A study of boiling on surfaces with temperature-dependent wettability by lattice Boltzmann method

Effects of surface wettability have been the focus of boiling heat transfer research in recent years, due to its important role on boiling performance. It is reported that hydrophobic surface has higher boiling heat transfer coefficient while hydrophilic surface has higher critical heat flux. In this study, a surface with temperature-dependent wettability was proposed to take advantages of both hydrophilic and hydrophobic surfaces. A hybrid thermal lattice Boltzmann model with an improved forcing scheme was used to simulate and evaluate the effects of wettability control. First, single bubble dynamics on hydrophilic and hydrophobic surfaces were depicted to analyze the heat transfer features on both surfaces. Second, boiling curves for each condition have been obtained under stepwise heat flux control condition, and the controlled wettability surface shows higher boiling performance than both hydrophobic and hydrophilic surfaces. In addition, we found an optimal relation between temperature and surface wettability for heat transfer rate, and it is evaluated through the parameter test of the temperature-wettability relation. This research may provide a potential way of controlling surface wettability to improve boiling performance and also offer conceptual design of enhanced boiling surface.