U.S. patent application number 10/577436 was filed with the patent office on 2007-05-17 for flow channel for a heat exchanger, and heat exchanger comprising such flow channels.
This patent application is currently assigned to BEHR GMBH & CO. KG. Invention is credited to Peter Geskes, Rainer Lutz, Ulrich Maucher, Martin Schindler, Michael Schmidt.
Application Number | 20070107882 10/577436 |
Document ID | / |
Family ID | 34485135 |
Filed Date | 2007-05-17 |
United States Patent
Application |
20070107882 |
Kind Code |
A1 |
Geskes; Peter ; et
al. |
May 17, 2007 |
Flow channel for a heat exchanger, and heat exchanger comprising
such flow channels
Abstract
The invention relates to a flow channel of a heat exchanger with
two parallel heat transfer areas that are arranged at a distance
corresponding to a channel height 11. Each heat transfer area (F1,
F2) is provided with a structure that is formed by a plurality of
structural elements which are placed next to each other in rows
running perpendicular to the direction of flow P and extend into
the flow channel. Each structural element has awidth B, a length L,
a height h, a flow-off angle a, and an overlap U while being
provided with a longitudinal axis.
Inventors: |
Geskes; Peter; (Stuttgart,
DE) ; Lutz; Rainer; (Steinheim, DE) ; Maucher;
Ulrich; (Korntal-Munchingen, DE) ; Schindler;
Martin; (Kurnach, DE) ; Schmidt; Michael;
(Bietigheim-Bissingen, DE) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
BEHR GMBH & CO. KG
Stuttgart
DE
D-70469
|
Family ID: |
34485135 |
Appl. No.: |
10/577436 |
Filed: |
September 20, 2004 |
PCT Filed: |
September 20, 2004 |
PCT NO: |
PCT/EP04/10516 |
371 Date: |
November 16, 2006 |
Current U.S.
Class: |
165/109.1 ;
165/177 |
Current CPC
Class: |
F28F 3/04 20130101; F28F
13/02 20130101; F28F 13/12 20130101; F28D 21/0003 20130101; F28F
1/40 20130101 |
Class at
Publication: |
165/109.1 ;
165/177 |
International
Class: |
F28F 13/12 20060101
F28F013/12 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 28, 2003 |
DE |
130 50 418.4 |
Claims
1. A flow passage through which a medium can flow in a direction of
flow P, of a heat exchanger having two heat exchanger surfaces
which lie substantially opposite one another, are in particular
arranged parallel and/or at a spacing of a passage height H and
each have a structure formed from a multiplicity of structure
elements that are arranged next to one another in rows transversely
with respect to the direction of flow P and project into the flow
passage, the structure elements each having a width B, a length L,
a height h, a flow-off angle .alpha. and a longitudinal axis,
wherein at least two rows comprising structure elements on
substantially opposite heat exchanger surfaces have an overlap with
one another.
2. The flow passage as claimed in claim 1, wherein the overlap is
100%.
3. The flow passage as claimed in claim 1, at least one structure
element is elongate, in particular rectangular in form and has a
straight longitudinal axis.
4. The flow passage as claimed in claim 1, wherein at least one
structure element is elongate and angled in form and has an angled
longitudinal axis which forms the flow-off angle .alpha. and a
flow-on angle .beta. with the direction of flow P.
5. The flow passage as claimed in claim 1, wherein at least one
structure element is arcuate in form and has a longitudinal axis
which is curved with a radius R and forms the flow-off angle
(.alpha.) and a flow-on angle .beta. with the direction of flow
P.
6. The flow passage as claimed in claim 1, wherein at least one
structure element is approximately Z-shaped in form and has a
doubly curved longitudinal axis with radii which forms the flow-off
angle .alpha. and a flow-on angle .beta. with the direction of flow
P.
7. The flow passage as claimed in claim 1, at least one structure
element is V-shaped in form and has straight V limbs.
8. The flow passage as claimed in claim 1, wherein at least one
structure element is V-shaped in form and has V limbs which are
curved away from the direction of flow.
9. The flow passage as claimed in claim 1, wherein the height h of
at least one of the structure elements is 20% to 50% of the passage
height H.
10. The flow passage as claimed in claim 9, wherein the length L of
at least one structure element is from two to twelve times the
height h of the structure element.
