger in a partial view,

Fig. 14

a heat exchanger in a partial view,

Fig. 15

a front view of a heat exchanger,

Fig. 16

a drape view of the heat exchanger of Fig. 15,

Fig. 17

a side view of the heat exchanger of Fig. 15,

Fig. 18

a partial view of a sectional view of the heat exchanger of Fig. 15 in the longitudinal direction of the injection tube,

Fig. 19

a partial view of another sectional view of the heat exchanger of Fig. 15 in the longitudinal direction of the suction tube,

Fig. 20

a partial view of a further sectional view of the heat exchanger of Fig. 15 in the longitudinal direction of the transfer tube,

Fig. 21

a top view of the distributor plate of the heat exchanger of Fig. 15,

Fig. 22

a sectional view of the injection plate of the heat exchanger of Fig. 15,

Fig. 23

a top view of the injection plate of Fig. 22,

Fig. 24

a top view of the bottom plate of the heat exchanger of Fig. 15,

Fig. 25

a sectional view of a flat tube of the heat exchanger of Fig. 15,

Fig. 26

a plan view of a distributor plate according to a variant of the heat exchanger of Fig. 15, and

FIG. 27 of FIG. 26.

a plan view of the injection plate of the heat exchanger

A double-row evaporator 1, which is flowed through by a refrigerant, in the present case of R744 (CO ₂ ), during operation in cross-counterflow operation, has a plurality of flat tubes 2 arranged side by side with corrugated fins 3 arranged therebetween. Furthermore, an injection pipe 4, through which cold refrigerant enters the evaporator 1, an injection plate 5, a distributor plate 6 and a bottom plate 7 are provided. The injection plate 5 is disposed between the injection pipe 4 and the flat tubes 2, and forms an upper header box in communication with the distributor plate 6 and the bottom plate 7. Below is a corresponding lower header (not shown), in which the refrigerant is deflected, and an outlet pipe (not shown), through which the heated refrigerant is discharged from the evaporator 1, is provided.

The injection plate 5 is formed such that it has a plurality of passages 8, which correspond to holes 9 in the injection tube 4, wherein the passages 8 extend into the holes 9 in the injection tube 4 by the present relatively flat with the inner surface of the same end. According to the present embodiment, twelve passages 8 are provided for the introduction of refrigerant and correspondingly twelve holes 9 in the injection pipe 4, which passages 9 'to the flat tubes 2, wherein the distance between adjacent passage openings 9' is constant.

The injection pipe 4 is formed according to the first embodiment, as shown in the plan view of Fig. 2, with a uniformly decreasing in the normal flow direction of the refrigerant inner diameter (and outer diameter) in a horizontal plane.

The refrigerant that has flowed through the evaporator 1, is via a suction pipe 10, which is also connected via a plurality of passage openings with the collecting box, derived. In this case, the suction pipe has a larger inner diameter than the injection pipe 4 in the region of the first passage opening 9 ', wherein the intake pipe inside diameter is present constant over the entire length of the suction pipe.

According to a first variant of the first embodiment, the inner diameter of the injection tube 4 decreases in the normal flow direction of the refrigerant such that the cross sections over the entire length of the injection tube 4 at least in the region of the passage openings 9 'at the most frequently occurring operating conditions as constant as possible, ie in the present case, if possible within a fluctuation range of +/- 20%, in particular +/- 10% and particularly preferably of +/- 5%, mass flow density. In this case, a non-linear relationship between the distance from the first passage opening in the normal refrigerant flow direction and the diameter or hydraulically equivalent diameter of the injection tube is provided in order to meet the said condition.

According to a second variant, also not shown in the drawing, the distance of the passage openings in the direction of the injection tube end is reduced in addition to a reduction in the inner diameter of the injection tube 4. In order to take into account the greater distance between the passage openings, the flat tubes 2 also have a correspondingly adapted Distance to each other. As a result of the uneven distribution of the passages 8, in order to realize the decreasing distance of the passage openings 9 'in the longitudinal direction of the injection tube 4, not all flat tubes 2 are acted upon by refrigerant, resulting in a more uniform temperature distribution over the flat tubes 2 and corrugated fins 3 formed Heat transfer surface results.

In order to enable as uniform a mass flow density as possible and as uniform a temperature distribution over the heat transfer surface with relatively easy to implement technical measures, in particular the first and second variants can be combined accordingly, so that the fluctuation range of the mass flow density of the refrigerant is minimized, i. within the o.g. Limits moved.

