Boiling heat transfer characteristics of ethylene glycol and water mixture based ZnO nanofluids in a cylindrical vessel

Pool boiling heat transfer characteristics including boiling heat transfer coefficient (HTC) and critical heat flux (CHF) of ethylene glycol (EG) and deionized water (DW) mixtures based ZnO nanofluids are experimentally investigated in a cylindrical vessel under atmospheric pressure. As the heat flux goes on, the boiling HTC of nanofluids increases in an obvious way for the natural convective region while gradually increases in the nucleate boiling region. In addition, a significant enhancement of CHF between nanofluids and their respective base fluids is observed. The HTC and CHF are enhanced due to the surface wettability reduction and nanoparticle coating on heater surface. Results also show that only the nanofluids with ZnO mass fraction less than ∼7.25% could enhance the boiling heat transfer capability of vol.% = 85% EG aqueous solution.