11. The flow passage as claimed in claim 1, wherein the distance s
between the rows amounts to 0.5 to eight times the depth T.
12. The flow passage as claimed in claim 1, wherein the distance s
between in each case two rows varies in the direction of flow
P.
13. The flow passage as claimed in claim 1, wherein at least one
structure element has a constant width B in the range from 0.1 to
6.0 mm, preferably in the range from 0.1 to 3.0 mm.
14. The flow passage as claimed in claim 1, wherein at least one
structure element has a width which increases in the direction of
flow between a starting width B1 and a finishing width B2, the
starting width B1 being in the range from 0.1 to 4 mm and the
finishing width B2 being in the range from 0.1 to 6 mm.
15. The flow passage as claimed in claim 1, wherein the flow-off
angle .alpha. is in the range from 20 to 70.degree., preferably in
the range from 40 to 65.degree., and in particular has a value of
from 50 to 60.degree..
16. The flow passage as claimed in claim 4, wherein the flow-on
angle .beta. is in each case larger than the flow-off angle
.alpha..
17. The flow passage as claimed in claim 6, wherein the radius R is
in the range from 1 to 10 mm, preferably in the range from 1 to 5
mm.
18. The flow passage as claimed in claim 5, wherein the radii R1
and R2 are equal to the radius R.
19. The flow passage as claimed in claim 1, wherein a row in each
case has identical structure elements.
20. The flow passage as claimed in claim 1, wherein a row in each
case has different structure elements.
21. The flow passage as claimed in claim 19, wherein individual
structure elements are arranged next to one another in pairs at a
distance a and in mirror-image fashion with respect to one
another.
22. The flow passage as claimed in claim 19, wherein some or all
the structure elements are parallel but offset with respect to one
another and are arranged in pairs at a distance a transversely with
respect to the direction of flow.
23. The flow passage as claimed in claim 21, wherein a distance a
between two structure elements may vary within at least one
row.
24. The flow passage as claimed in claim 21, wherein the distance a
is in the range from 0 to 8 mm.
25. The flow passage as claimed in claim 19, wherein individual
structure elements of a row are offset by an amount f with respect
to one another in the direction of flow P, the amount f being less
than the depth T of the structure elements and T being the
projection of the length L transversely with respect to the
direction of flow P.
26. The flow passage as claimed in claim 22, wherein individual
structure elements of a row are not arranged parallel and have a
differing flow-off angle .alpha..
27. The flow passage as claimed in claim 22, wherein individual
structure elements of a row have different lengths L1, L2.
28. The flow passage as claimed in claim 1, wherein opposite rows
have an offset f in the direction of flow P, f being less than the
depth T of a row.
29. The flow passage as claimed in claim 1, wherein some or all the
structure elements of rows lying opposite one another are
oppositely oriented, in particular have an opposite flow-off angle
.alpha..
30. The flow passage as claimed in claim 1, wherein the rows lying
opposite one another have voids between the structure elements with
structure elements of the other row in each case lying opposite
these voids.
31. The flow passage as claimed in claim 1, wherein the structure
elements of opposite rows touch one another, in particular are
joined to one another by welding or soldering.
32. The flow passage as claimed in claim 1, wherein opposite rows
of structure elements have the same depth T in the direction of
flow P.
33. The flow passage as claimed in claim 1, wherein opposite rows
of structure elements have different depths T1, T2 in the direction
of flow P.
34. The flow passage as claimed in claim 1, wherein the heat
exchange surfaces which lie substantially opposite one another, and
in particular the structure elements arranged thereon, are
curved.
35. The flow passage as claimed in claim 1, wherein the heat
exchange surfaces which lie substantially opposite one another are
heat-engineering primary surfaces or secondary surfaces, the
secondary surfaces being formed in particular by fins, webs or the
like which are preferably clamped, welded or soldered to the flow
passage.
36. The flow passage as claimed in claim 1, wherein the height h is
in the range from 2 mm to 10 mm, in particular in the range from 3
mm to 4 mm, and is preferably around 3.7 mm.
37. The flow passage as claimed in claim 1, wherein the flow
passage is rectangular and has a width b which is in particular in
the range from 5 mm to 120 mm, preferably in the range from 10 mm
to 50 mm.
38. The flow passage as claimed in claim 1, wherein a hydraulic
diameter of the flow passage is in the range from 3 mm to 26 mm, in
particular in the range from 3 mm to 10 mm.
