Duct Separating Element Geometry for Filler-Free Annular Gaps
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Solution Overview
Problem
Existing braze-welding processes in heat exchangers can fill the annular gap between separating elements with molten filler material, compromising leak detection and performance.
Innovation Solution
The opening angle α between the plates of the separating element is set to θ + α ≥ 90°, creating a convex fillet shape that increases capillary pressure, preventing the annular gap from being filled with molten filler material during braze-welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If braze-welding is performed to join the separating element to the duct, then the connection strength is improved, but the annular gap becomes filled with molten filler material, compromising leak detection functionality
Solution Approach 1:
The invention changes the geometric parameters of the separating element, specifically the opening angle α of the plates, to control the capillary pressure in the corner fillet. By setting θ + α ≥ 90°, the capillary pressure becomes positive, preventing molten filler material from entering the annular gap while allowing braze-welding to proceed for strong connection.
Solution Approach 2:
The invention converts the potentially harmful effect of capillary action (which could draw molten filler into the gap) into a beneficial effect by designing the geometry to create positive capillary pressure. This positive pressure actively repels the molten material from the annular gap, protecting the leak detection function while maintaining the benefits of braze-welding.
2Reliability
If the opening angle α is increased to prevent filler material from filling the annular gap, then the capillary pressure increases and prevents clogging, but the structural configuration becomes more complex
Solution Approach 1:
The invention modifies a single geometric parameter (the opening angle α) of the existing separating element structure. This parameter change achieves the desired effect of preventing filler material intrusion through capillary pressure control without requiring fundamental redesign or additional components, thus minimizing structural complexity.
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 geometry ensures the annular gap remains free from filler material, maintaining leak detection functionality and enhancing the heat exchanger's performance by preventing clogging.
Implementation Method 1
The corner fillet between the plates has a capillary pressure corresponding to its shape. Increasing the angle α results in an increase in the capillary pressure of the fillet.
Implementation Method 2
where θ is the wetting angle between the molten braze-welding filler material and the base material of the separating element
Data Source
Figure 1
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Figure 4~5
AI summary
A duct or vessel comprising a separating element (30) which includes a pair of plates (31, 32), each of which comprises a central portion (31a, 32a) and a peripheral edge (31b, 32b) raised with respect to the central portion (31a, 32a), the plates (31, 32) being joined to each other at their respective central portions (31a, 32a) so as to define an annular gap (G) around the central portions (31a, 32a), interposed between the peripheral edges (31b, 32b) of the plates (31, 32). Each of the plates (31, 32) has a profile in radial cross-section comprising an inflection point (P1, P2) between the central portion (31a, 32a) and the peripheral edge (31b, 32b), wherein the tangent to the plate (31, 32) at the inflection point (P1, P2) defines an opening angle α with respect to an interface plane (M) between the plates (31, 32). The opening angle α satisfies the relation: θ+α≥90°, where θ is the wetting angle between the molten braze-welding filler material and the base material of the separating element (30).