Significance of Chemical Engineering in Surface Wettability Tuning and Its Boiling Hydrodynamics: A Boiling Heat Transfer Study

Experimental studies are shown to have higher enhancement in critical heat flux (CHF) with a nanoporous surface. Understanding the mechanism of CHF is the key to enhance heat transfer through boiling. In general, the classical theories account some aspects of surface, liquid, and interfacial properties and boiling phenomena. In this study, the experimental observations on pool boiling heat transfer are compared with the standard theoretical models. The porous nanotube surface enabled capillary wicking (wicking length, ∼0.4 mm) that induced faster dry-spot rewetting. The post-treatment of the nanotube surface with stearic acid resulted with hydrophobicity due to alkyl chain adherence to the nanotube pores. The loss of superhydrophilicity increases thermal resistance for pool boiling. Hence, the nanoporous superhydrophilic surface enabled a higher CHF (119 W/cm²) of 36% than that of the low-surface-energy hydrophobic surface (91 W/cm²). The experimental results observed here follow the trend of the Liaw and Dhir model accounting surface wettability as the governing factor.