39. The flow passage as claimed in claim 1, wherein at least one,
in particular each row of structure elements comprises in each case
a plurality of structure elements.
40. A heat exchanger, in particular an exhaust-gas cooler, in
particular for a motor vehicle, having flow passages for a fluid,
wherein at least one flow passage is designed as described in claim
1.
41. The heat exchanger as claimed in claim 39, wherein the flow
passages are formed as soldered or welded flat or rectangular tubes
and the heat exchanger surfaces are formed as flat tube walls.
42. The heat exchanger as claimed in claim 1, wherein the flow
passages are formed by stacking plates or disks which have
structure elements on top of one another.
43. The heat exchanger as claimed in claim 1, wherein the structure
elements are formed into the tube walls in particular by
stamping.
44. The heat exchanger as claimed in claim 1, wherein exhaust gas
can flow through the tubes and a liquid coolant can flow around the
tubes.
45. The heat exchanger as claimed in claim 1, wherein the rows of
structure elements are at a distance s from one another in the
direction of flow which amounts to two to six times the length L of
a structure element.
46. The heat exchanger as claimed in claim 1, wherein between the
rows with structure elements there are further rows with structure
elements which project outward into fluid 2.
47. The heat exchanger as claimed in claim 45, wherein the
outwardly projecting structure elements are supporting studs, webs
or elements and touch one another or are welded or soldered to one
another.
48. The heat exchanger as claimed in claim 45, wherein the
outwardly projecting structure elements contribute to improving the
heat transfer.
Description
[0001] The invention relates to a flow passage, through which a
medium can flow in a direction of flow, of a heat exchanger in
accordance with the preamble of patent claim 1. The invention also
relates to a heat exchanger having flow passages in accordance with
the preamble of patent claim 40.
[0002] A first medium, for example an exhaust gas or a liquid
coolant, flows through flow passages for heat exchangers, and these
flow passages delimit this first medium from a second medium, to
which the heat of the first medium is to be transferred. Flow
passages of this type may be tubes with a round cross section,
rectangular tubes, flat tubes or also pairs of disks, in which case
two plates or disks are connected at the edge sides. The media
which exchange heat with one another are generally different; by
way of example, a hot exhaust gas laden with particulates flows
within the tubes, and a liquid coolant flows around the exhaust-gas
tubes on the outer side, leading to different heat transfer
conditions on the inner and outer sides of the tubes. It has
therefore been proposed, in particular for exhaust-gas tubes, that
turbulence generators arranged in a V-shape and in diffuser fashion
be arranged on their inner side, these turbulence generators being
responsible for swirling up the flow and improving the heat
transfer on the exhaust-gas side while at the same time preventing
deposition of particulates. Solutions of this type for exhaust-gas
heat exchangers are known from the following documents in the name
of the Applicant: EP-A 677 715, DE-A 195 40 683, DE-A 196 54 367
and DE-A 196 54 368. These known exhaust-gas heat exchangers have
rectangular tubes made from stainless steel which are assembled
from two half-shells welded together, into which the turbulence
generators, known as winglets, are formed or stamped, arranged one
behind the other. The winglet pairs of the two half-shells are
offset with respect to one another either in the longitudinal
direction of the tubes, i.e. in the direction of flow (DE 196 54
367, DE 196 54 368) or are arranged opposite one another (DE 195 40
683).
[0003] DE-A 101 27 084 in the name of the Applicant has proposed a
heat exchanger, in particular a coolant/air cooler with flat tubes
and corrugated fins, in which the flat sides of the flat tubes have
a structure comprising structure elements. The structure elements
are elongate in form, are arranged in a V shape in rows
transversely with respect to the direction of flow of the coolant
and/or transversely with respect to the longitudinal axis of the
tubes and function as swirl generators in order to increase the
heat transfer on the coolant side. The swirl generators are stamped
into the two opposite tube walls and project inwardly into the
coolant flow. The rows of swirl generators on a flat tube side are
offset in the direction of flow with respect to the rows on the
other flat tube side. It is therefore also possible for the
inwardly projecting height of the swirl generators to be greater
than half the clear width of the cross section of the flat
tube.
