Heat and Mass Transfer Characteristics of a Temperature and Concentration Combined Convection Due to a Vertical Ice Plate Melting

Abstract

The melting of a vertical ice plate into a calcium chloride aqueous solution (CaCl2-H2O mixture) in a rectangular cavity is considered numerically and experimentally. The ice plate melts spontaneously with decreasing temperature at the melting front even when there exists no initial temperature difference between ice and liquid. Visual observations in the liquid reveal a complicated natural convection affected by the concentration/temperature gradients which appear near the melting front. Melt water gradually contaminates an upper region in the initially homogeneous liquid, that causes the melting rate to decrease. Aspect ratio H/W of the liquid region does not affect the melting rate within an early melting stage, however large aspect ratio causes the melting rate to decrease during the melting process. A two-dimensional numerical model reflecting actual ice melting conditions predicts, approximately, the transient melting mass, and the transient temperature/concentration decrease in the melting system. It is seen that the Sherwood number at the melting front is larger when compared with previous results concerning double diffusive convection. The Nusselt number at the melting front is quantitatively considered experimentally and analytically.