Removable Frame Bars for Distortion-Resistant Heat Exchanger Cores
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Solution Overview
Problem
The fabrication of plate-fin heat exchangers faces issues such as distortion due to heat treatment, shrinkage during brazing, deformation from 'butter-passing', and collapsing of fin passages, which affect the integrity and efficiency of the heat exchanger core.
Innovation Solution
A heat exchanger core is fabricated using a frame with removable bars that surround the fin passages, allowing for easier alignment and brazing, eliminating the need for additional welding and reducing gaps between fins and tube sheets, while enabling air flow and eliminating the butter-pass weld.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional brazing and butter-pass welding methods are used to assemble heat exchanger cores, then the core structure can be formed, but distortion, shrinkage, and deformation occur during fabrication
Solution Approach 1:
The frame is attached to the core layers before brazing, providing pre-positioning and support. This preliminary action prevents distortion and deformation during the subsequent brazing process by maintaining proper alignment and structural integrity of the core components.
Solution Approach 2:
The frame acts as an intermediary structural element that mediates between the core layers and the brazing process. It provides a rigid framework that holds the core components in correct position while withstanding thermal stresses, thereby preventing direct deformation of the heat exchanger passages.
2Ease of manufacture
If butter-pass welds are applied around the perimeter of core layers, then assembly to next core is enabled, but deformation due to welding occurs
Solution Approach 1:
The frame is attached to the core layers before brazing, providing pre-positioning and support. This preliminary action prevents distortion and deformation during the subsequent brazing process by maintaining proper alignment and structural integrity of the core components.
Solution Approach 2:
The frame acts as an intermediary structural element that mediates between the core layers and the brazing process. It provides a rigid framework that holds the core components in correct position while withstanding thermal stresses, thereby preventing direct deformation of the heat exchanger passages.
3Reliability
If frame with removable bars is used instead of traditional welding, then structural integrity is enhanced and deformation is reduced, but additional fabrication steps are required
Solution Approach 1:
The frame is divided into multiple bars that can be individually attached to the core layers. This segmentation allows for simplified attachment processes and enables selective removal of certain bars after brazing to create air passages, while maintaining the overall structural integrity during the critical brazing phase.
Solution Approach 2:
Certain bars of the frame are temporarily retained during brazing to provide structural support and prevent deformation, then selectively removed after brazing to create air passages. This approach allows the frame to serve dual purposes: structural support during fabrication and flow passage formation after fabrication.
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
This method enhances the structural integrity and efficiency of the heat exchanger core by reducing deformation and shrinkage, resulting in a stronger braze joint and simplified assembly process, with the ability to withstand greater forces during stacking and brazing.
Implementation Method 1
brazing the core
Data Source
AI summary
A heat exchanger core includes a first fin passage. A first frame surrounds a perimeter of the first fin passage. The first frame includes a plurality of bars configured to be removable from the first frame.