EP1203922A2 - Condenser and tube therefor - Google Patents

Abstract

The tube (10) of a condenser (20) operating under pressure of approximately 20 bar, has width greater than height and has a flat profile along the width. Several flow channels are arranged side by side along the width of the tube. The flow channels have a circular cross-section and diameter of 1.10-1.30 mm. Independent claims are included for the following: (1) Condenser operating under pressure of approximately 20 bar; (2) Tube production method; and (3) Motor vehicle with condenser.

Description

The invention relates to a condenser and in particular a tube therefor, which is particularly suitable for use in capacitors operating at operating pressures of around 20 bar. On the capacitor according to the invention is in particular a so-called Flat tube condenser, in which between pipes with tubes in run essentially flat cross-section, between which in turn Cooling fins are arranged on the flat surfaces of the pipes support. With such an arrangement, the heat from the Refrigerant circulating to a condenser in the condenser essential cooling medium flowing through, mostly air become.

In U.S. Patent 5,307,870, manifolds for flat tube condensers are included described in cross section arc-shaped manifolds. Between these Collecting tubes run parallel tubes in such a way that a parallel current capacitor is formed. That is, refrigerant vapor in one of the manifolds is introduced, through which parallel tubes are guided, in it condensed, led to the other manifold and then the Condenser leaves. In one embodiment, this describes Publication pipes with parallel flow channels formed therein round cross section. Such a capacitor is according to the US patent intended for high pressure condensers.

German Offenlegungsschrift 198 45 336 relates to a heat exchanger which is operated at high operating pressures of up to 100 bar with CO ₂ as the refrigerant. A multi-chamber flat tube is used therein, which is designed as a straight tube for a parallel flow condenser or as a serpentine bent tube for a parallel flow condenser. The channels in the tube are preferably provided with an oval and also with a round cross section. The circular cross section is disclosed as being suitable for high compressive strength. In order to obtain a high heat transfer capacity, the two flat tube broad sides are also profiled with wavy lines in the case of round cross sections of the channels.

There are also flat tubes in parallel flow or serpentine flow Use heat exchangers whose flow channels are rectangular or have triangular cross sections. This is exemplified by GB-A-2 133 525, JP-A-59-13877, US-A-3 689 972, US-A-2 136 641, GB-A-1 601 954, JP-A-57-66389, JP-A-58-221390 or EP-A-583 851. In many cases the surfaces of the flow channels are suitable Measure, such as fins and grooves, enlarged to allow for higher heat transfer to achieve (see JP-A-59-13877, JP-A-57-66389 and JP-A-58-221390). In JP-A-114145, these shapes are rhombic Flow channels are shown that have better contact of the gaseous Refrigerant with the walls of the flow channels and a better one Ensure drainage of condensate.

So-called meandering current capacitors are also known, in which a refrigerant several times between two with partitions Collected pipes through different pipe groups back and forth be, cf. EP-A-255 131. The pipes used for this have only flow channels with square or rectangular Cross-sections.

The present invention has for its object an improved Tube for a condenser with operating pressures of about 20 bar and one also improved capacitor, especially meander current capacitor, provide.

This object is achieved with the features of the claims.

The applicant has surprisingly found that a pipe with essentially flat cross section and several side by side arranged flow channels for a condenser with operating pressures of around 20 bar works particularly effectively when the flow channels are essentially round and have a hydraulic diameter of 1.10 mm to 1.30 mm. A tube has a further advantageous effect with flow channels that have a hydraulic diameter of 1.14 mm have up to 1.26 mm, and more preferred is a diameter of 1.18 mm to 1.22 mm. The best results are achieved with a tube with a hydraulic diameter of about 1.20 mm.

It was also found that tubes with a flat cross section and round, in Series arranged flow channels of particularly advantageous Effect work in meandering current capacitors. This is special remarkably the case in capacitors as they appear later in be described with respect to the preferred embodiments. This is attributed to the fact that the pressure drop in the - compared to Parallel current capacitors - total in meandering current capacitors longer distances to be covered by the refrigerant. So that will achieved that larger amounts of refrigerant per unit time with total same energy expenditure through the condenser can. Furthermore, a better heat transfer is apparently compared Flow paths achieved in known meandering flow condensers.

In addition, the manufacture of such tubes is less expensive and thus less expensive, which is particularly important in mass production plays. The production takes place by extrusion, the shape of the Flow channels is generated by appropriately designed matrices. Round matrices have proven to be advantageous because the delay in Cooling is minimal and relatively even and the matrices inside In contrast to square matrices, they show significantly less wear. The With conventional angular dies, wear occurs particularly on the Corners on.

