晶体硅定向凝固过程中凝固界面形状及热应力场的动力特性

项目名称： 晶体硅定向凝固过程中凝固界面形状及热应力场的动力特性

项目编号： No.50876084

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 生物科学

项目作者： 刘立军

作者单位： 西安交通大学

项目金额： 35万元

中文摘要： 针对太阳电池用矩形多晶硅铸锭定向凝固过程，建立包含凝固炉内部所有传热传质模式和整个凝固过程的三维热动力学过程数值模型，开发高效的算法和分析软件。针对矩形坩埚内高温硅熔体流动的强非定常湍流特性，以及凝固过程中对流传热的多时间尺度特点，开发高温熔体湍流的大涡模拟技术和凝固过程的多时间尺度模型。结合对凝固过程中炉内温度场的实验研究，将本软件进一步发展成为分析大尺寸矩形多晶硅铸锭定向凝固过程的有效工具。分别研究铸锭炉主要结构参数、石墨加热器的布置方案和晶体生长条件对熔体对流、固液凝固界面形状和凝固速度的影响。在此基础上，建立凝固过程中铸锭内部热应力场的动力学模型，研究凝固过程中固液凝固界面形状及铸锭内热应力场随时间的发展演化动力特性，并阐明其影响机制。为太阳能级晶体硅定向凝固过程的热场管理和凝固炉的开发设计提供科学理论依据。

中文关键词： 多晶硅铸锭；定向凝固法；晶体生长；传热与传质；过程模拟

英文摘要： A three-dimensional global model is established for the thermodynamic process of a directional solidification for producing multi-crystalline Si ingots in square shape used for solar cells. The model involves all modes of heat and mass transfers in the solidification furnace and the whole solidification process. Efficient algorithms and the corresponding analysis software are developed. Basing on the strong instability and turbulent features of the melt flow in the crucible with square shape and the multi-time scale feature of the convective heat transfer in the solidification process, the technique of large eddy simulation (LES) for turbulent melt flow and the multi-time scale model for the solidification process are developed. Being validated with the experiment investigation of the thermal field in the furnace during a solidification process, the software is further developed as an effective tool for analysis of the directional solidification process for multi-crystalline Si ingots with large size in square shape. Using this analysis tool, the influence of the primary geometrical parameters of the furnace, the heater's design and the crystal growth conditions on the melt convection, the melt-solid interface shape and the solidification rate are respectively investigated. Further more, the dynamic model of the thermal stress in the Si ingot during a solidification process is established. The dynamic evolution of the melt-solid interface shape and the thermal stress in the ingot are investigated. This study aims to provide guidance for the furnace design and the thermal management of a directional solidification process for multi-crystalline Si ingot for solar cells.

英文关键词： multi-crystalline Si ingot; directional solidification; crystal growth; heat and mass transfer; process simulation