Steam flash dewatering can rapidly reduce the moisture content of low-rank coal, but the coupling between evaporation and liquid drainage remains insufficiently understood. An experimentally validated multiphysics model was developed in COMSOL Multiphysics to investigate coupled heat transfer, non-equilibrium phase change, and moisture migration during steam pressurization, holding, and rapid depressurization. Pressurization and holding primarily promoted sensible-heat accumulation and water redistribution, with limited direct dewatering. Rapid depressurization dominated water removal through concurrent flash evaporation and pressure-driven liquid drainage. Evaporation provided the larger contribution, and its rate peaked before the liquid-drainage rate, indicating different response times for phase change and liquid transport. Particle size and holding pressure affected dewatering more strongly than holding time. Increasing pressure enhanced heat storage and the flash driving force, although gains diminished at higher pressures. Prolonged holding mainly improved temperature uniformity. A quadratic regression model described final moisture content with a coefficient of determination of 0.992 within the investigated operating range. These findings demonstrate that steam flash dewatering depends on the interaction between stored thermal energy and accessible discharge pathways, providing a basis for process optimization.

low-rank coal；porous media；steam flash dewatering；heat and mass transfer；prediction model