Flat Tube Deformations for Thermal Shock Resistance
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Solution Overview
Problem
Traditional B-shaped flat tube constructions in heat exchangers are susceptible to thermal cycling failure, especially at the intersection with header tanks, due to restricted thermal expansion and elevated stresses.
Innovation Solution
A flat tube design formed by bending a sheet metal strip with strategically placed deformations on the walls, which increase rigidity without additional elements or increased thickness, allowing for better thermal shock resistance and fluid path deflection for enhanced heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the tube is formed with a central partition to divide flow channels, then the tube gains structural reinforcement and flow separation, but the tube becomes susceptible to thermal cycling failure at header tank intersections
Solution Approach 1:
The patent applies local quality by creating deformations (protrusions or recesses) at specific locations on the tube outer surface, particularly near header tank intersections. These localized deformations modify the thermal expansion characteristics only where needed, without changing the overall tube structure or partition design, thereby maintaining flow separation while improving thermal cycling resistance at critical areas.
Solution Approach 2:
The patent changes the geometric parameters of the tube by introducing deformations that alter the outer surface profile. These deformations modify the thermal expansion behavior and stress distribution patterns, allowing the tube to better accommodate thermal cycling loads at header intersections without compromising the structural reinforcement provided by the central partition.
2Reliability
If additional elements or increased thickness are used to prevent thermal cycling failure, then thermal shock resistance improves, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of uniformly increasing thickness or adding complex external elements throughout the tube, the patent applies localized deformations only at critical areas where thermal cycling failure is most likely to occur. This approach improves thermal shock resistance where needed while maintaining simplicity in non-critical areas, avoiding unnecessary complexity and manufacturing cost increases.
Solution Approach 2:
The patent segments the tube surface by creating discrete deformations at specific locations rather than applying a uniform structural modification throughout. This segmentation allows targeted improvement of thermal shock resistance at header intersections without requiring complex overall structural changes or increased material usage across the entire tube.
3Stability of the object's composition
If the tube outer surface is restricted from deforming at header tank openings, then the tube maintains positional stability, but thermal expansion stresses increase leading to failure
Solution Approach 1:
The patent introduces localized deformations at specific areas of the tube outer surface, particularly near header tank intersections. These deformations create zones that can accommodate thermal expansion through controlled geometric variation, reducing stress concentrations while maintaining overall positional stability of the tube within the header tank opening.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The tube design effectively withstands thermal shock and enhances heat exchanger performance by maintaining structural integrity and improving heat transfer efficiency through deformation-induced fluid path alterations.
Implementation Method 1
allowing for better thermal shock resistance and fluid path deflection for enhanced heat exchange
Implementation Method 2
The first fluid exchanges heat energy with a second fluid flowing through the spaces between adjacent ones of the flat tubes
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5b
AI summary
The object of the invention is, among others, a flat tube (1) for the flow therein of a fluid in a heat exchanger, the tube (1) being formed by bending a sheet metal strip (2) along the length of the strip, the tube comprising: a first main wall (4); a second main wall (5) parallel to the first main wall (4), said main walls (4, 5) being substantially flat; and two complementary side wall portions (6) joining said main walls together so as to define a closed profile of the tube (1), said strip (2) defining over its width a middle region and two intermediate regions on either side of said middle region, the first main wall (4) of the tube (1) being formed from said middle region, said second main wall (5) of the tube (1) comprising two wall portions (5A, 5B) each formed from a respective one of said intermediate regions, with said wall portions (5A. 5B) of the second main wall (5) being juxtaposed in substantially a common plane, a median wall (7) defined by a double thickness of the sheet metal strip (2) with one part attached to a first wall portion (5A) and the other part attached to a second wall portion (5B), and inner walls (8A, 8B) each formed from a respective one of said parts of the median wall (7), wherein a first piece of said inner wall is at least partially fixed and parallel to the first main wall (4), and a second piece of said inner wall is joining the main walls (4,5) within the middle region of the tube (1), wherein the strip 2 further comprises at least one deformation (9) configured to locally deviate the surface of any of the walls (4,5,6 5A, 5B).