SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2016, Vol. 24 ›› Issue (6): 711-718.DOI: 10.1016/j.cjche.2016.01.011

• 第25届中国过程控制会议专栏 • 上一篇    下一篇

Simulation of the mixing process in a straight tube with sudden changed cross-section

Yangcheng Lü, Shan Zhu, Kai Wang, Guangsheng Luo   

  1. State Key Laboratory of Chemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
  • 收稿日期:2015-03-17 修回日期:2015-07-22 出版日期:2016-06-28 发布日期:2016-07-12
  • 通讯作者: Yangcheng Lü
  • 基金资助:

    Supported by the National Natural Science Foundation of China (21176136, 21422603) and the National Science and Technology Support Program of China (2011BAC06B01).

Simulation of the mixing process in a straight tube with sudden changed cross-section

Yangcheng Lü, Shan Zhu, Kai Wang, Guangsheng Luo   

  1. State Key Laboratory of Chemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
  • Received:2015-03-17 Revised:2015-07-22 Online:2016-06-28 Published:2016-07-12
  • Contact: Yangcheng Lü
  • Supported by:

    Supported by the National Natural Science Foundation of China (21176136, 21422603) and the National Science and Technology Support Program of China (2011BAC06B01).

摘要: In this work,we revised the expression ofmixing intensity to describe the mixing output through a cross section in a flow system by considering heterogeneity of flow field, and carefully investigated the mixing process along a straight tube with expanding/contracting cross section by simulation method. The simulation results show that a sudden expansion of cross section has remarkable mixing intensification effect within a limited period (on the sub-second scale) or tube-length (on the millimeter scale), corresponding to the generation of considerable local vortices determined by both the flow capacity and the ratio of cross section change; a sudden contraction of cross section has instantaneous but weak mixing intensification effect; through introducing a local expansion structure with proper length, as the combination of sudden expansion and sudden contraction, their mixing intensification effects could be superposed. Besides, the rationality and importance are experimentally verified to explore the time profile of mixing intensity and carry out the vortex analysis by simulation for enhancing the selectivity of a complicated reaction system. These progresses may lead to more meaningful quantitative description of mixing process in a flow microreactor for some specific chemical processes.

关键词: Mixing, Intensification, Simulation, Sudden change in cross-section, Vortex

Abstract: In this work,we revised the expression ofmixing intensity to describe the mixing output through a cross section in a flow system by considering heterogeneity of flow field, and carefully investigated the mixing process along a straight tube with expanding/contracting cross section by simulation method. The simulation results show that a sudden expansion of cross section has remarkable mixing intensification effect within a limited period (on the sub-second scale) or tube-length (on the millimeter scale), corresponding to the generation of considerable local vortices determined by both the flow capacity and the ratio of cross section change; a sudden contraction of cross section has instantaneous but weak mixing intensification effect; through introducing a local expansion structure with proper length, as the combination of sudden expansion and sudden contraction, their mixing intensification effects could be superposed. Besides, the rationality and importance are experimentally verified to explore the time profile of mixing intensity and carry out the vortex analysis by simulation for enhancing the selectivity of a complicated reaction system. These progresses may lead to more meaningful quantitative description of mixing process in a flow microreactor for some specific chemical processes.

Key words: Mixing, Intensification, Simulation, Sudden change in cross-section, Vortex