According to a third variant of the first exemplary embodiment, in a modification of FIG. 1, with an arrangement of the injection tube 4 on the upper side of the evaporator 1, the passages 8 are formed projecting beyond the bores 9 into the interior of the injection tube 4. As a result, the inlets of the passage openings 9 'in the present case are displaced upwards in the direction of the region in which the gaseous phase of the refrigerant accumulates, so that gaseous and less liquid refrigerant can be specifically aspirated.

In place of protruding into the interior of the injection tube 4 passages can also pipes or the like. arranged in the holes 9, or the holes may be formed as inwardly projecting passages, which has the same effect.

Of course, it is also conceivable that passages can be realized by an additional application of material on the pipe inside, or by pressing the pipe wall in the corresponding area.

The targeted suction from the upper region is particularly advantageous for D-shaped pipes, since the way up here is relatively short.

According to the second embodiment shown in Fig. 3, the inner diameter of the injection pipe 4 is reduced by a sleeve 20, whereby the refrigerant flow velocities in the injection pipe 4 are increased. The sleeve 20 is in this case arranged in the upper region of the injection tube 4, wherein it is formed continuously slotted on its downwardly facing longitudinal side, so that it extends over only about half of the inner circumference of the injection tube 4 is soldered to the injection tube 4 present What happens in the same operation as the soldering of the entire evaporator 1.

According to a variant of the second exemplary embodiment, the sleeve 20 can also be designed in such a way that the slot narrows in the normal direction of refrigerant flow, so that the sleeve covers a larger part of the inner circumference of the injection tube and thereby the free flow cross section is reduced, so that - with a corresponding slot profile - Also a relatively constant mass flow density of the refrigerant is possible, preferably within the above Fluctuation.

Especially with short injection pipes 4 can - as in Fig. 4 schematically indicated in the form of a third embodiment - even over the length of the injection pipe 4 constant reduction of the inner diameter d against the inner diameter in the supply line cause a sufficient increase in the refrigerant flow rate. The inner diameter d of the injection tube is in the range of Passage openings (not shown) preferably 2 to 3 mm, in particular 2.2 to 2.6 mm. In addition, the diameter D of the suction tube 10 is larger, in particular greater than 3 mm. If, in addition, an overflow pipe 11 is provided, as shown in FIG. 5, the inside diameter d _{0 of} the overflow pipe 11 lies between that of the injection pipe and the suction pipe.

Particularly suitable for designs with a constant inner diameter are tubes (in particular injection tubes, but possibly also overflow and / or suction tubes) with a D-shaped profile. An example is shown in Fig. 6 - Here, instead of the "normal" inner diameter, the hydraulically equivalent inner diameter, so that the o.g. Diameter specifications apply accordingly for hydraulically equivalent inner diameter of such trained tubes.

According to a fourth embodiment, the inner diameter of the injection pipe 4 is constant, however, for increasing the flow velocity and equalizing the refrigerant distribution to the flat tubes, the suction pipe 10 is formed with an inner diameter increasing in the normal flow direction, as shown in FIG.

The tube geometries of the injection tube 4 according to the first and the suction tube according to the fourth embodiment can also be combined, as shown in Fig. 8

In order to support the most uniform possible temperature distribution of the heat transfer surface, and the inner diameter of the passage openings in the normal flow direction of the refrigerant can be changed. The inner diameters (or free cross-sectional areas in the case of non-circular passage openings) of the rear passage openings are larger than those in the front region of the injection tube.

All of the above-mentioned embodiments can be combined with each other to effect an optimal increase in the refrigerant flow velocity in the injection tube. The measures can in principle also be used for injection tubes arranged at the bottom or correspondingly also for transfer tubes.

Particularly preferred embodiments of evaporators, in which the design of the injection tube and the passage openings can be made according to the embodiments described above, will be described in their general structure with reference to the figures 9 et seq. The evaporators of Figures 9 to 15 are in the DE 102 60 107 A1 discloses the entire disclosure content with respect to the general design of the evaporator is explicitly included.

