U.S. patent application number 11/455369 was filed with the patent office on 2006-12-28 for heat exchange element and heat exchanger produced therewith.
Invention is credited to Michael Kozica, Joerg Leuschner.
Application Number | 20060289152 11/455369 |
Document ID | / |
Family ID | 37075961 |
Filed Date | 2006-12-28 |
United States Patent
Application |
20060289152 |
Kind Code |
A1 |
Leuschner; Joerg ; et
al. |
December 28, 2006 |
Heat exchange element and heat exchanger produced therewith
Abstract
A heat exchange element is described having adjacent,
heat-transferring, smooth walls (1) which, between each other,
delimit flow channels (4) with preselected channel widths (B) for
at least one fluid and are provided with undulations (6) which
protrude on both sides and transversely relative to imaginary
central planes (7), said undulations having preselected wavelengths
(.lamda.) as well as apexes (9a, 9b) with radii of curvature (R)
and apex spacings (W) measured transversely relative to the central
planes (7). According to the invention inequalities
0.1.ltoreq.B/W.ltoreq.0.55 and R.gtoreq.1.2 B apply at least
partially to ratios of channel width (B)/apex spacing (W) and
channel width (B)/radius of curvature (R) (FIG. 2).
Inventors: |
Leuschner; Joerg; (Liebenau,
DE) ; Kozica; Michael; (Immenhausen, DE) |
Correspondence
Address: |
STRIKER, STRIKER & STENBY
103 EAST NECK ROAD
HUNTINGTON
NY
11743
US
|
Family ID: |
37075961 |
Appl. No.: |
11/455369 |
Filed: |
June 19, 2006 |
Current U.S.
Class: |
165/152 |
Current CPC
Class: |
F28F 1/126 20130101;
F28F 3/025 20130101; F28D 9/0062 20130101; F28F 3/046 20130101;
F28F 3/02 20130101; F28D 2021/0029 20130101 |
Class at
Publication: |
165/152 |
International
Class: |
F28D 1/02 20060101
F28D001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 23, 2005 |
DE |
20 2005 009 948.1 |
Claims
1. Heat exchange element having adjacent, heat-transferring, smooth
walls (1, 11, 12, 20, 33, 46, 48) which, between each other,
delimit flow channels (4, 41, 42, 51) with preselected channel
widths (B) for at least one fluid and are provided with undulations
(6, 14) which protrude on both sides and transversely relative to
imaginary central planes (7), said undulations having preselected
wavelengths (.lamda.) and apexes (9a, 9b) with radii of curvature
(R) and apex spacings (W) measured transversely relative to said
central planes (7), wherein an inequality
0.1.ltoreq.B/W.ltoreq.0.55 applies at least partially to a ratio of
said channel width (B) to said apex spacing (W) and wherein an
inequality R.gtoreq.1.2 B applies at least partially to a ratio of
said channel widths (B) to said radius of curvature (R).
2. Heat exchange element according to claim 1, wherein an
inequality 0.ltoreq.B/R.ltoreq.0.75 applies to said ratio of
channel width (B)/radius of curvature (R).
3. Heat exchange element according to claim 2, wherein an
inequality 0.2.ltoreq.B/R.ltoreq.0.55 applies to said ratio of
channel width (B)/radius of curvature (R).
4. Heat exchange element according to claim 1, wherein an
inequality 0.35.ltoreq.B/W.ltoreq.0.50 applies to said ratio of
channel width (B)/apex spacing (W).
5. Heat exchange element according to claim 1, wherein an
inequality 16 mm.ltoreq..lamda..ltoreq.30 mm applies at least
partially to said wavelength (.lamda.).
6. Heat exchange element according to claim 1, wherein an
inequality 2.4 mm.ltoreq.R.ltoreq..infin. applies at least
partially to said radii of curvature (R), R=.infin. corresponding
to a wall portion (17) being disposed in a straight plane in the
relevant apex and preferably parallel to an associated central
plane (7).
7. Heat exchange element according to claim 1, wherein said
undulations (6, 14) have first flat portions (15, 16) which rise
and fall in straight planes and at the apexes second wall portions
which connect the first portions (15, 16) and are continuously
curved or are modelled as a polygon.
8. Heat exchange element according to claim 1, wherein said
undulations (14) have first flat portions (15, 16) which rise and
fall in straight planes and at the apexes second flat, straight
wall portions (17) which connect said first portions (15, 16).
