微型锥形双螺杆挤出机的循环混合特性  

Mixing performance in a miniature conical twin screw extruder with batch filling

作　　者：陈世昌[1] 张先明[1] 徐俊杰[1] 陈文兴[1] 冯连芳[2] 

机构地区：[1]浙江理工大学纺织纤维材料与加工技术国家地方联合工程实验室,浙江杭州310018 [2]浙江大学化学工程国家重点实验室,化学工程与生物工程系,浙江杭州310027

出　　处：《化工进展》2017年第4期1217-1223,共7页Chemical Industry and Engineering Progress

基　　金：国家重点研发计划项目(2016YFB0303002)

摘　　要：利用基于三维有限元的计算流体力学(CFD)方法数值模拟了微型锥形双螺杆挤出机(MCTSE)中聚丙烯熔体的循环挤出混合过程,得到流场中物料的剪切应力和速度等分布场量。通过计算放置流场中的示踪粒子的运动轨迹,对粒子运动路径上的剪切应力、混合指数、拉伸长度、分离尺度以及混合效率等进行统计分析,定量表征了MCTSE循环挤出过程的分散和分布混合特性,并进一步考察了加工条件和螺杆构型对混合性能的影响规律。结果表明,聚丙烯熔体循环挤出混合由拉伸流和剪切流共同作用,MCTSE具有较好的混合效果;增大螺杆转速或减小螺距均有利于提高MCTSE的分散混合和分布混合性能,但不利于提高MCTSE的混合效率;分析表征混合性能的不同参数可知,相对于改变MCTSE的螺杆构型,选取合适的加工条件更为重要。The circulatory mixing in a miniature conical twin screw extruder （MCTSE） under the condition of batch filling was evaluated numerically using finite element modeling. The simulation was implemented with mesh superposition technique to generate velocity profiles and particle trajectories for the extrusion process of polymer melt. Based on the statistical analysis of tracking particles, the dispersive mixing was evaluated using shear stress and mixing index, and the distributive mixing was assessed using the length of stretch and the scale of separation. The mixing performance in different screw pitch and rotating speed were also examined. The results showed that the mixing of MCTSE was dependent on stretching flow cooperation with shear flow. Both the dispersive mixing and distributive mixing were improved by either increasing the rotating speed of screw or decreasing the screw pitch, yet an opposite tendency was displaying for the mixing efficiency. The preference was given to the proper process rather than the screw structure of MCTSE on the basis of the composite analysis of different mixing parameters.

关 键 词：微型锥形双螺杆挤出机 数值模拟 层流 分散 混合 

分 类 号：TQ320.5[化学工程—合成树脂塑料工业]