EP1798505A2 - Heat exchanger, more particularly evaporator - Google Patents

Abstract

The heat exchanger has an injection pipe (4) with passage openings (9`) via which a cooling medium is distributed to a partial region of the exchanger. Units forming a heat transmitting surface are directly or indirectly connected with the pipe via the passage openings. A free flow cross section of the passage openings in a fluid guiding direction to the heat transmitting surface satisfies a specific condition. A suction pipe has an inner diameter between 4.5 millimeter and 6.0 millimeter.

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 DE 1 065 453 B1 For example, an evaporator is known in which the collecting containers are provided with plates with throttle openings for reducing the refrigerant passage cross-section between the individual distribution tank sections. The throttle openings are provided here exclusively in the lower reservoir and serve to equalize the refrigerant distribution to the individual multi-channel flat tubes of the evaporator. Such an evaporator still leaves something to be desired.

Furthermore, in the case of a two-phase refrigerant for equalizing the refrigerant distribution to four individual tubes arranged parallel to one another, it is known to reduce the diameter of the feeding tube continuously over the length ( Patent abstracts of Japan, application number 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.

genügt. Hierbei sind n die Nummer der Durchtrittsöffnung in Fluidzuführrichtung, a, b, c und d Konstanten, wobei Δ maximal 0,2, vorzugsweise 0,1 und besonders bevorzugt 0,05 beträgt. Im Falle nicht kreisförmiger Querschnitte tritt der hydraulisch gleichwertige Durchmesser an Stelle des Durchmessers.According to the invention, a heat exchanger is provided, in particular an evaporator, with at least one tube via which a medium can be fed to at least one subregion of the heat exchanger, a plurality of passage openings in the tube, which allow a distribution of the medium to at least the subregion of the heat exchanger, a plurality of over the passage openings with the tube directly or indirectly connected, a heat transfer surface forming elements through which the medium can flow, which undergoes at least partially a phase change during operation, and at least one suction tube through which the medium can be derived from the heat exchanger, wherein the free flow cross-section of the individual passage openings of at least one of the feeding tubes in the fluid supply direction to the subsequent heat transfer surface of the condition $$\mathrm{d}\left(\mathrm{n}\right)\mathrm{=}\left(\mathrm{a}\mathrm{+}\mathrm{bxn}\mathrm{+}\mathrm{cx}{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="imgf0001.png"\; state="\{\{state\}\}">n</figure-callout>}}^{\mathrm{2}}\right)\mathrm{\pm }\mathrm{Ax}\mathrm{(}\mathrm{a}\mathrm{+}\mathrm{bxn}\mathrm{+}\mathrm{cx}{\mathrm{n}}^{\mathrm{2}}\mathrm{)}$$

enough. Here, n is the number of the passage opening in the fluid supply direction, a, b, c and d constants, wherein Δ is at most 0.2, preferably 0.1 and more preferably 0.05. In the case of non-circular cross-sections, the hydraulically equivalent diameter will replace the diameter.

The constants a, b and c are preferably in the following ranges: a in a range of +3.2 to +3.6, especially +3.4286 ± 5%, b in a range of -0.5 to -0 , 2, in particular -0.3536 ± 5%, and c in a range of 0 to +0.1, in particular +0.0179 ± 5%. Particularly preferred value for a is +3.4286, for b -0.3536 and for c + 0.0179. In this case, three to twelve, in particular five to ten and in particular preferably six to eight through openings are preferably provided on an infeed pipe. The indicated values make it possible, especially with exactly seven passage openings, to achieve an optimal distribution of the refrigerant serving as the medium and thereby lead to a uniform temperature distribution. In this case, such a configuration can be provided both in an injection pipe and in an overflow pipe. In particular, when an overflow pipe is present, it is important to ensure a uniform distribution of the mass flow, since in the region of the overflow pipe, the proportion of gaseous phase is greater than at the injection pipe, so that the risk of uneven temperature distribution is significantly greater in the subsequent heat exchanger area.

Preferably, the difference between the maximum and the minimum diameter of the passage openings divided by the maximum diameter of the passage openings is at least 0.3, preferably at least 0.4.

The free flow cross section in the injection tube and / or overflow tube is preferably substantially constant, which is understood below to mean changes of less than ± 5%. However, too Measures are taken to at least partially change the cross-section, in particular to reduce, so that the flow rate of the medium is increased, whereby a better mixing of the liquid and gaseous phase takes place.

