B-Tube Partition Layout for Thermal Cycling at Header Tanks
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Solution Overview
Problem
Traditional B-shaped flat tube heat exchangers are susceptible to thermal cycling failure at the intersection with header tanks due to restricted thermal expansion and elevated stresses caused by the central partition and rigid construction, leading to potential permanent deformation or failure.
Innovation Solution
A modified heat exchanger tube design featuring a partitioning wall that is bent away from the base portion in a section to form a single flow channel, reducing stress and allowing for uniform thermal distribution, and is inserted into the header tank through an opening with a cross-sectional shape matching the tube's outer surface, eliminating the central reinforcing partition at the intersection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a central partition is added to reinforce the B-shaped flat tube, then structural strength is improved, but thermal cycling reliability deteriorates due to restricted thermal expansion and elevated stresses
Solution Approach 1:
The partition is positioned only in the central region of the tube, leaving the end regions (where thermal expansion occurs) without partition reinforcement. This local differentiation allows the tube ends to expand freely during thermal cycling while maintaining structural strength in the central region, thereby resolving the contradiction between strength and thermal cycling reliability.
2Stability of the object's composition
If the tube construction is made rigid to prevent deformation, then structural stability is improved, but thermal expansion freedom deteriorates leading to stress concentration at header tank intersections
Solution Approach 1:
The tube is segmented into three distinct regions: a rigid central region with partition reinforcement for structural stability, and two flexible end regions without partitions that can freely expand during thermal cycling. This segmentation allows different parts of the same tube to have different mechanical properties, resolving the contradiction between overall structural stability and local thermal expansion freedom.
3Manufacturing precision
If the partition extends the full length of the tube, then flow channel separation is improved, but stress distribution deteriorates due to restricted movement at tube-header tank intersections
Solution Approach 1:
The partition is implemented only in the central region of the tube rather than extending the full length. This local implementation provides sufficient flow channel separation where needed while leaving the end regions open for stress relief during thermal cycling, thereby resolving the contradiction between flow channel separation precision and stress distribution.
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 design significantly reduces failure due to thermal cycling by allowing for relative movement between tube sections, minimizing stress risers, and maintaining the integrity of the seam for brazing, thus enhancing the durability and efficiency of the heat exchanger.
Implementation Method 1
The first fluid exchanges heat energy with a second fluid flowing through the spaces between adjacent ones of the flat tubes
Implementation Method 2
The repeated presence of varying characteristics within different portions of each of the tubes, such as varying temperatures experienced in different regions of each of the tubes, may lead to the formation of a bending moment within each of the tubes
Data Source
AI summary
A tube for use in a heat exchanger includes an upper portion, a base portion spaced from the upper portion, and a partitioning wall depending from the upper portion. The partitioning wall is bent away and spaced from the base portion in a first section of the tube to form a single flow channel within the tube along the first section. The partitioning wall contacts the base portion in a second section of the tube to form a partition separating a first flow channel from a second flow channel along the second section. The first section of the tube is configured for reception into an opening of a header tank of the heat exchanger.