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.

Melting of a vertical ice cylinder inside a rotating cylindrical cavity filled with binary aqueous solution

“…Therefore, a stable stagnation region without flow that includes a solution of low temperature and low density is formed at the upper part of the solution layer. This stagnation region is reported in studies of melting of vertical ice plates [8] and it is a characteristic of the fact that the melting rate of this region is slow. It is certain that the flow field caused by the melting of a vertical Table 2.…”

“…The phenomenon of melting into a solution is an important problem in environmental and engineering fields, such as the melting of glaciers in seawater, thermal storage devices using latent heat, and the melting of snow on roads. In addition, convection due to the combination of temperature and concentration gradients is a complicated problem and therefore there are many studies [3][4][5][6][7][8] related to this. However, these reports are investigations of ice plates melting in a rectangular cavity.…”

Theoretical Study on the Ice Melting with Transient Double Effects of Temperature and Concentration

“…So, we can omit this condition. Of course, the temperature at the melting front changes with time, but the change of the melting front temperature is not so violently (6) . For this reason, we can understand the reliability of this assumption Here, we introduce the following non-dimensional quantities.…”

“…This abrupt change causes the transient double diffusive natural convection which significantly influences the melting behavior of ice. For this reason, the transient double diffusive natural convection has attracted the interest of many researchers and many studies have been carried out (for example, Carey and Gebhart (1), (2) ; Sugawara, Inaba, Nishimura and Mizuno (3) ; Beckermann and Viskanta (4) ; Fukusako, Tago, Yamada, Kitayama and Watanabe (5) ; Sugawara, Irvin and Tago (6) ; Komatsu, Sugawara and Fujita (7) ). In these existing studies, the experimental approaches or the numerical approaches were mainly adopted to understand the melting of ice in mixture.…”

“…3, 2013 * φ is given in Eq. (18) and the values of the non-dimensional parameters were determined after the study of Sugawara, Irvin and Tago (6) . Some additional explanations are presented here.…”