降膜熔融结晶过程的数值模拟

通过对降膜熔融结晶过程中晶层界面的热质传递特征及降膜表面上液膜流动和传质传热的分析,建立了描述该过程晶层生长的稳态模型,并进行了无量纲变化。在自制降膜结晶装置中,以二元共晶混合物DDH I-D IPP为例,考察了流量、Stefan数及过热度变化时晶层厚度的变化,结果表明,晶体厚度随着Stefan数增加而增加,晶层厚度随着时间而增加,达到一定时间后,晶层厚度变化趋于平缓。同时,晶层厚度随着初始过热度的增加而急剧降低,随后趋于平缓。同时,采用所建立的模型对晶层厚度进行了计算,计算结果与实验结果基本吻合。

Numerical simulation of falling film melt crystallization

The hydrodynamics of falling film and convective heat transfer at crystal interface were analyzed.And the steady state model of the prediction of solid layer growth in falling film melt crystallization was developed,which is dimensionless.The experiment was performed by using a binary organic mixture(DDHI-DIPP).The effect of(parameters) such as Stefan number(sub-cooling),initial superheat on the thickness of crystal was examined.The results show that with the increasing Stefan number,the thickness of melt is increased,and after some time the change of thickness of melt layer becomes mild;the thickness of melt layer is decreased with the initial over heat increasing,and after some time the change of thickness of melt layer becomes mild.The thickness of melt layer was calculated according to the established model.The predicted and the experimental results are in a good agreement.