The evaporator 70 shown in FIGS. 9 to 11 has a plurality of shapelessly curved flat tubes 71a, 71b, 71c, etc. Each flat tube has two legs 72 and 73. The free ends of the legs 72 and 73 are secured in a bottom plate 74 (see Figures 10 and 11). Arranged above the base plate 74 is a distributor plate 75, which alternately has two slit-shaped openings 76, 77 lying one behind the other in the depth direction, leaving a web 78 and a deflecting channel 79 extending in the depth direction. An injection plate 80 disposed adjacent to the distributor plate 75 is omitted in the illustration of FIG. 9.

The flow of the refrigerant is carried out according to the arrows, ie the refrigerant enters at E in the front flow section of the flat tube 71 a, first flows down, then deflected down, then flows upwards and enters the deflection channel 79, where it the arrow U is deflected according to the depth, then flows on the back below, is deflected there and then flows back up to pass through the arrow A through the opening 77.

The supply and removal of the refrigerant can be seen from Fig. 10, in which the injection plate 80 and the injection tube 81 and the suction tube 82 are shown. The distributor plate 75 has two openings 76c and 77c, which are separated from each other by the web 78c. In the injection plate 80, a refrigerant inlet opening 83 is provided, which is arranged in the injection tube 81 with an aligned Kättemittetdurchbruch 84.

In the present case, the refrigerant inlet breakthrough 83, as well as the refrigerant opening 84 are formed by flashless bores, but also a configuration according to the embodiment of Fig. 1 may be provided, i. the distributor plate 75 has protruding edges which project into the injection tube 81 and terminate flush with the refrigerant passage 84. The edges can also protrude into the interior of the injection tube 81.

Similarly, on the side of the suction pipe 82, a refrigerant discharge opening 85 in the injection plate 80 and an aligned refrigerant opening 86 are arranged in the suction pipe 82. Also in this case, the apertures 85, 86 formed as bores in the present case can be formed as shown in FIG.

The injection tube 81 and the suction tube 82 are sealingly and pressure-resistant soldered to the injection plate 80, as well as the other parts 75, 74 and 71c.

The deflection into the depth is particularly well from the sectional view of Fig. 11 can be seen, which shows a section through the deflection channel 79d. According to the arrows of FIG. 11, the refrigerant coming from below flows upward into the deflection channel 79d, in which it moves to the right (depth direction). is deflected and enters the rear portion of the flat tube 71d, in which it flows from top to bottom. It is thus provided in each case a simple deflection in the width and in the depth.

As can be seen from the illustration of FIG. 9, a plurality of passage openings from the injection tube 81 into the collecting box and from the collecting box to the suction tube 82 are required, in the present case one per U-shaped bent flat tube 71.

In order to allow a uniform temperature distribution over the entire heat transfer surface of the evaporator, the injection tube 81 is formed such that the free flow cross section of the injection tube 81 in the normal flow direction - in the present case evenly, i. in a linear relationship over the length - reduced. In contrast, in the present case, the free flow cross section of the suction pipe 82 increases in the flow direction.

12 shows an embodiment of an evaporator 90 which has a plurality of U-shaped bent flat tubes 91a, 91b, 91c, etc., which allows a double deflection in the width and a simple deflection in depth. For this purpose, the distributor plate 93 is designed such that that for the deflection in the width two openings 96 and 98 are connected to each other via a transverse channel 101, wherein the apertures 96, 98 and the transverse channel form an H-shaped opening in the distributor plate 93. For the deflection into the depth, a long deflection channel 102 is provided, which corresponds to the deflection channel 79 of the previously described evaporator. The refrigerant flow is shown in Fig. 12 by arrows in the left part of the evaporator. Here, the refrigerant enters at A in the front part of the left leg of the flat tube 91a, flows down, is deflected in the width, flows up again and exits the flat tube 91a, in an opening of the distributor plate 93, flows along the Arrow B through the transverse channel 101 and enters the adjacent flat tube 91 b, which flows through it. From there it passes into the deflection channel 102 and is guided by the arrow C into the rear part of the flat tube 91b, which it flows through counter to the direction of flow through the front part. Via a transverse channel 100, which is arranged between two apertures 97 and 99 and corresponds in its embodiment present to the transverse channel 101 between the apertures 96 and 98, the refrigerant passes to the first flat tube 91a, which also flows through it opposite to the flow direction of the front part, and exits at D again, from where it enters the suction tube (not shown). As a result of the double deflection in the width of the required number of passages in the injection and suction pipe is halved compared to the previously described evaporator. The design of injection and suction pipe corresponds to that of the previously described evaporator.

