EP1527311B1 - Flat pipe-shaped heat exchanger - Google Patents

Description

The invention relates to a heat exchanger, in particular for motor vehicles, with a consisting of flat tubes and corrugated ribs, soldered heat transfer network according to the preamble of claim 1, known from the figure 6B US 6,308,527 B1 ,

In the known Wärmeübertragem for Kräftfahrzeuge such as Kühlmittelkühlem, radiators, condensers and evaporators, the flat tubes of a liquid and / or vaporous medium, eg. B. flows through a coolant or refrigerant, which dissipates its heat to the ambient air or absorbs heat from the ambient air. In this respect, two very different heat capacity flows are in heat exchange with each other. In order to achieve a balance between both sides, one must take additional measures on the air side in order to improve the heat transfer there. This is done by the arrangement of corrugated fins between the flat tubes, whereby the heat exchange surface is increased on the air side. In addition, the surface of the corrugated fins is slotted, ie occupied with gills, which break up the forming boundary layer flows and a deflection of the air flow from one flow channel in the other and thus cause an extension of the flow path for the air.

In the corrugated fins there are basically two different types, the so-called V-type with obliquely arranged to each other rib surfaces, known by the US-A 3,250,325 , The second embodiment of the corrugated fin is the so-called U-type, in which the rib surfaces and thus also arranged on them gills are aligned parallel to each other-this U-type was by the US-A 5,271,458 known. Seen thermodynamically, the U-type has some advantages over the V-type, namely a relatively uniform flow through the approximately rectangular rib channel, a uniform flow deflection through the gills, a higher air flow and thus a higher heat transfer performance. From a manufacturing point of view, the V-type is more advantageous because different rib densities can be produced with a constant rib bending radius for the wave comb by shirring or pulling apart the corrugated strip. By contrast, in the case of the U type, ie the so-called parallel rib, the rib radius or the rib distance is determined by the bending radius of the wave crest. A disadvantage of the known parallel rib is further that the gill length is dependent on the rib bending radius, ie the larger the radius, the shorter the gill falls out, which has a performance-reducing effect.

It has therefore been proposed to replace the rib bending radius by a flat piece, which runs parallel to the pipe wall and is soldered to it. The production of such a rectangular or meandering corrugated fin is relatively expensive - corresponding manufacturing processes have been described in the EP-B 0 641 615 and in the EP-A 1,103,316 proposed. Although this "rectangle rib" has the advantage that the gills extend almost over the entire rib height (distance from tube to tube), however, this comes at a high manufacturing cost.

It is an object of the present invention to improve a heat exchanger of the type mentioned, in particular with a parallel rib to the effect that the parallel rib has the advantages of a rectangular shape, which optionally allows large gill lengths, but can be produced with relatively little manufacturing effort.

The solution to this problem arises from the features of claim 1. The known, formed by a constant curvature wave crest is inventively replaced by a bend, which is composed of three sections of different curvatures: The middle section has a relatively small curvature, d. H. he is almost flat and thus is as far as possible on the outer surface of the pipe wall. The radius of curvature of the elbow is larger in the central area than a rib height RH of the corrugated fin, more preferably 5 to 15 times the fin height RH.

At this middle section, two outer sections with relatively large curvatures follow, wherein the two curvatures may be different, so that the entire elbow has an asymmetrical course to the median plane. A first outer portion has a radius of curvature R2 that is less than half the rib height RH of the corrugated fin, more preferably 3 to 20% of the fin height RH. One. The radius of curvature R3 of the second outer portion of the elbow is greater than the radius of curvature R2 of the first outer portion.

This rib geometry, in particular that of the elbow piece, can be produced relatively easily on conventional ribbed rollers. In addition, the advantages of a parallel or rectangular rib are maintained, ie a relatively wide soldering surface with good heat transfer and optionally a large gill length, which extends almost over the entire rib height. If the rib surfaces deviate slightly (up to about 6 degrees) from parallelism, in which case they are still to be regarded as substantially parallel in the context of the invention, the thermodynamic advantages of the parallel rib are scarcely impaired as a result. The rib geometry according to the invention is particularly applicable to automotive heat exchangers such as Kühlkühlkühlem, radiators, condensers and evaporators.