9. Heat exchange element according to claim 8, wherein said second
flat wall portions (17) which are provided at the apexes are
disposed parallel to said central planes (7).
10. Heat exchange element according to claim 1, wherein said
undulations have respectively two half-waves (6a, 6b; 14a, 14b;
21a, 21b) which are disposed on opposite sides of said central
planes (7).
11. Heat exchange element according to claim 10, wherein said
half-waves (21a, 21b) are connected by flat portions (22) which are
disposed essentially in said central planes (7).
12. Heat exchange element according to claim 1, wherein said
undulations (6, 14) have an identical configuration.
13. Heat exchange element according to claim 1, wherein said flow
channels (4) have inlet and/or outlet ends (27, 28) for said fluid
extending essentially parallel to said central planes (7).
14. Heat exchange element according to claim 1, wherein said
undulations are provided with wavelengths (.lamda..sub.1 to
.lamda..sub.3) and/or apex spacings (W.sub.3 to W.sub.5) which are
of different sizes in a direction of said flow channels.
15. Heat exchange element according to claim 1, wherein said walls
(1, 11, 12, 20, 33, 46, 48) have a thickness (S) of 0.08 m to 5
mm.
16. Heat exchange element according to claim 1, wherein said
undulations (6, 14) are provided with wavelengths (.lamda.) which
are at least four times as great as said apex spacing (W).
17. Heat exchange element according to claim 1, wherein said
undulations (6, 14) of adjacent walls (1, 11, 12, 20, 33, 46, 48)
are disposed without an offset relative to each other in a flow
direction.
18. Heat exchange element according to claim 1, and being a part of
a ribbed cooling body.
19. Heat exchange element according to claim 1, and being a part of
a flat pipe heat exchanger.
20. Heat exchange element according to claim 1, and being
configured as a fin.
21. Heat exchange element according to claim 1, and being
configured as a lamella (corrugated rib) (32, 43, 44).
22. Heat exchanger having at least one heat exchange element
according to claim 1.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a heat exchange element having
adjacent, heat-transferring, smooth walls which, between each
other, delimit flow channels with preselected channel widths for at
least one fluid and are provided with undulations which protrude on
both sides and transversely relative to imaginary central planes,
said undulations having preselected wavelengths and apexes with
radii of curvature and apex spacings measured transversely relative
to the central planes. The invention also relates to a heat
exchanger provided with such a heat exchange element.
BACKGROUND OF THE INVENTION
[0002] Heat exchange elements having adjacent, smooth walls which
delimit, between each other, flow channels are, according to the
purpose of use, components of pipe, plate or ribbed heat exchangers
and/or are configured as fin arrangements or lamellae (corrugated
ribs). They are used e.g. in automotive vehicles, compressors,
washer-dryers, air-conditioning and refrigeration plants or
refrigeration dryers for compressed air plants and also used for
cooling electronic components and in numerous machines, such as
e.g. building, agricultural and forestry machines. The flow
channels of heat exchange elements of this type are generally
delimited by smooth, flat walls through which, according to the
purpose of use, a fluid, such as e.g. air, water or oil flows, and
serve for the purpose of transferring heat to the respective fluid
or respectively absorbing heat therefrom. In the flow channels,
laminar or turbulent flows are thereby formed which, in the zones
abutting on the walls, lead to characteristic boundary layers in
which the throughflowing fluids are located in the ideal case of a
laminar flow substantially in a stationary manner. In comparison
thereto the fluids are moved forwards within the central core zones
of the flow channels at the greatest speed.
[0003] The formation of the boundary layers has the result that the
wall surfaces which are present are only incompletely usable for
heat transfer and that the achievable heat exchange outputs are
small. It has therefore already been known for a long time (DE-PS
596 871) to provide the walls of the flow channels with embossings
which emerge from the wall surface and generate turbulence, said
embossings being parallel or at acute angles to the flow axis. As a
result, the parts of the fluid flows close to the walls are divided
repeatedly with formation of local turbulences and the otherwise
forming boundary layers are disrupted and destroyed. As a
consequence thereof, a noticeable improvement in the heat exchange
output occurs.
