Additive Heat Exchanger Mixing Chambers for Thermal Stress Reduction
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Solution Overview
Problem
Traditional heat exchangers face challenges with thermal stress and low-cycle fatigue due to brazed or welded joints, and they often experience flow mal-distribution and design limitations that affect heat exchange efficiency, particularly in high-temperature applications like aircraft engines.
Innovation Solution
The design incorporates integral return headers and additive manufacturing techniques to create seamless connections between tubes and manifolds, allowing for flexible tube counts and pitches, and includes features like tapered structures, fins, and thermal compliance elements to enhance heat transfer and reduce thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If brazed or welded joints are used to connect tubes and manifolds, then the heat exchanger can be assembled, but thermal stress and low-cycle fatigue strength are severely reduced
Solution Approach 1:
The patent merges the tube and manifold into a single monolithic structure formed by additive manufacturing, eliminating the separate assembly step and the associated brazed or welded joints. This integration removes the weak points that cause thermal stress and fatigue failure while maintaining manufacturing capability.
Solution Approach 2:
The patent replaces the mechanical joining system (brazing or welding processes) with an additive manufacturing process that creates seamless monolithic structures. This substitution eliminates the harmful effects of thermal cycles and stress concentrations inherent in traditional joining methods.
2Device complexity
If traditional u-bend geometries are used, then the heat exchanger structure is simple, but tube pitch and tube count are limited to specific values
Solution Approach 1:
The patent utilizes additive manufacturing to enable continuous variation of geometric parameters including tube pitch, tube count, and return header configurations. This allows optimization of these parameters for specific applications without being constrained by the discrete values required by traditional u-bend geometries and assembly methods.
3Productivity
If space, weight and pressure drop constraints are applied, then the heat exchanger is compact, but flow distribution among tubes becomes non-uniform
Solution Approach 1:
The patent incorporates flow distribution features directly into the return header geometry, creating localized flow control elements that ensure uniform flow allocation to each tube. This local optimization of flow distribution is integrated into the compact monolithic structure, achieving both compactness and uniform flow without requiring separate flow control components.
4Reliability
If thermal compliance features are added to reduce thermal stress, then thermal stress is alleviated, but the assembled component has reduced fatigue strength due to stress concentrations at brazed/welded joints
Solution Approach 1:
The patent combines the thermal compliance features with the tube and manifold structures into a single monolithic component. This integration eliminates the discontinuities and stress concentrations at joints, allowing thermal compliance to function without compromising fatigue strength. The seamless structure maintains high cycle fatigue resistance while providing necessary thermal stress relief.
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 improves heat transfer rates, reduces thermal stress, and achieves more uniform flow distribution, increasing the heat exchanger's efficiency and flexibility in high-temperature applications.
Implementation Method 1
a return manifold integrally and seamlessly formed with the first supply and first return tubes that allows fluid from at least two first supply tubes to mix before flowing into the first return tubes
Implementation Method 2
Heat exchangers are useful in a variety of industrial application from chemical processing to engine components
Implementation Method 3
significantly diminishing the negative thermal performance impact associated with flow mal-distribution while simultaneously increasing total heat transfer rate from the internal impinging flow
Implementation Method 4
allowing for the inclusion of mechanical compliance features to attenuate thermal stress at critical locations between the tubes and the heat exchanger body
Data Source
AI summary
A heat exchanger is provided having an integrally and seamlessly formed return manifold connecting multiple supply tubes and return tubes. The heat exchanger may also include a return manifold having one or more structures providing a flow restriction within or proximate the return manifold.