Plate Heat Exchanger Brazing With Targeted Paste Placement
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Solution Overview
Problem
Existing brazing methods for plate heat exchangers often result in large crevices between plates, leading to inefficient use of brazing material and potential melt-through issues, especially with iron-based materials, which can compromise the strength of the brazing joints and require excessive amounts of material.
Innovation Solution
Applying brazing material on skirts surrounding the plates and in minute grooves around port openings, using an iron-based or copper-based material with melting point depressants, and ensuring capillary suction forces draw the material into the crevice between the plates' contact points, while minimizing the application area to less than 5% of the plate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If brazing material paste is applied to areas to be brazed only, then brazing material usage is reduced, but large crevices between plates cause brazing material particles to be trapped and insufficient filling
Solution Approach 1:
The patent applies brazing material not only at contact points but also in minute grooves surrounding port openings and on skirts, creating different application zones with different material distribution densities. This local quality variation ensures proper filling in critical areas while minimizing overall material usage.
Solution Approach 2:
The patent prepares minute grooves in advance around port openings before brazing. These pre-formed grooves act as receptacles that guide and concentrate brazing material into the crevices during the brazing process, ensuring proper filling before the material solidifies.
2Manufacturing precision
If excessive amounts of iron-based brazing material are used to fill large crevices, then crevice filling is improved, but melt-through of the heat exchanger plate material occurs
Solution Approach 1:
The patent concentrates brazing material application in specific localized areas (contact points, minute grooves, skirts) rather than distributing it uniformly. This prevents excessive material accumulation in any single location, avoiding melt-through while ensuring adequate filling where needed.
Solution Approach 2:
The patent applies brazing material in controlled partial amounts at specific locations rather than excessive amounts uniformly. The minute grooves and targeted application areas provide just enough material to fill crevices without overfilling that would cause melt-through.
3Manufacturing precision
If brazing material is applied in a ring surrounding contact points, then crevice filling is improved, but the application area increases to more than 5% of plate surface
Solution Approach 1:
The patent segments the brazing material application into distinct, separated locations: contact points, minute grooves around port openings, and skirts. This segmentation replaces continuous ring application with discrete, minimal-area applications that collectively provide adequate filling.
Solution Approach 2:
The patent uses partial action by applying material only where absolutely necessary (contact points and minute grooves) rather than continuously around entire contact perimeters. This selective partial application achieves crevice filling with minimal total area coverage.
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 method reduces crevices and enhances the strength of brazing joints by allowing closer contact between plates, reducing material usage, and preventing melt-through, while maintaining a liquid-tight seal and economic production.
Implementation Method 1
ensuring capillary suction forces draw the material into the crevice between the plates' contact points
Implementation Method 2
a brazing material is placed between plates of a stack of heat exchanger plates... The stack of plates is then placed in a furnace which is heated to a temperature above the melting temperature of the brazing material
Implementation Method 3
After the heating in the furnace, the temperature is lowered, such that the brazing material solidifies, hence fastening the plates to one another
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A method of brazing a plate heat exchanger comprising a stack of heat exchanger plates (110,115) is provided with a pressed pattern of ridges (R) and grooves (G) adapted to form contact points between the plates (110, 115) and provide for interplate flow channels for media to exchange heat is provided. The interplate flow channels are in selective fluid communications with port openings (120, 130, 140, 150) provided near comers of the heat exchanger plates (110, 115). The method comprises the steps of calculating or measuring the exact position of all contact points between the ridges (R) and grooves (G) of the neighboring plates (110, 115), applying brazing material (B) close to, but not at, the contact points, stacking heat exchanger plates (110, 115) provided with brazing material to a stack,placing the stack of heat exchanger plates (110, 115) in a furnace, heating the stack of heat exchanger plates (110, 115) to a temperature sufficient for melting the brazing material (B), andallowing the stack of heat exchanger plates (110, 115) to cool down such that the brazing material (B) solidifies and binds the plates (110, 115) together.