[0004] The described embossings which form turbulence can however
lead to two disadvantages. On the one hand they are able not only
to deflect the parts of the flow close to the walls in the
direction of the core zones and consequently to increase the heat
exchange output but also to reduce the flow cross-sections and
consequently to lead to an undesired increase in the pressure
losses occurring along the flow channels. As a result, the volume
flows passing along the flow channels are correspondingly reduced
with natural convection, whereas, with forced convection, more
powerful fans, pumps or the like are required in order to maintain
a preselected volume flow. On the other hand, embossings of the
described type can have a tendency to become soiled because of
their cross-sectional forms, in particular if they are used e.g. in
coolers for agricultural, forestry and building machines or
vehicles or in household washer-dryers and if the fluid is process
air and/or cooling air.
[0005] Heat exchange elements of the initially described type have
therefore also already become known (e.g. U.S. Pat. No. 3,907,032)
in which the walls delimiting the flow channels are provided with
undulations which extend transversely relative to the flow
direction or are configured in a continuous undulating shape. Even
with such heat exchange elements, no optimum results have been
achieved to date since either an unfavourable output/pressure loss
ratio is obtained or, in the attempt to optimise this, an increased
tendency to become soiled. This applies even when the undulations
are provided with predetermined dimensions or comparatively
complicated forms (e.g. DE 195 03 766 A1, EP 1 357 345 A2).
Likewise known heat exchange elements, in which adjacent walls are
provided with differently structured undulations (e.g. DE 102 18
274 A1), have the disadvantage above all that their flow channels
have greatly varying cross-sections which is not useful for
reducing pressure losses.
SUMMARY OF THE INVENTION
[0006] It is an object of the present invention to design the heat
exchange element described above such that the heat exchange output
(power) is enhanced and the pressure losses are reduced.
[0007] It is another object of the present invention to increase
the ratio of heat exchange output to pressure loss of the heat
exchange element mentioned above.
[0008] Another object of the present invention is to design the
heat exchange element such that a reduction in the tendency to
become soiled is achieved, particularly in case of heat exchange
with gaseous fluids.
[0009] Yet another object of the present invention is to provide a
heat exchanger with an increased ratio of heat exchange output to
pressure loss and at the same time with a reduced tendency to
become soiled.
[0010] These and other objects of the present invention are
obtained by means of a heat exchange element of the type mentioned
above and being characterized in that inequalities
0.1.ltoreq.B/W.ltoreq.0.55 and R.gtoreq.1.2 B apply at least
partially to ratios of channel width/apex spacing and channel
width/radius of curvature. The invention further provides a heat
exchanger having such a heat exchange element.
[0011] By means of the invention, increased heat exchange outputs
are achieved, in particular in conjunction with gaseous fluids such
as e.g. air without correspondingly increased pressure losses
requiring to be taken into account. In addition, the undulations
are configured such that the tendency to become soiled is low. The
heat exchange elements according to the invention and heat
exchangers equipped therewith are therefore very suitable in
particular for applications in coolers for agricultural, forestry
and building machines and also in washer-dryers, charge coolers of
vehicles or devices for cooling electronic components.
[0012] Further advantageous features of the invention are revealed
in the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1a perspective representation of a heat exchange
element according to the invention which has undulating walls in
the form of a lamella (corrugated rib);
[0014] FIG. 2 an enlarged plan view on a plurality of adjacent
walls of the heat exchange element according to FIG. 1, configured
according to the invention;
[0015] FIG. 3 a plan view corresponding to FIG. 2 on a single wall
of the heat exchange element according to FIG. 1;
[0016] FIG. 4 to 6 plan views corresponding to FIG. 3 on three
further embodiments of walls according to the invention for a heat
exchange element;
[0017] FIG. 7 a plan view corresponding to FIG. 2 on four heat
exchange elements with different total lengths;
[0018] FIG. 8 a plan view corresponding to FIG. 3 on a single wall
of a further embodiment of a heat exchange element according to the
invention;
[0019] FIGS. 9 and 10 perspective views of a flat pipe heat
exchanger and of a heat exchanger with a plate-like construction,
both being provided with heat exchange elements according to the
invention; and
[0020] FIG. 11 a perspective representation of a ribbed cooling
body provided with a heat exchange element according to the
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0021] FIG. 1 to 3 show a heat exchange element according to the
invention and according to an embodiment deemed to be the best one
up to now. The heat exchange element comprises a plurality of
adjacent, heat-transferring walls 1 which are preferably disposed
parallel to each other. The walls 1 are formed by thin plates which
have a height D (FIG. 1) and a thickness S (FIG. 2) and are
connected to each other in a meandering shape at their upper and
lower longitudinal edges in FIG. 1 by upper and lower, likewise
plate-shaped connecting portions 2a, 2b. In a longitudinal
direction of the heat exchange element indicated by arrows 3, a
plurality of adjacent flow channels 4 for a fluid, which have
U-shaped cross-sections, is consequently produced, these flow
channels 4 respectively being delimited by two adjacent walls 1
and, in addition in FIG. 1, alternately by an upper or lower
connecting portion 2a, 2b.
