Title:
Heat exchange element and heat exchanger produced therewith
Kind Code:
A1


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 (λ) 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≦B/W≦0.55 and R≧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)
Application Number:
11/455369
Publication Date:
12/28/2006
Filing Date:
06/19/2006
Primary Class:
International Classes:
F28D1/02
View Patent Images:
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Primary Examiner:
ROSATI, BRANDON MICHAEL
Attorney, Agent or Firm:
STRIKER, STRIKER & STENBY (HUNTINGTON, NY, US)
Claims:
What is claimed as new and desired to be protected by Letters Patent is set forth in the appended 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 (λ) 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≦B/W≦0.55 applies at least partially to a ratio of said channel width (B) to said apex spacing (W) and wherein an inequality R≧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≦B/R≦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≦B/R≦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≦B/W≦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≦λ≦30 mm applies at least partially to said wavelength (λ).

6. Heat exchange element according to claim 1, wherein an inequality 2.4 mm≦R≦∞ applies at least partially to said radii of curvature (R), R=∞ 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 (λ1 to λ3) and/or apex spacings (W3 to W5) 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 (λ) 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

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

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.

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.

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.

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

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.

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.

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.

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.

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≦B/W≦0.55 and R≧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.

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.

Further advantageous features of the invention are revealed in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

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);

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;

FIG. 3 a plan view corresponding to FIG. 2 on a single wall of the heat exchange element according to FIG. 1;

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;

FIG. 7 a plan view corresponding to FIG. 2 on four heat exchange elements with different total lengths;

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;

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

FIG. 11 a perspective representation of a ribbed cooling body provided with a heat exchange element according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

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.

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.

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.

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.

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.

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.

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.

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≦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≦B/W≦0.55, the inequality 0.35≦B/W≦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≦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.

In order to obtain despite the undulations 6 and the condition B≦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≦1.3 B applies. It is particularly advantageous if the ratio B/R of the inequality 0≦B/R≦0.75 and even more preferred the inequality 0.2≦B/R≦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.

The configuration according to the invention of the undulations 6 and the channel widths B makes it possible in addition to use larger angles α and β (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 λ, 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 α and β should preferably not be greater than 40°.

Furthermore, the heat exchange elements are provided with dimensions λ≧15 mm or ≧4 W, preferably e.g. 18 mm, 2.4 mm≦R≦6.5 mm, α=β=approx. 30°, 0.08 mm≦S≦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.

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.

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.

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 α, a flat section 16 which falls in a straight line at the angle β 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=∞ 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. L1) 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 L1 to L4, of different lengths.

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.

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 W1 and W2 relative to the central planes 7, which apex heights sum up to the apex spacing W. Correspondingly different apex heights W1, W2 can also be provided in the embodiments according to FIG. 1 to 5 without deviating from the indicated dimensions for the apex spacing W.

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.

Furthermore, it can be expedient within the scope of the invention to let the wave lengths λ 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 λ1, λ2 and λ3 and the apex spacings W3, W4 and W5—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.

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.

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.

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.

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.

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.

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.

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.

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.