A STUDY OF THE FREEZING OF BINARY-SOLUTIONS SATURATING A POROUS MATRIX

The freezing of a binary solution saturating a porous matrix is investigated experimentally and numerically. An aqueous solution of sodium chloride constituted the binary solution. Spherical glass beads constituted the porous matrix. The freezing was initiated at one of the vertical walls of a rectangular cavity. The temperature distribution in the solid, liquid and mush regions were recorded. A mathematical model that considered conduction as the only mode of heat transfer was developed. The predictions of the model were compared with experimental data. In general, as the model ignored natural convection, the predicted temperatures agreed well with the data during early times in the freezing when conduction was the dominant mode of heat transfer. But as freezing progressed the predictions departed from the data and this departure was larger when the initial superheat was high i.e., when the natural convective flow was vigorous and its influence strong on the freezing process.