Offset Fin with Fenestrated Zones for Heat Exchangers
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Solution Overview
Problem
Finned tube heat exchangers face challenges in achieving low pressure drop, high heat exchange efficiency, and stability, particularly due to the design of fins which affect airflow and heat transfer efficiency.
Innovation Solution
The fin design features multiple subunits arranged in offset rows with specific geometric configurations, including fenestrated zones and circular-arc boundaries, optimizing the balance between flat and fenestrated areas to reduce pressure drop while enhancing heat exchange efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional fin designs with simple geometric configurations are used, then manufacturing is easier and device complexity is lower, but pressure drop increases and heat exchange efficiency decreases
Solution Approach 1:
The fin surface is segmented into multiple functional zones: flat zones for stable airflow guidance, fenestrated zones for heat exchange enhancement, and transition zones for smooth flow adaptation. This segmentation allows each zone to perform its specific function optimally, improving overall heat exchange efficiency while managing complexity through functional decomposition
Solution Approach 2:
Different regions of the fin are given different geometric properties: flat zones have uniform thickness for flow stability, fenestrated zones have patterned openings for heat transfer enhancement, and transition zones have gradual geometry changes for smooth flow adaptation. This local differentiation optimizes performance in each region without requiring complete redesign of the entire fin structure
2Productivity
If fins with high heat exchange efficiency are designed, then heat transfer performance improves, but pressure drop increases
Solution Approach 1:
The airflow path is designed to maintain continuous, smooth flow through the fin structure using parabolic arc transition zones that gradually guide air from flat zones into fenestrated zones. This continuous flow design prevents turbulence and pressure losses that would occur with abrupt transitions, maintaining low pressure drop while enabling efficient heat exchange in the fenestrated zones
Solution Approach 2:
The design converts the potential harm of airflow disruption into benefit by using carefully designed transition zones that transform the flow smoothly. The parabolic arc geometry converts what would be turbulent flow separations into controlled, attached flow patterns, turning a potential source of pressure loss into a mechanism for maintaining flow stability and heat exchange efficiency
3Productivity
If airflow speed is increased to improve heat exchange, then heat transfer efficiency improves, but flow stability decreases and pressure drop increases
Solution Approach 1:
Parabolic arc curves are used in the transition zones between flat and fenestrated zones to create smooth, curved flow paths. This curvature design allows high-speed airflow to follow the contour of the transition zone without separating or becoming turbulent, maintaining flow stability even at elevated velocities while still achieving high heat exchange efficiency in the fenestrated zones
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 optimized fin design reduces air pressure drop and increases heat exchange efficiency, maintaining stability even at high airflow speeds, thereby improving the overall performance of the heat exchanger.
Implementation Method 1
Heat exchange takes place between a fluid (generally a refrigerant) circulating in the heat exchange tubes and a fluid (generally air) flowing between the fins
Implementation Method 2
a fluid (generally air) flowing between the fins, in order to achieve the objective of heat exchange
Data Source
AI summary
A fin, comprising: multiple fin subunits arranged in multiple rows, the fin subunits in two adjacent rows being arranged in an offset fashion. Each of the fin subunits comprises: a first direction center line and a second direction center line perpendicular to the first direction center line; a hole located at a central part of the fin subunit; four fenestrated zones, with two adjacent fenestrated zones in the four fenestrated zones being arranged as mirror images of each other, centered at the first or second direction center line therebetween; a flat zone comprising a hole periphery flat zone, the hole periphery flat zone being disposed between the hole and each fenestrated zone; each fenestrated zone comprises first, second, third and fourth boundaries, wherein the first boundary is located at that side of each fenestrated zone which faces the hole, the second boundary is located at that side of each fenestrated zone which faces away from the hole, and the third and fourth boundaries extend in a direction parallel to the first direction center line; the first boundary forms a demarcation line between the hole periphery flat zone and each fenestrated zone, and at least a portion of the first boundary is an elliptical arc or a circular arc that is not concentric with the circle center of the hole.