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

The freezing of a binary solution saturating a porous matrix is invest igated experimentally and numerically. An aqueous solution of sodium c hloride constituted the binary solution. Spherical glass beads constit uted the porous matrix. The freezing was initiated at one of the verti cal walls of a rectangular cavity. The temperature distribution in the solid, liquid and mush regions were recorded. A mathematical model th at considered conduction as the only mode of heat transfer was develop ed. The predictions of the model were compared with experimental data. In general, as the model ignored natural convection, the predicted te mperatures agreed well with the data during early times in the freezin g when conduction was the dominant mode of heat transfer. But as freez ing progressed the predictions departed from the data and this departu re was larger when the initial superheat was high i.e., when the natur al convective flow was vigorous and its influence strong on the freezi ng process.