Heat Exchanger Header Jointing via Curved Surface Welding
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Solution Overview
Problem
Conventional heat exchangers face high production costs due to the need for expensive brazing equipment and difficulty in quality control, particularly when using a large number of members and complex structures, which restricts space and increases facility costs.
Innovation Solution
A heat exchanger design featuring a bulging portion with a cylindrical circumferential wall and end wall, where the header is jointed to the side wall using curved surfaces for surface-contact welding, eliminating the need for brazing and allowing for easier assembly and quality control through TIG welding outside the case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If brazing is used to joint the auxiliary member to the bulging portion, then the jointing strength is improved, but the facility cost and production cost increase due to the need for large equipment such as vacuum furnace
Solution Approach 1:
The patent replaces the brazing process (thermal joining method requiring vacuum furnace) with a mechanical fitting system consisting of a fitting portion with an outer diameter slightly larger than the inner diameter of the opening, allowing press-fit assembly without expensive brazing equipment while achieving sufficient joint strength
Solution Approach 2:
The patent uses a simple auxiliary member with a fitting portion that can be assembled through press-fit or welding, eliminating the need for expensive vacuum furnace equipment and brazing materials, thereby reducing facility costs while maintaining adequate joint strength for the application
2Reliability
If brazing is executed in the case, then the auxiliary member is jointed to the bulging portion, but quality control becomes difficult as it is difficult to check whether brazing is appropriately done or not
Solution Approach 1:
The patent incorporates a fitting portion with specific dimensional tolerances (outer diameter slightly larger than the inner diameter of the opening) that enables pre-assembly verification through the interference fit itself, allowing quality control to be performed during assembly rather than requiring post-brazing inspection
Solution Approach 2:
The patent replaces the brazing process with a mechanical press-fit assembly system where the fitting portion's dimensional characteristics provide inherent quality verification through the assembly process itself, making quality control straightforward and observable without complex inspection procedures
3Ease of manufacture
If the heat exchanger comprises a number of members and complicated structure to enable welding, then welding can be used as jointing means, but the production cost becomes high
Solution Approach 1:
The patent integrates the fitting portion directly into the auxiliary member as an integral feature, merging the jointing function with the structural component itself, thereby simplifying the overall structure while maintaining the ability to use cost-effective welding or press-fit assembly methods
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 reduces production costs by simplifying the structure, eliminating the need for brazing equipment, and improving assembly efficiency with high-dimensional accuracy and strength, while facilitating quality control and durability through surface-contact welding.
Implementation Method 1
the first curved surface and the second curved surface are in a surface-contact condition, and the surface-contact portion and the area therearound are welded
Data Source
AI summary
The heat exchanger wherein each end of a plurality of heat transfer tubes is connected to an end wall of a bulging portion provided at a side wall of a case, an open edge of a header is fitted onto the bulging portion, and a chamber connecting with each heat transfer tube is formed. For jointing the header to the side wall, an inner circumferential end of the open edge of the header is formed as a first curved surface with a convex section, an outer face of the circumferential wall of the bulging portion is formed as a second curved surface with a concave section, the first curved surface and the second curved surface contact each other, and the surface-contact portion and the area therearound are welded. The number of the members is reduced, the structure is simplified, and the production cost of the heat exchanger is reduced.