Flat Tube Seam Design for Heat Exchanger Stress
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Solution Overview
Problem
Conventional heat exchanger tubes face challenges in withstanding external and internal stresses, such as high-speed impacts and thermal expansion, especially in bent tubes, which lack material reinforcement options without increasing costs or using additional components.
Innovation Solution
A flat tube design with inclined longitudinal edges and a second section along the seam, allowing increased flexibility and robustness without additional components, achieved through bending and brazing techniques, enhancing the tube's ability to handle pressure and temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the wall of the tube is locally increased to withstand impact and internal stresses, then the tube strength is improved, but the manufacturing cost increases and the tube complexity increases
Solution Approach 1:
The patent applies local quality by creating a second section with different geometric properties (increased distance between opposite generatrices) at specific locations along the tube, rather than uniformly increasing wall thickness. This localized geometric modification provides enhanced strength and stress resistance at critical areas while maintaining cost-effective manufacturing through the existing bending process.
2Strength
If inserts are added to the open ends of the tube to increase material thickness, then the tube strength is improved, but the device complexity increases and the manufacturing cost increases
Solution Approach 1:
The patent merges the reinforcement function into the tube structure itself by creating a second section through bending, rather than adding separate insert components. This integration eliminates the need for additional parts, simplifies the overall device structure, and removes the complexity of precise brazing operations while still achieving the desired strength enhancement.
3Ease of manufacture
If the tube is bent to reduce manufacturing cost, then the ease of manufacture is improved, but the tube flexibility decreases and the ability to withstand stress is reduced
Solution Approach 1:
The patent applies dynamics by creating a tube structure with varying geometric properties along its length. The second section with increased distance between opposite generatrices provides enhanced flexibility and stress absorption capability, allowing the tube to dynamically adapt to thermal expansion and mechanical stresses while maintaining the cost-effective bent tube manufacturing approach.
Data Source
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AI summary
The object of the invention is, among others, a flat tube (1) for a heat exchanger (100) for a flow of a fluid therein, the tube (1) being formed by bending a sheet metal strip (2) along its length, the metal strip (2) comprising longitudinal edges (2A, 2B), the flat tube (1) further comprising: a first wall (3), a second wall (4) parallel to the first wall (3), said walls (3, 4) being substantially flat, two complementary side wall portions (6) joining said first and second walls (3, 4) together, wherein the first fall (3) comprises a seam (5) extending along the longitudinal axis of the flat tube (1) so that juxtaposed longitudinal edges (2A, 2B) of the metal strip (2) join together in parallel manner towards the second wall (4) to form a closed profile of the tube (1), wherein the seam (5) comprises a first section (5A) fixed to the second wall (4) and extending along the first portion of the seam (5) along the longitudinal axis of the flat tube (1), characterized in that the seam (5) further comprises a second section (5B) extending along the second portion of the seam (5) arranged in series with respect to the first portion of the seam (5) and along the longitudinal axis of the flat tube (1), wherein the second section (5B) is separated from the second wall (4).