Nucleate pool boiling enhancement with the application of a hybrid technique involving the addition of alumina nanoparticles to stirred water above heating surface

Abstract

The nucleate boiling heat transfer coefficient (HTC) can be improved using either active or passive techniques. According to the present disclosure, both techniques are used in combination. In the passive technique, nanoparticles are added to water, whereas a rotating mixer is used in the active technique to improve the boiling HTC of pure water. This study uses hybrid techniques for HTC enhancement at nucleate pool boiling regime. Experiments were carried out using circular brass as a horizontal heating surface. Different concentrations of Al2O3 nanoparticles were tested. The rotation speed of the mixer varied at 0, 350, 600, and 800 rpm. This combined technique resulted in 58.8% enhancement in HTC at 280 kW/m2 heat flux and 0.03% nanoparticle concentration. By comparison, the HTC was enhanced by 23.6% when nanoparticles were added without a mixer, whereas the enhancement ratio was 27.1% when a mixer was used in the absence of nanoparticles under the same conditions.