[0004] EP-A 1 061 319 has disclosed a flat tube for a motor vehicle
radiator which on its flat sides has a structure comprising
individual elongate structure elements arranged in rows. Rows with
differently oriented structure elements are arranged in the
direction of flow, so that the flow in the interior of the flat
tube is diverted approximately in a zigzag shape. In particular,
however, the rows comprising structure elements on one flat tube
side are arranged offset in the direction of flow with respect to
the rows on the opposite flat tube side. Therefore, a smooth region
of the flat tube inner wall in each case lies opposite a row of
structure elements. The flow within the coolant tube is therefore
alternately but not simultaneously influenced by the structure
elements on one flat tube side and the other flat tube side. This
is intended, inter alia, to prevent the tubes from becoming
blocked. There is also potential in this respect with regard to the
heat transfer capacity.
[0005] It is an object of the present invention to improve a flow
passage and a heat exchanger of the type described in the
introduction with regard to its heat transfer capacity, in
particular to increase the formation of turbulence and swirl, while
the pressure loss should only rise by an acceptable degree.
[0006] This object is achieved by the features of patent claim 1.
According to the invention, it is provided that the structure
elements arranged in particular in rows on one side and the other
side of the flow passage are positioned substantially opposite one
another, i.e. are in each case arranged at approximately the same
level as seen in the direction of flow. The structure elements or
rows lying opposite one another may also be offset with respect to
one another in the direction of flow, although only to such an
extent that an overlap still exists. Therefore, structure elements
projecting into the flow passage from one heat exchanger surface
and the other heat exchanger surface intervene simultaneously in
the flow and swirl up the flow, which leads to an improvement in
the heat transfer on the inner side of the flow passage.
Furthermore--for example in the case of an exhaust-gas flow--under
certain circumstances deposition of particulates is prevented. The
pressure loss is kept within acceptable limits. The flow within the
flow passage is therefore disturbed from both sides simultaneously,
i.e. both boundary layers are detached simultaneously, which leads
to particularly extensive swirling. The structure elements or rows
of structure elements lying opposite one another may likewise be
located on the outer side of the flow passage--in the case of an
exhaust-gas cooler on the coolant side. Advantageous configurations
of the invention will emerge from the subclaims.
[0007] In the context of the present invention, a row comprising
structure elements is formed by one or more structure elements
which are arranged substantially next to one another in the
direction of flow P. In particular, therefore, a row may also be
formed by a single structure element with, for example, no further
structure elements arranged next to it.
[0008] Advantageous configurations of the invention provide for
different embodiments of the structure elements, which may be
rectilinear or curved in form, i.e. may have a constant or variable
flow-off angle with respect to the direction of flow. Changing the
flow-off angle from a relatively large flow-on angle to the
flow-off angle results in a "gentle" diversion of the flow and
therefore a somewhat reduced pressure loss. According to a further
advantageous configuration of the invention, the structure elements
within a row may be arranged offset, i.e. the structure elements,
although arranged in a row running transversely with respect to the
direction of flow, are arranged staggered in the direction of flow.
This likewise has the advantage of a lower pressure loss.
Furthermore, opposite rows, i.e. on one flat tube side or the
other, may be arranged offset with respect to one another in the
direction of flow, in which case, however, an overlap is always
retained between the two rows. This offset in the direction of flow
also results in a lower pressure loss. If the structures lying
opposite one another touch one another and if they are joined to
one another by welding or soldering, it is possible to increase the
strength. According to another variant, the structure I elements
are not arranged at equal distances within a row, but rather these
rows have voids, which in each case have structure elements lying
opposite them on the opposite side, thereby "filling up" these
voids, as seen in plan view. This likewise has the advantage of a
lower pressure loss.
[0009] It is also possible for studs and/or webs to be stamped
inward or outward (as seen in the direction of flow P) between or
next to the structure elements and/or between or within the
"structure rows" (rows comprising structure elements), in order
thereby to achieve a "supporting" action and therefore an increase
in strength. The swirl-generating structures may likewise be
completely or partially responsible for this function.
[0010] According to an advantageous embodiment, the heat exchange
surfaces which lie substantially opposite one another, and in
particular the structure elements arranged thereon, are curved. The
advantages according to the invention are achieved in particular
with tubes having a circular or oval cross section.
[0011] According to an advantageous embodiment, the heat exchange
surfaces which lie substantially opposite one another are
heat-engineering primary surfaces. According to a variant, the heat
exchange surfaces, by contrast, are heat-engineering secondary
surfaces, which are formed in particular by fins, webs or the like
which are preferably clamped, welded or soldered to the flow
passage.