Fig. 13 shows a variant of the evaporator of Fig. 12, wherein the individual units are arranged in mirror image to each other. As indicated in the region of the leftmost, adjacent deflection channels, an H-shape of the opening in the distributor plate is also possible in this area, so that a refrigerant exchange between adjacent units in the region of the deflection in depth is possible.

Fig. 14 shows a variant of the evaporator of Fig. 13, wherein the subdivisions differ in depth.

Although not shown in the drawing, a merging of the inlets and outlets of adjacent units is possible, for which the corresponding openings in the injection plate and distributor plate are suitable form. The opening in the distributor plate is in this case preferably H-shaped with a widened web for the refrigerant inlet or outlet formed.

FIGS. 15 to 27 show a further heat exchanger and a variant for this, in which the configuration of the injection tube and the passage openings can be made in accordance with the exemplary embodiments described above.

The heat exchanger illustrated in FIGS. 15 to 25 is an evaporator for a motor vehicle air conditioning system and has a tubular supply line 1001 and a tubular discharge line 1002. The two lines 1001 and 1002 are arranged parallel to one another in a longitudinal direction of the evaporator above a collecting box 1003 extending over the entire length of the evaporator. Beyond the collecting tank 1003 supply and discharge are continued to a common flange plate 1004, via which they are connected to the other air conditioning system of the vehicle (not shown). In the area of continuations 1001 a, 1002a between collecting box 1003 and flange plate 1004, the lines 1001 and 1002 have a number of kinks and bends, whereby they are adapted to the individual geometry of the installation space in the vehicle.

Due to the function of a part of the supply line 1001 and a part of the discharge line 1002, this part is also referred to as injection or suction pipe. In parallel with the corresponding part of the lines 1001 and 1002, an overflow pipe 1005 is furthermore arranged above the collecting tank 1003 at the latter and extends over the entire width of the evaporator. The overflow pipe 1005 is designed as a tube section which is closed at each of its two ends and, in the present case-not shown in the drawings-has an inner diameter which increases in the flow direction. The same applies to the injection and intake manifold. The diameter change takes place here by means of inserted sleeves.

On the underside of the collecting tank 1003, a plurality of U-shaped bent flat tubes 1006, here twenty, are arranged, the leg heights of the U-shaped flat tubes 1006 plus the collecting box height and the injection pipe, overflow pipe or Saugrohraußendurchmesser overall yield the height of the evaporator ,

Each of the flat tubes 1006 has a plurality of chambers or channels 1006a (see cross-section through one of the flat tube legs of FIG. 25). In the present exemplary embodiment, only half of the chambers 1006a of each of the flat tubes 1006 forms a flow path together or is arranged hydraulically in parallel. In the direction of the air flow, that is to say perpendicular to the plane of the drawing according to FIG. 15, there are thus two flow paths in each flat tube 1006 in depth one behind the other.

The flat tubes 1006 are each inserted with their ends in openings 1007a of a bottom plate 1007 (see FIG. 24) and soldered to the same. A central, longitudinally extending web 1007b of the bottom plate 1007 separates the two groups of chambers 1006a of the flat tubes 1006 from one another.

For a further embodiment of the collecting tank 1003, a distributor plate 1008 (see FIG. 21) is placed flat on the lower base plate 1007 and soldered to the same over the entire surface but at least along closed marginal lines. The distributor plate 1008 has a number of slot-like openings 1008 a, which are partially aligned with the openings 1007 a of the bottom plate 1007 and thus with the end faces of the flat tubes 1006. Out of alignment portions of the apertures, eg H-shaped apertures 1008b of the manifold plate 1008, are intended to interconnect different flow paths. Connect the H-shaped openings shown in each case two adjacent flat tubes 1006 and four flow paths with each other.

Above the distributor plate 1008, an upper plate element, hereinafter referred to as injection plate 1009, of the header 1003 is soldered flush to the distributor plate 1008. The injection plate 1009 has a number of circular passages 1009a made by punching each on the same side. The punching creates on the side facing away from the distributor plate in each case a protruding collar 1009b (see side view of the distributor plate in Fig. 22), by means of which the supply line 1001, i. the injection tube, the drain 1002, i. the suction tube, and the overflow 1005 are particularly easy to attach.

