Transport phenomena in microchannels in liquid–liquid extraction (LLE) systems operating in a slug flow regime—A review

Abstract In the present work, the effects of various parameters (capillary size, shape, flow ratio, presence of additives, and presence of wall film) on both reactive and non‐reactive LLE systems are presented and analyzed. The literature data for a constant liquid flow ratio of 1 ( Q c / Q D = 1) has been correlated to give rise to two empirical correlations relating the Sherwood number (Sh), Reynolds number (Re), capillary number (Ca), and Schmidt number (Sc) have been developed for 0.1 < Re < 10 and 10 < Re < 200. The concept of j‐factor for micro‐channels has been introduced and named as Pandit–Kunzru–Ganguli analogy. Three new dimensionless numbers have been introduced, namely Pandit number (), Ganguli number , and Kunzru number (). The j‐factor is found to be a strong function of Capillary number for 10 < Re < 200 while it is a strong function of surface renewal for 0.1 < Re < 10. Empirical correlations to calculate j ‐factor as a function of Re or Weber number (We) are also presented. Recommendations for future work have been presented based on the review in the present work.