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 (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).

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 refrigera...

AI Technical Summary

Benefits of technology

[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.

Problems solved by technology

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.

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.

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.

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.

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.

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.

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