Desalinization by macrosegregation

The unidirectional solidification is one of the methods for the purificatio n of materials. In this method, the problem that the solute is trapped into the solid during the solidification can be encountered. To overcome this p roblem, the method of unidirectional solidification under fluid flow has be en developed and was applied to the desalinization, where concentrations of salt, relative velocity of fluid flow against solid, V, and solidification rate, R, were employed as experimental parameters. The effective distribut ion coefficient, k(eff), defined as the ratio of the solute concentration i n solid to that in liquid, was introduced to evaluate desalimzation. The va lue of k(eff) became smaller as the value of V increased and that of R decr eased. When the conditions of V and R were constant, the value of k(eff) be came larger with increasing the concentration of salt. From the crosssectio nal view of the microstructure for solid, it has been found that the crysta l grows along the centrifugal direction and the size of crystal cell decrea ses with increasing the concentration of salt. Moreover, it has been found that the logarithm of k(eff) can be expressed as a function of RV-05 when t he concentration of salt is low. It will be shown that the boundary layer t heory can be applied to the system.