Additive Heat Exchanger Tubes With Selective Surface Roughness
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Solution Overview
Problem
Aviation heat exchanger designs face challenges in balancing weight, size, and performance requirements, with existing designs struggling to optimize geometry and surface roughness for efficient heat transfer and fluid flow.
Innovation Solution
The development of a heat exchanger core with selectively roughened surfaces and customized tube geometries, manufactured using additive techniques, allows for optimized surface roughness and geometry to enhance heat transfer and fluid flow efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform surface roughness is applied to all tubes, then manufacturing process is simple, but heat transfer efficiency cannot be optimized in different flow regions
Solution Approach 1:
The patent applies different surface roughness characteristics to different regions of the tube outer surface. Specifically, the leading edge region has a first surface roughness while the trailing edge region has a second surface roughness that is different from the first. This local differentiation allows optimization of heat transfer in high-flow regions (leading edge) versus low-flow regions (trailing edge), resolving the contradiction between manufacturing simplicity and heat transfer efficiency.
2Reliability
If complex tube geometries are designed to optimize heat transfer, then heat transfer efficiency improves, but manufacturing complexity increases
Solution Approach 1:
Rather than designing entirely complex tube geometries, the patent maintains relatively simple tube shapes while introducing localized surface roughness variations. The tubes have distinct leading edge and trailing edge regions with different roughness characteristics, achieving heat transfer optimization through surface property differentiation rather than geometric complexity. This resolves the contradiction by keeping the overall device simple while enhancing performance locally.
3Reliability
If surface roughness is increased to enhance heat transfer, then heat transfer coefficient improves, but pressure drop increases
Solution Approach 1:
The patent strategically applies increased surface roughness only to the leading edge region where flow velocity and heat transfer coefficients are naturally higher, while maintaining smoother surfaces in the trailing edge region. This localized approach enhances heat transfer where it is most needed without proportionally increasing pressure drop across the entire tube length, thus resolving the contradiction between heat transfer coefficient and pressure drop.
Solution Approach 2:
Rather than applying uniform roughness enhancement across the entire tube surface, the patent applies roughness enhancement partially - specifically to the leading edge region. This partial action provides sufficient heat transfer improvement in the critical high-flow region without the excessive pressure drop penalty that would result from full-surface roughness application.
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 approach enables improved heat transfer coefficients and reduced pressure drop, optimizing the efficiency of heat exchangers while managing metal temperatures within safe limits.
Implementation Method 1
engaging a first setting to form a relatively smooth region on a surface of one tube of the plurality of tubes, the first setting comprising a first laser scanning speed and a first laser power, and engaging a second setting to form a roughened region on the surface of the one tube of the plurality of tubes, the second setting comprising a second laser scanning speed and a second laser power
Data Source
AI summary
A heat exchanger core comprises a plurality of tubes extending along a first fluid axis, each of the plurality of tubes comprising a leading edge, a trailing edge opposite the leading edge, and a pair of oppositely disposed sidewalls extending from the leading edge to the trailing edge. The leading edge, trailing edge, and the pair of sidewalls define an inner surface and an outer surface of each of the plurality of tubes. Each of a first subset of the plurality of tubes further comprises a roughened region on the outer surface of one of the pair of sidewalls.