Study of Melting of Snow Layr with a Combined Effect of Temperature and Concentration

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When a snow layr is quickly immersed in a binary aqueous solution, the snow melts with a temperature fall in the melting system, even when there is initially no temperature difference between the snow layr and the aqueous solution. Experiment of the melting of snow is conducted by using two kinds of aqueous solutions of calcium chloride and propylene grycol. Temperature of the solutions are 0,10,20degree C higher than the snow temperature at the beginning of the melting. The higher temperature of the solutions melts much more snow compared with the lower temperature solutions.It is impossible to predict the melting manner by only using a cell and diffusion controlled model for the same temperature between snow and solution due to the higher temperature solution than the snow. To overcome this difficulty, it is assumed that the snow melts according to the two process due to the high Lewis number. After snow melts with a driving force of the temperature difference between snow and solution, the melting subsequently begins controlled with the diffusion of concentration. The period in the first process is very small as about 0.04 seconds. On the other hands, the period in the second is very long as about 4 seconds. Although the melting manner is strongly dependent on the thickness of the diffusion layr, the thickness near the 0.03mm in the Nernst model predicts well the abrupt temperature depression in the melting system and the melting amount. It is demonstrated that the maximum melting amount is largely affected by the temperature of solutions, concentration, and porosity of snow. The special temperature difference is defined for the calculation of the maximum melting amount that is strongly dependent on the conditions of the melting.