In the injection tube and / or in the overflow tube, a sleeve for reducing the free flow cross section is preferably provided. The sleeve is in this case preferably formed slotted at least in regions, wherein the sleeve is preferably applied over a maximum of three quarters, in particular over half, of the inner circumference of the injection tube.

The slot in the sleeve can narrow to influence the flow velocity of the medium in the flow direction of the medium, so that the free flow cross-section of the injection pipe or overflow pipe is reduced.

The injection tube and / or the suction tube and / or an overflow tube, which is arranged between two rows of tubes, preferably has a substantially D-shaped cross-section. Here, the distances of the passage openings to the upper region of the tube, in which usually accumulates the gaseous phase, low, so that even with relatively simple measures an increased suction of the gaseous phase 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 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.

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.

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 ± 20% maximum, in particular ± 10%, more preferably ± 5%, between the individual cross sections. 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 pipe or the overflow pipe is attached to the upper side of the heat exchanger. In principle, however, another attachment is possible.

Fig. 1

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

Fig. 2

eine Draufsicht auf einen Teil der Einspritzplatte,

Fig. 3

einen Schnitt in Längsrichtung durch die in Fig. 2 dargestellte Einspritzplatte,

Fig. 4

eine Detailansicht eines Bereichs von Fig. 3,

Fig. 5

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

Fig. 6

eine Verteilerplatte gemäß dem dritten Ausführungsbeispiel,

Fig. 7

eine Einspritzplatte gemäß dem dritten Ausführungsbeispiel,

Fig. 8

einen Verdampfer mit U-förmig gebogenen Flachrohren,

Fig. 9

einen Schnitt IX-IX durch den Verdampfer von Fig. 8,

Fig. 10

einen Schnitt X-X durch den Verdampfer von Fig. 8,

Fig. 11

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

Fig. 12

einen Wärmetauscher in einer Teilansicht,

Fig. 13

einen Wärmetauscher in einer Teilansicht,

Fig. 14

eine Vorderansicht eines Wärmetauschers,

Fig. 15

eine Drausicht auf den Wärmetauscher von Fig. 14,

Fig. 16

eine Seitenansicht des Wärmetauschers von Fig. 14,

Fig. 17

eine Teilansicht einer Schnittdarstellung des Wärmetauschers von Fig. 14 in Längsrichtung des Einspritzrohres,

Fig. 18

eine Teilansicht einer anderen Schnittdarstellung des Wärmetauschers von Fig. 14 in Längsrichtung des Saugrohres,

Fig. 19

eine Teilansicht einer weiteren Schnittdarstellung des Wärmetauschers von Fig. 14 in Längsrichtung des Übertrittrohres,

Fig. 20

eine Draufsicht auf die Verteilerplatte des Wärmetauschers von Fig. 14,

Fig. 21

eine Schnittdarstellung der Einspritzplatte des Wärmetauschers von Fig. 14,

Fig. 22

eine Draufsicht auf die Einspritzplatte von Fig. 21,

Fig. 23

eine Draufsicht auf die Bodenplatte des Wärmetauschers von Fig. 14,

Fig.24

eine Schnittdarstellung eines Flachrohres des Wärmetauschers von Fig. 14,

Fig. 25

eine Draufsicht auf eine Verteilerplatte gemäß einer Variante des Wärmetauschers von Fig. 14, und

Fig. 26

eine Draufsicht auf die Einspritzplatte des Wärmetauschers von Fig. 25.

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 injection plate,

Fig. 3

a longitudinal section through the injection plate shown in Fig. 2,

Fig. 4

a detailed view of a portion of Fig. 3,

Fig. 5

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

Fig. 6

a distributor plate according to the third embodiment,

Fig. 7

an injection plate according to the third embodiment,

Fig. 8

an evaporator with U-shaped flat tubes,

Fig. 9

a section IX-IX through the evaporator of Fig. 8,

Fig. 10

a section XX through the evaporator of Fig. 8,

Fig. 11

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

Fig. 12

a heat exchanger in a partial view,

Fig. 13

a heat exchanger in a partial view,

Fig. 14

a front view of a heat exchanger,

Fig. 15

a drape view of the heat exchanger of Fig. 14,

Fig. 16

a side view of the heat exchanger of Fig. 14,

Fig. 17

a partial view of a sectional view of the heat exchanger of Fig. 14 in the longitudinal direction of the injection tube,

