EP1488184A1

EP1488184A1 - Heat exchanger

Info

Publication number: EP1488184A1
Application number: EP03720308A
Authority: EP
Inventors: Gerrit WÖLK
Original assignee: Behr GmbH and Co KG
Current assignee: Mahle Behr GmbH and Co KG
Priority date: 2002-03-09
Filing date: 2003-02-24
Publication date: 2004-12-22
Anticipated expiration: 2023-02-24
Also published as: AU2003223946A1; CN1639533A; WO2003076860A1; CN100354592C; JP2005520113A; ATE380324T1; EP1488184B1; WO2003076860A8; US20050126767A1; US7147047B2; DE50308729D1

Abstract

The invention relates to a heat exchanger ( 1 ), especially for motor vehicles, which comprises flat pipes ( 2 ) through whose interior a first fluid (FL 1 ) flows and that can be impinged upon externally by a second fluid (FL 2 ). The flat pipes ( 2 ) are substantially disposed at an angle to the direction of flow (S 2 ) of the second fluid (FL 2 ) and parallel relative one another and are spaced apart so as to configure flow paths for the second fluid (FL 2 ) that extend through the heat exchanger. Cooling ribs ( 3 ) are disposed in the flow paths and extend between respective adjacent flat pipes ( 2 ). A plurality of wavy ribs ( 3 ) are provided as the cooling ribs. These wavy ribs are disposed one behind the other in the direction of flow (S 2 ) of the second fluid (FL 2 ) and are off-set from one another in the direction of flow (S 1 ) of the first fluid (FL 1 ).

Description

BEHR GmbH & Co.

Mauserstrasse 3, 70469 Stuttgart

heat exchangers

The invention relates to a heat exchanger, in particular for power

vehicles with the features of the preamble of claim 1.

Such a heat exchanger is for example from DE 198 13 989 A1

known. This heat exchanger can, for example, be a condenser

Air conditioning system for motor vehicles. Alternatively, the

Heat exchanger can be designed, for example, as a coolant cooler

for cooling coolant of a coolant circuit in a motor vehicle

stuff serves. The heat exchanger has a number arranged side by side

ordered, parallel flat tubes, i.e. Pipes whose

Cross section is substantially rectangular. It flows in these flat tubes

a first fluid, for example a coolant in the case of a coolant cooler or a gaseous refrigerant to be condensed in the case of a condenser

an air conditioner. The flat tubes are connected to manifolds or manifolds and the flow of a second fluid, e.g. Ambient air exposed to cause heat transfer between the fluids. Between the individual, spaced apart

Flat tubes have flow paths for the second fluid.

To improve heat transfer between the fluids are

arranged between the flat tubes attached to these cooling fins. The

Surfaces of the cooling surfaces are in that from DE 198 13 989 A1

known heat exchanger essentially transversely to the direction of flow

of the second fluid. As a result, the second fluid is opposed to a considerable flow resistance. Through the formation of the Kühl¬

ribs as flow obstacles, the flow velocity of the second fluid is to be reduced in a targeted manner. On the one hand, this increases the residence time of the second fluid when it flows through the heat exchanger, i.e. the time in which the second fluid absorbs heat from the first fluid

or can transfer to this. On the other hand, the low

Flow rate of the second fluid, however, limits the amount of heat that can be transferred between the first and the second fluid, ie the heat exchanger output. Another heat exchanger with cooling fins is from, for example

US 4,676,304 known. In this heat exchanger, the cooling fins are essentially parallel to the direction of flow of the second fluid (here: air). Despite the formation of flow-conducting fins on the individual cooling fins, however, it cannot be ruled out that parts of the second fluid flowing through the heat exchanger between adjacent cooling elements

flow through the fins without absorbing or releasing relevant amounts of energy from them. This problem is especially then

significant if the heat exchanger is in the flow direction of the second

Fluid has small dimensions. In this case, a high mass results

throughput of the second fluid does not necessarily have a high heat

transfer performance. The available temperature difference

between the first and the second fluid only becomes relative to one

small part used.

The invention has for its object to provide a heat exchanger with flat tubes, in particular for motor vehicles, with cooling fins

are designed to be particularly streamlined and at the same time have a high heat

Ensure transmission performance.