[0022] The flow channels 4 are open at their front and rear ends in
the longitudinal direction. The regions of the flow channels 4
which are open at the top or bottom in FIG. 1 transversely relative
to the longitudinal direction are in contrast closed as a rule by a
functional part of a heat exchanger or the like, not shown, when
using the heat exchange element according to FIG. 1. The flow
channels 4 serve for the purpose to guide a fluid (e.g. air, water,
oil or the like) flowing through in the direction of the arrows 3
or in the opposite direction, said fluid thereby coming into
heat-exchanging contact with the walls 1 and the connecting
portions 2a, 2b and therefore being cooled or heated according to
the case.
[0023] The walls 1 comprise materials which are normal in heat
exchangers (e.g. a metal such as aluminium or copper, graphite, a
plastic material or the like). They are in addition preferably
smooth, i.e. are provided at their broad sides 5a, 5b which are
orientated towards the flow channels 4 and disposed between the
upper and lower edges, neither with knobs, flakes, scales or other
embossings nor with openings in the form of cuts, holes or the
like. Consequently, disruptive dirt-collecting corners or the like
are extensively or entirely avoided in the flow channels 4.
[0024] FIG. 2 shows four adjacent walls 1 in plan view, the
connecting portions 2a, 2b (FIG. 1), which are not essential here,
being omitted in order to avoid lack of clarity. It is assumed in
the embodiment that all the walls 1 have an essentially identical
configuration and are situated opposite each other in pairs with
their broad sides 5a and 5b forming the flow channels 4.
[0025] In order to improve the heat transfer between the walls 1
and the fluid which is reduced by slowly-moving or entirely
immobile boundary layers, the walls 1 are provided in a manner
known per se with undulations or sinusoidal undulations 6, these
undulations 6 being obtained by deformation of the plates forming
the walls 1 about lines which extend according to FIG. 1 in the
direction of their height D and essentially parallel to the broad
sides 5a, 5b of the walls 1. In addition, in particular FIG. 3
shows that the undulations 6 extend alternately on one or the other
side of an imaginary central plane 7 indicated by a broken line,
said central plane corresponding to the central plane of the
original, non-deformed, plane-parallel plate. As a result, the
undulations 6 respectively contain a first half-wave 6a leading in
the flow direction 3 (FIG. 3) and a second half-wave 6b trailing in
the flow direction 3, respectively, the first half-wave 6a being
disposed on one side and the second half-wave 6b on the other side
of the central plane 7 and both half-waves 6a, 6b abutting against
each other or being connected to each other along a connecting line
8 situated in the central plane 7. As a result, the half-waves 6a
respectively form an embossing which protrudes in one direction
from the central plane 7 of the wall 1, whilst the half-waves 6b
respectively represent an embossing which protrudes in the opposite
direction from the central plane 7 of the wall 1. These embossings
or half-waves form continuously closed surfaces without open slots
or other interruptions.
[0026] In the embodiment, the undulations 6 in all the walls 1 of
the heat exchange element according to FIG. 1 are configured in the
same way and are disposed parallel and without offset in the flow
direction 3, i.e. with a constant clear spacing relative to each
other so that the flow channels 4 according to FIG. 2 essentially
continuously have the same channel width corresponding to a
dimension B. It is revealed further in FIGS. 2 and 3 that the
undulations 6 have upper and lower apexes 9a and 9b which are
curved about lines situated in the central planes 7. The apex
spacings measured transversely relative to the central planes 7
have, according to FIGS. 2 and 3, a dimension W, measured between
the high or low points of imaginary central lines of the walls 1.
In addition, the undulations 6 in the region of the apexes 9a, 9b
have respectively radii of curvature corresponding to a dimension R
in FIGS. 2 and 3.