Fig. 18

a partial view of another sectional view of the heat exchanger of Fig. 14 in the longitudinal direction of the suction tube,

Fig. 19

a partial view of a further sectional view of the heat exchanger of Fig. 14 in the longitudinal direction of the transfer tube,

Fig. 20

a top view of the distributor plate of the heat exchanger of Fig. 14,

Fig. 21

a sectional view of the injection plate of the heat exchanger of Fig. 14,

Fig. 22

a plan view of the injection plate of Fig. 21,

Fig. 23

a top view of the bottom plate of the heat exchanger of Fig. 14,

Figure 24

a sectional view of a flat tube of the heat exchanger of Fig. 14,

Fig. 25

a plan view of a distributor plate according to a variant of the heat exchanger of Fig. 14, and

Fig. 26

a plan view of the injection plate of the heat exchanger of Fig. 25.

An evaporator 1, which is flowed through during operation of a refrigerant, in this case of R744, has a plurality of juxtaposed, U-shaped bent flat tubes 2 with interposed corrugated fins 3. Further, an injection pipe 4, through which cold refrigerant enters the evaporator 1, an injection plate 5, which is disposed between the injection pipe 4 and the flat tubes 2 and in conjunction with a distributor plate 6 and a bottom plate 7 forms a collecting box arranged above, and a Exit or suction pipe (not shown) provided by which the heated refrigerant is discharged from the evaporator 1.

The injection plate 5 is formed such that it has a plurality of passages produced by punching 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, in which they are relatively flush with the present Inner circumferential surface of the same end. According to the present embodiment, seven passages 8 for the introduction of refrigerant and correspondingly seven holes 9 are provided in the injection pipe 4, which passages 9 'to the flat tubes 2 form. Corresponding passages 8 'and bores are provided for the outlet of the refrigerant in a suction pipe (not shown) after it has passed through the evaporator 1. Figures 3 and 4 show sections through the passages 8 ', these correspond but - except for the diameter of the passages - the passages 8 for the refrigerant inlet. The suction pipe has, as a result of the evaporation of refrigerant, a larger volume flow must be passed through, a larger inner diameter than the injection pipe 4.

wobei relativ geringe Abweichungen vom durch die Formel angegebenen I-dealwert, insbesondere aus Toleranzgründen, möglich sind. Hierbei beträgt vorliegend a +3,4286, b -0,3536 und c +0,0179 und n entspricht der Nummer der Durchtrittsöffnung in Strömungsrichtung, so dass sich für den ersten Durchmesser 3,1 mm, den zweiten Durchmesser 2,8 mm, der dritte Durchmesser 2,5 mm, der vierte Durchmesser 2,3 mm, der fünfte Durchmesser 2,1 mm, der sechste Durchmesser 2,0 mm und der siebte Durchmesser als 1,8 mm ergibt. Vorliegend beträgt das Verhältnis der Differenz des größten und kleinsten Durchmessers zum größten Durchmesser 0,42. Der Außendurchmesser des Einspritzrohres beträgt vorliegend 10 mm, die Wandstärke 2 mm, so dass sich ein Innendurchmesser D_h von 6 mm ergibt. Im Gegensatz hierzu ist der Durchmesser der Bohrungen und Durchzüge 8' für den Kältemittelaustritt konstant, wie auch der Innendurchmesser des Saugrohres.According to the invention, the passages 8, which form the passage openings 9 ', have an (inner) diameter d which is dependent on the position in the injection pipe 4, the cross-section free of the refrigerant at all injection openings decreasing over the length of the injection pipe 4. The diameter d results here essentially from the formula: $$\mathrm{d}\left(\mathrm{n}\right)\mathrm{=}\mathrm{a}\mathrm{+}\mathrm{bxn}\mathrm{+}\mathrm{cx}{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="imgf0001.png"\; state="\{\{state\}\}">n</figure-callout>}}^{\mathrm{2}}$$

whereby relatively small deviations from the I-deal value indicated by the formula, in particular for tolerance reasons, are possible. Here, a is +3.4286, b is -0.3536 and c is +0.0179 and n corresponds to the number of the passage opening in the flow direction, so that for the first diameter 3.1 mm, the second diameter 2.8 mm, the third diameter is 2.5 mm, the fourth diameter is 2.3 mm, the fifth diameter is 2.1 mm, the sixth diameter is 2.0 mm and the seventh diameter is 1.8 mm. In the present case, the ratio of the difference between the largest and smallest diameter to the largest diameter is 0.42. The outer diameter of the injection tube is in this case 10 mm, the wall thickness 2 mm, so that there is an inner diameter D _h of 6 mm. In contrast, the diameter of the bores and passages 8 'for the refrigerant outlet is constant, as well as the inner diameter of the suction pipe.

