Behavior of the Two-Phase Mushy Zone During Freeze Coating on a Continuous Moving Plate

Abstract

The process of freeze coating of a binary substance on a chilled moving plate is studied theoretically with special emphasis on the behavior of the two-phase mushy zone. The flow and heat transfer in five separate regions of the system, i.e., the moving plate, the freeze coat, the two-phase packing region, the two-phase dispersed region and the molten substance region, are formulated mathematically to describe the freeze-coating process. A supplemental equation derived from a simplified phase diagram and an appropriate viscosity model are employed to complete the mathematical description of the two-phase mushy zone. The system of equations is solved by a combined analytical-numerical technique to determine the spatial variations of the solidus and liquidus fronts. Effects of seven controlling parameters, including the freeze coat-to-wall thermal ratio, the wall subcooling parameter, the molten substance superheating parameter, the Prandtl number, the Stefan number, the equilibrium partition ratio, and the packing limit fraction, on the behavior of the two-phase mushy zone and the freeze-coating process are determined.