Figur 1

eine Vorderansicht auf einen bevorzugten Mäanderstromkondensator,

Figur 2

eine Seitenansicht von rechts auf den Kondensator gemäß Figur 1,

Figur 3

eine Unteransicht auf den Kondensator gemäß Figur 1,

Figur 4

einen Querschnitt durch ein bevorzugtes erfindungsgemäßes Rohr und

Figur 5

eine Einzelheit des rechten Endes des Querschnitts gemäß Figur 4 mit einer 20-fach vergrößerten Darstellung

Preferred embodiments of the invention are explained below by way of example with reference to the figures. Show it:

Figure 1

2 shows a front view of a preferred meandering current capacitor,

Figure 2

2 shows a side view from the right of the capacitor according to FIG. 1,

Figure 3

2 shows a bottom view of the capacitor according to FIG. 1,

Figure 4

a cross section through a preferred pipe according to the invention and

Figure 5

a detail of the right end of the cross section according to Figure 4 with a 20-fold enlarged view

Figure 1 shows a front view of a preferred meandering current capacitor 20 in the assembled state. This capacitor 20 has a first header 21 and a second header 22, the are preferably arranged in parallel. In another preferred The embodiment is a refrigerant inlet 24 and a refrigerant outlet 25 connected to the first manifold 21. Since the refrigerant in the occurs essentially in the gaseous state and in the liquid state emerges, the refrigerant inlet 24 has a larger cross section than that Refrigerant outlet 25. Introduces from the refrigerant inlet 24 Supply pipe in the upper part of the first view shown Manifold 21 is shortly before entering the first manifold 21 advantageously a pressure relief valve is provided. A is more preferred upper part of the manifold 21 through a partition 27a in the first Collector tube 21 separated. Between the first manifold 21 and the second manifold 22 run a plurality of tubes 10 spaced and parallel to each other. These tubes 10 stand with the inside of the Collecting tubes 21, 22 in tight connection. 1 are at the top left Cooling fins 23 indicated, which are essentially wavy or extend parallel between the tubes 10. The pipes have one in essential flat cross-section, as further explained below becomes. In the view shown in Figure 1, you only see the relatively small height of the tubes 10 which are in the direction perpendicular to Paper level have a greater width than the height shown (also compare Figure 4). The cooling fins 23 are each based on the flat surfaces of adjacent pipes and are therefore preferred connected. This enables good heat transfer between the Tubes 10 and the cooling fins 23 and overall good structural Stiffness of the capacitor 20.

The located in the upper region of the first manifold 21 in refrigerant, which is essentially gaseous, flows through a first Set of tubes 10a to the second header tube 22. This will ensures that from the coolant inlet 24, due to the partition 27a, only refrigerant in the first set of tubes 10a that can flow connected to the upper, separated area of the first collecting pipe 21 are. On the way from the first manifold 21 to the second manifold 22 finds a first heat exchange between the refrigerant and the coolant flowing perpendicular to the paper plane instead. Such one Condenser is preferably used in automotive air conditioning systems. Through capacitor 20, i.e. through the tubes 10 and the cooling fins 23, air usually flows as a coolant. The structure shown is intended the best possible heat transfer between the refrigerant and the Ensure coolant. In this way, a first heat exchange takes place and also a first condensation of the refrigerant in the first set of pipes 10a instead.

Arrived in the second header 22, the refrigerant is able to to flow to the first partition 26a in the second header 22. As the Partition wall 27a, this partition wall 26a forms one for the refrigerant Barrier so that the refrigerant does not pass through the partition 26a in the second Flow manifold 22 flow down in the view shown can. Instead, it is forced through a second set of tubes 10b to flow back to the first manifold 21. Here is another Heat exchange and further condensation take place.

Another partition 27b in the first header 21 forces this Refrigerant then through a third set of tubes 10c again into the second Collecting pipe 22. Through further partitions 26b in the second collecting pipe and 27c in the first manifold, the refrigerant becomes again first manifold 21, then to the second manifold 22 and back to first header pipe through a fourth set of pipes 10d, a fifth set Tubes 10e and a sixth set of tubes 10f guided. from lowest area of the first collecting pipe 21, separated by the third Partition 27c, then leads a pipe to the refrigerant outlet 25.

The above description makes clear why such a Capacitor is also called "meander current capacitor" because namely the refrigerant through several loops or meanders through the Capacitor is guided. This means that the refrigerant in the Capacitor covered distance compared to a parallel current capacitor, multiplied depending on the number of sets of pipes.

