Transport Phenomena and Fluid Mechanics

Microdroplet coalescences at microchannel junctions with different collision angles

  1. Kai Wang*,
  2. Yangcheng Lu,
  3. Lu Yang,
  4. Guangsheng Luo*

Article first published online: 11 MAY 2012

DOI: 10.1002/aic.13825

Issue

AIChE Journal

AIChE Journal

Volume 59, Issue 2, pages 643–649, February 2013

Additional Information

How to Cite

Wang, K., Lu, Y., Yang, L. and Luo, G. (2013), Microdroplet coalescences at microchannel junctions with different collision angles. AIChE J., 59: 643–649. doi: 10.1002/aic.13825

Author Information

  1. Dept. of Chemical Engineering, The State Key Laboratory of Chemical Engineering, Tsinghua University, Beijing, People's Republic of China

*Correspondence concerning this article should be addressed to K. Wang at kaiwang@tsinghua.edu.cn, or G. S. Luo at gsluo@tsinghua.edu.cn.

Publication History

  1. Issue published online: 23 JAN 2013
  2. Article first published online: 11 MAY 2012
  3. Accepted manuscript online: 23 APR 2012 02:58PM EST
  4. Manuscript Revised: 8 APR 2012
  5. Manuscript Received: 19 DEC 2011

Funded by

  • National Natural Science Foundation of China. Grant Numbers: 21036002, 20111300342
  • Postdoctoral Science Foundation of China. Grant Numbers: 20100480283, 201104095

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Keywords:

  • microdroplet;
  • microchannel junction;
  • coalescence;
  • critical capillary number;
  • film drainage theory

Microdroplet coalescence mechanism is very important for the miniaturization of multiphase chemical processes with microstructured devices. Using three working systems with different physical properties, this article presents an experimental study on the fluid dynamics of microdroplet coalescence at different microchannel junctions. The critical capillary number to distinguish coalescence or noncoalescence of microdroplet is investigated and its variations with droplet size, collision angle, and physical properties are analyzed with two important parameters – the film drainage time and droplet contact time. Experimental results indicate that microdroplet coalescence can be enhanced by reducing the droplet collision angle. The differences of microdroplet coalescences in confined microchannels and free-flowing spaces are provided with the analysis of critical capillary number. A model equation is proposed to predict the critical capillary numbers in this study, which may provide valuable information for the design and development of new microstructured chemical device. © 2012 American Institute of Chemical Engineers AIChE J, 59: 643–649, 2013

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