Numerical study on influence of a type of nanoparticles and volume fraction on turbulent heat transfer coefficient and pressure loss inside a tube

Conventional liquids have some limitations regarding the thermal properties. The nanoparticles addition is one of the techniques which can transcend them. In this research, heat transfer coefficient (h) and pressure loss (Δp) of various nanofluids containing Al2O3, SiO2, and MgO nanoparticles dispersed in water in an annular tube with constant wall temperature is considered. According to the literature, five different nanofluid volume concentrations (1%, 2%, 3%, 4% and 5%) are selected. Two models involving the mixture and VOF are applied, and the results are compared. The average convective heat transfer coefficient and pressure loss is enhanced with volume fraction and Reynolds number (Re) increment (3000 Re 10000) although the friction factor (f) is decreased. It is concluded that the simulated data for pressure loss and heat transfer coefficient were in good agreement with the experimental ones specially for SiO2 nanoparticles (particularly in low concentrations). The SiO2 nanofluid showed the best heat transfer compared to the other nanofluids. Moreover, the simulated data obtained from the mixture method showed more agreement with the experimental ones specially the high Reynolds numbers.