[0012] According to an advantageous embodiment, the height h of the
structure elements is in the range from 2 mm to 10 mm, in
particular in the range from 3 mm to 4 mm, and is preferably around
3.7 mm.
[0013] According to an advantageous embodiment, the flow passage is
rectangular and has a width b which is in particular in the range
from 5 mm to 120 mm, preferably in the range from 10 mm to 50
mm.
[0014] According to an advantageous embodiment, a hydraulic
diameter of the flow passage is in the range from 3 mm to 26 mm, in
particular in the range from 3 mm to 10 mm.
[0015] According to an advantageous embodiment, at least one, in
particular each row of structure elements, comprises in each case a
plurality of structure elements.
[0016] The object of the invention is also achieved by the features
of patent claim 40. According to the invention, the abovementioned
flow passages are provided as flat, round, oval or rectangular
tubes of a heat exchanger, advantageously an exhaust-gas heat
exchanger. The arrangement of the structure elements according to
the invention, i.e. the way they are advantageously stamped into
the tube inner walls, improves the performance of the heat
exchanger. The structure elements arranged in rows are particularly
advantageous for exhaust-gas heat exchangers, since in this case
deposition of particulates in the interior of the flat tubes is
also avoided. A coolant which is taken from the coolant circuit of
the internal combustion engine discharging the exhaust gases flows
around the outer side of the exhaust-gas tubes. It is also possible
for the structures to be stamped into plates or disks in order for
heat exchangers to be produced therefrom.
[0017] Exemplary embodiments of the invention are illustrated in
the drawings and described in more detail in the text which
follows. In the drawings:
[0018] FIG. 1 shows a flow passage according to the prior art,
[0019] FIGS. 2a,b,c show a cross section through flow passages,
[0020] FIG. 3 shows a flat tube with a structure according to the
invention,
[0021] FIG. 4 shows a half-shell of the flat tube from FIG. 3,
[0022] FIGS. 5a,b,c,d show various structure elements,
[0023] FIGS. 6a,b,c,d,e,f,g,h show structures according to the
invention on flow passages,
[0024] FIGS. 7a,b show further structures according to the
invention,
[0025] FIG. 8 shows a further structure according to the
invention,
[0026] FIGS. 9a,b,c,d show mirror-image structure elements,
[0027] FIGS. 10a,b,c,d show parallel-offset structure elements,
[0028] FIGS. 11a,b,c,d show rows of structure elements with
modifications, and
[0029] FIGS. 12a,b, show further structure elements.
[0030] FIG. 1 shows a simplified illustration of a flow passage 1
which is formed as a rectangular tube and has a rectangular entry
cross section 2, two opposite flat sides Fl, F2 and two opposite
narrow sides S1, S2. A flow medium, for example an exhaust gas,
flows through the passage 1 in the direction indicated by arrow P.
Swirl generators 3a, 3b, 4a, 4b oriented in V shapes are arranged
on the lower flat side F2 and, by generating swirl, effect
increased turbulence of the flow and at the same time - in the case
of an exhaust-gas flow - prevent deposition of particulates. This
illustration corresponds to the prior art mentioned in the
introduction. Accordingly, the swirl generators 3a, 3b and 4a, 4b,
which are in each case arranged in pairs, set up in a V shape and
widen in diffuser fashion in the direction of flow, are also
referred to as what are known as winglets.
[0031] FIG. 2a shows the cross section through a flow passage 1
which is formed as a flat tube and in which winglet pairs 5a, 5b
and 6a, 6b are arranged on both the upper flat side Fl and the
lower flat side F2. The passage cross section has a passage height
H and a passage width b. The winglets 5a, 5b, 6a, 6b have a height
h projecting into the passage cross section. This arrangement of
winglets likewise corresponds to the prior art cited in the
introduction. The designations F1, F2 also apply to the exemplary
embodiments according to the invention described below.
[0032] FIG. 2b shows the cross section through a flow passage 1'
which is formed as a round tube and in which structure elements 13'
and 13 are arranged both on the upper flat side F1 and on the lower
flat side F2, respectively. The passage cross section has a passage
height H.
[0033] FIG. 2c shows a cross section through a flow passage 1 which
is formed as a flat tube and in which the heat exchange surfaces
F1, F2 represent heat-engineering secondary surfaces, since they do
not directly transfer heat from one medium to the other. The heat
exchange surfaces have structure elements 13, 13'.
