Brazed Plate Heat Exchanger Sealing to Prevent Bypass Flow
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Solution Overview
Problem
Brazed plate heat exchangers face challenges with high pressing forces required for large plates, leading to expensive and energy-intensive manufacturing, and inefficiencies in sealing methods that result in reduced heat transfer due to lateral channels with no heat exchange.
Innovation Solution
A heat exchanger design featuring skirts along the long sides and flat seals along the short sides of plates, allowing for efficient heat transfer and manufacturing through roll forming, with selective fluid communication achieved by varying port opening levels and orientations, and a combination of skirt-to-skirt and flat sealing for effective sealing without extra rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If heat exchanger plates are pressed in one single operation using powerful hydraulic presses, then the pressed pattern, port openings and circumferential skirt are formed simultaneously, but the pressing forces become very large (several thousands of tons) requiring expensive and energy-consuming large presses
Solution Approach 1:
The pressing process is divided into two separate operations: first forming the pressed pattern with ridges and grooves using moderate pressure, then separately forming the circumferential skirt and port openings. This segmentation allows each pressing step to use smaller, more economical presses rather than requiring one extremely large press capable of handling all features simultaneously.
Solution Approach 2:
The pressed pattern of ridges and grooves is formed in advance during the first pressing operation, creating a preliminary structure that maintains plate separation. This preliminary action allows the second pressing operation to focus only on forming the circumferential skirt and port openings without needing to simultaneously create all features, thereby reducing the required pressing force.
2Ease of manufacture
If heat exchanger plates are provided with flat sealing areas instead of circumferential skirts, then manufacturing is simplified, but lateral channels are formed where no heat exchange takes place reducing efficiency
Solution Approach 1:
The invention merges the advantages of both sealing approaches by combining circumferential skirts that provide efficient sealing along the long sides with flat sealing areas at the short sides. This hybrid configuration maintains manufacturing simplicity while preventing the formation of lateral channels that would cause energy loss, as the skirts ensure proper fluid flow paths for heat exchange.
Solution Approach 2:
Different sealing structures are applied to different locations on the heat exchanger plates: circumferential skirts are used along the long sides where they effectively prevent lateral channel formation and maintain heat transfer efficiency, while flat sealing areas are used at the short sides where they provide sufficient sealing without creating harmful flow paths. This localized application of different sealing qualities optimizes both manufacturing and thermal performance.
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 reduces manufacturing costs and energy consumption by enabling roll forming and achieves efficient heat transfer by preventing bypass and short-circuiting, ensuring effective fluid distribution and heat exchange across the interplate channels.
Implementation Method 1
the heat exchanger plates are joined by brazing
Implementation Method 2
interplate flow channels for media to exchange heat
Implementation Method 3
ridges and grooves of neighboring plates form contact points keeping the plates on a distance from one another such that interplate flow channels are formed
Data Source
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AI summary
A brazed plate heat exchanger (100) for exchanging heat between at least two fluids comprises several elongate heat exchanger plates (110) provided with a pressed pattern comprising depressions and elevations adapted to keep the plates on a distance from one another by contact points between the elevations and depressions of neighboring plates under formation of interplate flow channels for media to exchange heat. At least four port openings are placed in corner regions of the elongate heat exchanger plates and have selective fluid communication with the interplate flow channels such that the fluids to exchange heat will flow between port openings parallel to long sides of the elongate heat exchanger plates. A circumferential seal sealing off the interplate flow channels from communication with the surroundings is provided, and the heat exchanger plates are joined by brazing. The circumferential seal results partly from contact between skirts of neighboring plates contacting one another, said skirts extending at least partly along two sides of each heat exchanger plates, and partly from contact between flat areas extending along two other sides of the heat exchanger plates.