Experimental Studies on Heat Transfer and Friction Factor Characteristics of Al₂O₃/Water Nanofluid in a Circular Pipe Under Transition Flow With Wire Coil Inserts

Abstract

Heat transfer and friction factor characteristics in a circular tube fitted with wire coil inserts are investigated experimentally using Al₂O₃/water nanofluid as the working fluid. The effects of the pitch ratio and nanofluid on the Nusselt number and the friction factor are determined in a circular tube with fully developed transition flow for Reynolds number in the range of 2500 to 5000. The experiments were performed using wire coil inserts having different pitch ratios with Al₂O₃/water nanofluid having 0.1% volume concentration of nanoparticles as the working fluid. Experiments using the plain tube and with wire coil inserts were also carried out with distilled water as the working fluid for experimental setup validation and comparison. The experimental results reveal that the use of nanofluids increases the heat transfer rate with negligible increase in friction factor in the plain tube and the tube fitted with wire coil inserts. In addition, empirical correlations are proposed based on the experimental results of the present study, which are found to be sufficiently accurate for prediction of the heat transfer and friction factor characteristics.

Acknowledgments

M. Chandrasekar is a research student in the Department of Mechanical Engineering of the National Institute of Technology, Tiruchirappalli, India. His research interests lie in the areas of thermal engineering, heat transfer, energy conservation, and nanofluids.

S. Suresh is a faculty member in the Department of Mechanical Engineering of the National Institute of Technology, Tiruchirappalli, India. He received his Ph.D. in 2007 from the National Institute of Technology, Tiruchirappalli. His teaching and research interests lie in the areas of thermodynamics, internal combustion engines, energy conservation, and emission studies in internal combustion engines with fuel additives and heat transfer augmentation using nanofluid along with inserts.

A. Chandra Bose received his Ph.D. in the area of nanocrystalline materials from the University of Madras in 2002. He pursued his postdoctoral research in NIMS and AIST, Tsukuba, Japan, until 2006. He joined as assistant professor in the Department of Physics of the National Institute of Technology, Tiruchirappalli, India, in 2006. His current research interests include synthesis and characterization of oxide nanoparticles.