CONCENTRATION DISTRIBUTION IN CRYSTALLIZATION FROM SOLUTION UNDER MICROGRAVITY

Concentration distribution in crystallization from solution under micr ogravity is numerically studied. A quasi-steady state growth and disso lution in a 2D rectangular enclosure filled with sodium chlorate (NaCl O3) aqueous solution, in which one wall is the growth surface of the c rystal and the opposite one is the dissolution surface, is considered. The solute transport process at the growth surface is described by th e diffusion-reaction theory with finite interface kinetics coefficient . The results show that the concentration at the growth surface is sup ersaturated and the supersaturation distribution is of non-uniformity, i.e. the supersaturation in a region facing an incoming flow is high. On the other hand, the non-uniformity of supersaturation at the growt h surface is closely related to the gravity level even under micrograv ity, it exponentially increases as the thermal Rayleigh number on beha lf of the gravity level rises.