[0034] FIG. 3 shows a flow passage according to the invention,
which is formed as a flat tube 7, part of which is illustrated in
plan view. The flat tube 7 has a longitudinal axis 7a, a width b
and two rows 8, 9 of structure elements or winglets 10, 11 which
are arranged in a V shape and are in each case stamped both into
the upper side F1 and the underside F2 of the flat tube 7,
specifically in the same pattern, so that in each case the upper
winglet row covers the row below it. In each case eight winglets,
distributed uniformly over the entire width b, are arranged in a
row; however, it is also possible for there to be six or seven
winglets for the same width. In the case of narrow tubes, disks or
plates, the number of winglets may also be fewer than six, and in
the case of wider tubes or disks/plates, there may also be more
than eight winglets. The two rows 8, 9 are at a distance s, which
is measured from center to center and amounts to approximately two
to six times the length of the winglets, from one another. Between
the individual rows, there is therefore in each case a smooth
region into which, for example, supporting structures have been
stamped. The rows of winglets extend over the entire length of the
flat tube 7, in each case at the distance s, specifically on both
sides of the flat tube 7.
[0035] FIG. 4 shows a lower half-shell 7b of the flat tube 7 as
seen in the direction of the longitudinal axis 7a of the flat tube
7. The half-shell 7b has a base F2 and two lateral limbs 7c, 7d,
winglets 11' being arranged on the base or underside F2, i.e.
stamped into the tube wall. The upper half-shell is not
illustrated; it is formed in mirror-image fashion and is
longitudinally welded to the lower half-shell 7b at the lateral
limbs 7c, 7d. The winglets 11' have a height h by which they
project into the clear cross-sectional region of the flat tube 7.
The tube may also be produced from a metal sheet which is deformed
and welded on one side.
[0036] In a preferred exemplary embodiment, the width b of the flat
tube is 40 mm or 20 mm, the total height of the flat tube is
approximately 4.5 mm and the height h of the winglets is
approximately 1.3 mm. As a result of the winglets projecting into
the passage cross section from both sides, in each case to a height
of 1.3 mm, given a clear passage height of 4.0 mm, a clear
cross-sectional height of 1.4 mm remains for a core flow. The
distance s between the rows is approx. 20 mm.
[0037] The flat tube 7 is preferably used for exhaust-gas heat
exchangers (not shown) which are known per se, i.e. an exhaust gas
from an internal combustion engine of a motor vehicle flows through
it on its inner side, while coolant from a coolant circuit of the
internal combustion engine cools it on its outer side. The outer
side of the flat tubes 7--as known from the prior art--may be
smooth and held at a distance from adjacent tubes for example by
stamped-in studs. However, it is also possible for fins to be
provided on the outer side of the flat tubes 7 in order to improve
the heat transfer on the coolant side.
[0038] FIGS. 5a, 5b, 5c and 5d show individual structure elements
which are provided for a structure according to the invention on
the flow passages.
[0039] FIG. 5a shows an elongate structure element 13 having a
longitudinal axis 13a which forms an angle .alpha., the flow-off
angle, with a reference line q. The direction of flow is the same
for all the illustrations in FIGS. 5a to 5d and is indicated by an
arrow P. The reference line q runs perpendicular to the direction
of flow P. The structure element 13 has a length L and a width B.
The latter may be constant or variable, i.e. may increase in
direction P.
[0040] FIG. 5b shows an elongate but angled structure element 14
with two longitudinal axes 14a, 14b which are at an inclination
with respect to one another and respectively include an angle
.alpha. and .beta. with the reference line q. .beta. is referred to
here as the flow-on angle and .alpha. as the flow-off angle. The
flow indicated by arrow P is therefore diverted in two stages, i.e.
initially only slightly and then to a greater extent. This results
in a lower pressure loss compared to a structure element as shown
in FIG. 5a with the same flow-off angle .alpha.. The length of the
structure element 14 along the longitudinal axes 14a, 14b is
denoted by L.