This object is inventively achieved by a heat exchanger having the features of claim ^'1. Here, the heat exchanger of

a first fluid to flow through flat tubes, the outside with a second fluid can be acted upon and are arranged essentially parallel to one another in a direction transverse to the flow direction of the second fluid such that flow paths are formed for the second fluid in which

Cooling fins are arranged, each extending between adjacent flat tubes. The cooling fins are designed as corrugated fins,

wherein a plurality of corrugated fins are arranged one behind the other in the direction of flow of the second fluid and these laterally, i.e. in the flow direction of the first fluid, are offset from one another. Through the shift behind

on the corrugated fins arranged a very high proportion of the heat

second flowing fluid used for heat transfer.

In the case of corrugated fins with gills, a higher total may flow

Mass flow of the second fluid through gills, which are arranged in the region of the downstream side of a rib for the second fluid, as

without the offset between the corrugated fins. This may result in increased heat transfer performance in this area. Furthermore

a temperature boundary layer, which may form on a pipe wall, is influenced, so that heat transfer may occur

is increased from the pipe wall to the second fluid or vice versa.

A streamlined configuration of the corrugated fins is preferably achieved in that their surfaces are essentially parallel to the flow

direction of the second fluid, i.e. the surface normals of the corrugated fins

essentially a right angle with the flow direction of the include second fluid. Despite this streamlined design of the corrugated fins, the lateral offset means that they are arranged one behind the other

Corrugated fins ensure that only a small proportion of the second fluid is unused, i.e. without significant heat transfer, between the

Flat tubes flow through as without such an offset. This advantage becomes clearer the higher the rib spacing b between two ribs. Preferably two or three well-shaped are

ribs staggered one behind the other. To a high

To ensure heat transfer performance, the individual corrugated

ribs are preferably directly adjacent, i.e. without distance in

Direction of flow of the second fluid. This provides a large heat exchanger area. As an alternative to this, the flow

to reduce resistance, a spaced arrangement of the in this case narrower corrugated ribs may be provided.

According to a preferred embodiment, the corrugated ribs have gills for guiding the second fluid. A so-called start-up flow which forms on the gills and has a high temperature gradient in an area of the corrugated fin, improves

transmission between the second fluid and the corrugated fins ensured.

All gills of a fin section enclosed between two flat tubes are preferably opposite a corrugated fin in the same direction the flow direction of the second fluid is inclined. A like one

Inclination of the gills within a rib section has the advantage that, if necessary, the flow can thus be directed in a targeted manner to a downstream rib section.

The gills staggered rib sections are preferably inclined in opposite directions, so that the heat exchanger

a longer flow path is predetermined by the flowing second fluid

becomes. The gills of two adjacent gill fields can also be

be sensibly slanted, it may then be advantageous if the gills one of the two gills adjacent to each other

fields gills arranged upstream or downstream

field are inclined in opposite directions to the gills of the two adjacent gill fields.

Uniform coverage of the flow through which the second fluid flows

Flow cross-section is preferably achieved by offset behind

mutually arranged rib sections run parallel to one another. Hier¬

in the mutually offset fin sections are preferably perpendicular to the flat tubes. If the rib surfaces deviate somewhat (up to about 6 degrees) from the parallelism, in which case they can still be regarded as essentially parallel within the scope of the invention, the thermo-

the dynamic advantages of the staggered ribs are hardly affected adversely. Likewise, the use of so-called V-ribs or

of any rounded ribs conceivable. The rib geometry according to the invention can be used in particular in motor vehicle heat exchangers such as coolant coolers, radiators, condensers and evaporators.

In an advantageous manner in terms of production technology, a plurality of corrugated ribs arranged one behind the other are preferably made from a common band

educated. The corrugated fins including the gills are particularly through

Rolls can be made from a metal strip. Is technically advantageous

furthermore an odd number of Well¬ rolled from a strip

ribs, for example three or five corrugated ribs.

