Thermosolutal transport and macrosegregation during freeze coating of a binary substance on a continuous moving object

The process of freeze coating of a binary substance on a continuous moving plate is investigated theoretically. A comprehensive model describing the momentum, heat, and mass transport in the freeze-coating system has been developed that accounts for the coupling between the macroscopic and microscopic aspects of the process. The problem is formulated using the single-domain approach and the governing equations are solved by the finite difference method. Effects of various controlling parameters on the freeze-coat thickness and the macrosegregation pattern have been determined. It is found that macrosegregation could be important in the freeze-coating process. As the distance from the surface of the plate is increased, the solid species concentration considerably decreases, reaching a minimum value and rising toward the ambient concentration. The macrosegregation pattern appears to be most sensitive to the equilibrium partition ratio. As the latter is increased, the difference between the solid and liquid species concentrations tends to decrease, leading to a substantial reduction of macrosegregation within the freeze coat.