Rectangular Multi-Helical Heat Exchanger Core for Thermal Stress Relief
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Solution Overview
Problem
Heat exchangers used in high-temperature applications, such as aircraft engines, face short service lifetimes due to thermal stresses, which cause expansion and cracking, and require improvements in heat transfer efficiency, pressure loss reduction, and vibration mitigation.
Innovation Solution
A heat exchanger with a multi-helical core design featuring structurally independent helical tubes distributed in a rectangular assembly, providing increased heat transfer surface area, mechanical compliance to alleviate thermal stresses, and reduced pressure losses through fractally branching manifolds and additive manufacturing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heat exchanger designs are used, then structural simplicity is maintained, but thermal stresses cause expansion and cracking leading to short service lifetimes
Solution Approach 1:
The patent applies helical curvature to the core tubes, transforming straight cylindrical structures into helical shapes. This curvature provides structural compliance that allows the tubes to flex and accommodate thermal expansion without cracking, directly resolving the thermal stress damage issue while maintaining reliability in high-temperature applications
Solution Approach 2:
The patent changes the geometric parameters of the core structure by introducing helical configurations with specific pitch ratios and curvature radii. These parameter changes enable the structure to absorb thermal stresses through controlled deformation, preventing the expansion and cracking that would otherwise occur in conventional straight-tube designs
2Productivity
If heat exchanger surface area is increased to improve heat transfer, then heat transfer efficiency increases, but pressure losses increase
Solution Approach 1:
The helical curvature of the core tubes enhances heat transfer efficiency by promoting turbulent flow and increasing the effective heat transfer surface area. Simultaneously, the smooth continuous curvature avoids sharp bends and abrupt directional changes that would cause excessive pressure losses, thus resolving the contradiction between heat transfer enhancement and pressure loss reduction
3Object-affected harmful factors
If conventional core geometry is used, then manufacturing simplicity is maintained, but harmful resonance conditions occur
Solution Approach 1:
The helical geometry of the core tubes naturally dampens vibrations and avoids resonant frequencies that occur in straight-tube configurations. The continuous curved structure distributes mechanical stresses more evenly and reduces vibration excitation, eliminating harmful resonance conditions while remaining manufacturable through established helical tube forming 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 multi-helical core design enhances heat transfer efficiency, reduces pressure losses, and mitigates thermal stresses by providing structural compliance and increased surface area, while maintaining mechanical integrity and avoiding harmful resonance conditions.
Implementation Method 1
provides structural compliance that allows the core to serve as a spring to relieve thermal and other stresses
Implementation Method 2
thermal stresses, which can cause expansion and cracking of the fluid conduits
Data Source
Figure 1
Figure 2~3
AI summary
A heat exchanger (10) includes a first fluid manifold (12) extending along a first fluid axis from a first fluid inlet to a first fluid outlet. The first fluid manifold comprises a inlet header (16), a outlet header (18), and a multi-helical core section (20). The inlet header is disposed to fork the first fluid inlet into a plurality of first fluid branches distributed laterally across a plane normal to the first fluid axis. The outlet header is disposed to combine the plurality of first fluid branches into the first fluid outlet. The multi-helical core section fluidly connects the inlet header to the outlet header via a plurality of laterally distributed helical tubes (30), each helical tube corresponding to one of the plurality of first fluid branches and oriented parallel to all others of the plurality of helical tubes at each axial location along the first fluid axis.