According to an advantageous development of the invention, the gill depth LP is in the range from 0.7 to 3 mm with a gill angle of 20 to 30 degrees

increasing performance because this means the flow angle, i.e. the redirection

of the second fluid is increased from one channel to the adjacent, which in turn results in a longer flow path for the second fluid. The rib height for such a system is advantageously in the range from 4 to 12 mm. The rib density for this system is advantageously in the range from 40 to 85 Ri / dm, which means a rib spacing or

corresponds to a rib pitch of 1.18 to 2.5 mm. Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. Show here:

Fig. 1a, 1 b a heat exchanger with two staggered one behind the other

arranged corrugated fins as cooling fins between two adjacent flat tubes,

2a, 2b a heat exchanger with three staggered one behind the other

arranged corrugated fins as cooling fins between two neighboring ones

Flat tubes,

3 two corrugated ribs formed from a single band,

4 three corrugated ribs formed from a single band,

5a a corrugated fin without offset with two gill fields in cross section,

5b a corrugated fin without offset with two gill fields in cross section,

Fig. 5c a Wellr ppe from a tape m 12 rows in cross section Fig. 5d a Wellr ppe from a tape m 13 rows in cross section

Fig. 5e a Wellr ppe from a tape m 14 rows in cross section

Fig. 5f a Wellri ppe from a tape m 15 rows in cross section

Fig. 5g a Wellr ppe from a tape m 1 5 rows in cross section

Fig. 5h a Wellr ppe from a tape m 1 5 rows in cross section Fig. 5i a Wellri ppe from a tape m 13 rows in cross section

Fig. 5j a Wellri ppe from a tape m 13 rows in cross section 6 shows a snapshot of a simulated air flow through

Corrugated fins without offset,

7 shows a snapshot of a simulated air flow through

Corrugated ribs with offset, Fig. 8 shows the proportion of one through a lamella opening

flowing air mass flow on a total air mass flow against the depth of the tubes with low Luftanström¬

speed, and

Fig. 9 plots the portion of a through a slat opening

flowing air mass flow in a total air mass flow against the depth of the tubes at high air inflow

speed.

Corresponding parts are provided with the same reference symbols in all figures.

1a, 1b and 2a, 2b show sections of a heat exchanger 1

with parallel flat tubes 2, through which a first fluid FL1 flows in a first flow direction S1. The flat tubes 2 are equipped with flow guiding elements 2a and connected to manifolds or manifolds (not shown). The fluid

FL1 is, for example, a cooling liquid or a refrigerant that condenses in the heat exchanger 1. Two (Fig. 1a, 1b) and three (Fig. 2a, 2b) corrugated beads 3 are arranged as cooling fins between two adjacent flat tubes 2. Embodiments with a higher number of corrugated fins 3 are also

realizable. The corrugated fins 3 are meandering from a sheet metal

bent, wherein in each case a rib section 4a abutting a flat tube 2 connects with two adjacent flat tubes 2

Rib section 4b alternates. The rib sections 4a abutting the flat tubes 2 are connected to the flat tubes 2 in a heat-conducting manner,

especially soldered. The two adjacent flat tubes 2 connecting

Rib sections 4b are perpendicular to the flat tubes 2 and form

Flow paths for a second fluid FL2, for example air, that the

Flows through heat exchanger 1 in flow direction S2. The second fluid FL2 flows essentially parallel to the surface 5 of the corrugated fins 3, i.e.

the second fluid FL2 strikes when it flows into the heat exchanger 1

initially only on the narrow end faces 6 of the corrugations 3. The second fluid FL2 can thereby flow through the heat exchanger 1 at high speed and correspondingly high mass throughput.

3, 4, gills 7 are formed, which extend transversely to the flow direction S2 of the second fluid FL2 and transversely to the flow direction S1 of the first

Extend FL1 fluids. The gills 7 within a rib section 4b cause a particularly good heat transfer between the

second fluid FL2 and this Rippeπabschnitt 4b, on the other hand a targeted line of the second fluid FL2 to the flow direction S2

rib portion 4b arranged obliquely behind it. In this way, the mass flow of the second fluid FL2 flowing through the heat exchanger 1 becomes practically complete with high utilization of the temperature

difference between the first fluid FL1 and the second fluid FL2 used for heat transfer.

Two corrugated fins 3 arranged one behind the other between two flat tubes 2 are half a width b between adjacent fin sections 4b

offset against each other. In the case of three corrugated ribs 3 arranged one behind the other, as shown in FIGS. 2 and 4, there is alternatively also an offset

of b / 3 preferably selectable, with other values for the offset also being conceivable.

