Pool boiling heat transfer to zinc oxide-ethylene glycol nano-suspension near the critical heat flux

Abstract

Experimental study is conducted on the thermal performance of the ZnO nanoparticles dispersed in water-ethylene glycol (water/EG) as the base fluid under the pool boiling condition. Experimental facility provides condition to apply heat fluxes up to the critical heat flux point. Influence of different operating parameters such as heat flux and mass concentration on the boiling heat transfer coefficient and thermal fouling resistance is investigated. Results showed that with an increase in heat flux and mass concentration, the heat transfer coefficient increases; however, at concentration of 0.5 % by weight for ZnO/water/EG nano-fluid. Deposition of particles on the heating surface was a significant disadvantage of the nano-fluid. However, with an increase in mass concentration of nanoparticles, the critical heat flux point is enhanced, which is due to the enhancement in deposition layer of the nanoparticles, resulting in capillary wick and keeping more liquid inside the deposition layer.