TRANSIENT SOLIDIFICATION OF A BINARY MIXTURE IN AN INCLINED RECTANGULAR CAVITY

This paper reports the main procedures and results of an experimental investigation of the problem of transient freezing of a binary mixture in an inclined rectangular cavity. The mixture was a solution of NH4Cl in water. One wall of the cavity was cold and the remaining walls adiabatic. Three different regions existed in the cavity during the solidification phenomenon. A solid region, a liquid region, and a mixed-phase region. The mixed-phase region consisted of a solid matrix saturated with liquid and was located between the solid and the liquid regions. Characteristic temperature distributions in the cavity for a host of inclination angles were obtained. The history of the solidification process was studied by tracing the evolution of the interface between the solid and the mixed-phase regions as well as the interface between the mixed-phase and the liquid regions. The natural convection flow in the liquid, driven by both temperature and concentration gradients, seriously affected the solidification process. An engineering correlation for the dependence of the solidified volume fraction of the cavity on time, inclination angle, and initial concentration is also reported in the course of the study.