Experimental Evaluation in Thermal Conductivity Enhancement and Heat Transfer Optimization of Eco-Friendly Al2O3–Pure Coconut Oil Based Nano Fluids

Abstract

Abstract The present study reports an experimental evaluation of thermal conductivity of Al2O3/pure coconut oil nano fluids with solid volume fraction varying from 0.1% to 1.2% at a temperature ranging from 303 K to 413 K, respectively. Additionally, the thermophysical properties such as thermal diffusivity, density, and specific heat were also measured. The effect of solid volume fraction and temperature on thermophysical properties of nano fluids was examined. The results confirmed that the thermal conductivity of nano fluids was higher than that of the base fluid with an increase in the solid volume fraction and temperature. Apart from this, the efficiency of nano fluids for the heat transfer application has been evaluated for optimization based on different figures of merit. Further, the experimental thermal conductivity data were compared with different existing models and correlations as the thermal conductivity enhancement of the nano fluid is directly or indirectly a function of almost all thermophysical properties. Hence, a novel dimensionless correlation was developed for predicting the thermal conductivity of pure coconut oil/Al2O3 nano fluids in terms of almost all the thermophysical parameters calculated from the experimental data.