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

当雪层迅速浸入二元水溶液中时，即使在最初雪层和水溶液之间没有温差的情况下，雪也会随着融化系统中的温度下降而融化。用氯化钙和丙三醇两种水溶液进行了融雪实验。溶液的温度比融化开始时的雪温高出0、10、20摄氏度。温度较高的溶液与温度较低的溶液相比，融化的积雪更多，由于温度较高的溶液与雪之间的温度相同，仅用晶胞和扩散控制模型无法预测融雪的方式。为了克服这一困难，假设由于刘易斯数较高，雪按照这两个过程融化。在雪和溶液之间的温差的驱动力下，雪融化后，随后开始控制浓度的扩散。第一个过程的周期很小，只有0.04秒左右。另一方面，秒中的周期很长，约为4秒。虽然熔化方式强烈地依赖于扩散层的厚度，但Nernst模型中0.03 mm附近的厚度很好地预测了熔化系统中的突然温降和熔融量。结果表明，最大融化量受溶液温度、浓度和积雪孔隙率的影响较大。为了计算与熔化条件密切相关的最大融化量，定义了特殊的温差。

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.