Corrugated Fin Heat Exchanger Bonding Strength
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Solution Overview
Problem
The bonding strength between corrugated fins and flat tubes in heat exchangers is compromised due to the uneven surface of the corrugated fins, which affects the overall performance and reliability of the heat exchanger.
Innovation Solution
A plate fin heat exchanger design featuring corrugated fins with protruding ribs and gently sloping portions, where the intermediate portion of the fin divides the channel into subchannels, enhancing fluid flow turbulence and wettability, and the crest and trough portions have even contact surfaces with tube plates, increasing adhesion and brazing strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fine asperities are formed on the surface of the corrugated fin to improve heat transfer performance, then the heat exchanger performance is improved, but the bonding strength between the corrugated fin and flat tube decreases
Solution Approach 1:
The patent applies local quality by creating different surface characteristics in different regions of the corrugated fin. The intermediate portion has protruding ribs that create asperities for improved heat transfer, while the crest and trough portions have even contact surfaces for optimal bonding. This localized differentiation allows each region to fulfill its specific function without compromising the other.
Solution Approach 2:
The corrugated fin is segmented into distinct functional zones: crest portions, trough portions, and intermediate portions with protruding ribs. This segmentation allows the heat transfer surface (intermediate portion) to be differentiated from the bonding surfaces (crest and trough portions), enabling simultaneous optimization of both heat transfer performance and bonding strength.
2Productivity
If the corrugated fin has an uneven surface with asperities to prevent boundary layer development, then heat transfer efficiency is improved, but the contact area with tube plates decreases
Solution Approach 1:
The patent creates local quality differences by providing even contact surfaces at the crest and trough portions for maximum contact area with tube plates, while the intermediate portions have protruding ribs that create asperities for enhanced heat transfer efficiency. This spatial differentiation resolves the contradiction between contact area and heat transfer efficiency.
Solution Approach 2:
The fin surface is segmented into bonding regions (crest and trough portions with even surfaces) and heat transfer regions (intermediate portions with protruding ribs). This segmentation ensures that the contact area for bonding is maximized at specific locations while the heat transfer efficiency is enhanced at other locations.
3Productivity
If protruding ribs are added to the intermediate portion to enhance fluid flow turbulence, then heat transfer performance is improved, but the structural complexity of the fin increases
Solution Approach 1:
The protruding ribs are localized only to the intermediate portions of the corrugated fin, not the entire surface. This localized addition provides the necessary turbulence for improved heat transfer while minimizing the overall structural complexity compared to a fully ribbed surface.
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 design improves the bonding strength between the corrugated fins and tube plates, enhances heat transfer efficiency, and accelerates fluid flow and condensate discharge, leading to a more robust and effective heat exchanger.
Implementation Method 1
The protruding ribs accelerate a turbulent flow of the fluid flowing along the surface of the corrugated fin
Implementation Method 2
if the fluid condenses, the protruding ribs of the intermediate portion of the corrugated fin improve the wettability of the fin surface, and accelerate the discharge of droplets
Implementation Method 3
the protruding ribs of the intermediate portion of the corrugated fin improve the wettability of the fin surface
Implementation Method 4
the corrugated fin and a flat tube are bonded together by brazing with the outer surface of the flat tube being in contact with the surfaces of crest or trough portions of the corrugated fin
Data Source
AI summary
A plate fin heat exchanger 1 includes a corrugated fin 3 and tube plates 2. An intermediate portion 33 of the corrugated fin between crest and trough portion 31 and 32 thereof has a plurality of protruding ribs 34 protruding beyond a surface of the corrugated fin and arranged in a first direction. Surfaces of the crest and trough portions being in contact with the tube plates are configured as contact surfaces 310, 320 with no protruding rib. Gently sloping portions 341 are provided between the protruding ribs and the contact surfaces of the crest and trough portions to gradually protrude from the surface of the corrugated fin with increasing distance from the contact surfaces, and are continuous with the protruding ribs.