The embodiment shown is particularly preferred six meanders, which is the refrigerant six times the effective width of the Can flow through the capacitor. More preferably, the number of Tubes 10 between a set of tubes 10a to 10e and another, downstream adjacent set of pipes 10b to 10f, or remains at least the same. This advantageously makes a degressive Switching of the pipe sets reached.

In a particularly preferred embodiment, the first set comprises tubes 10a 17 pipes, the second set of pipes 10b 10 pipes, the third set of pipes 10c 7 Pipes, the fourth set of pipes 10d 6 pipes, the fifth set of pipes 10e 4 Pipes and the sixth set of pipes 10f also 4 pipes. In this way is achieved that the initially predominantly gaseous refrigerant comparatively more surface and cross section for heat exchange More and more is made available in liquid form than downstream present refrigerant.

A heat exchanger according to the invention preferably has a width of 300 to 1000 mm and particularly preferably of approximately 400 to 700 mm and further preferably approximately 560 to 600 mm. The overall height is more preferably from 200 to 700 mm, more preferably from 400 to 550 mm and particularly preferably from 460 to 500 mm. One embodiment, which is particularly preferred for the above-mentioned number of tubes in the individual sets of tubes, has an effective end face of approximately 27.8 dm ² , which gives an effective width of the flowed-through condenser of approximately 580 mm and an effective height of about 480 mm. A preferred density of ribs is 75 ribs per dm. Figure 1 also shows elements for anchoring the capacitor in the engine compartment of a vehicle. However, this will not be discussed further.

In a preferred embodiment, the previously explained elements of the Capacitor soldered together, chromated yellow and black powder coated, to optimize heat exchange even further.

As already discussed in the introduction to the description, such a Condenser usually operated at an operating pressure of 20 bar. A preferred embodiment of one in such capacitors used tube or flat tube 10 is enlarged in Figure 4 shown. Such a tube particularly preferably has a width of about 12 to 20 mm, more preferably 15 to 17 mm and particularly preferred about 16 mm. The height H is preferably 1 to 3 mm, more preferably 1.5 to 2.1 mm and particularly preferably about 1.8 mm. such External dimensions allow a relatively small end face of the tube, so that the pressure drop of the air flowing through the condenser does not increase gets big. On the other hand, the effective surface especially towards the cooling fins (the top and bottom in Figure 4 outside pages) optimized.

Figure 4 shows the flat tube cross section with eleven circular flow channels 11, the webs 12 in between and those with the outer walls walls 13 formed. A preferred minimum thickness of the webs 12 is S = 0.20 mm. The minimum thickness of the walls 13 is advantageously W = 0.30 mm. The flow channels 11 have according to the invention a substantially round cross section and a hydraulic diameter from 1.10 to 1.30 mm. The hydraulic With a circular cross-section, the diameter corresponds to that Kreisdruchmesser. The hydraulic diameter is more preferably 1.14 to 1.26 mm, more preferably 1.18 mm to 1.22 mm and am most preferably about 1.20 mm. It was found that such hydraulic diameter in a special way when using a Tube 10 in meandering current capacitors an optimal, dimensional Allows heat transfer. Figure 5 shows a detail Figure 4, in particular the air-facing side of the tube 10. Es it was found that with a bevel X from the center of the tube to to the upper or lower end of the tube in the aforementioned Orders of magnitude around 0.3 mm and a radius R of around 0.2 mm ensure an optimal flow of the coolant air. On particularly preferred heat transfer between the most outer located flow channel 11 and this front surface results in an effective distance Y from the flow channel 11 to the front surface, which is preferably about 0.38 mm.

A pipe according to the invention is preferably made of aluminum or one Extruded aluminum alloy. The round flow channels generated by essentially round dies in the extrusion die. A Round design of the flow channels not only allows one optimized heat transfer, especially when using the pipes in meander current capacitors, but also has great advantages the manufacture of the pipes. The distortion when extruding is even and minimal and the wear of the round dies is much less than matrices with an angular contour would be used, as in the prior art. This results in the same, due to the shape of the flow channels several advantages at the same time.

