Heat Exchanger Header Structure for Low-Stress Tube Positioning
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Solution Overview
Problem
Existing heat exchangers face challenges in preventing thermal stress on heat transfer tubes due to header part alignment issues, which can lead to distortion, and current solutions either complicate manufacturing or increase costs.
Innovation Solution
A heat exchanger design featuring a header part with burring parts and extension parts that protrude from the header's circumferential edge, allowing accurate positioning without additional spacers, reducing thermal stress and simplifying manufacturing by minimizing the abutment area and eliminating the need for separate spacers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the header part is positioned close to the sidewall part of the case, then positioning is simplified, but thermal stress on heat transfer tubes increases due to large abutment area
Solution Approach 1:
The header part is segmented into a main body and protruding parts that extend toward the sidewall. The protruding parts make contact with the sidewall to provide positioning, while the main body remains separated from the sidewall to minimize thermal stress transmission to the heat transfer tubes.
Solution Approach 2:
Different parts of the header have different functions: the protruding parts are designed to contact the sidewall for positioning purposes, while the main body is kept away from the sidewall to reduce thermal stress. This local differentiation of contact and non-contact zones resolves the contradiction between positioning ease and thermal stress reduction.
2Stress or pressure
If the header part is positioned away from the sidewall part of the case, then thermal stress on heat transfer tubes is reduced, but positioning of the header part becomes difficult
Solution Approach 1:
The header part is divided into a main body and protruding parts. The protruding parts serve as positioning elements that contact the sidewall, while the main body remains separated to reduce thermal stress, thus achieving both positioning ease and thermal stress reduction.
Solution Approach 2:
The protruding parts act as intermediary elements between the header main body and the sidewall. They provide the necessary contact for positioning while isolating the main body from direct thermal stress, effectively mediating between the conflicting requirements.
3Ease of manufacture
If a plate material spacer is used between the header part and sidewall part, then positioning is ensured, but the number of components increases and manufacturing complexity increases
Solution Approach 1:
The positioning function previously performed by a separate plate material spacer is merged into the header part itself through the protruding parts. This integration eliminates the need for additional spacer components, reducing part count and manufacturing complexity while maintaining positioning accuracy.
Solution Approach 2:
The header part provides its own positioning function through the protruding parts that contact the sidewall, eliminating the need for external spacer components. The header is self-sufficient for positioning, reducing overall device complexity.
4Ease of manufacture
If a plate material spacer is used between the header part and sidewall part, then positioning is ensured, but manufacturing costs increase
Solution Approach 1:
The positioning function is merged into the header part structure itself through protruding parts, eliminating the need for separate spacer components. This reduces the total quantity of materials and components required, thereby reducing manufacturing costs.
Solution Approach 2:
The header part is designed to be self-positioning through its protruding parts that contact the sidewall, eliminating the need for additional spacer materials. This self-service approach reduces component quantity and associated manufacturing costs.
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 design effectively suppresses thermal stress on heat transfer tubes, facilitates accurate header part positioning, and reduces manufacturing complexity and costs by eliminating the need for additional spacers, while enhancing the brazing process and attachment stability.
Implementation Method 1
If the header part abuts against the sidewall part of the case by a large area, once the temperature of the sidewall part of the case rises due to the supply of the heating medium such as the combustion gas into the case, the temperature of the header part also rises similarly and a large thermal stress occurs, which acts on the heat transfer tubes
Implementation Method 2
The plurality of burring parts in a tubular shape are provided to protrude from circumferential edge parts of the plurality of hole parts of the header part toward a sidewall part side of the case, and are externally fitted to the end parts of the respective heat transfer tubes
Data Source
AI summary
A heat exchanger includes a header part that is arranged on an outer surface side of a sidewall part of a case into which a combustion gas is supplied, and has hole parts through which end parts of heat transfer tubes are inserted and forms a chamber communicating between insides of the heat transfer tubes. The heat exchanger further includes a burring part in a tubular shape that protrudes from a circumferential edge part of each hole part of the header part toward the sidewall part side and is externally fitted to the end part of each heat transfer tube, and an extension part that partially extends from a part of a tip circumferential edge part of the burring part toward the sidewall part side and has a tip part abutting against the sidewall part.