The tubular lines 1001, 1002 and 1005 are each provided with bores which correspond to the above-described passages 1009a of the injection plate 1009. In the course of assembly of the evaporator, the lines are thus attached to the collar 1009b and soldered cold-resistant, whereby at the same time a mechanically secure connection between the collection box and pipes is made.

The distances of the farthest holes result in an effective length of the respective lines 1001, 1002 and 1005. An effective in terms of heat exchange evaporator length is meaningful defined as the largest distance between two flow paths in the width direction of the evaporator. It follows that in the present embodiment, the effective length of the feed line 1001 is less than 40% of the effective evaporator width.

The evaporator works as follows:

Through the supply line 1001, a high-pressure liquid consisting of liquid and gaseous phase refrigerant is supplied to the evaporator (in the present case carbon dioxide, ie R744). The refrigerant enters through the passages 1009a or holes of the feed line 1001 into a first group of eight flow paths. There is in the H-shaped openings a transfer to the eight corresponding, opposite flow paths, each one first and one subsequent continuous flow path to the same flat pipe belong ("transfer to the depth"). After passing sixteen of the evaporator's total of forty flow paths, the refrigerant enters the transfer tube 1005 through somewhat larger holes. These sixteen first flow paths, which correspond to the first eight flat tubes from the right according to FIG. 15, are thus grouped into a first section.

The overflow pipe 1005 has the function of an intermediate collector, so that the refrigerant of the different flow paths is remixed. At the same time, according to FIG. 15, it flows to the left, wherein the flow velocity with respect to the supply line 1001 has already increased significantly.

On the left side of the evaporator, the remaining twelve flat tubes form a second group or a second section of a total of twenty-four flow paths 1006. In this case, through the passages 1009a, first of all, the inlet from the overflow pipe 1005 into the first twelve flow paths of the second section and then into the second twelve flow paths of the second section by means of the H-shaped openings of the distributor plate. The higher number of flow paths of the second section is accommodated in the overflow tube 1005 in that the diameter of the passages 1009a of the second section is smaller than the diameter of the eight passages of the first section.

Finally, the substantially vaporized and expanded refrigerant from a particularly large twelve passages enters the discharge line 1002, in order to be supplied from there to the further refrigeration cycle.

According to the function of the evaporator, during the above-described operation, the flat tubes 1006 are surrounded by air, which is subsequently used for air conditioning of a vehicle interior.

The variant shown in FIGS. 26 and 27 differs from the previous exemplary embodiment only in the design of the passages 1009a 'and their corresponding bores in the lines 1001, 1002 and 1005, as well as in the shape of the distributor plate 1008'. In contrast to the previous embodiment, here some of the openings 1009a 'are each formed so that two flow paths 1006a are directly charged with refrigerant by a single bore. However, just as in the previous embodiment, two flow paths per section of the evaporator are flowed through, for which H-shaped openings 1008a 'are also responsible for the transition between the flow paths. As in the previously described embodiment, a sleeve is provided in each of the lines 1001, 1002 and 1005, which changes the free flow cross section corresponding to the flow path and increases the flow velocity in comparison with a tube without sleeve, in particular without changing the free flow cross section over the length. so that a very uniform temperature distribution over the entire evaporator width is possible.

Claims (22)