According to an advantageous development of the invention, the ribbed surfaces are occupied by gills, which preferably have a gage depth LP in a range of 0.5 to 1.5 mm, particularly advantageously in a range of 0.7 to 1.1 mm, with a gill angle between 20 and 35 degrees, particularly advantageous between 24 and 30 degrees. Such gills have a performance-enhancing effect, because this improves the deflection of the air from one channel to the adjacent one, which in turn results in a longer flow path for the air.

Further advantageous embodiments of the invention according to the subclaims 4 to 7 result in further performance increases, especially in a 12 to 20 mm deep tube / rib system with a rib density of 55 to 75 ribs / dm, giving a rib spacing or a rib pitch of 1.33 to 1 , 82 mm corresponds. The rib height for this system is in the range of 3 to 15 mm, more preferably in the range of 6 to 10 mm.

According to an alternative advantageous development of the invention, the Kiementiefe in the range of 0.9 to 1.1 mm at a gill angle of 23 to 30 degrees is favorable for a pipe / rib system with a depth of 40 to 52 mm with a rib density of 45 to 65 ribs / dm, which corresponds to a rib distance of 1.538 to 2.222 mm. The rib height for such a system is advantageously 7 to 9 mm.

Fig. 1

einen Querschnitt durch eine Parallelrippe,

Fig. 2

einen Längsschnitt durch die Parallellrippe in der Ebene II-II gemäß Fig. 1 und

Fig. 3

einen weiteren Längsschnitt in der Ebene III-III gemäß Fig. 2.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below. Show it

Fig. 1

a cross section through a parallel rib,

Fig. 2

a longitudinal section through the parallel rib in the plane II-II according to Fig. 1 and

Fig. 3

another longitudinal section in the plane III-III according to Fig. 2 ,

Fig. 1 shows a so-called parallel rib 1, which extends between two flat tubes 2, 3 shown only partially. The parallel or corrugated fin 1 and the flat tubes 2, 3 form a not shown brazed network of a heat exchanger, z. B. a coolant radiator for cooling an internal combustion engine of a motor vehicle or a condenser for a motor vehicle air conditioning. The corrugated fin 1 has two mutually parallel, planar rib surfaces 4, 5, which are connected by a curved section 6. The elbow 6 is in each case on the flat tubes 2, 3 and is soldered to them. The flat rib surfaces 4, 5 are occupied by gills 7, which have a longitudinal extent LL. The corrugated fin 1 has a fin height RH that is greater than the gill length LL. The rib surfaces 4, 5, the elbow 6 and the tube wall 2, 3 each form an approximately rectangular rib channel 8. The corrugated fin 1 has a certain rib density, which is characterized by the rib pitch, ie the dimension FP. FP is the reciprocal of the rib density, ie a rib density of 50 ribs / dm corresponds to a rib pitch of FP = 2 mm. The elbow 6 is composed of three arc sections, namely a central portion 6a and two adjacent outer portions 6b, 6c. All three sections are formed by radii, the middle section having a relatively large radius R1 of about 50 to 70 mm. The two outer radii R2 and R3 are considerably smaller, ie the radius R2 is in the range of 0, 4 to 0.6 mm, while the radius R3 is greater than the radius R2. R3 is in the range of 0.6 to 1.1 or 1.3 mm. This design of the elbow 6 results on the one hand a relatively wide soldering surface F, on the other hand a relatively large gill length LL, which is favorable for the heat transfer. In addition, such a parallel rib, whose elbow 6 has the dimensions mentioned, can be easily manufactured on conventional ribbed rollers.

Fig. 2 shows a longitudinal section in the plane II-II, ie through the rib channel 8. The rib surface 5 has a gill 9, which is composed of a plurality of individual gills 7. The rib 5 has a rib depth RT, ie an extent in the air flow direction X.

Fig. 3 showed a section in the plane III-III in Fig.2 The gill field consists of front, in the drawing to the right rising gill 7a, a central roof-shaped Doppelkieme 7b and rear sloping right gill 7c. The gills 7a, 7b, 7c are each inclined at a gill angle α. The gills 7a, 7c have, measured in the air flow direction X, a dimension LP, which is referred to as the depth of the kite. Through the gills 7, the boundary layer of the air flow is broken in the rib channels and deflected by a rib channel 8 in the adjacent rib channel. This results in a longer flow path for the air flow, which increases the heat transfer. The deflection of the air flow depends on the gill angle α and on the depth of the kite LP.