[0027] According to the invention, the heat exchange element is
configured such that, on the one hand, an increase in output is
achieved by increasing the heat-exchanging surfaces per unit of
volume, and on the other hand, due to great radii of curvature
within the flow channels 4, both the pressure loss and the tendency
to become soiled is kept within limits.
[0028] In order to increase the output, it is provided to choose
the channel width B of the heat exchange element according to the
invention corresponding to the inequality B.ltoreq.0.55 W
significantly less than the apex spacing W. A ratio of B/W has
proved to be advantageous which fulfils the inequality
0.1.ltoreq.B/W.ltoreq.0.55, the inequality
0.35.ltoreq.B/W.ltoreq.0.50 being maintained particularly
preferably. It is consequently achieved that the fluid flow, as
indicated in FIG. 2 by arrows, is deflected in the region of each
half-wave 6a, 6b instead of being conducted without substantial
deflection and practically in a straight line through the flow
channels 4, as applies to conventional heat exchange elements in
which the channel width B is greater than the apex spacing W or at
best slightly smaller than this. The dimension B.ltoreq.0.55 W hat
the result that the undulations 6 corresponding to FIG. 2 overlap
to a great extent in a direction transversely to the central planes
7, i.e. each half-wave 6a, 6b protrudes deeply into the half-wave
6a, 6b of the adjacent wall 1 which is located thereabove or
therebelow, and in fact by somewhat more than corresponds to the
position of the relevant central plane 7. The consequently achieved
tighter packing or smaller pitch or spacing T (FIG. 1) of the walls
1 leads to a significant increase in output of the heat exchange
element per unit of volume.
[0029] In order to obtain despite the undulations 6 and the
condition B.ltoreq.0.55 W percentage pressure losses which are--as
compared with flat walls--at best smaller than the percentage
increases in output obtained by the undulations 6, it is proposed
to choose the radii of curvature R in the region of the apexes 9a,
9b to be comparatively large. According to the invention, values of
R have proved to be favourable for which the inequality
R.ltoreq.1.3 B applies. It is particularly advantageous if the
ratio B/R of the inequality 0.ltoreq.B/R.ltoreq.0.75 and even more
preferred the inequality 0.2.ltoreq.B/R.ltoreq.0.55 is fulfilled.
The advantage is consequently achieved that the deflection of the
fluid in the flow channels 4 is effected in fact noticeably but
comparatively gently, in comparison to configurations in which the
radii of curvature are at most 3 mm or even substantially lower,
which results in substantially smaller pressure losses.
[0030] The configuration according to the invention of the
undulations 6 and the channel widths B makes it possible in
addition to use larger angles .alpha. and .beta. (FIG. 3) for the
portions of the undulations, 6 which start from the central planes
7 and rise or, respectively, slope down and lead into the central
planes 7. As a result, the advantage is achieved that, in the case
of equal channel widths B and wavelengths .lamda., greater
overlappings of the undulations 6 or half-waves 6a, 6b are possible
and hence the heat-exchanging surfaces can be enlarged. However,
the angles .alpha. and .beta. should preferably not be greater than
40.degree..
[0031] Furthermore, the heat exchange elements are provided with
dimensions .lamda..gtoreq.15 mm or .gtoreq.4 W, preferably e.g. 18
mm, 2.4 mm.ltoreq.R.ltoreq.6.5 mm, .alpha.=.beta.=approx.
30.degree., 0.08 mm.ltoreq.S.ltoreq.5 mm and B<2 mm, these
dimensions of course representing merely examples from which a
deviation can be made in the individual case according to
requirement.
[0032] Finally, FIG. 3 above all shows that the rising and falling
portions of the half-waves 6a, 6b are preferably straight or flat
and are connected in the region of the apexes 9a, 9b by curved
portions having the radii R. As a result, a triangular appearance
is produced for the walls 1, merely the apexes 9a, 9b being convex,
i.e. rounded towards the central planes 7.
[0033] FIG. 4 shows a wall which corresponds essentially to the
embodiment according to FIG. 3. There is a difference only in that
the curved portions situated in the apexes have different radii of
curvature R1 to R4. All the radii R1 to R4 are situated within the
above-indicated regions.