The spacing of the bore centers of the first and second bores, the third and fourth bores, the fifth and sixth bores is constant, as is the distance between the second and third bores, the fourth and fifth hole and the sixth and seventh hole. The same applies to the distances of the passages 8, as well as the holes and passages 8 'for the refrigerant outlet.

The refrigerant flow is predetermined by the distributor plate 6. This has a structure with approximately 1-shaped and H-shaped openings, which in some areas, ie omitting the stacked H-shaped openings in shortening and changing the design of one of the two end portions, the. Structure of the distributor plate 6, which is shown in Fig. 6, corresponds. Here, in each case an I-shaped opening in the region of the passage openings 9 and in extension thereof is also provided correspondingly in the region of the passage openings for the refrigerant outlet. In order to improve the inflow and outflow of the refrigerant, the I-shaped openings in the middle region on a circular extension. The introduced refrigerant is relatively evenly distributed to the front, ie the air inlet side arranged half of the flow channels of the flat tubes, flows down, is deflected by the arc of the U-shaped flat tube, flows back up, where it again in the region of the distributor plate. 6 arrives. The H-shaped opening has approximately twice the height of the I-shaped opening, wherein the central region has a transition from one flat tube to the next. The H-shaped opening has an approximately twice as high height as the I-shaped openings Flat tube, which is flowed through in mirror image to the central longitudinal axis of the H-shaped opening (which runs in the air flow direction), allows. Through the H-shaped opening, the refrigerant is deflected backwards and flows from top to bottom in the other part of the flat tube channels, which are flowed through opposite to the front channels, so that the refrigerant exits at the rear I-shaped opening and the evaporator again leaves via the corresponding passage to the suction pipe.

In the following, the second exemplary embodiment is explained in more detail with reference to FIG. 5. This is true - unless otherwise specifically described below - the structure of the evaporator 1 including the dimensions of the first embodiment match, so that the same and equivalent elements are provided with the same reference numerals.

According to the second embodiment, a sleeve 20 is additionally provided in the otherwise corresponding to the first embodiment, the evaporator 1 in the injection tube 4, which is formed by a longitudinally wide slotted wide tube. The slot in this case occupies about half of the corresponding hollow cylinder, so that the sleeve 20, as shown in Fig. 5, only in the holes 9 opposite region of the injection tube 4 is arranged and reduces the free flow area, whereby the flow rate of the refrigerant is increased , In addition, the upper region, in which the gaseous phase preferably accumulates, is brought closer to the entry into the passage openings 9 '. The sleeve 20 extends substantially over the entire straight length of the injection tube 4, that is, it begins before the first hole 9. It has a wall thickness of 1.5 mm, so that the cross section correspondingly decreases from above and the upper region of the sides , which results in a reduced height and a correspondingly reduced equivalent effective hydraulic diameter D _h of 4.5 mm, which is correspondingly smaller than in the first embodiment. As a result of the reduced hydraulic diameter of the injection tube 4 results in a ratio of mean diameter of the passages to the hydraulic diameter of 0.53, resulting in an optimal temperature distribution of the evaporator even at relatively low refrigerant flow rates (about 10 kg / h).

In the figures 6 and 7, the distributor plate 6 and the injection plate 5 of an evaporator is shown, which has ten passage openings. Here, starting from each of the passage openings, a double deflection into the width of the evaporator (both on the front and on the back) and a simple deflection in the depth of the evaporator. The dimensions of the individual passage openings correspond essentially to the aforementioned formula.

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, are described in their general structure with reference to the figures 8 et seq. The evaporators of Figures 8 to 13 are in view of their general configuration 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 Figures 8 to 10 has a plurality of U-shaped bent flat tubes 71a, 71b, 71c, etc. on. 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 9 and 10). 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. 8.

