Welded Heat Exchanger Plates Double Weld System
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Solution Overview
Problem
Heat exchangers with welded plates face issues under significant thermomechanical constraints, particularly due to expansion stresses that can lead to weld rupture at the docking zone between plates and connecting walls, necessitating a reduction in expansion force or an increase in weld section to prevent rupture.
Innovation Solution
The solution involves a unique assembly configuration where metal plates are juxtaposed over a predefined width with a double weld system, including a spot or laser weld for mechanical strength and a TIG or plasma weld for sealing, and chamfered edges on frame posts to allow bending and absorption of expansion stress, along with bellows conformations for additional flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the weld section is increased to reduce expansion stress, then the mechanical strength and resistance to rupture improve, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The welding process is segmented into two distinct operations: a first weld (spot weld or laser weld) that ensures mechanical strength, and a second weld (TIG or plasma weld) that provides sealing. This segmentation allows each welding type to be optimized for its specific function, achieving both high strength and reliability without requiring a single overly complex welding procedure.
Solution Approach 2:
The invention transitions from edge-to-edge welding (one-dimensional contact) to face-to-face welding with a predefined width of at least 15mm (two-dimensional contact area). This dimensional change significantly increases the weld section and resistance to expansion stress while maintaining manageable assembly complexity through standardized plate geometry.
2Device complexity
If the plates are assembled edge-to-edge, then the device complexity is reduced, but the weld section is insufficient to resist expansion stresses
Solution Approach 1:
The invention changes the welding configuration from edge-to-edge (line contact) to face-to-face (area contact) with a predefined width of at least 15mm. This dimensional transition dramatically increases the weld section available to resist expansion stresses while keeping the assembly process relatively simple through standardized plate geometry and positioning.
Solution Approach 2:
The invention changes the critical parameter of weld section area by modifying the assembly configuration. By requiring plates to be applied flat against each other over a predefined width of at least 15mm rather than edge-to-edge contact, the weld section is increased from a narrow line to a substantial area, providing adequate resistance to expansion stresses.
3Ease of manufacture
If a single weld is used for both strength and sealing, then the manufacturing process is simplified, but the reliability under thermomechanical stress decreases
Solution Approach 1:
The welding process is divided into two separate operations: a first weld (spot weld or laser weld) optimized for mechanical strength, and a second weld (TIG or plasma weld) optimized for sealing. This segmentation allows each welding type to be independently optimized for its specific function, achieving both high strength and reliability under thermomechanical stress while maintaining a relatively simple overall manufacturing process.
Solution Approach 2:
Different welding methods are applied to different locations and functions within the same joint. The first weld provides localized mechanical strength at the plate interface, while the second weld provides localized sealing along the same interface. This local differentiation of welding quality ensures both strength and reliability without requiring a single complex welding procedure.
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 configuration significantly increases the weld section, making the assembly more resistant to expansion stresses and preventing weld rupture, while allowing for effective deformation and stress absorption, thereby enhancing the heat exchanger's temperature behavior and mechanical integrity.
Implementation Method 1
are joined together to each other by a first weld made in this width and ensuring the mechanical strength of the assembly
Implementation Method 2
are also joined together, along their outer edges, by a second weld ensuring the tightness
Implementation Method 3
each post or corner post of the frame of the heat exchanger with welded exchange plates has a chamfered inner edge, the adjacent connecting wall joining the post or corner post in the region of this chamfered edge
Implementation Method 4
during the heating of the exchange block, taking into account the temperature gradient existing in service, the exchange plates tend to expand along their length
Data Source
Figure 1
Figure 2~5
Figure 6~7
AI summary
The heat exchanger comprises metal plates (6, 7) which have been press-formed and assembled in pairs by welding two opposite sides to make modular elements (2) that are stacked and which define two independent circuits for a first and a second fluid. The two metal plates (6, 7) of the modular element (2) are set flatly against each other over a predefined width (L) and are joined by solder (12) along this width and meant to ensure the mechanical cohesion of the assembly and by another solder (13) performed along the external edges of the plates and ensuring their sealing. The ends of the plates (6, 7) are welded to opposite connection partitions forming an exchange block which is itself mounted on four corner posts of the heat exchanger body.