Bent Flat Tube Geometry for Compact Heat Exchangers
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Solution Overview
Problem
Existing heat exchangers with flat tubes have poor heat exchange performance due to a relatively long bent section that reduces the length of non-bent sections, limiting the arrangement of fins and overall performance.
Innovation Solution
A flat tube design with a bent section in the middle featuring a bent portion and two twisting portions, where the minimum radius of curvature is less than five times the tube thickness, allowing for reduced bent section length and increased straight section length, with fins arranged between adjacent tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the bent section length is reduced to increase straight section length, then the heat exchange area increases, but the bending radius must be decreased which may compromise strength and corrosion resistance
Solution Approach 1:
The patent changes the bending radius parameter from conventional values (greater than 5t) to a smaller value (0.5t to 5t), allowing reduction of bent section length while maintaining structural integrity. This parameter change enables the dual benefit of increased straight section length for heat exchange and acceptable mechanical properties.
2Area of stationary object
If the bent section length is reduced, then the straight section length increases improving heat exchange, but the bending angle must be increased which complicates manufacturing
Solution Approach 1:
The patent optimizes the bending angle parameter to a specific range (30° to 150°) that balances the need for compact configuration with manufacturing feasibility. This parameter optimization allows achieving the desired compact form factor while maintaining ease of manufacture.
3Length of stationary object
If the bending radius is decreased to reduce bent section length, then the heat exchanger height is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a bending radius range (0.5t to 5t) that achieves compact heat exchanger height while remaining within manufacturable precision limits. This parameter range optimization resolves the contradiction between compact size and manufacturing precision requirements.
Data Source
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AI summary
The present invention provides a flat tube and a heat exchanger, in which a bent section is formed in the middle of the flat tube, regions of the flat tube outside the bent section form two straight sections, the bent section includes a bent portion and two twisting portions, two ends of each twisting portion are connected to one end of the bent section and one straight section respectively; wherein the bent portion bends around an axis parallel to the thickness direction of the flat tube, the minimum radius of curvature of the inner side of the bent portion is RNmin, and the thickness of the flat tube is t, t<RNmin<5t. In the solution, bending deformation can be completed in cases where the minimum radius of curvature of the inner side of the bent portion is set to be relatively small, thus reducing the length of the bent section of the flat tube, increasing the length of the straight sections, and further improving the heat exchange performance of the flat tube and a heat exchanger using the flat tube.