Flat Tube Heat Exchanger Folded Reinforcement
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Solution Overview
Problem
Conventional heat exchanger tubes face challenges in achieving efficient heat transfer and structural integrity with thin wall materials while maintaining strength and corrosion resistance, particularly in applications where thermal stresses and pressure loads are significant.
Innovation Solution
The development of heat exchanger tubes with thin sheet material walls, where the sheet material is folded to create reinforced narrow sides and internal folds, forming a unique cross-sectional shape that enhances strength and heat transfer efficiency, and includes an internal insert for additional reinforcement and flow channel definition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If thin sheet material is used for heat exchanger tubes, then material usage is reduced and heat transfer efficiency is improved, but structural strength and corrosion resistance deteriorate
Solution Approach 1:
The tube cross-section is segmented into multiple narrow sides and broad sides, with the sheet material folded to create internal partitions. This segmentation allows thin material to be distributed into multiple load-bearing sections, collectively providing the required structural strength while maintaining low material usage.
Solution Approach 2:
The invention transitions from a conventional circular cross-section to a flat, multi-sided cross-section with internal folds. This dimensional change creates multiple narrow sides that act as reinforcement ribs, distributing stress across multiple surfaces rather than relying on wall thickness alone, thereby maintaining strength with thinner material.
2Temperature
If thin sheet material is used for heat exchanger tubes, then heat transfer efficiency is improved, but resistance to thermal stresses and pressure loads deteriorates
Solution Approach 1:
The tube wall is segmented into multiple folded sections creating internal partitions and narrow sides. These segments act as individual stress-bearing elements, distributing thermal and pressure loads across multiple surfaces rather than concentrating stress on thick walls, enabling efficient heat transfer with adequate stress resistance.
Solution Approach 2:
The folded sheet material creates a composite-like structure where multiple layers of thin material work together to provide the mechanical strength of a single thick layer. The overlapping and folded sections create a multi-layered configuration that resists thermal stresses and pressure loads effectively while maintaining thin overall wall thickness for heat transfer efficiency.
3Strength
If the sheet material is folded to create reinforced narrow sides, then structural strength is improved, but manufacturing complexity increases
Solution Approach 1:
The sheet material is pre-folded along predetermined lines to create the narrow sides and internal partitions before the tube is assembled and sealed. This preliminary folding action establishes the reinforced structure in advance, simplifying the subsequent assembly process and ensuring consistent structural strength without requiring complex post-processing operations.
Data Source
AI summary
A number of flat tubes, flat tube heat exchangers, and methods of manufacturing both are described and illustrated. The flat tubes can be constructed of one, two, or more pieces of sheet material. A profiled insert integral with the flat tube or constructed from another sheet of material can be used to define multiple flow channels through the flat tube. The flat tubes can be constructed of relatively thin material, and can be reinforced with folds of the flat tube material and/or of an insert in areas subject to higher pressure and thermal stresses. Also, the relatively thin flat tube material can have a corrosion layer enabling the material to resist failure due to corrosion. Heat exchangers having such flat tubes connected to collection tubes are also disclosed, as are manners in which such tubes can be provided with fins.