薄膜蒸发器内流体流动特性的数值模拟  

Numerical Simulation on Fluid Flow in a Thin Film Evaporator

作　　者：贺小华[1] 唐平[1] 李佳[1] 陆小华[2] 

机构地区：[1]南京工业大学机械与动力工程学院,江苏南京210009 [2]南京工业大学化学工程学院,江苏南京210009

出　　处：《过程工程学报》2005年第4期364-369,共6页The Chinese Journal of Process Engineering

摘　　要：建立了薄膜蒸发器的计算模型,采用大型计算流体力学(CFD)分析软件CFX4.4模拟了薄膜蒸发器内水及粘性料液的流动过程,得到了各种速度分布.结果表明,刮板转速、进料量对流体流动状态影响显著.提高刮板转速,可明显促进液膜和圈形波内流体的物质交换.在任一转速下,各料液均存在同一最佳进料量,此时其圈形波截面内平均速度达到最大值.对纯物质水,最佳进料量对应的流动边界层厚度与膜厚之比最小.粘性料液和水的轴向速度分布存在差异,且在液膜厚度内未形成明显的流动边界层.The heat transfer calculation model of water and viscous fluid in a thin film evaporator was developed using CFD software CFX4.4. The mean temperature distributions along axial and film thickness directions were obtained, and the film heat transfer coefficient α under different conditions was calculated. The results show that feeding rate and rotor speed have great influence on the film temperature distribution and the film heat transfer coefficient. There is one common optimum feeding rate under different operation conditions for different fluids. At this feeding rate, the mean velocity in fillet section reaches the maximum value and so does the film heat transfer coefficient α For water, both the ratio of flow boundary layer thickness to film thickness and that of temperature boundary layer thickness to film thickness reach the minimum value under high rotor speed or the optimum feeding rate. There exists an inherent relation between the flow boundary layer and temperature boundary layer, and the film temperature distribution and heat transfer coefficient are affected seriously by the thickness of transfer boundary layers. For viscous fluid, no obvious temperature boundary layer forms under the parameter range considered in this work.

关 键 词：薄膜蒸发器 温度场 给热系数 传递边界层 数值模拟 

分 类 号：TK124[动力工程及工程热物理—工程热物理]