Sea water frozen crystalisation impacted by flow and heterogeneous nucleation: PFM-LBM coupled modeling, simulation and experiments

Abstract

This study presents a novel phase field method (PFM) - lattice Boltzmann method (LBM) coupled model that describes the ice crystal growth in sea water freezing. Sea water frozen crystalisation impacted by flow and heterogeneous nucleation was numerically and experimentally investigated. The PFM-LBM model was established to conduct simulation. A microscope observation experimental system was built to conduct verification. The results show that flow of sea water effectively promotes the diffusion of discharged salt and the growth of ice crystals, and reduces the probability of dendrite closure. In the directional competitive growth of ice crystals, the salt content trapped in the ice crystals decreased by 17.4% at 0.025 m/s and 21.9% at 0.05 m/s, while the existence of heterogeneous particles resulted in a narrower the brine channel and higher ice crystal growth rate, of which the ice crystal area increased by 10.8% and the trapped salt content in the ice crystals decreased by 14.8%. The study provides both a methodology of numerically simulate sea ice crystallisation which includes the phase change, solute migration, heat transfer and flow, and a feasible controlling approach to improve desalination efficiency of sea water frozen crystallisation.