Streamlined Wavy Fin for Heat Exchanger Flow Separation
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Solution Overview
Problem
Existing fin designs for finned tube heat exchangers, such as louvered and transversally wavy fins, increase flow resistance and dust accumulation, leading to poor heat transfer performance and high pressure loss, especially in circular/elliptical tube banks where flow separation occurs, resulting in inefficient heat transfer.
Innovation Solution
A streamlined wavy fin design featuring convex and concave ripples aligned with airflow streamlines, with amplitudes adjusted based on velocity zones and distributed symmetrically, reduces flow separation and pressure loss while maintaining stability and preventing dust accumulation by guiding fluid flow in streamlined channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional fin patterns (louvered, transversally wavy, vortex generators) are used to increase fluid disturbance, then heat transfer performance is improved, but flow resistance increases and pressure loss increases
Solution Approach 1:
The fin surface is designed with longitudinal convex and concave ripples that follow the streamline curvature of the airflow. This curved geometry guides the fluid flow smoothly along the fin surface, reducing flow separation and turbulence while maintaining extended heat transfer area, thereby improving heat transfer performance without excessive pressure loss
2Productivity
If conventional fin patterns are used to increase heat transfer area, then heat transfer performance is improved, but dust accumulation increases
Solution Approach 1:
The streamlined curved surfaces of the longitudinal ripples prevent dust particles from settling in sharp corners or recesses. The smooth continuous curvature allows dust to be carried away by the flowing fluid, reducing accumulation while maintaining the extended heat transfer area needed for high performance
3Area of stationary object
If conventional fin patterns are used in circular/elliptical tube banks, then heat transfer area is increased, but flow separation occurs and pressure loss increases
Solution Approach 1:
The longitudinal ripples are specifically designed to follow the streamline patterns around circular and elliptical tubes. The curved fin surfaces align with the natural flow curvature, preventing flow separation at the tube rear regions and reducing recirculation zones, thereby minimizing pressure loss while maintaining extended heat transfer area
Solution Approach 2:
The fin structure incorporates varying ripple amplitudes and configurations at different locations along the flow direction. The ripple characteristics are optimized for local flow conditions, with greater ripple amplitude in regions where flow disturbance is beneficial and reduced amplitude where flow attachment is critical, allowing localized optimization of heat transfer versus pressure loss
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 streamlined wavy fin design enhances heat transfer performance by reducing pressure loss and preventing recirculation, maintaining stability and preventing dust accumulation, resulting in improved fluid flow and heat transfer efficiency.
Implementation Method 1
the flow separation occurs on the wall of the circular/elliptical tubes, and the flow recirculation regions will be formed downstream the circular/elliptical tubes, the flow separation will cause large pressure loss
Data Source
AI summary
The present invention relates to a streamlined wavy fin for a finned tube heat exchanger, which comprises a fin body, an airflow inlet on one end of the fin body, an airflow outlet on the other end of the fin body, mounting holes for mounting tubes on the fin body, and several convex/concave ripples consecutively formed from the airflow inlet to the airflow outlet on the fin body in an orientation of an airflow streamlines. A connection line of the wave crests of the same one convex ripple and a connection line of the wave troughs of the same one concave ripple neighboring the same one convex ripple are both streamlines. The present invention efficiently suppresses the flow separation downstream the circular tubes, and obviously reduces the pressure loss of airflow. And at the same time, the surface areas of the fins are increased, heat transfer resistance on the fin side is decreased, the streamlined fluid flow makes that it is not easy to producing a recirculation flow downstream the circular tubes, and heat transfer performance of the fins at the rear part of the tube bank may be obviously improved, which has better fluid flow and heat transfer performances, the fins is not easy to accumulate dust in use, and stability of heat transfer performance is maintained.