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Empirical correlations to predict thermophysical and heat transfer characteristics of nanofluids

Velagapudi Vasu (Department of Mechanical Engineering, National Institute of Technology Warangal, India)
Konijeti Krishna Rama (Freshman Eng. Department, KL College of Engineering, Vaddeswaram, Guntur District, India)
Aduru Kumar Sekhara Chandra (Department of Mechanical Engineering J N T University, Hyderabad, India)

Nanofluids exhibits larger thermal conductivity due to the presence of suspended nanosized solid particles in them such as Al2O3, Cu, CuO,TiO2, etc. Varieties of models have been proposed by several authors to explain the heat transfer enhancement of fluids such as water, ethylene glycol, engine oil containing these particles. This paper presents a systematic literature survey to exploit the thermophysical characteristics of nanofluids. Based on the experimental data available in the literature empirical correlation to predict the thermal conductivity of Al2O3, Cu, CuO, and TiO2 nanoparticles with water and ethylene glycol as base fluid is developed and presented. Similarly the correlations to predict the Nusselt number under laminar and turbulent flow conditions is also developed and presented. These correlations are useful to predict the heat transfer ability of nanofluids and takes care of variations in volume fraction, nanoparticle size and fluid temperature. The improved thermophysical characteristics of a nanofluid make it excellently suitable for future heat exchange applications. .

Keywords: nanofluids, thermal conductivity, heat transfer coefficient, laminar, turbulent