[0041] FIG. 5c shows an arcuate structure element 15 having a
curved longitudinal axis 15a which corresponds to an arc of radius
R. The upstream angle is referred to as the flow-on angle .beta.
and the downstream angle as the flow-off angle .alpha.. In this
case too, the flow is initially diverted gently through the angle
(90.degree.-.beta.) and then to a greater extent by the angle
(90.degree.-.alpha.). This continuously increasing diversion of the
flow likewise results in a lower pressure loss compared to the
structure element 13 shown in FIG. 5a. The length of the structure
element 15 along the longitudinal axis 15a is denoted by L.
[0042] FIG. 5d shows a further embodiment of a structure element
16, which is approximately Z-shaped in form and also has a
longitudinal axis 16a running in a Z shape. The longitudinal axis
16a connects two arc sections of different curvature, but with the
same radius R1=R2. The flow-on angle is denoted here by .beta., the
flow-off angle by .alpha., corresponding to a flow diversion of
(90.degree.-.alpha.), which takes place in the central region of
the structure element 16. The flow onto and off this structure
element takes place practically in direction of flow P. This
results in the flow being diverted with particularly low pressure
losses. The length of the structure element along the longitudinal
axis 16a is denoted by L.
[0043] FIGS. 6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h show arrangement
patterns of the structure elements 13 in accordance with FIG. 5a,
specifically in rows on part of a flow passage. In exemplary
embodiments which are not illustrated, only single structure
elements lie opposite one another.
[0044] FIG. 6a shows the elongate structure elements 13 in each
case arranged in two rows 17, 18 which are at a distance s in the
direction of flow P. The structure elements 13 illustrated by solid
lines are stamped into the upper side F1 of the flow passage.
Structure elements 13' illustrated by dashed lines and likewise
arranged in rows 19, 20 have been formed in the lower heat
exchanger surface or side F2 of the flow passage. The rows are
illustrated by dashed demarcating lines. The structure elements 13'
on the lower surface F2 are oriented in the opposite direction to
the structure elements 13 on the upper surface F1, i.e. they have
an opposite flow-off angle .alpha. (cf. FIG. 5a). Furthermore, the
rows 19, 20 are offset in direction of flow P with respect to the
rows 17, 18, specifically by the amount f. The structure elements
13 and 13' and the associated rows 17, 18, 19, 20 each have a depth
T, i.e. an extent in the direction of flow P. The offset f is less
than the depth T, so that an overlap U which results from the
difference between T and f remains between the rows 18, 20 and 17,
19. An overlap U of 100%, in the case of rows with the same depth
T, means that the offset is equal to 0 (f=0). In the case of rows
with different depths T1 and T2, i.e. for example T1<T2, an
overlap of 100% means that the overlap U is equal to the smaller
depth T1 (U=T1). An offset between the rows 17, 19 and 18, 20 lying
opposite one another advantageously results in a lower pressure
loss than in the case of rows without an offset.
[0045] FIG. 6b shows a different pattern of structure elements 13
arranged in rows, specifically in a row 21 and a row 22 with
different flow-off angles .alpha. (not shown). The structure
elements 13 shown by solid lines have been stamped into the upper
side F1 of the flow passage. Structure elements 13' illustrated by
dashed lines at the same level, in the direction of flow P, with an
opposite orientation are arranged on the lower surface F2 of the
flow passage, with the result that an upper structure element 13
and an opposite lower structure element 13', when seen in plan
view, in each case appear in the form of a cross. The upper row
having structure elements 13 is therefore not offset with respect
to the lower row comprising structure elements 13'; the overlap U
is 100%.
[0046] FIG. 6c to FIG. 6h show further arrangement patterns for the
structure elements 13, 13' on the upper side F1 (illustrated by
solid lines) and the underside F2 (illustrated by dashed lines) of
the flow passage.
[0047] Furthermore, FIG. 6h shows supporting elements 13'' on the
outer side of the flow passages, which supporting elements in this
exemplary embodiment are arranged adjacent to the structure
elements 13, 13' and in particular within the rows formed by the
structure elements 13, 13'. It is preferable for the supporting
elements to be stamped into the wall of the flow passage. For
desired supporting of the respective flow passage, the supporting
elements 13'' advantageously have a height which corresponds to the
desired distance between two flow passages or between the
respective flow passage and a housing wall of a heat exchanger.
[0048] FIGS. 7a and 7b show further variants for the arrangement of
the structure elements 13 in rows.
[0049] FIG. 7a shows part of a flow passage with two rows 23, 24 of
structure elements 13 arranged in a V shape on the upper side F1.
