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论文类型：期刊论文

发表时间：2012-05-01

发表刊物：EXPERIMENTAL THERMAL AND FLUID SCIENCE

收录刊物：SCIE、EI

卷号：39

页面范围：148-157

ISSN号：0894-1777

关键字：Nanofluids; Flow characteristics; Flow visualization; Flow resistance; Micro-flow; Nanoparticles

摘要：Employing nanofluids is a novel way to enhance heat transfer. However, the micro-flow enhancement due to the adding of nanoparticles, which is one of the key mechanisms behind heat transfer enhancement in nanofluids, still lacks experimental observation and a microscale-level understanding. The aim of this work was to experimentally research flow characteristics of nanofluids and to explore the microscopic mechanism for micro-flow enhancement by molecular dynamics simulation. Utilizing a wavy-walled tube, the experiment measured flow characteristics and took flow visualization photos of nanofluids in different flow regimes. In addition, internal flow characteristics of nanofluids were simulated by MD method and statistically analyzed. The measuring results for frictional resistance showed that compared to that of de-ionized water the frictional resistance of nanofluids increases slightly in laminar and transition flow regimes, and shows no obvious increase in turbulent regime, which indicates no additional pump work is needed and is advantageous to engineering application. The visualization experiment results showed at the same Reynolds number the adding of nanoparticles causes more homogeneous longitudinal mixing and enhances mass transferring of nanofluids, which indicates the microflow in nanofluids is enhanced. And the MD simulation results showed the microscopic mechanism for micro-flow enhancement is mainly because the irregular micro-motions of nanoparticles enhance momentum exchange and increase the intensity of turbulence. The present work suggests the mechanism of micro-flow enhancement in nanofluids, which is the basis of proposing suitable theory to mathematically describe flow of nanofluids. (C) 2012 Elsevier Inc. All rights reserved.