Title: Turbulent forced convection of Al₂O₃ nanofluid in a circular tube with tape inserts at low volume concentration

Authors: L. Syam Sundar, K.V. Sharma, Y. Raja Sekhar, V. Dharma Rao, T. Subramanyam, J.V. Ramana Rao

Addresses: Center for Energy Studies, Department of Mechanical Engineering, JNTU College of Engineering, Kukatpally, Hyderabad 500085, India. ' Center for Energy Studies, Department of Mechanical Engineering, JNTU College of Engineering, Kukatpally, Hyderabad 500085, India. ' Center for Energy Studies, Department of Mechanical Engineering, JNTU College of Engineering, Kukatpally, Hyderabad 500085, India. ' AU College of Engineering, Visakhapatnam 530003, India. ' AU College of Engineering, Visakhapatnam 530003, India.' Centre for Nano Technology, JNT University, Hyderabad 500085, India

Abstract: Convective heat transfer coefficients with Al₂O₃ nanofluid under turbulent flow in a circular tube fitted with twisted tape insert is estimated. The thermo-physical properties such as thermal conductivity and viscosity are established experimentally in a wide range of volume concentration and validated with values obtained by others. The heat transfer coefficient obtained with Al₂O₃ nanofluid having volume concentration of 0.02% is 10% higher when compared with water flowing in the tube at Re = 22,000. Tapes of different twist ratios in the range of 5 < H/D < 15 are used as tube inserts to evaluate nanofluid heat transfer and pressure drop. Nanofluid heat transfer coefficient is enhanced by 23% and maximum pressure drop by 1.7 times with tape insert in the range of H/D tested when compared to flow in a plain tube.

Keywords: aluminium oxide nanofluids; turbulent forced convection; twisted tape insert; convective heat transfer; heat transfer enhancement; nanofluid pressure drop; nanotechnology; turbulent flow; tubes.

DOI: 10.1504/IJNBM.2009.027698

International Journal of Nano and Biomaterials, 2009 Vol.2 No.1/2/3/4/5, pp.60 - 69

Published online: 08 Aug 2009 *

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