Two or three adjacent corrugated ribs 3, which extend over the depth T of

Extend heat exchanger 1 are produced by rolling from a strip 8. During rolling, the strip 8 is cut in the region of the respective offset between the two (FIGS. 1a, 1b, FIG. 3) or three (FIGS. 2a, 2b, FIG. 4) corrugated ribs 3 and the gills 7 in the corrugated ribs 3 cut. A simple (Fig. 1a, 1b, Fig. 3, 5c) or double (Fig. 2a, 2b, Fig. 4, Fig.

5d) offset or higher-order offset (FIGS. 5e, 5f, 5g) of the corrugated fins 3 can alternatively be produced by arranging separate corrugated fins 3 of the same type with an offset between 0.1 mm and b / 2, where b is the distance between two adjacent flat tubes 2.

The finned sections 4a of the corrugated fins 3 resting on the flat tubes 2 have no gills. A laminar flow of the fluid FL2 is therefore formed in this area rather than in the one provided with gills 7

Rib sections 4b that connect adjacent flat tubes 2. The

Laminar flow can form with increasing barrel length

Guide boundary layer with decreasing temperature gradient on flat tube 2. However, this effect is limited to an insignificant extent by

which are between two adjacent rib sections 4b of a corrugated fin

3 forming flow of the second fluid FL2 after the short

Distance T / 2 (Fig. 1a, 1b, Fig. 3, 5c) or T / 4 (Fig. 2a, 2b, Fig. 4, Fig.

5d) is disturbed by the corrugated fin 3 connected downstream in the flow direction S2, so that an increase in the temperature gradients is generated, which causes an increase in the heat transfer. In this way, even with a heat exchanger 1 with a small depth T of, for example, 12 to 20 mm, there is a highly effective heat transfer between the second

Given fluid FL2 and the first fluid FL1.

Fig. 5 shows corrugated ribs 10a, b ... j, each with several gill panels in Quer¬

sectional view. In the prior art of cooling fins with flow conductive lamellae (gills) usually lie in the individual ribs

a rib between two pipes in the main flow direction of the second fluid only in one plane without offset (Fig. 5a, 5b). These cooling fins have at least two so-called gill panels 11, 12 and 13, 14, respectively, which have a web of different design

are separated from each other. The alignment of the flow-guiding lamellae (gills) of adjacent gill fields is customary here

in opposite directions.

According to the present invention there are preferably two, three or also

more similarly shaped corrugated fins (cooling ridges) offset from one another

arranged one behind the other, i.e. which is a corrugated fin with flow-guiding

Slats (gills) can be offset from one another in several levels. The number of corrugated fins, which are arranged one behind the other in the direction of flow of the second fluid, can be selected depending on the depth of the heat exchanger and / or the depth of the corrugated fins

become. For example, with a construction depth of 12 to 18 mm

2, 3 or more rows are used, with a construction depth of up to 24 mm, for example 2, 3, 4 or more rows can be used for

with a construction depth of up to 30 mm, 2, 3, 4, 5 or more rows can be used, for example, with a construction depth of up to 36 mm, 2,

3, 4, 5, 6 or more rows are used, with a depth of up to 42

mm can use, for example, 2, 3, 4, 5, 6, 7 or more rows 2, 3, 4, 5, 6, 7, 8 or more rows can be used for a construction depth of up to 48 mm, for a construction depth of up to 54 mm

For example, 2, 3, 4, 5, 6, 7, 8, 9 or more rows can be used.With a construction depth of up to 60 mm, for example 2, 3, 4, 5, 6, 7, 8, 9, 10

or more rows are used, with a construction depth of up to 66 mm, for example 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or more rows can be used.

5c shows an exemplary embodiment for two rows 15 and 16 in a transverse

sectional view.

5d shows an exemplary embodiment for 3 rows 17, 18 and 19 in a cross-sectional view.

An exemplary embodiment for 4 rows 20, 21, 22 and 23 is shown in FIG. 5e in one

Cross-sectional view.

5f shows an exemplary embodiment for 5 rows 24, 25, 26, 27 and 28 in a cross-sectional view.

