Plate Heat Exchanger Cell Segmentation for Residual Stress Reduction
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Solution Overview
Problem
Plate heat exchangers suffer from high residual stress and potential cracking due to intense welding, leading to reduced endurance and reliability, especially in high-temperature applications.
Innovation Solution
A plate heat exchanger design featuring cells with inner and outer spacing elements, where leakage passageways are intentionally left between heat transfer plates to reduce welding and residual stress, allowing for a more flexible and cost-efficient manufacturing process while maintaining performance by minimizing weld joint failure risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intense welding is performed to create a self-supporting gas-tight structure, then structural integrity and gas-tightness are improved, but residual stress increases leading to cracks and reduced endurance
Solution Approach 1:
The heat exchanger stack is divided into multiple cells, each independently supported by spacing elements. This segmentation allows localized welding within cells rather than continuous welding throughout the entire stack, reducing cumulative residual stress while maintaining structural integrity of each segment.
Solution Approach 2:
Welding is applied selectively at specific locations where structural support is needed (at the corners and edges of cells) rather than uniformly across all surfaces. This localized welding approach minimizes the total welded area and associated residual stress while providing sufficient structural support.
2Reliability
If extensive welding is performed to join all elements, then structural rigidity and gas-tightness are improved, but manufacturing complexity and time increase
Solution Approach 1:
The stack is segmented into cells that can be assembled and welded independently. This allows parallel manufacturing of multiple cells and reduces the total sequential welding time compared to joining all elements in a single continuous process.
Solution Approach 2:
Spacing elements are pre-positioned between heat transfer plates to define cell boundaries and provide support before welding begins. This preliminary arrangement simplifies the subsequent welding process by establishing precise joint locations and reducing alignment time.
3Strength
If complete welding of all joints is performed, then structural strength is improved, but residual stress and crack risk increase
Solution Approach 1:
Instead of welding all possible joints, the invention applies welding only to critical locations where structural support is necessary (cell corners and edges). This partial welding approach provides sufficient structural strength while minimizing the total heat input and residual stress that lead to cracking.
Solution Approach 2:
Spacing elements serve as intermediaries between heat transfer plates, providing mechanical support and defining cell boundaries. These spacing elements act as mediators that reduce the need for extensive direct welding between plates, thereby reducing residual stress and crack risk while maintaining structural integrity.
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 design enhances the endurance and reliability of the heat exchanger by reducing residual stress and the risk of cracking, allowing for longer operational lifetimes with minimal performance reduction, even at high temperatures up to 1000°C.
Implementation Method 1
outer spacing elements arranged and welded to at least one of the heat transfer plates on at least one of the sides of the heat transfer plates facing away from each other, along at least two of the four edge parts. The cells are stacked against each other, preferably on top of each other and joined together by welding via the outer spacing elements.
Data Source
AI summary
The plate heat exchanger and method for manufacturing a plate heat exchanger comprise a stack of heat transfer plates, with first and second flow channels arranged between the plates. Pairs of heat transfer plates form cells. A cell comprises inner spacing elements arranged between the heat transfer plates leaving open a first inlet opening and a first outlet opening for the one of the fluids. The cell also comprises outer spacing elements welded to the heat transfer plates on the sides of the heat transfer plates facing away from each other. The cells are stacked against each other and joined together by welding via the outer spacing elements. The plate heat exchanger further comprises cover plates for covering sides of the stack of heat transfer plates with interruption for an inlet port section formed by the first inlet openings and an outlet port section formed by the first outlet openings. The two first sides of the cell comprising the first inlet opening or the first outlet opening comprise leakage passageways provided between the heat transfer plates for the one of the fluids, in addition to the passages provided by the first inlet opening and the first outlet opening.