Relationship between turbulent structures and heat transfer in microfin enhanced surfaces using large eddy simulations and particle image velocimetry

被引:16
作者
Li, Puxuan [1 ]
Campbell, Matthew [1 ]
Zhang, Ning [2 ]
Eckels, Steven J. [1 ]
机构
[1] Kansas State Univ, Dept Mech & Nucl Engn, Inst Environm Res, Manhattan, KS 66506 USA
[2] McNeese State Univ, Dept Chem Civil & Mech Engn, Lake Charles, LA 70609 USA
关键词
Micro-fins; Particle image velocimetry (PIV); Large eddy simulation (LES); Heat transfer enhancement; Coherent structures; Q criterion; FRICTION CHARACTERISTICS; 3-DIMENSIONAL BLOCKS; 2-DIMENSIONAL RIBS; FLOW; GEOMETRY; TUBES; PIV; OPTIMIZATION; LAMINAR;
D O I
10.1016/j.ijheatmasstransfer.2019.03.063
中图分类号
O414.1 [热力学];
学科分类号
摘要
Internally enhanced surfaces such as micro-fins are an important class of heat transfer enhancement in commercial applications. Many research papers discuss the design and optima of these surfaces. However, most previous studies have demonstrated only the macro relationship between the geometries of the micro-fins and heat transfer. The need for a deeper understanding of these fins arose from some currently unsolved problems that limit future development of enhanced surfaces. First, why are increases of heat transfer larger than area increases in micro-finned tubes in most cases? Second, why do internally micro-finned tubes typically have lower heat-transfer-enhanced ratios in laminar and transition flows? This work presents a novel method to analyze the detailed relationship between flow characteristics and heat transfer for one type of micro-fin. The goal of the paper was not to find a new Reynolds number-based correlation, but to find flow patterns responsible for heat transfer enhancement and understand the mechanisms that cause this. First, this paper introduces comprehensive experimental measurements including particle image velocimetry (Ply), measurement of the heat transfer coefficient and accuracy of pressure-drop measurements, all used to validate numerical approaches. Validated large eddy simulations (LES) are then used to predict flow characteristics and coherent structures (Q criterion). The numerical simulation includes both heat conduction in the metal structure and heat convection on the solid-fluid interface. Finally, the paper documents how the flow structures link with the enhancement of heat transfer in the micro-finned duct. (C) 2019 The Authors. Published by Elsevier Ltd.
引用
收藏
页码:1282 / 1298
页数:17
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