Numerical simulation of pool boiling heat transfer on smooth surfaces with mixed wettability by lattice Boltzmann method

摘要

In this paper, pool boiling heat transfer from smooth surfaces with mixed wettability is investigated based on a recently developed phase-change lattice Boltzmann method, which is capable of simulating the entire ebullition cycle beginning from the bubble nucleation process. It is demonstrated that addition of hydrophobic spots on smooth hydrophilic surfaces promotes bubble nucleation, enhancing boiling heat transfer and reducing nucleation time drastically. The mixed wettability surface is also expected to enhance critical heat flux (CHF) by regulating vapor spreading behaviors over the heater surface. Temperature variations beneath the growing vapor bubble and total boiling heat flux variations during bubble growth process are also investigated. The ebullition cycle is found to have a dominant effect on temporal variations of temperature and total boiling heat flux. Local heat flux distributions on the hydrophobic and the hydrophilic regions are analyzed, and the three-phase contact line (TCL) region is found to have the highest local heat flux. Effects of the size of the hydrophobic spots and pitch distance between these hydrophobic spots on boiling heat transfer are illustrated.