Profiled Joint for Heat Exchanger Flow Occlusion
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Solution Overview
Problem
In heat exchangers, particularly plate-and-fin types, the mitre joints used to manage fluid flow changes direction lead to 'flow starvation' due to occlusion of corrugated sheet sections, and narrowing the gap between sections to improve support reduces fluid flow, while manufacturing tolerances complicate achieving a smaller divergent angle without increasing the gap.
Innovation Solution
A secondary heat exchange surface channel portion with concave edge faces, diverging from the fluid flow direction by specific angles, and a joint configuration that maintains a gap between channel portions to facilitate fluid flow while providing structural support, using a method that profiles edge faces to ensure consistent gap dimensions and reduce occlusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a mitre joint is used to change fluid flow direction, then the heat exchanger structure is simple and easy to manufacture, but flow starvation occurs due to occlusion of corrugated sheet sections
Solution Approach 1:
The patent applies curvature by transitioning from straight mitre joints to curved transitions. The curved transition piece gradually changes the flow direction instead of using sharp angular joints, eliminating occlusion of corrugated sheet sections and preventing flow starvation while maintaining manufacturing feasibility
Solution Approach 2:
The patent introduces a third dimension by adding curvature in the flow direction change. Instead of changing direction in a single plane with mitre joints, the curved transition creates a gradual three-dimensional path that avoids occlusion while maintaining structural simplicity
2Strength
If the gap between corrugated sheet sections is narrowed to improve structural support, then support for tube plates is improved, but fluid flow is reduced
Solution Approach 1:
The curved transition eliminates the need for gaps between sections by providing a continuous smooth surface. This maintains structural integrity and support for tube plates while allowing uninterrupted fluid flow through the curved path, resolving the contradiction between structural support and fluid flow
3Ease of manufacture
If manufacturing tolerances are relaxed to simplify production, then ease of manufacture is improved, but achieving consistent gap dimensions becomes difficult
Solution Approach 1:
The curved transition design provides a continuous surface without sharp joints or gaps, eliminating the need for precise gap dimension control. This allows relaxed manufacturing tolerances while maintaining consistent flow characteristics and structural integrity throughout the transition
Data Source
AI summary
A secondary heat exchange surface channel portion for a heat exchanger 7 comprises multiple joints between adjacent channel portions 2a, 2b, 101, for redirecting flow of fluid along a tortuous path. One of the channel portions at each joint has a concave profiled edge face 120, thereby providing a gap 110 between adjacent channel portions. The primary use of this arrangement is in heat exchangers which have corrugated secondary heat exchange surfaces.