To Study the Effect of Silver Coated Silica and Copper Oxide Nanofluids on Heat Transfer Performance of a Car Radiator

Abstract

Nanofluids are the suspension of nanoparticles in the base fluid. Nanofluids having the anomalously high thermal conductivity makes them the promising fluids for enhancing the heat transfer. At present, there is still some significant incongruity in thermal conductivity data of the nanofluids in the literature. At the same time, mechanisms of thermal conductivity enhancement of the nanofluids are still not understood. The Experimental studies presented over here is in terms of altering the properties of nanofluids such as: thermal conductivity, specific heat, density and viscosity of nanofluids with the change in concentration of nanofluids. The Enhancement mechanisms proposed for explaining nanofluid thermal conductivity are also summarized. Some discrepancies between the predicted data from the thermal conductivity data and the experimental data have been indicated. Recent experiments on nanofluids have shown that the heat transfer enhancement surpass the thermal conductivity enhancement of nanofluids. Therefore, the obtained agreement is the indication of validity of experimental results. We concluded that the heat transfer coefficient and the nusselt no. of the nanofluids are higher than those of base fluid and they increase with increasing the particle concentration as well as the Reynolds number. For volume concentration 0.01% the enhancement of heat transfer coefficient of copper oxide as compared to the base fluid ranges between 9% and 32%. For 0.02% it ranges from 21% to 37%and for 0.03% it ranges between 14% and 31%. Whereas the enhancement in heat transfer coefficient of silver coated silica nanofluids as compared to base fluid for volume concentration 0.01% is from 26% to 46%, for 0.02% it is from 30% to 58% and for 0.03%, it is from 29% to 45% respectively. Also, the hike in heat transfer coefficient by using silver coated silica nanoparticles as compared to copper oxide nanoparticles comes out to be from 20% to 35%. Moreover, the increase in thermal conductivity leads to an increase in the heat transfer performance whereas the viscosity increment of the fluid increases the boundary layer thickness, which decreases the heat transfer performance. So, at volume concentration ≤ 1.0vol%, the effect of thermal conductivity enhancement may overcome the effect of the viscosity increment.