Duct Separating Element Geometry for Braze-Weld Leak Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing heat exchanger separators are prone to internal leaks due to braze-welding filling the annular gap, making leak detection complex and performance loss significant, and existing detection systems lack sensitivity for small leaks.
Innovation Solution
The opening angle α between the plates of the separating element is set to satisfy θ+α≥90°, creating a convex fillet shape that prevents the annular gap from being filled with molten filler material during braze-welding, enhancing capillary pressure and ensuring leak detection through a through-hole.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If braze-welding is used to join the separating element to the duct or vessel, then the joint strength and sealing are improved, but the annular gap becomes filled with molten filler material, causing internal leaks and performance loss
Solution Approach 1:
The patent changes the geometric parameters of the separating element, specifically the opening angle α of the V-shaped groove and the radius R of the fillet, to control the capillary pressure during braze-welding. By optimizing these parameters (α ≥ 90° and R ≥ 0.5mm), the capillary pressure becomes positive, preventing molten filler material from entering the annular gap while maintaining effective braze-welding joint strength.
Solution Approach 2:
The patent creates a capillary pressure equilibrium by designing the fillet geometry such that the capillary pressure in the annular gap equals or exceeds the pressure of the molten filler material. This equipotential condition prevents the harmful flow of filler material into the gap while allowing the braze-welding process to proceed effectively.
2Measurement precision
If the annular gap is left open for leak detection, then leak detection sensitivity is improved, but the gap becomes filled with filler material during braze-welding, nullifying the detection function
Solution Approach 1:
The patent applies preliminary action by pre-forming the V-shaped groove with specific geometric parameters (opening angle α ≥ 90° and fillet radius R ≥ 0.5mm) before the braze-welding process. This preliminary geometric configuration ensures that during subsequent braze-welding, the capillary pressure automatically prevents filler material from entering the gap, preserving the annular gap's leak detection function without requiring additional protective measures.
Solution Approach 2:
The patent applies preliminary anti-action by designing the fillet geometry to create positive capillary pressure that actively repels the molten filler material from entering the annular gap. This preemptive geometric design counteracts the tendency of filler material to invade the gap during braze-welding, maintaining the gap open for effective leak detection.
3Reliability
If the opening angle α is increased to prevent filler material entry, then capillary pressure is improved, but the braze-welding process complexity increases
Solution Approach 1:
The patent identifies and optimizes two key geometric parameters (opening angle α and fillet radius R) that directly control capillary pressure. By setting α ≥ 90° and R ≥ 0.5mm, the design achieves positive capillary pressure that prevents filler material entry. This parameter optimization balances reliability improvement with manufacturing feasibility, avoiding excessive geometric 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
Prevents the annular gap from being filled with molten filler material, allowing effective leak detection and maintaining heat exchanger performance by directing leaks to the exterior for detection.
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
the wetting angle between the molten braze-welding filler material and the base material of the separating element
Data Source
AI summary
A duct or vessel has a separating element having a pair of plates, each of which has a central portion and a peripheral edge raised with respect to the central portion. The plates are joined to each other at their central portions so as to define an annular gap around the central portions, interposed between the peripheral edges of the plates. Each of the plates has a profile in radial cross-section having an inflection point between the central portion and the peripheral edge. A tangent to the plate at the inflection point defines an opening angle α with respect to an interface plane between the plates. The opening angle α satisfies the relation θ+α≥90°, where θ is a wetting angle between a molten braze-welding filler material and a base material of the separating element.