Investigation on thermophysical properties, convective heat transfer and performance evaluation of ultrasonically synthesized Ag-doped TiO2 hybrid nanoparticles based highly stable nanofluid in a minichannel

Ag-doped TiO2 hybrid nanoparticles have been synthesized by ultrasonic-assisted method for nanofluid application for heat transfer in minichannel heat exchanger at constant wall temperature condition. Prepared nanoparticles were dispersed in water by ultrasonication to form an extremely stable nanofluid. Thermal conductivity of the nanofluid was found to be 1.84 W/mK at 45 celcius for nanofluid concentration of 0.25 vol%. The overall heat transfer coefficient increased from 1211.71 to 2727.38 W/m2K as the nanofluid concentration increased form 0.01 vol% to 0.1 vol% at Reynolds number of 3480 +/- 3. A new correlation for Nusselt number has been proposed. The pressure drop and friction factor of the nanofluids were also advantageously lesser than that of water. The overall performance of the Ag-doped TiO2 hybrid nanoparticles based nanofluid was assessed by comparing the heat transfer with the pumping power and by determining the entropy generation and thus the Bejan number.