Flat Tube With Double-Layer Wall And Internal Fin
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Solution Overview
Problem
Existing flat tubes for heat exchangers face challenges in manufacturing complexity and cost, space constraints, and suboptimal pressure stability, particularly under higher pressures, due to their design and assembly requirements.
Innovation Solution
A flat tube design featuring a material strip with double-layered third side walls and an internal fin that is pre-stressed or fits snugly between the side walls, providing enhanced stability and corrosion resistance while maintaining ease of manufacture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-part tube with interior fin is manufactured (as in DE 102006054814 A1), then the tube can be equipped with internal fins for heat exchange, but the production complexity and costs increase due to joining at least three parts
Solution Approach 1:
The patent combines the tube wall and internal fin into a single integrated component formed from one continuous metal strip. The metal strip is folded to create the tube structure with the fin protruding into the interior space, eliminating the need to join multiple parts together. This merging approach maintains heat exchange functionality while dramatically reducing production complexity.
Solution Approach 2:
The single metal strip serves multiple functions simultaneously: it forms the tube walls, creates the internal fin structure, and provides the structural integrity of the tube. This multi-functionality eliminates the need for separate components and assembly operations, resolving the contradiction between performance and manufacturing complexity.
2Reliability
If the sheet metal strip is bent with lateral closure (as in DE 102006050319 A1), then the tube can be sealed, but the space available for the interior of the tube is limited
Solution Approach 1:
Instead of closing the tube laterally by bending the edges together, the patent uses the longitudinal dimension of the metal strip to create the tube structure. The strip is folded along its length to form the tube walls, allowing the interior space to extend along the tube axis without being constrained by lateral closure requirements.
3Ease of manufacture
If a center bar is provided with hook-like molding (as in EP 1243884 A2), then the tube structure is formed, but the interior pressure stability is not optimal and leaks can occur under higher pressures
Solution Approach 1:
The patent employs curved or angled contours in the tube walls instead of sharp hook-like moldings. The curved geometry distributes stress more evenly across the structure, improving pressure stability while maintaining ease of manufacture through forming operations. The smooth transitions eliminate stress concentration points that would lead to leaks.
Solution Approach 2:
The tube structure utilizes the metal strip's inherent material properties combined with the folded geometry to create a composite-like structure that provides both ease of manufacture and high pressure stability. The integration of the fin and walls from a single material source ensures uniform stress distribution and eliminates weak joints.
Data Source
AI summary
A flat tube, in particular for a heat exchanger, is provided that has an areal material strip with two mutually opposite first and second side walls which are connected to one another via third and fourth side walls, wherein the third side wall is formed by two sections of the material strip that are laid one against the other in double-layer form, wherein an internal fin is arranged in the interior of the flat tube, which fin, at the end sides, bears against the third side wall and against the fourth side wall, and which fin, between the third side wall and the fourth side wall, is supported alternately against the first side wall and against the second side wall.