Experimental study of thermal conductivity, heat transfer and friction factor of Al2O3 based nanofluid

Presented research paper is an investigation of water, paraffin and ethylene glycol based Al2O3 nanofluid. Heat transfer coefficient is measured using shell and tube heat exchanger under the conditions of fully developed laminar and turbulent flow. Concentration of nanoparticles in the respective base fluids was varied from 0.01 vol% to 0.08 vol% in the step of 0.1%. Nanofluids were used as the working fluid and sent to tubular side. The effects of Reynold's number and concentration of nanoparticles in nanofluid on heat transfer characteristics were studied. A significant enhancement in heat transfer coefficient and thermal conductivity of nanofluid over base fluid is found in the study. As the concentration of nanoparticles was increased, heat transfer coefficient was also improved marginally. At greater turbulence, the improvement in the heat transfer coefficient of nanofluid over base fluid was found to be more than that at lower turbulence. This is due to homogeneous distribution of nanoparticles in a base fluid at higher temperatures was achieved. The various factors that were considered in the characterization of nanofluid heat transfer coefficients are: sonication time, temperature, pressure difference, base fluid (water, paraffin and EG). Pressure drop in case of nanofluid was higher than base fluid in the turbulent regime; however, no significant change was observed in the laminar region.