The structure elements 13 are not arranged at constant distances
next to one another, but rather have voids 25, 26, 27 which,
however, are filled on the underside F2 by structure elements 13',
so that when seen from above the impression is of a continuous,
uniform arrangement of structure elements 13 and 13'. This
arrangement of rows 23, 24 with "voids" and of the corresponding
rows on the underside results in a lower pressure loss for the flow
in direction P, because the structure elements--as seen in the
width direction--only intervene in the flow alternately from above
and below.
[0050] FIG. 7b shows a similar arrangement of structure elements 13
oriented parallel to one another with voids between them on the
upper side F1 in rows 28, 29. The voids between the structure
elements 13 are once again filled by structure elements 13' on the
underside F2, the structure elements 13 on the upper side F1 and
the structure elements 13' on the underside F2 complementing one
another to form a zigzag arrangement when seen from above. This
arrangement likewise involves relatively low pressure losses.
[0051] FIG. 8 shows another embodiment for the arrangement of
structure elements 13 and 13' in two rows 30, 31 on the upper side
F1. The structure elements 13 of the row 30 and the structure
elements 13' of the opposite row (on the underside F2) are arranged
parallel to and at the same distance from one another. The same
applies analogously to the second row 31, except that the flow-off
angle is oppositely directed, resulting in a diversion of the flow
as seen in the direction of flow P.
[0052] FIGS. 6a, 6b, 7a, 7b and 8 in each case illustrated
structures having the structure elements 13 as shown in FIG. 5a.
The structure elements 13 may equally be replaced by structure
elements 14 (in FIG. 5b), 15 (FIG. 5c) or 16 (FIG. 5d). It would
equally be possible to use different structure elements, for
example 13 and 14, within a single row.
[0053] FIGS. 9a, 9b, 9c, 9d show variants of the structure elements
13, 14, 15, 16 which are in a mirror-image arrangement: the result,
therefore, is what are known as winglet pairs 32, 33, 34, 35, with
a minimum distance a in each case being provided between two
structure elements. The direction of flow generally takes place in
the direction indicated by arrow P, with the flow onto the winglet
pairs customarily taking place at the narrowest point a. This
results in the different winglet pairs 32 to 35 having decreasing
pressure losses in that order. These winglet pairs may be arranged
in rows next to one another, for example as illustrated in FIGS. 6
to 8.
[0054] FIGS. 10a, 10b, 10c, 10d show further variations of the
structure elements 13, 14, 15, 16 brought about by a parallel
shift. This results in double elements 36, 37, 38, 39 in each case
having the same distances a at the flow-on and flow-off sides,
which, for example, can be integrated in the structures shown in
FIGS. 6 to 8.
[0055] It is in this context important that the structure elements
of a row at the top and/or the bottom do not necessarily have to
have the same geometric shape or dimensions, as shown by way of
example on the basis of four structure elements in FIG. 11a.
Rather, as shown in FIG. 11b, it is possible for the structure
elements to be arranged with an offset f in the direction of flow
P.
[0056] In FIG. 11c, the flow-off angles of the structure elements
13 vary, and in FIG. 11d the lengths L1, L2 of the structure
elements 13 vary. A combination (not illustrated) of the variants
illustrated in FIGS. 11b, 11c, 11d is likewise possible. It is also
possible for these variations to occur in the upper and/or lower
surface F1 or F2, respectively.
[0057] FIG. 12a shows a further structure element 43, which is
formed as an angle with two straight limbs 43a, 43b which are
connected by an arc 43c at their apex. In this respect, this
structure element 43 represents a modification of the winglet pair
32 illustrated in FIG. 9a. The medium preferably flows on in the
direction of the apex 43c, as indicated by arrow P.
[0058] FIG. 12b shows a further modification of the structure
element pair 34 as shown in FIG. 9c, namely a structure element 44
with two curved limbs 44a, 44b which are connected by an arc 44c at
the apex. The structure element 44, onto which medium likewise
flows in the direction of the apex 44c as indicated by arrow P,
initially effects a small flow diversion, which then becomes
greater on account of the limbs 44a, 44b curving into the flow.
[0059] The elements shown in FIG. 12a and FIG. 12b can be used in
all the arrangements shown above where two structures arranged in a
V shape are employed.
[0060] In principle, it is possible for all the structures
described to be combined with one another in any desired way.
* * * * *