[0034] FIG. 5 shows a wall 12 of a heat exchange element according
to the invention, said wall having exclusively straight and flat
portions. In particular a first half-wave 14a of an undulation 14
has a flat portion 15 which rises in a straight line at the angle
.alpha., a flat section 16 which falls in a straight line at the
angle .beta. and a flat portion 17 which connects both and is
disposed in the region of the apex, said portion 17 being disposed
preferably parallel to the central plane 7. In this case, R=.infin.
applies to the radius of curvature. With respect to the
dimensioning of the portion 17, it should be taken, however, into
account that it has a length (e.g. L.sub.1) which is so large that
the two relevant ends of the portions 15, 16 could be connected
optionally also by an imaginary curved portion 18, indicated in
broken lines, the radius of curvature of which is situated in the
above-indicated regions. As a result, comparatively long portions
15 and 16 can also be achieved, as is desired for a good
overlapping of the half-waves 14a, 14b without the occurence of
pressure losses which are not tolerable. The lengths of the
straight portions 17 can all be of the same length or, as indicated
in FIG. 5 by dimensions L.sub.1 to L.sub.4, of different
lengths.
[0035] According to a further embodiment, not shown, it is possible
to replace the curved portions 18, shown in broken lines in FIG. 5,
by a plurality of short portions which approximate to the portions
18 shown in broken lines in the manner of a polygon. The same
measurements as in FIG. 3 are produced for the consequently
obtained, imaginary radii of curvature.
[0036] FIG. 6 shows finally an embodiment of a wall 20 according to
the invention which has half-waves 21a, 21b which are configured
corresponding to the above description and are connected to each
other by straight, flat portions 22 which are situated preferably
in the central planes 7 and which can have the same or different
lengths. In addition, FIG. 6 shows that the half-waves 21a, 21b can
have different apex heights W.sub.1 and W.sub.2 relative to the
central planes 7, which apex heights sum up to the apex spacing W.
Correspondingly different apex heights W.sub.1, W.sub.2 can also be
provided in the embodiments according to FIG. 1 to 5 without
deviating from the indicated dimensions for the apex spacing W.
[0037] FIG. 7 shows four heat exchange elements 23 to 26 according
to the invention, which are distinguished by different total
lengths as measured in the flow direction 3, and are obtained by a
different number of three, four, five or six undulations following
one behind the other in the flow direction 3. It is thereby evident
that the undulations can have different shapes and/or dimensions.
In addition, FIG. 7 shows that the flow channels 4 preferably have
inlet and/or outlet ends 27, 28 which are arranged parallel to the
central planes, not shown here, in order that fluid is diverted
also when entering the heat exchange element 23 to 27 or when
flowing out of the latter, in a manner which does not assist
pressure losses.
[0038] Furthermore, it can be expedient within the scope of the
invention to let the wave lengths .lamda. and/or the apex spacings
W, in the flow direction 3, become gradually larger or--as is shown
in the embodiment according to FIG. 8 by wavelengths .lamda..sub.1,
.lamda..sub.2 and .lamda..sub.3 and the apex spacings W.sub.3,
W.sub.4 and W.sub.5--gradually smaller. It is consequently possible
to achieve, in the direction of flow, a turbulence formation which
becomes gradually more intensive and a heat transfer output which
hence becomes gradually larger. In addition, FIG. 8 shows that the
half-waves on both sides of their apexes can also have an
asymmetrical configuration.
[0039] The described heat exchange elements can be applied in
different ways. For example, FIG. 9 shows a flat tube (pipe) heat
exchanger with flat tubes 31 between which heat exchange elements
configured according to FIG. 1 to 8 are disposed in the form of
lamellae 32 (corrugated ribs). The lamellae 32 are folded here in a
meandering shape analogously to FIG. 1 and provided with lateral
walls 33 which are connected to each other by essentially flat
upper or lower connecting portions 34a, 34b. The lateral walls 33
are provided according to the invention with undulations which are
configured analogously to FIG. 3 to FIG. 8. The lateral walls 33
respectively delimit flow channels through which for example a
gaseous cooling medium flows in order to cool a liquid fluid which
flows in the flat pipes 31. The flow directions are indicated by
way of example by arrows 35, 36.
