刮膜式分子蒸馏器传热特性及壁面优化.pdfVIP

2016 年第 35 卷第 9 期 CHEMICAL INDUSTRY AND ENGINEERING PROGRESS ·2685· 化 工 进 展 刮膜式分子蒸馏器传热特性及壁面优化 邓立文，许松林 （天津大学化工学院，天津 300350） 摘要：使用 CFD 软件建立了刮膜式分子蒸馏器的三维模型，以 EHP-EHS 混合物为研究对象，并通过编写用户 自定义函数（UDF），研究刮膜式分子蒸馏过程传质存在时的传热特性，得到充分发展的温度场及流场，分析了 蒸发壁面温度的分布及转子转速对其影响和局部 Nu 数的分布。结果表明：液膜表面的升温过程是周期地和波动 地达到动态稳定温度的；转子转速越大，周期越小，温度波动次数越多，温度稳定性越好；局部 Nu 数在刮膜器 刮擦的位置突增，刮膜器的刮擦作用是影响平均 Nu 数增大的主要因素。经过壁面优化，液体湍流程度增大，传 热效果得到不同程度的增强，凸起矩形排列、三角形排列、螺旋形排列时平均 Nu 数分别是光滑蒸发面的 1.32 倍、1.23 倍、1.04 倍，为进一步优化刮膜式分子蒸馏器提供参考。 关键词：刮膜式分子蒸馏；计算流体力学；传热；壁面优化 中图分类号：TQ 021.3；TQ 051.8 文献标志码：A 文章编号：1000–6613（2016）09–2685–08 DOI：10.16085/j.issn.1000-6613.2016.09.008 Characteristics of heat transfer and wall optimization in the wiped film molecular distiller DENG Liwen，XU Songlin （School of Chemical Engineering and Technology，Tianjin University，Tianjin 300350，China） Abstract：In this paper，a two phase flow of di-(ethylhexyl)-phthalate and di-(ethylhexyl)-sebacate (EHP-EHS) mixture with a three dimensional model was simulated by CFD software with UDF，by which the heat transfer characteristics of wiped molecular distillation process was studied with full developed temperature and flow field. The results showed that the change of film surface temperature is periodic and waved. With faster rotor speed，the period is shorter，the number of fluctuations is bigger and the film surface temperature is more stable. The Nu number increases sharply where the wiper wipes and the wiped wiper effect is the main factor influencing the increase of average Nu number. With the optimization of the evaporating cylinder，the liquid turbulence increases. The average Nu number of rectangular arrangement，triangular arrangement and the spiral arrangement of fins on the evaporating cylinder are 1.32，1.23 and 1.04 times as large as the smooth one，respectively，which provide a reference for further optimization of wiped film molecular distiller. Key words：wiped molecular distiller；computational fluid