摘要
基于混合物理论和实验观察所获得的有关结晶形态及形貌特征 ,建立了描述降膜结晶过程液相区、枝晶状固液两相共存区及固相区的动量、热量和质量传递过程的分区域统一数学模型 .模型的一个重要特点是认为在降膜结晶过程中 ,于熔体液相区和固相区之间存在一薄厚不匀且不断变化的固液两相共存区 .随着结晶过程的进行 ,二相区内固相体积分数不断增加并不断向液相区推移直至完全固化 .二相区的存在为降膜结晶时含杂质低纯度液体提供了在晶层内栖身的场所 ,这可能是产生杂质包藏的实际原因。引入多孔介质传递理论并采用Brinkman扩展的非稳态Darcy方程来描述固液两相区多孔介质内的流体流动 .进一步 。
Based on mixture theory and experimental crystal morphology,a numerical continuum model describing momentum,heat and mass transport phenomena occurring during Falling Film Crystallization Process is set up.One distinct characteristic of the present model is that there is an irregular two-phase mushy region existing between the liquid and solid phases.With Falling Film Crystallization going on,the solid fraction within the mushy region keeps increasing until complete solidification and the mushy region as well as solid region keeps in growing into the liquid region,The mushy region provides various locations for impure inclusion,which may be one of the practical reason for inclusion occurring.In order to model the coupled momentum, heat and mass transport in porous mushy region,the theory of transport phenomena in porous media is introduced and unsteady Darcy equation with Brinkman extension is adopted.Further more,Van Driest-modified Prandtl's mixing length model is used to reflect the turbulent transport phenomena occuring in the liquid region.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2001年第7期580-586,共7页
CIESC Journal
基金
国家自然科学基金资助项目 (No .598760 0 4 )&&