Claims (23)

1. Pipe for a condenser with operating pressures of approximately 20 bar, with: a) a cross section whose width is greater than the height, b) a cross section which is essentially flat in the vertical direction, c) a series of flow channels (11) arranged side by side in the width direction, d) wherein the flow channels (11) have a substantially round cross section and e) the flow channels (11) have a hydraulic diameter of 1.10 to 1.30 mm. 1. Pipe according to claim 1, wherein adjacent flow channels (11) are separated from one another by a continuous web (12) between the flow channels. 2. Pipe according to claim 1 or 2, wherein the pipe (10) has flow channels (11) arranged next to one another in the width direction. 3. Pipe according to one of the preceding claims, wherein the flow channels (11) have a hydraulic diameter of 1.14 mm to 1.26 mm. 4. Pipe according to one of the preceding claims, wherein the flow channels (11) have a hydraulic diameter of 1.18 mm to 1.22 mm. 5. Pipe according to one of the preceding claims, wherein the flow channels (11) have a hydraulic diameter of about 1.20 mm. 6. Pipe according to claim 6, wherein the cross section of the tube (10) has a width of about 16 mm, a height of about 1.8 mm, a minimum thickness (W) of a wall (13) between the flow channels (11) and an outer wall of the tube is approximately 0.30 mm and a minimum thickness (S) of the webs (12) between the flow channels is approximately 0.20 mm. 7. Pipe according to one of the preceding claims, wherein the tube (10) has 11 parallel flow channels (11) in a row. 8. condenser with operating pressures of about 20 bar with at least one tube (10) according to any one of the preceding claims. 9. The capacitor of claim 9, further comprising: a) two manifolds (21, 22), between which a plurality of tubes (10) according to one of claims 1-8 are arranged spaced, b) the interior of the tubes (10) being in tight connection with the interior of the header tubes (21, 22), and c) cooling fins (23) which are arranged between adjacent tubes (10). 1. Condenser according to claim 9 or 10, wherein the collecting tubes (21, 22) have a substantially round cross section and the tubes (10) extend through suitable openings in the collecting tubes (21, 22) and are thus firmly connected. 2. Condenser according to one of claims 9-11, wherein the first manifold (21) with a refrigerant inlet (24) and the second manifold (22) is connected to a refrigerant outlet (25). The condenser of claim 12, wherein the refrigerant inlet (24) is connected to the first manifold (21) substantially at a first end and the refrigerant outlet (25) is connected to the second manifold (22) substantially at a second end, which of the end of the second collecting pipe (22) opposite the first end of the first collecting pipe (21) is removed. 4. The condenser of claim 12, wherein the refrigerant inlet (24) is connected to the first manifold (21) at one end and the refrigerant outlet (25) is connected to the other end of the first manifold (21). 5. A condenser according to any one of claims 9-14, wherein the manifolds (21, 22) and the tubes (10) are designed and arranged such that the refrigerant from the first manifold (21) first through a first set of tubes (10a) is led to the second collector pipe (22), then is led back through a second set of pipes (10b) from the second collector pipe (22) to the first collector pipe (21) and this course is repeated if necessary, so that a multi-flow meandering flow condenser is formed becomes. 6. A condenser according to claim 15, wherein in the second header (22) for each return of the refrigerant through a set of tubes (10a, c, e) to the first header (21) a partition (26) downstream behind the last tube (10) this Set (10a, c, e) is provided and optionally in the first manifold (21) for each return of the refrigerant through a further set of tubes (10b, d, f) to the second manifold (22) a partition (27) downstream behind the last Tube (10) of this further set (10b, d, f) is provided. 7. A condenser according to claim 15 or 16, wherein the number of tubes (10) between a set of tubes (10a-e) and another, downstream adjacent set of tubes (10b-f) decreases or at least remains the same. A condenser according to any one of claims 15 to 17, wherein 6 sets of tubes (10a-f) are provided and the first set (10a) leading away from the refrigerant inlet (24) has 17 tubes, the second (10b) the first downstream adjacent set of 10 pipes, the third (10c) the second downstream set of 7 pipes, the fourth (10d) the third downstream set of 6 pipes, the fifth (10e) the fourth downstream set of 4 pipes and the sixth (10f) the fifth downstream set includes 4 pipes. 19. A condenser according to any one of claims 9-18, wherein the refrigerant inlet (24) for the inlet of substantially refrigerant vapor, the manifolds (21, 22) and the tubes (10) for condensing refrigerant vapor and the refrigerant outlet (25) for the outlet of essentially refrigerant condensate is suitable. 20. A method of manufacturing a tube (10) according to any one of claims 1-8, wherein the tube (10) is extruded. 21. The method according to claim 20, wherein the tube (10) is extruded from aluminum or an alloy thereof. 22. Use of a tube (10) for a meandering flow condenser, in particular according to one of claims 15-19, wherein the tube has the following features: a) a cross section whose width is greater than the height, b) a cross section which is essentially flat in the vertical direction and c) a series of flow channels (11) arranged side by side in the width direction, d) wherein the flow channels (11) have a substantially round cross section. 23. Use of a tube (10) according to any one of claims 1-8 for a condenser according to any one of claims 15-19.

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