Heat exchanger, in particular evaporator, with at least one injection tube (4, 81), a plurality of passage openings (9 '), a plurality of over the passages (9') with the injection tube (4; 81) directly or indirectly connected, forming a heat transfer surface Elements through which preferably a medium flows, which at least partially undergoes a phase change in the region of the heat exchanger (1), and a suction pipe (10, 82), characterized in that the heat exchanger (1) is designed such that in the injection pipe (4 81), the flow velocity of the medium is increased in at least one region at least in the case of part of the passage openings (9 '). Heat exchanger according to claim 1, characterized in that the free flow cross-section of the injection tube (4; 81) decreases in the normal flow direction. Heat exchanger according to claim 1 or 2, characterized in that the free flow cross-section of the suction pipe (10, 82) increases in the normal flow direction. Heat exchanger according to one of the preceding claims, characterized in that the free flow cross-section of an overflow pipe (11; 1005), which forms the transition between a region of the heat exchanger and a second region of the heat exchanger, increases in the normal flow direction. Heat exchanger according to one of the preceding claims, characterized in that at least one sleeve (20) is provided in the injection tube (4, 81), in the suction tube (10, 82) and / or in the overflow tube (11, 1005) for at least partially reducing the free flow cross section is. Heat exchanger according to claim 5, characterized in that the sleeve (20) is formed slotted, wherein the sleeve (20) over a maximum of three quarters, in particular over half, of the inner circumference of the injection tube (4, 81) and / or the overflow tube (11; 1005). Heat exchanger according to one of the preceding claims, characterized in that the injection pipe (4) and / or the suction pipe (10) and / or an overflow pipe (11) have a D-shaped cross section. Heat exchanger according to one of the preceding claims, characterized in that the inner diameter of the injection tube (4; 81) at least in a region in which through openings (9) are provided, between 2.0 and 3.0 mm, in particular between 2.2 and 2.6 mm, wherein in the case of non-circular cross sections of the hydraulically equivalent inner diameter occurs in place of the inner diameter. Heat exchanger according to one of the preceding claims, characterized in that the inner diameter of the suction tube (10; 82) is between 4.0 and 6.6 mm, in particular between 4.5 and 6.0 mm, wherein in the case of non-circular cross-sections, the hydraulically equivalent inner diameter occurs in place of the inner diameter. Heat exchanger according to one of the preceding claims, characterized in that the inner diameter of the injection tube (4, 81) is 2.0 to 3.0 mm, in particular between 2.2 and 2.6 mm, the inner diameter of an overflow tube (11, 1005) 2 , 0 to 4.5 mm, in particular between 3.0 and 4.0 mm, and the inner diameter of the suction tube (10; 82) between 4.0 and 6.6 mm, in particular between 4.5 and 6.0 mm, is, wherein in the case of non-circular cross-sections of the hydraulically equivalent inner diameter occurs in place of the inner diameter. Heat exchanger according to one of the preceding claims, characterized in that the inner diameter of the injection tube (4; 81) and / or the inner diameter of an overflow tube (11; 1005) and / or the inner diameter of the suction tube (10; 82) each formed substantially equal is in particular between 2.5 and 4.0 mm, preferably between 2.8 and 3.7 mm, more preferably between 3.0 and 3.4 mm, wherein in the case of non-circular cross-sections of the hydraulically equivalent inner diameter in place of Inside diameter occurs. Heat exchanger according to one of the preceding claims, characterized in that in the injection pipe (4; 81) and / or in the overflow pipe (11; 1005) in the free flow cross sections at least in the region of the passage openings (9 ') under normal operating conditions of the heat exchanger (1) Constant mass flow density with a maximum fluctuation of +/- 20%, in particular +/- 10%, more preferably of +/- 5%, exists between the individual cross-sections. Heat exchanger according to one of the preceding claims, characterized in that the heat exchanger (1) is a plate-type heat exchanger or serpentine construction. Heat exchanger according to claim 13, characterized in that at least one distribution plate (75, 93, 1008) is provided, which slits (76, 77, 79, 94, 95, 96, 97, 98, 99, 100, 101, 102, 1008a, 1008a '), Heat exchanger according to claim 14, characterized in that the heat exchanger provides at least a simple deflection in the depth of the heat exchanger and an at least simple, preferably at least twice deflection in the width of the heat exchanger. Heat exchanger according to one of the preceding claims, characterized in that the injection pipe (4) is mounted on the lower side of the heat exchanger. Heat exchanger according to one of the preceding claims, characterized in that the inlet of at least one passage opening (9 ') above the lowest point of the injection pipe (4) is arranged. Heat exchanger according to one of the preceding claims, characterized in that the injection pipe (4) is mounted on the upper side of the heat exchanger. Heat exchanger according to one of the preceding claims, characterized in that the inlet of at least one passage opening (9 ') below the highest point of the injection pipe (4) is arranged. Heat exchanger according to one of the preceding claims, characterized in that the inlet is formed by a projecting into the interior of the injection tube passage or by a pipe arranged in the passage opening Heat exchanger according to claim 20, characterized in that the height of the protruding into the interior of the injection tube passage or arranged in the passage opening tube 20% to 70%, preferably 30% to 60%, particularly preferably 40% to 55%. Heat exchanger according to one of the preceding claims, characterized in that the heat exchanger (1) is a heat exchanger for the refrigerant R744 (CO ₂ ) or R134a.

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