Experimental study on flow boiling CHF characteristics for Fe3O4-water nanofluid

Abstract

In this study, magnetite-water nanofluid is suggested as a promising coolant option for the thermal-hydraulic applications including the nuclear power generation area. Compared to the other kinds of nanofluids, magnetite-water nanofluid has its own and unique advantages: it could be controlled by using magnetic field. (1) Concentration control: effective concentration of nanofluid could be controlled at the point of interest, (2) Withdrawal of nanoparticles: useless nanoparticles could be withdrawn from the base fluid using magnets, and (3) Decontamination: the radioactive isotopes, such as iodine-131 or cesium-137 dissolved in working fluid, could be removed easily by using both the magnetite nanoparticles with proper functional groups and the magnetic filter (adsorption and filtration method).Experimental studies were conducted to understand the flow boiling CHF characteristics of magnetite-water nanofluid. Flow boiling CHF enhancement using nanofluid was assessed for the wide range of critical quality conditions, especially for intermediate and relatively high critical quality conditions. Focusing on the fundamental features of two-phase liquid film flow, effects of nanoparticle deposition, in terms of surface wettability, on the two-phase liquid film flow were investigated. The time-dependent behavior of CHF enhancement using nanofluid and the effects of magnetic field on the CHF of magnetite-water nanofluid were investigated, too.Air-water two-phase flow experiments were performed for the two different surface specimens to investigate the effects of surface wettability on the two-phase liquid film flow. Relative speed of gas and liquid phase was in the same range (order of magnitude) compared to that for the flow boiling CHF experiments conducted in this study. Both liquid film and liquid droplet flow fractions were measured at the given two-phase flow conditions. For the nanoparticle deposited surface with better surface wettability, liquid film flow fra...