According to the invention, two preferred embodiments with the following dimensions are optimal for the parallel rib described above:

First embodiment

• Rippentiefe RT: 12 ≤ RT ≤ 20 mm.
• Rippenteilung FP: 1,33 mm ≤ FP ≤ 1,818 mm,
• entsprechend einer Rippendichte von 55 bis 75 Rippen/dm,
• Kiemenwinkel α: 24° ≤ α ≤ 30°,
• Kiemenlänge LL: 6,4 mm ≤≤ LL ≤ 7,2 mm,
• Rippenhöhe RH: 6 mm ≤ RH ≤ 10 mm,
• Kiementiefe LP: 0,7 mm ≤ LP ≤ 1,1 mm,
• Verhältnis von Kiementiefe LP zu Rippenteilung FP: 0,385 ≤ LP/FP ≤ 0,825,
• Krümmungsradius R1 des mittleren Bogenstückabschnitts: $$50\mathrm{mm}\le \mathrm{R}1\le 70\mathrm{mm},$$
  
• Krümmungsradius R2 des ersten äußeren Bogenstückabschnitts: $$0,4\mathrm{mm}\le \mathrm{<figure-callout\; id="2"\; label="R"\; filenames="imgf0001.png"\; state="\{\{state\}\}">R</figure-callout>}2\le 0,6\mathrm{mm},$$
  
• Krümmungsradius R3 des zweiten äußeren Bogenstückabschnitts: $$0,6\mathrm{mm}\le \mathrm{R}3\le 1,1\mathrm{mm}\mathrm{.}$$
  

The first embodiment relates to a condenser for an air conditioning system of a motor vehicle. The flat tubes of the capacitor thus become of refrigerant, eg. B. R 134a flows through. For such a condenser, a heat transfer network consisting of flat tubes and a parallel rib with the following dimensions is provided:

• Rib depth RT: 12 ≤ RT ≤ 20 mm.
• Rib pitch FP: 1.33 mm ≤ FP ≤ 1.818 mm,
• according to a rib density of 55 to 75 ribs / dm,
• Gill angle α: 24 ° ≤ α ≤ 30 °,
• Gill length LL: 6.4 mm ≤≤ LL ≤ 7.2 mm,
• Rib height RH: 6 mm ≤ RH ≤ 10 mm,
• Kiementiefe LP: 0,7 mm ≤ LP ≤ 1,1 mm,
• Ratio of Kiementiefe LP to fin pitch FP: 0.385 ≤ LP / FP ≤ 0.825,
• Radius of curvature R1 of the middle elbow section: $$50\mathrm{mm}\le \mathrm{R}1\le 70\mathrm{mm}.$$
  
• Radius of curvature R2 of the first outer curve piece section: $$0.4\mathrm{mm}\le \mathrm{<figure-callout\; id="2"\; label="R"\; filenames="imgf0001.png"\; state="\{\{state\}\}">R</figure-callout>}2\le 0.6\mathrm{mm}.$$
  
• Radius of curvature R3 of the second outer arch piece section: $$0.6\mathrm{mm}\le \mathrm{R}3\le 1.1\mathrm{mm}\mathrm{,}$$
  

A parallel rib system of the aforementioned dimensions is superior to a conventional rib system with a V-shaped rib in many respects, in terms of air flow, flow deflection, homogenization of flow velocity and temperature profile, and thus heat transfer performance.

Second embodiment

• Rippentiefe RT: 40 ≤ RT ≤ 52 mm
• Rippenteilung FP: 1.538 ≤ FP ≤ 2,222 mm,
• entsprechend einer Rippendichte von 45 bis 65 Rippen/dm
• Kiemenwinkel α: 23°≤ α ≤ 30°
• Kiemenlänge LL: 6,5 ≤ LL ≤ 7,2 mm
• Rippenhöhe RH: 7 ≤ RH ≤ 9 mm
• Kiementiefe LP: 0,9 ≤ LP ≤ 1,1 mm
• Verhältnis Kiementiefe LP zu Rippenteilung LP: 0,405 ≤ LP/FP ≤ 0,715.
• Krümmungsradius R1 des mittleren Bogenstückabschnitts: $$50\mathrm{mm}\le \mathrm{R}1\le 70\mathrm{mm},$$
  
