Pressure drop of three-phase liquid–liquid–gas slug flow in round microchannels

Abstract

demonstrated that pressure drop increases substantially if dry slug flow occurs or if microchannels with significant surface roughness are employed. Those influences were not accounted for in the models presented. KeywordsMultiphase flow • Three-phase flow • Liquidliquid-gas • Slug flow • Microchannel • Pressure drop • Surface roughness List of symbols A Area (m 2 ) c Constant in Bretherton's pressure drop equation, c = 9.04 in this work (-) Ca Capillary number (-) Ca b Capillary number based on bubble velocity at the tube outlet and gas-liquid surface tension (-) Ca d Capillary number based on bubble velocity at the tube outlet and liquid-liquid surface tension (-) D Diameter (m) d c Diameter of the test tube (m) f Slug frequency (1/s) h Film thickness (m) L Length (m) ΔP Pressure drop (Pa) r Radius (m) Re Reynolds number (-) RS t Surface roughness parameter: absolute peak to valley distance (m) U Superficial velocity (m/s) u Velocity of bubble or droplet (m/s) We Weber number (-) z Distance in the z-direction (m)

Modeling of Slug Velocity and Pressure Drop in Gas‐Liquid‐Liquid Slug Flow

“…The average relative error between experiment and model is 16.6 %. Pressure drop prediction for three‐phase systems with a wall film is thus feasible and comparable to the results of Ładosz et al which also lay within ± 20 %. The results presented in Fig.…”

“…The deviation for the non‐wetting toluene/gas/water system, which does not form a wall film, is sometimes substantially higher than 20 %. It is obvious that the pressure drop is underestimated in most cases and that the accuracy of the estimation is increasing with the overall pressure drop and velocity, which was also observed by Ładosz et al . Compared to Ładosz et al , the presented results are more accurate, with the estimated pressure drop being in the range of 30 to 100 % of the experimental results, where the results of Ładosz et al are below 40 %.…”

“…The developed model is similar to the model developed by Ładosz et al but differs from it in some points. The model of Ładosz et al is a straightforward expansion of the model of Warnier et al for gas‐liquid slug flow to a triphasic flow.…”

“…The developed model is similar to the model developed by Ładosz et al but differs from it in some points. The model of Ładosz et al is a straightforward expansion of the model of Warnier et al for gas‐liquid slug flow to a triphasic flow. The model does not differentiate between the wetting and the non‐wetting condition in triphasic flow, which leads to large deviations between the experimental and the calculated pressure drop for the latter case.…”

“…One last difference is the use of the slug frequency instead of the slug length in the model of Ładosz et al. . Since both quantities can be derived from each other, this is only a superficial difference.…”