Conformal Heat Exchanger Diffusion Bonding for Curved Fin Integrity
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Solution Overview
Problem
Conventional heat exchangers with annular conformal geometry face manufacturing challenges due to layers separating during the formation of curvatures, limiting their performance and reliability.
Innovation Solution
A method using field-assisted sintering technology (FAST/SPS) is employed to diffusion bond parting sheets and conventional fin packs, forming a compound fin-plate structure that conforms to annular passages, ensuring the bonds survive curvature imparting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional folded fin packs are used to form annular conformal heat exchangers, then the heat exchanger can achieve improved performance with additional layers and lower pressure drop, but the layers tend to separate from one another during manufacturing processes that provide curvatures
Solution Approach 1:
The patent applies preliminary action by forming diffusion bonds between layers before imparting curvatures during manufacturing. The field-assisted sintering process creates strong metallurgical bonds in advance, preventing layer separation that would otherwise occur during subsequent curvature formation steps.
Solution Approach 2:
The patent replaces conventional mechanical joining methods with field-assisted sintering (FAST/SPS) diffusion bonding. This substitution uses electrical fields and controlled sintering to create metallurgical bonds, eliminating the mechanical separation issues that plague traditional assembled fin pack constructions during curvature formation.
2Shape
If multiple parting sheets are disposed to separate interleaved fin layers in a packed, non-conformal HX, then the structure provides separation and support, but the rectangular cross-section does not fit perfectly into the curvature of the annular passage, limiting the number of layers
Solution Approach 1:
The patent applies curvature principles by designing the heat exchanger with annular conformal geometry that matches the curved annular passage. The diffusion-bonded layers are formed with inherent curvature compatibility, allowing the rectangular fin packs to be transformed into conformal annular structures that maximize space utilization and layer density within the passage.
Solution Approach 2:
The patent changes the geometric parameters of the heat exchanger from rectangular non-conformal to curved conformal geometry. By modifying the shape parameters during the diffusion bonding and curvature imparting process, the heat exchanger achieves optimal fit within the annular passage, increasing the number of layers that can be accommodated.
3Reliability
If diffusion bonds are formed along entire length of fins to diffusion bond fins to parting sheets, then the bonds survive curvature imparting and manufacturing is reliable, but the manufacturing process complexity increases due to FAST/SPS processing requirements
Solution Approach 1:
The patent merges multiple manufacturing operations into the field-assisted sintering process. The diffusion bonding of fins to parting sheets, the formation of metallurgical joints, and the preparation for curvature acceptance are combined into a single FAST/SPS processing step, creating integral bonds that survive subsequent curvature imparting without requiring additional complex processes.
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
The method enables reliable manufacturing of conformal heat exchangers with improved performance and lower pressure drop characteristics by maintaining integral bonds throughout the curvature process.
Implementation Method 1
diffusion bonds formed along an entire length of a fin to diffusion bond the entire length of the fin to the parting sheets
Implementation Method 2
the diffusion bonds are formed by field assisted sintering technology/spark plasma sintering (FAST/SPS) processing
Data Source
AI summary
A heat exchanger is provided and includes parting sheets flat along a first axis and curved along a second axis perpendicular to the first axis, a fin sheet interposed between the parting sheets and corrugated along the first axis to form fins that are curved along the second axis and diffusion bonds formed along an entire length of a fin to diffusion bond the entire length of the fin to the parting sheets.