Heat Exchanger Header Brazing with Differential Melt-Rate Layers
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Solution Overview
Problem
Existing heat exchangers face issues with defective brazing due to uneven melting of brazing filler materials, particularly those farther from the heat source, leading to poor joining of header components.
Innovation Solution
The heat exchanger design includes a header with specific brazing layers between members, such as the second and third members, having a higher melt rate than other brazing layers, ensuring uniform brazing even at lower temperatures, and a configuration that allows for efficient insertion of heat transfer tubes with minimal obstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If brazing filler material is positioned far from the heat source, then the brazing process can be simpler, but the brazing filler material is less likely to melt causing defective brazing
Solution Approach 1:
The patent applies local quality by providing different brazing filler materials with different melt rates at different locations within the header. Specifically, the brazing filler material positioned far from the heat source has a lower melting point (higher melt rate) than those closer to the heat source, ensuring that all brazing joints melt and bond properly despite the temperature gradient during the brazing process.
2Reliability
If brazing filler material is positioned close to the heat source, then the brazing process is more reliable, but the brazing filler material melts too quickly causing uneven brazing
Solution Approach 1:
The patent implements local quality by varying the melt rate characteristics of brazing filler materials based on their position relative to the heat source. Brazing filler materials closer to the heat source have higher melting points (lower melt rates) to prevent premature melting, while those farther away have lower melting points (higher melt rates) to ensure complete melting. This spatial variation in material properties achieves both reliable and uniform brazing across the entire header structure.
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 achieves excellent brazing joints, enhancing the strength and integrity of the header while minimizing friction and blocking of flow paths, thus improving the overall performance and reliability of the heat exchanger.
Implementation Method 1
the brazing layer between the second member and the third member has a melt rate, at a predetermined temperature, being larger than a melt rate, at the predetermined temperature, of at least one of a brazing layer between the first member and the second member and a brazing layer between the first member and the third member
Implementation Method 2
When the plurality of members mentioned above is joined by brazing, a brazing filler material positioned far from a heat source for provision of heat is less likely to melt
Data Source
AI summary
A heat exchanger includes: a header; and heat transfer tubes connected to the header. The header includes a first member, a second member, and a third member. A brazing layer between the second member and the third member has a melt rate, at predetermined temperature, that is larger than a melt rate, at the predetermined temperature, of at least one of: a brazing layer between the first member and the second member; and a brazing layer between the first member and the third member.