Multichannel Heat Exchanger Flow Layout for Leading-Edge Heat Transfer
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Solution Overview
Problem
In multichannel heat exchangers, heat transfer efficiency is reduced at the trailing edge of tubes due to decreased temperature difference between the external fluid and the refrigerant, as the external fluid has already absorbed or transferred heat by the time it reaches the end of the tube.
Innovation Solution
The multichannel tubes are configured with varying flow paths along their length, with larger flow areas near the leading edge and smaller areas near the trailing edge, and flow control mechanisms are used to concentrate refrigerant flow near the leading edge, where the temperature difference is greatest, enhancing heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If refrigerant flow is distributed uniformly across all flow paths, then the flow distribution is simple and uniform, but heat transfer efficiency decreases at the trailing edge where temperature difference is reduced
Solution Approach 1:
The patent applies local quality by varying the flow area of individual flow paths based on their position along the tube. Flow paths near the leading edge have larger cross-sectional areas to accommodate higher refrigerant flow rates where the temperature difference between external fluid and refrigerant is greatest. Flow paths near the trailing edge have smaller areas since the temperature difference is reduced. This non-uniform distribution optimizes heat transfer efficiency by matching flow characteristics to local thermal conditions.
Solution Approach 2:
The patent segments the heat exchanger tube into multiple independent flow paths, each with its own flow area characteristics. By dividing the tube into discrete flow channels and assigning different flow areas to different segments (particularly varying areas along the length of the tube), the system can independently optimize refrigerant flow distribution to match the thermal gradient from leading to trailing edge.
2Productivity
If flow area is increased near the leading edge to maximize heat transfer, then heat transfer efficiency improves where temperature difference is highest, but the overall tube volume and complexity increase
Solution Approach 1:
The patent implements local quality by creating flow paths with varying cross-sectional areas along the tube length. Flow paths have larger areas near the leading edge where heat transfer demand is highest, and progressively smaller areas toward the trailing edge. This localized variation in flow area optimizes heat transfer efficiency without requiring uniform increases in flow area throughout the entire tube, thereby avoiding excessive volume increases.
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 configuration maximizes heat transfer by focusing refrigerant flow where the temperature difference is highest, improving overall efficiency and performance of the heat exchanger.
Implementation Method 1
Heat transfer between the external fluid and the refrigerant is dependent on, among other things, the temperature difference between the external fluid flowing across the multichannel tubes and the refrigerant flowing inside the multichannel tubes
Data Source
AI summary
Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and heat exchangers are provided that include multichannel tube configurations designed to promote flow of refrigerant within the multichannel tubes near the edges of the tubes that are contacted first by an external fluid. The tube configurations include flow paths of varying cross-sections, spacings, and sizes. Flow control mechanisms, such as inserts, blocking plates, sleeves, crimped sections, and crushed sections, may be employed with the flow paths to favor flow near the edges of the tubes that are contacted first by an external fluid.