[0040] FIG. 10 shows a heat exchanger in the normal plate-like
construction. The heat exchanger contains a multiplicity of
rectangular plates 38 which are disposed parallel and in a stack
one above the other, said plates being kept at a spacing at their
edges alternately by profiles 39 which extend parallel to the long
sides and profiles 40 which extend parallel to the short sides. As
a result, flow channels 41, which extend in the longitudinal
direction as well as flow channels 42, which extends transversely
thereto are produced between the plates 38 and profiles 39 or 40
for guiding a first fluid and a second fluid. In addition,
schematically indicated fin plates or lamellae 43, 44, which are
configured here with a zigzag or undulating configuration instead
of a meandering one, are disposed in the flow channels 41 and/or
42, said lamellae serving to improve the heat transfer between the
two fluids. In addition, one of the two normal collection tanks
(headers) is indicated with the reference number 45, by means of
which the first fluid, e.g. a liquid, is distributed to the flow
channels 41 or is removed therefrom. The plates 38, profiles 39 and
40, lamellae 43 and 44 and also collection tanks 45 can be
connected to each other in a manner known per se, e.g. by glueing
or soldering. The lamellae 43 and/or 44 have lateral walls 46 which
are configured corresponding to FIG. 1 to 8. The flow directions
for the fluids are indicated by way of example by arrows.
[0041] FIG. 11 shows finally a heat exchange element with a
plurality of heat-transferring walls 48 which are disposed parallel
to each other and are formed by thin plates deformed in an
undulating shape. The walls 48 are attached by lower narrow sides
by means of soldering, glueing or otherwise to a base plate 49
which connects the walls 48 securely to each other, and, starting
from the base plate 49, have a height D. Two broad sides 50 of the
walls 48 which are situated opposite each other respectively in
pairs delimit a flow channel 51 for a fluid. The base plate 49
abuts for example on an electronic component to be cooled so that
the heat exchange element forms a ribbed cooling body. In the
embodiment, e.g. cooling air flows through the flow channels 51 in
the direction of their longitudinal axis which extends parallel to
the base plate 49, a chosen flow direction being indicated by way
of example by an arrow 52. Furthermore, the general embodiments for
FIG. 1 to 10 apply correspondingly.
[0042] The described embodiments offer in addition to a significant
increase of the output (power) an only small percentage increase in
pressure losses. This is a consequence of the fact that, on the one
hand, there is a substantially greater, heat-exchanging surface and
that the flow path for the fluid is correspondingly longer, whilst,
on the other hand, the flow can follow the rounded flow channels
easily. In addition, the advantage in particular is produced that
the tendency to become soiled in the flow channels is low despite
the undulations because the broad sides delimiting the flow
channels are continuously flat or slightly rounded and smooth and
no disruptive corners and angles are formed. This applies even if
the dimension of the overlapping of the undulations 6, described
with reference to FIG. 2, is comparatively large so that the heat
exchange elements of the described type are well suited above all
to applications in the agricultural, forestry and building field.
In addition, in particular those heat exchange elements, the walls
of which comprise essentially flat portions, offer the advantage of
being easily produced.
[0043] The invention is not restricted to the described embodiments
which can be modified in many ways. This applies above all to the
indicated shapes and/or sizes of the different undulations and also
to the density of the arrangement thereof. The choice of different
parameters is extensively dependent upon the individual case and
the desired heat exchange or heat transfer output. In addition, it
is possible to dispose the undulations of adjacent walls in the
flow direction at a preselected offset if, as a result, the
pressure losses are not increased in an undesired manner.
Furthermore, the curved portions provided in the apexes of the
undulations can have both a circular and an elliptical
configuration or follow other curves. It is clear furthermore that
the invention can be applied also to heat exchange elements other
than those illustrated in the drawings, configured e.g. as fins,
and heat exchangers equipped with these. Apart thereof, the given
dimensions and/or inequalities should be used at least partly, with
particular advantage however in a continuous manner throughout the
heat exchange elements produced therewith. Deviations of these
dimensions and/or inequalities are, however, also possible within
one and the same heat exchange element or heat exchanger. Finally
it goes without saying that the different features can be combined
with each other in a manner other than that described and
illustrated in the drawing.
[0044] It will be understood, that each of the elements described
above or two or more together, may also find a useful application
in other types of construction differing from the types described
above.
[0045] While the invention has been illustrated and described as
embodied in a heat exchange element and a heat exchanger, it is not
intended to be limited to the details shown, since various
modifications and structural changes may be made without departing
in any way from the spirit of the present invention.
[0046] Without further analysis, the forgoing will so fully reveal
the gist of the present invention that others can, by applying
current knowledge, readily adapt it for various applications
without omitting features that, from the standpoint of prior art,
fairly constitute essential characteristics of the generic or
specific aspects of this invention.
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