Effects of Nanoparticle Size on Nanofluids Heat Transfer Characteristics in Minichannels

In this study, the effects of nanoparticles size on convective heat transfer characteristics of metal oxide nanofluids are numerically studied. A computational model is developed to solve the governing equations of fluid flow using finite volume technique with considering thermal conductivity and viscosity of nanofluid as a function of nanoparticles size, volume fraction and Brownian motion. The prepared algorithm and the computer code are applied to demonstrate the heat transfer characteristics in a minichannel with constant wall heat flux. Several numerical simulations with different nonoparticle sizes (ranging from 10 nm to 150 nm diameter) and different volume fractions are carried out and the results are validated by comparing with existing experimental data as well as semi-empirical correlations. The results show that the convective heat transfer coefficient is enhanced with decreasing nanoparticle sizes and increasing volume fraction.