Brazed Heat Exchanger Thermal Decoupling
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Solution Overview
Problem
Brazed heat exchangers experience material fractures and breakdown due to alternating temperature loadings, particularly around the finishing-off plate and adjacent moldings, leading to reduced resilience during operational conditions.
Innovation Solution
The introduction of thermally decoupling elements, which can be either separate parts or integrally configured with the adjacent plate, is placed between the finishing-off plate and the moldings to compensate for thermal expansions, thereby reducing the stress caused by temperature fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the finishing-off plate is directly brazed to the adjacent plate with moldings, then the structural integrity is maintained, but cracks and fractures occur due to alternating temperature loadings
Solution Approach 1:
A thermally decoupling element is introduced as an intermediary component between the finishing-off plate and the adjacent plate with moldings. This decoupling element has a thermal conductivity that is lower than that of the finishing-off plate and the adjacent plate, thereby reducing thermal stress transmission and preventing cracks and fractures caused by alternating temperature loadings while maintaining structural integrity through the brazed connection.
2Reliability
If the thermally decoupling element is inserted as a separate part, then thermal expansion compensation is achieved, but the device complexity increases
Solution Approach 1:
The thermally decoupling element is integrally configured with the adjacent plate to form a single piece, eliminating the need for separate assembly and reducing device complexity. The integrated design maintains the thermal expansion compensation function while simplifying the overall structure and reducing the number of discrete components.
3Ease of manufacture
If the thermally decoupling element is integrally configured with the further plate, then manufacturing is simplified, but the thermal decoupling effect may be reduced
Solution Approach 1:
The brazed connection between the thermally decoupling element and the finishing-off plate is specifically designed with controlled brazing parameters to create a localized thermal barrier. The brazing material and process are optimized to provide mechanical strength while maintaining low thermal conductivity at the interface, thus preserving thermal decoupling effectiveness despite the integral configuration with the further plate.
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 implementation of thermally decoupling elements significantly reduces the occurrence of cracks and fractures, enhancing the heat exchanger's resilience to alternating temperature loadings and improving its operational reliability.
Implementation Method 1
variable expansions on account of thermal loadings in the finishing-off plate and in the adjacent plate of the plate pair can be largely compensated for
Data Source
AI summary
A heat exchanger from a stack of plate pairs having fins which are disposed between the plate pairs, and having ducts which vertically extend through the stack, for conveying in and/or conveying out a medium which flows through the plate pairs and which exchanges heat with another medium which flows through the fins, wherein the ducts are formed from openings in the plates and have moldings which extend around opening peripheries, and having a plate, having corresponding openings, which finishes off the stack, wherein a thermally decoupling element, which is inserted either in an integrated or a separate manner and which is incorporated into the vertical duct formation, is disposed between the finishing-off plate and the stack. Such a heat exchanger displays improved resilience to alternating temperature loadings.