Plate-Fin Heat Exchanger Core Bands for Weld Heat Isolation
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Solution Overview
Problem
Plate-fin heat exchanger cores are prone to damage during the welding process for attaching inlet and outlet manifolds, leading to potential premature material failure due to temperature-induced stress and latent damage, which affects the integrity and longevity of the heat exchanger.
Innovation Solution
A method involving precision machining to create vertical core bands on closure bars, isolating welding heat-affected zones from the interior region, thereby reducing material stress and enhancing the robustness of the heat exchanger core to withstand subsequent welding operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If welding is performed to attach manifolds to the heat exchanger core, then the heat exchanger becomes operational, but the thin metallic components of the core are damaged by temperature-induced stress and latent damage
Solution Approach 1:
The closure bar is segmented into two distinct zones: an original closure bar portion and a vertical core band portion. This segmentation allows the welding operation to be localized to the vertical core band while protecting the original closure bar and interior region from welding damage. The manifold is welded to the vertical core band outer face, creating isolated welding heat-affected zones that do not compromise the integrity of the thin metallic components in the interior region.
Solution Approach 2:
The vertical core band acts as an intermediary element between the manifold and the interior region of the heat exchanger core. By providing a dedicated welding surface on its outer face, it mediates the thermal and mechanical stresses of the welding process, preventing direct transmission of damage to the vulnerable thin metallic components while still enabling operational capability through manifold attachment.
2Reliability
If precision machining is performed to create vertical core bands, then welding heat-affected zones are isolated from the interior region, but additional manufacturing steps are required
Solution Approach 1:
The vertical core bands are created through precision machining as a preliminary action before the welding operation. By pre-forming these protective zones on the closure bars, the subsequent welding process can be performed without risking damage to the interior region. This preliminary structuring simplifies the overall manufacturing process by enabling a straightforward welding operation that does not require complex protective measures during execution.
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 the manufacturability and robustness of the heat exchanger core, reducing the incidence of defects and extending its service life by isolating welding heat-affected zones and distributing structural loads, thus enhancing its ability to withstand thermal and pressure cycles.
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
Implementation Method 2
each configured to be joined to a manifold by welding
Data Source
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AI summary
A method for producing a plate-fin heat exchanger core includes the steps of stacking a bottom end sheet (42'), multiple alternately stacked individual hot (47) and cold (53) layers, and a top end sheet, each of the individual hot (47) and cold (53) layers including a fin element forming multiple parallel open-ended fluid channels, a parting sheet (18,48') 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 (42'), the various layers, and the top end sheet (54') 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.