• Krümmungsradius R2 des ersten äußeren Bogenstückabschnitts: $$0,4\mathrm{mm}\le \mathrm{<figure-callout\; id="2"\; label="R"\; filenames="imgf0001.png"\; state="\{\{state\}\}">R</figure-callout>}2\le 0,6\mathrm{mm},$$
  
• Krümmungsradius R3 des zweiten äußeren Bogenstückabschnitts: $$0,6\mathrm{mm}\le \mathrm{R}3\le 1,3\mathrm{mm}\mathrm{.}$$
  

The second embodiment relates to a coolant radiator which is installed in motor vehicles in the coolant circuit for cooling the internal combustion engine and flows through coolant, ie a water / glysantin mixture becomes. Parallel ribs with the following dimensions are provided between the flat tubes, which are preferably arranged in a row:

• Rib depth RT: 40 ≤ RT ≤ 52 mm
• Rib pitch FP: 1,538 ≤ FP ≤ 2,222 mm,
• according to a rib density of 45 to 65 ribs / dm
• Gill angle α: 23 ° ≤ α ≤ 30 °
• Gill length LL: 6.5 ≤ LL ≤ 7.2 mm
• Rib height RH: 7 ≤ RH ≤ 9 mm
• Kiementiefe LP: 0.9 ≤ LP ≤ 1.1 mm
• Ratio of Kiementiefe LP to rib pitch LP: 0.405 ≤ LP / FP ≤ 0.715.
• Radius of curvature R1 of the middle elbow section: $$50\mathrm{mm}\le \mathrm{R}1\le 70\mathrm{mm}.$$
  
• Radius of curvature R2 of the first outer curve piece section: $$0.4\mathrm{mm}\le \mathrm{<figure-callout\; id="2"\; label="R"\; filenames="imgf0001.png"\; state="\{\{state\}\}">R</figure-callout>}2\le 0.6\mathrm{mm}.$$
  
• Radius of curvature R3 of the second outer arch piece section: $$0.6\mathrm{mm}\le \mathrm{R}3\le 1.3\mathrm{mm}\mathrm{,}$$
  

Also this compared to the first embodiment much deeper system brings a significant increase in performance over a comparable V-rib.

Claims (7)

1. A heat exchanger, in particular a coolant refrigerator or condenser for motor vehicles, with a soldered heat exchanger network consisting of flat tubes (2, 3) and of corrugated ribs (1), wherein a liquid and/or gaseous medium being capable of flowing through the flat tubes (2, 3) and air being capable of flowing around the corrugated ribs (1), wherein a corrugated rib (1) having in each case two rib surfaces (4, 5) which are arranged essentially parallel to one another and which are connected in each case by means of an arcuate piece (6) soldered to a flat tube (2, 3), characterised in that the arcuate piece (6) has a lower curvature in a middle portion (6a) than in a first outer portion (6b) and in a second outer portion (6c), wherein the arcuate piece (6) has a radius of curvature R1 in the middle portion (6a) which is greater than a rib height RH of the corrugated rib (1), and the arcuate piece (6) has a radius of curvature R2 in the first outer portion (6b) which is lower than half a rib height RH of the corrugated rib (1), and the arcuate piece (6) has a radius of curvature R3 in the second outer portion (6c) which is greater than a radius of curvature R2 in the first outer portion (6b).
2. The heat exchanger as claimed in claim 1, characterised in that the rib surfaces (4, 5) are equipped with gills (7).
3. The heat exchanger as claimed in claim 2, characterised in that the grills (7, 7a, 7c) have a gill depth LP in a range of 0.5 to 1.5 mm and a gill angle α in the range of 20° to 35°.
4. The heat exchanger as claimed in one of claims 1 to 3, characterised in that the corrugated rib (1) has a rib division FP in the range of 1 to 3 mm.
5. The heat exchanger as claimed in one of claims 1 to 4, characterised in that the corrugated rib (1) has a rib depth RT in the range of 10 to 70 mm, preferably 12 to 20 mm or 40 to 64 mm.
6. The heat exchanger as claimed in one of claims 2 to 5, characterised in that the ratio of gill depth LP to rib division FP is in a range of 0.385 to 0.825.
7. The heat exchanger as claimed in one of claims 1 to 6, characterised in that the corrugated rib (1) has a rib height RH in a range of 3 to 15 mm, preferably 6 to 10 mm.

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