An exemplary embodiment for 5 rows 29, 30, 31, 32 and 33 is shown in FIG. 5g in

a cross-sectional view. 5h shows an exemplary embodiment for 5 rows 34, 35, 36, 37 and 38

a cross-sectional view.

More than two mutually offset rows can preferably be distributed over a total of two mutually offset levels, as in the embodiments in FIGS. 5d, 5e and 5g. You can also choose three

or more different levels can be distributed as in the embodiments

shapes in Figures 5f and 5h, with the distances between two

Levels can be the same or different.

Alternatively, only the area 41 or 44 between two gill arrays 39, 40 or 42, 43 lying in one plane

be offset from the gill panels 39, 40 and 42, 43, respectively

(Figures 5i and 5j). The corrugated fin 10i or 10j has no gill in the area 41 or 44. This configuration also has an influence on the temperature boundary layer on the tube walls and / or an improved flow through the fins.

The number of gills per row is, for example, between 2 and 30 gills depending on the number of rows and the depth of the heat exchanger. The number of gills per gill field is preferably from an engineering point of view with an odd number of rows,

ie not identical for 3, 5, 7, 9 or 11 rows. If the number is even In rows, the number of gills per gill field can be identical, although this is not necessary.

In the following (Fig. 6 to 9) a simulation of an air flow through a heat exchanger with three different configurations of the corrugated fins is explained.

The simulation takes place under the following conditions: Pipe wall temperature =

60 ° C; Air inlet temperature = 45 ° C; Air density = 1,097 kg / m3; air inlet

speed vL = 1 and 3 m / s; Rib height = 8 mm; Rib depth = 16

mm. In the simulation, a corrugated fin is used as the basis in one

Row, i.e. without offset, consisting of a row with two gills

fields that are separated from each other by a web in the shape of a roof are considered (state of the art). Furthermore, a corrugated fin with 2 rows and a corrugated fin with 3 rows are considered. The simulation determines

in addition to the air-side pressure drop, the mass flow through the individual

Louvre openings and the radiation power from the pipe to the cooling air.

6 shows the flow field of the air at an air entry speed

V _LUH of 3 m / s into a heat exchanger 51 with corrugated fins 52, 53 under the boundary conditions described above in the area between two gills

fields 54, 55 and 56, 57, respectively. The webs 58 and 59

between two gill fields each have a roof shape. The Arrows 60 show the main flow path of the air particles passing through the

flow through the last slat opening 61 before the web 59, then

experience a flow deflection and through the lamella openings 62,

63 flow in the adjacent gill field 57. It can be seen from the figure that a higher number of air particles flows through the second lamella opening 62 of the gill field 57 again, only the speed field through the third lamella opening 63 again approaching

corresponds to the speed picture in the previous gill field 56.

7 shows the flow field of the air at an air entry velocity

V _L runs of 3 m / s in a heat exchanger 71 with corrugated fins 72, 73 under the above described conditions in the region of an offset location 74

and 75 between two gill arrays 76, 77 and 78, 79, respectively. The arrows 80 show the main flow path of the

Air particles in front of the offset 75, on the one hand through the last lamella opening 81 before the offset and on the other hand through the offset opening 75. The air particles undergo a flow deflection after flowing through the offset opening 75, the air particles passing through the offset opening

flow through, then mainly through the first and second

Flap opening 82, 83 of the adjacent gill panel 79 flow. The air particles that flow through the last lamella opening 81 before the offset flow after they also have a flow deflection have experienced, mainly through the third lamella opening 84 of the

subsequent gill field 79.

Fig. 8 and Fig. 9 show a graph of the ratio of

Mass flow m _K i _βme through the respective gill opening (lamella opening) to half the total mass flow ¹ m _total of air as fluid FL2 for the three

different corrugated fin configurations with an air flow

speed of v _L uf _t = 1 m / s (Fig. 8) and f v _Lu. = 3 m / s (Fig. 9) under the boundary conditions described above, plotted against the depth of the

Pipes or the heat exchanger. The percentage is not shown

tual mass flow through the opening at the offset point.

