Effects of SiO2 nanoparticles on pool boiling heat transfer characteristics of water based nanofluids in a cylindrical vessel

Abstract

Boiling heat transfer is widely used in energy power equipment, while the poor thermal property conventional fluids cannot meet the increase of heat transfer demand. The addition of nanoparticles into base fluids can modify the properties of base fluids and is a potential way to improve heat transfer characteristics. In present work, amorphous SiO2 nanoparticles with an average size of 98nm were synthesized via Stober process. And they were added into water with different mass fractions to investigate the pool boiling heat transfer characteristics. The heat transfer coefficient and critical heat flux were analyzed. Results show that the heat transfer coefficient of all fluids increases rapidly in the natural convective region but then rises gradually in the nucleate boiling region. Moreover, owing to the deposition of SiO2 nanoparticles, the heat transfer coefficients of SiO2-H2O nanofluids are lower than that of the base fluid and reduce as the concentration increase. On the other hand, because of the wettability improvement of the heating wire surface caused by the deposition of SiO2 nanoparticles, the critical heat fluxes of nanofluids are higher than that of the base fluid. When the concentration is 0.081%, the critical heat flux achieves a peak improvement of approximately 68.8%.