Experimental investigation of pool boiling of Fe3O4/ethylene glycol–water nanofluid in electric field

Nucleate boiling and critical heat flux (CHF) of Fe3O4/ethylene glycol–water nanofluid at atmospheric pressure on a horizontal thin Ni–Cr wire were investigated. Fe3O4 nanoparticles were dispersed in 50% (by volume) ethylene glycol/de-ionized water as base liquid in different concentrations (0.01–0.1% (by volume)). Experiments showed that boiling heat transfer coefficients deteriorate by increasing nanoparticle concentration in nanofluid. Addition of nanoparticles delays nucleate boiling incipience and increases CHF. Scanning Electron Microscope (SEM) graphs showed that porous layer of deposited nanoparticles formed on the heating surface boiled in nanofluid. The maximum CHF enhancement was obtained for 0.1% (by volume) nanofluid to be about 100%. Enhanced CHF was measured when previously boiled wire in nanofluid was used to boil the base fluid. Two different electrodes were used for applying electric field in the boiling nanofluids. Electric field applied in both configurations augmented boiling heat transfer coefficients while CHF remained almost unchanged.

► Boiling heat transfer coefficients deteriorate by increasing nanoparticle concentration in nanofluid. ► Addition of nanoparticles delays nucleate boiling incipience and increases CHF. ► Porous layer of deposited nanoparticles forms on the heating surface boiled in nanofluid. ► Electric field augments boiling heat transfer coefficients. ► CHF remains unchanged with electric field.