In this study, pool boiling heat transfer coefficient and critical heat flux (CHF) of nanofluid in saturated condition on horizontal thin wire in the presence of DC electric field was studied experimentally at atmospheric pressure. A mixture of Ethylene Glycol- deionized water in 50% volume fraction was used as base fluid. Fe 3 O 4 nanoparticles used in 0.01, 0.05, 0.1 and 0.2% volume fraction concentrations. Results show that low concentrations of nanofluid did not change boiling heat transfer coefficient. But at 0.2% concentration, 36% reduction was observed in boiling heat transfer coefficient. The most enhancement of critical heat flux was about 100% at 0.1% volume fraction nanofluid. Scanning Electron Microscopy (SEM) observation subsequent to the pool boiling experiment revealed that a porous layer of nanoparticle was deposited on heating surface during nucleate boiling of nanofluid. In order to investigate the role of the nanoparticle surface coating on pool boiling heat transfer, pool boiling parameters of base fluid was measured using a nano-coated heater prepared by pool boiling of nanofluid on a bare heater. The results show the layer is the main reason of changes in pool boiling parameters of nanfluid. This layer significantly improves the surface wettability, as shown by the reduction of the contact angle on the nanofluid-boiled surfaces compared with the base fluid-boiled surface. Effects of electrohydrodynamic on pool boiling parameters were investigated by using two different electrode configuration, needle and rod electrode, by applying high voltage about 15kV, separately. Electrohydrodynamic increased the pool boiling heat transfer coefficient of nanofluid about 70% at high concentrations, up to 0.1% volume fraction in the presence of rod electrode, but it has no obvious effect on nanofluid boiling heat transfer coefficient at low concentration. The critical heat flux of nanofluid was not affected by applying DC electric field. Keywords: pool boiling, heat transfer coefficient, critical heat flux, nanofluid, electrohydrodynamic
