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Estimation of mass transfer during drop formation: New flow expansion model

Javadi, A ; Sharif University of Technology | 2004

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  1. Type of Document: Article
  2. DOI: 10.1115/imece2004-62443
  3. Publisher: American Society of Mechanical Engineers , 2004
  4. Abstract:
  5. Although there is extensive experimental, theoretical and numerical research on dynamics of drop formation in liquid-liquid systems, the evaluation of mass transfer during drop formation is rather complex and there has been little research on that. The various mathematical models developed for this problem are generally based on a solution of the diffusion equation without any allowance for circulation within the drop. This is the main reason for the poor prediction of these models in many cases for which internal convection has an important effect on mass transfer rate. In this paper an attempt was made to define a parameter related to the extent of the convective mixing within the growing drop. For this purpose it is assumed that the entrance of the dispersed flow into the growing drop from the nozzle is analogous to the entrance of the flow from a smaller channel to a larger one (the expanding drops). This transfer mechanism presented in this paper has been dubbed "flow expansion". A global time-dependent Reynolds number was defined based on the equivalent diameter of growing drop as a length scale and also on a velocity scale, which is obtained using this flow expansion assumption. This time dependent Reynolds number of growing drop (Regd) has an important role on the mass transfer coefficient. The results of the model where predicting the effects of the nozzle diameter and dispersed phase flow rate on the mass transfer behavior showed good agreement with experimental data. This comparison demonstrates an improvement on famous models such as surface stretch and fresh surface elements for evaluation of mass transfer during drop formation. Copyright © 2004 by ASME
  6. Keywords:
  7. Drop Formation ; Extraction ; Liquid-Liquid Systems ; Mass Transfer Coefficient
  8. Source: 2004 ASME International Mechanical Engineering Congress and Exposition, IMECE, Anaheim, CA, 13 November 2004 through 19 November 2004 ; 2004 , Pages 27-34 ; 0791847179 (ISBN); 9780791847176 (ISBN)
  9. URL: https://asmedigitalcollection.asme.org/IMECE/proceedings-abstract/IMECE2004/47179/27/309430