Review and extension of pressure drop models applied to Taylor flow regimes

This paper investigates the pressure drop induced by both liquid-liquid and liquid-gas segmented Taylor flow regimes. A comprehensive experimental programme was completed using four different liquid-liquid and three different liquid-gas combinations over dimensionless slug length, Reynolds and Capillary numbers that spanned several orders of magnitude. Comparisons between the liquid-liquid pressure drop data and the most referenced expressions in the literature highlighted their lack of robustness and demonstrated their inapplicability for use with most practical systems that incorporate liquid-liquid Taylor flow regimes. The experimental pressure drop values obtained for the liquid-gas flows agreed well with existing pressure drop correlations. Interpretation of the liquid-liquid data using liquid-gas models unearthed the existence of a threshold viscosity ratio. Above this threshold, experimental liquid-liquid data was found to agree well with existing liquid-gas models. Below this threshold, results showed that the dispersed slug velocity needed to be considered as the flows were subject to higher interfacial contributions and inertial effects. A modification is proposed to an existing liquid-gas pressure drop correlation. This proposed modification extends the applicability of the correlation to liquid-liquid flows, and furthermore extends the non-dimensional limits of the correlation.