Normalization of wettability and heat transfer coefficient curve prediction model on biphilic surfaces

Abstract

The application of “biphilic surfaces” in boiling heat transfer has attracted widespread attention, and scholars have conducted numerous experimental studies in this field. Unfortunately, the relevant theoretical research is almost blank, especially in predicting essential parameters such as HTC. Therefore, it is necessary to develop a new correlation for the HTC of biphilic surfaces in boiling heat transfer. Firstly, in this study, biphilic surfaces composed of pure copper and Ag(S(CH₂)₁₇CH₃) were prepared using standard photolithography and chemical etching techniques. All of the surfaces feature 1000 μm square patterns, but there are variations in the contact angles (120.4°, 124.5°, 130.3°, 135°, 140°) of the hydrophobic surfaces. The maximum critical heat flux was 1203.5 kW/m², and the maximum heat transfer coefficient was 77.8 kW/m²K. Secondly, this study proposed the characteristic contact angle θ_char, which solves the issue of representing the wettability of biphilic surfaces with two contact angles. Next, the paper verified reliability of normalization process by combining the theory of homogeneous surfaces. Finally, this paper analyzed the undetermined coefficients in Rohsenow’s correlation by θ_char, enabling the prediction of HTC for biphilic surfaces. Compared with experimental data, the maximum prediction error does not exceed 24.13 %.