Perimeter Braze Frame Heat Exchanger for Copper-Free Flow Paths
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Solution Overview
Problem
Existing heat exchangers face challenges in preventing copper diffusion into fluid channels, which can contaminate the fluid and lead to mechanical system issues, and in efficiently brazing plates to maintain high thermal performance and corrosion resistance.
Innovation Solution
A heat exchanger design featuring a copper foil frame or braze foil sheet strategically placed between plates to minimize copper contact with the first fluid, using copper or iron-based filler materials, and a method of manufacturing involving a copper foil frame that extends around the perimeter of plates to create a braze joint, ensuring effective brazing and reducing copper usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper filler material is used for brazing plates, then brazing effectiveness and thermal performance are improved, but copper diffusion into the first fluid occurs causing contamination
Solution Approach 1:
The patent extracts the harmful copper filler material from the fluid channel interior and relocates it to the perimeter area. The copper foil frame is positioned at the peripheral corners and edges of the plates, away from the center flow region, so that copper is available for brazing but cannot diffuse into the first fluid during operation.
Solution Approach 2:
The patent applies different spatial zones with different functions: the perimeter area contains copper filler material for brazing, while the center flow region is kept free of copper to prevent fluid contamination. This local differentiation allows copper to serve its brazing function without causing harmful diffusion into the fluid.
2Reliability
If copper filler material is placed in the center flow region, then brazing is effective, but copper flows into other parts of the mechanical system
Solution Approach 1:
The copper filler material is extracted from the center flow region and relocated to the perimeter area. The copper foil frame is positioned at the peripheral corners and edges of the plates, ensuring copper remains confined to the brazing zone and cannot flow into the mechanical system through the fluid channels.
Solution Approach 2:
The heat exchanger is segmented into distinct functional zones: the perimeter area for brazing operations containing copper filler material, and the center flow region for fluid passage kept free of copper. This segmentation prevents copper from contaminating the fluid while maintaining effective brazing at the plate joints.
3Loss of substance
If copper foil frame is used to position filler material, then copper usage is minimized, but manufacturing precision is required for accurate positioning
Solution Approach 1:
The patent uses a copper foil frame - a thin film structure - to provide the necessary copper filler material for brazing. The foil frame is positioned at the peripheral corners and edges of the plates, and its flexible nature allows it to conform to the plate surfaces while minimizing the total amount of copper required compared to bulk filler materials.
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 solution effectively prevents copper diffusion into the first fluid, maintains the cleanliness of the mechanical system, and enhances the thermal performance by optimizing the brazing process, while minimizing copper usage and ensuring high corrosion resistance.
Implementation Method 1
the braze joint created, in part, by a copper filler material located specifically at a perimeter of the first fluid channel and contacting perimeter areas of the two plates
Implementation Method 2
a first heat transfer medium to flow therethrough and other heat transfer medium passages allow a second heat transfer medium to flow therethrough to thereby enable heat exchange to be effected between the first and second heat transfer media via the heat transfer plates
Data Source
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AI summary
A heat exchanger including a copper braze frame extending around a first fluid channel to braze a perimeter of the first fluid channel and to minimize contact between copper and a first fluid. The first fluid channel of the heat exchanger includes a center flow region between an inlet manifold opening and an outlet manifold opening. The copper braze frame includes a frame base and a frame wall that extends from the frame base at an angle of at least 20 degrees from the base. The frame base includes an inner edge, and the frame wall includes an outer edge. The inner edge surrounds and defines the area of the center flow region. The inner edge extends in parallel to the outer edge along the perimeter of the first fluid channel where the perimeter is adjacent to the center flow region. A width of the center flow region at the widest point of the center flow region is a separation distance between the inner edge on one side of the frame and the inner edge on another opposite side of the frame. The first fluid channel is further defined between a first plate and a second plate, which are brazed to each other at the perimeter of the first fluid channel by the braze frame. A third plate is stacked on the second plate to define a second fluid channel between the second plate and the third plate. The first fluid channel and the second fluid channel are fluidly separate but in thermal contact.