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 downwards, is then deflected down, flows then up and enters the deflection channel 79, where it is deflected according to the arrow U in the depth, then flows on the back down, is deflected there and then flows back up to pass through the aperture A through the opening 77 ,

The supply and discharge of the refrigerant can be seen from Fig. 9, 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 with an aligned refrigerant opening 84 in the injection tube 81.

In the present case, the refrigerant inlet breakthrough 83, as well as the Kätsemitteldurchbruch 84 are formed by flangeless holes, 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. According to a further variant, the edges can also protrude into the interior of the injection tube 81, so that an intensified mixing of the liquid and gaseous phase of the refrigerant takes place. However, the free flow cross sections correspond to the o.g. Formula.

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 visible from the sectional view of Fig. 10, which shows a section through the deflection channel 79d. According to the arrows of Fig. 10, the refrigerant coming from below flows upward into the deflection passage 79d, in which it is deflected to the right (depth direction) 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 representation of FIG. 8, 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 the most uniform possible temperature distribution over the entire heat transfer surface of the evaporator, the free passage openings are formed starting from the injection pipe according to the formula mentioned in the first embodiment including the above values for a, b and c.

Fig. 11 shows an embodiment of an evaporator 90 having a plurality of U-shaped bent flat tubes 91a, 91b, 91c, etc., which allows a double deflection in width and a simple deflection in depth. For this purpose, the distributor plate 93 is formed such that for the deflection in the width two openings 96 and 98 are interconnected 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. 11 by arrows in the left part of the evaporator. At this time, the refrigerant at A enters the front part of the left leg of the flat tube 91a, flows downward, becomes wide deflected, flows back up 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, following the arrow C, is directed into the rear part of the flat tube 91 b, which it flows through counter to the throughflow direction of 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, ie the diameter of the passage openings of the leads are formed according to the above formula.

Fig. 12 shows a variant of the evaporator of Fig. 11, 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 Käftemittelaustausch between adjacent units in the region of the deflection in depth is possible.

FIG. 13 shows a variant of the evaporator of FIG. 12, wherein the subdivisions differ in depth. The design of the injection tube including the dimensions of passage openings in turn corresponds to that of FIG. 1.

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. 14 to 26 show a further heat exchanger and a variant for this purpose, in which the design 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. 14 to 24 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 1001a, 1002a between collection 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 tube 1005 is than at its two ends each closed Pipe section formed. The diameter of the passage openings is formed according to the formula mentioned in the first embodiment.

On the underside of the collecting tank 1003 is a plurality of U-shaped bent flat tubes 1006, here twenty, arranged, the leg heights of the U-shaped flat tubes 1006 plus the collection box height and the injection tube, overflow or Saugrohraußendurchmesser total of the overall 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. 16). 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. 14, two flow paths in each flat tube 1006 are thus located one behind the other in depth.

The flat tubes 1006 are each inserted with their ends in apertures 1007a of a bottom plate 1007 (see FIG. 15) and soldered thereto. A central, longitudinally extending web 1007b of the bottom plate 1007 separates the two groups of chambers 1006a of the flat tubes 1006 from each other.

For the further construction of the collecting tank 1003, a distributor plate 1008 (see FIG. 12) is placed flat on the lower base plate 1007 and soldered to the same over the entire surface but at least along closed edge 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. Not aligned portions of the apertures, eg H-shaped apertures 1008b of the manifold plate 1008, are intended to interconnect various flow paths. The H-shaped openings shown here each connect two adjacent flat tubes 1006 or 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. 13), 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 a transfer to the eight corresponding, opposite flow paths in the H-shaped apertures, each with a first and a subsequent continuous flow path to the same flat tube belong ("transfer to the depth") After passing sixteen of the total of 40 flow paths of the evaporator enters the refrigerant through slightly larger holes in the overflow pipe 1005 a. These sixteen first flow paths, which correspond to the first eight flat tubes from the right according to FIG. 14, are thus grouped into a first section.

The overflow pipe 1005 has the function of an intermediate collector, so that the refrigerant of the various flow paths is remixed at the same time it flows to the left as shown in FIG. 14, wherein the flow rate is already significantly increased compared to the supply line 1001.

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. 25 and 26 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 embodiment described above, the passage openings in the lines 1001 and 1005 are formed according to the formula mentioned in the first embodiment, so that a very uniform temperature distribution over the entire evaporator width is possible.