As can be seen from FIG. 8, the percentage air mass flow is in the two corrugated fin configurations with two or three rows (one or two

Offsets) always above 9%, whereas with corrugated fins in one level / row the air mass flow at the two louvre openings in the

Connection to the web area drops to below 8% with a minimum of about 4%. If the air mass flow at the corrugated fin consists of a

The level at the slat opening in front of the web area decreases from about 12% to about 10%, so with the corrugated fin consisting of two levels / rows the mass flow through the last slat opening in front of the offset point increases from about 12 to about 13%. Following the offset

Here, too, there is a realignment of the air flow and the first Slat opening is only exposed to a percentage air mass flow of about 10%. In the corrugated fin consisting of three rows, the mass flow through the last lamella opening in front of the offset point is even

if to about 13%. Following the offset points also takes place here

realignment of the air flow and the first lamella opening are each only subjected to a percentage air mass flow of approximately 10-11%.

As is apparent from Fig. 9, the percentage air mass flow is at

two corrugated fin configurations with two or three rows (one or two

Offsets) always above 12%, whereas with corrugated fins in

one level / row of air mass flow at the two louvre openings

after the web area drops to below 11% with a minimum of about 4.5%. If the air mass flow at the corrugated fin falls

from one level at the lamella opening in front of the web area from about 16.5% to about 15%, so with the corrugated fin consisting of two

Levels / rows here the mass flow through the last lamella opening before the offset point increases from approximately 16.5 to approximately 18%. Following the offset point, the air flow and the

first slat opening is only subjected to a percentage air mass flow of about 14%. In the corrugated fin consisting of three rows, the mass flow through the last lamella opening before the offset takes place

also increase to about 18-19%. Following the offset points The air flow is also realigned here and the first

Slat opening is only with a percentage air mass flow

charged by about 14%.

Claims

Patent claims

1. heat exchanger, in particular for motor vehicles, with flat tubes (2),

which can be flowed through by a first fluid (FL1) on the inside

can be acted upon with a second fluid (FL2), which essentially

transverse to the flow direction (S2) of the second fluid (FL2) and parallel

are arranged to each other and which are spaced from each other and

flow paths penetrating the heat exchanger for the

Form second fluid (FL2), cooling fins in the flow paths

are arranged, each between adjacent flat tubes

(2) extend

characterized,

that as cooling fins several in the flow direction (S2) of the second

Fluids (FL2) arranged one behind the other corrugated fins (3)

are that are laterally offset from each other.

2. Heat exchanger according to claim 1,

characterized,

that the surfaces (5) of the corrugated ribs ((3) are substantially parallel

to the flow direction (S2) of the second fluid (FL2) are arranged.

3. Heat exchanger according to claim 1 or 2,

characterized in that a plurality of corrugated ribs (3) arranged offset from one another are shaped in the same way.

4. Heat exchanger according to one of claims 1 to 3,

characterized in that at least one of the corrugated ribs (3) gills (7) for steering the

second fluid (FL2).

5. Heat exchanger according to claim 4,

characterized in that all gills (7) of a fin section (4b) delimited by two flat tubes (2) are inclined in the same direction with respect to the flow direction (S2) of the second fluid (FL2).

6. Heat exchanger according to claim 5, characterized in that the gills (7) two offset one behind the other

Rib sections (4b) are inclined in the same direction.

7. Heat exchanger according to claim 5, characterized in that the gills (7) of two staggered one behind the other

Rib sections (4b) are inclined in opposite directions.

8. Heat exchanger according to one of claims 1 to 7,

characterized in that two staggered rib sections (4b) arranged one behind the other in the

are essentially parallel to each other.

9. Heat exchanger according to claim 8,

characterized,

that the rib sections (4b) are arranged substantially perpendicular to the flat tubes (2).

10. Heat exchanger according to one of claims 1 to 9,

characterized in that the corrugated fins (3) have the same or similar extension in the main flow direction of the second fluid.

11. Heat exchanger according to one of claims 1 to 10,

characterized in that several corrugated ribs (3) arranged one behind the other from one

common band (8) are formed. -25-

LIST OF REFERENCE NUMBERS

1 heat exchanger 2 flat tube

2a flow guide

2 corrugated fin, cooling fin

4a, b rib section

5 surface

6 end face

7 gill

8 volume

10a-j corrugated fin

11 -44 gill field

width

FL1 first fluid

FL2 second fluid

S1 flow direction

S2 flow direction

T depth