Plate-Fin Heat Exchanger Core Layout for Weld-Resistant Manifolds
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Solution Overview
Problem
Existing plate-fin heat exchanger core designs are prone to damage during the welding process for attaching inlet and outlet manifolds, leading to potential material integrity issues and premature failure due to temperature-induced stress and misalignment challenges during assembly.
Innovation Solution
A method involving the stacking of hot and cold layers with closure bars, followed by brazing and precision machining to create a robust design with reduced closure bar width and radiused corners, which enhances the heat exchanger's ability to withstand welding and reduces material stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If closure bars are made with sufficient width to maintain structural integrity during assembly, then manufacturing robustness is improved, but the heat exchanger core occupies excessive space and increases weight
Solution Approach 1:
The closure bars transition from a uniform wide cross-section to a variable cross-section where the width is reduced at the ends while maintaining full width at the center. This parameter change allows the closure bars to maintain structural integrity during assembly while reducing overall material usage and weight.
Solution Approach 2:
The closure bars feature radiused corners instead of sharp 90-degree angles. This curvature reduces stress concentration points and allows for more efficient material distribution, maintaining strength while reducing the overall volume of material required.
2Ease of operation
If welding is performed to attach inlet and outlet manifolds to the heat exchanger core, then fluid connection is achieved, but the thin metallic components suffer damage from welding heat and stress
Solution Approach 1:
The closure bars are designed with extended ends and radiused corners before the welding process. This preliminary design feature prepares the structure to better withstand the subsequent welding process by distributing thermal stress more evenly and preventing heat concentration at sharp corners.
Solution Approach 2:
The radiused corners and extended closure bar ends act as cushioning features that absorb and distribute the thermal stress and mechanical load from the welding process, protecting the thin metallic heat exchanger components from damage before the welding even occurs.
3Manufacturing precision
If precision machining is used to remove material from closure bars, then manufacturing precision is improved, but production time and complexity increase
Solution Approach 1:
The closure bar manufacturing process is segmented into distinct stages: initial formation of the closure bars, brazing of the heat exchanger core, and subsequent precision machining of the closure bar ends. This segmentation allows each stage to be optimized independently, with the machining stage focusing only on the specific features needed for manifold attachment.
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 solution improves manufacturability and robustness, reducing the incidence of defects and extending the service life of the heat exchanger by minimizing welding heat-affected zones and distributing structural loads effectively, thus enhancing its durability and operational resilience.
Implementation Method 1
brazing the bottom end sheet, the number of alternately stacked individual hot and cold layers, and the top end sheet in a brazing furnace
Data Source
AI summary
A method for producing a plate-fin heat exchanger core includes the steps of stacking a bottom end sheet, multiple alternately stacked individual hot and cold layers, and a top end sheet, each of the individual hot and cold layers including a fin element forming multiple parallel open-ended fluid channels, a parting sheet separating the various individual layers, and two closure bars positioned on opposite sides of the fin element, parallel to the open-ended channels and extending a length of the open-ended channels, brazing the bottom end sheet, the various layers, and the top end sheet in a brazing furnace; and removing material from each of the exterior faces by precision machining, thereby removing material from each closure bar outer face. The precision machining can include electrical discharge machining, laser cutting, band sawing, drilling, boring, hogging, acid etching, and ion milling, in any combination.