Claims (16)

Heat exchanger, in particular evaporator, with at least one tube (4; 1005) via which a medium at least a portion of the heat exchanger can be fed, a plurality of passage openings (9 ') in the tube (4; 1005), which distribution of the medium to at least the Allow a portion of the heat exchanger, a plurality of directly or indirectly connected via the passage openings (9 ') with the tube (4), a heat transfer surface forming elements through which the medium can flow, which undergoes at least partially a phase change during operation, and at least a suction pipe (10), through which the medium can be discharged from the heat exchanger (1), characterized in that the free flow cross section of the individual passage openings (9 ') of at least one of the feeding pipes (4, 1005) in the fluid supply direction to the subsequent heat transfer surface condition $$\mathrm{d}\left(\mathrm{n}\right)\mathrm{=}\left(\mathrm{a}\mathrm{+}\mathrm{bxn}\mathrm{+}\mathrm{cx}{\mathrm{n}}^{\mathrm{2}}\right)\mathrm{\pm }\mathrm{Ax}\mathrm{(}\mathrm{a}\mathrm{+}\mathrm{bxn}\mathrm{+}\mathrm{cx}{\mathrm{n}}^{\mathrm{2}}\mathrm{)}$$

is sufficient, where d is the diameter of the respective passage opening (9 ') and n is the number of the passage opening (9') in the fluid supply direction, and a, b, c and Δ are constants, wherein Δ is at most 0.2. Heat exchanger according to claim 1, characterized in that a is in a range of +3.2 to +3.6, in particular +3.4286 ± 5%, b is in a range of -0.5 to -0.2 , in particular -0.3536 t is 5%, and c is in a range from 0 to +0.1, in particular +0.0179 ± 5%. Heat exchanger according to claim 1 or 2, characterized in that Δ is at most 0.1, in particular at most 0.05. Heat exchanger according to one of the preceding claims, characterized in that the difference between the maximum and the minimum diameter of the passage openings (9 ') divided by the maximum diameter of the passage openings (9') is at least 0.3, preferably at least 0.4. Heat exchanger according to one of the preceding claims, characterized in that the free flow cross-section in the feeding tube (4; 1045) is substantially constant. Heat exchanger according to one of the preceding claims, characterized in that in the feeding tube (4) is provided a sleeve (20) for reducing the free flow cross-section. Heat exchanger according to claim 6, characterized in that the sleeve (20) is formed at least partially slotted, wherein the sleeve (20) over a maximum of three quarters, in particular over half, of the inner periphery of the tube (4). Heat exchanger according to one of the preceding claims, characterized in that the feeding pipe (4; 1005) and / or the suction pipe have a substantially D-shaped cross section. Heat exchanger according to one of the preceding claims, characterized in that the inner diameter or hydraulically equivalent inner diameter of the feeding tube (4; 1005), in particular an injection tube, at least in a region in which passage openings (9) are provided, between 2.0 and 3 , 0 mm, in particular between 2.2 and 2.6 mm. Heat exchanger according to one of the preceding claims, characterized in that the inner diameter or hydraulically equivalent inner diameter of the suction pipe is between 4.0 and 6.6 mm, in particular between 4.5 and 6.0 mm. Heat exchanger according to one of the preceding claims, characterized in that the inner diameter or hydraulically equivalent inner diameter of the medium at least a portion of the heat exchanger (1) supplying injection tube (4) 2.0 to 3.0 mm, in particular between 2.2 and 2, 6 mm, the inner diameter of the medium to a subsequent portion of the heat exchanger (1) supplying overflow pipe (1005) 2.0 to 4.5 mm, in particular between 3.0 and 4.0 mm, and the inner diameter of the suction pipe (10) between 4.0 and 6.6 mm, in particular between 4.5 and 6.0 mm. Heat exchanger according to one of the preceding claims, characterized in that in the feeding pipe (4; 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) a constant mass flow density with a maximum fluctuation of ± 20 %. in particular ± 10%, particularly preferably ± 5%, is present between the individual cross-sections. Heat exchanger according to one of the preceding claims, characterized in that the supply pipe (4; 1005) is mounted in the operational state on the upper side of the heat exchanger. 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 one of the preceding claims, characterized in that exactly seven from the supplying pipe (4) outgoing, in the direction of the heat transfer surface of refrigerant through-flow openings (9) are provided. 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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