The suitability of the dimensionless terms used in correlating slug liquid holdup with flow parameters in viscous two-phase flows

摘要

Empirical correlations have been proposed for estimating slug liquid holdup, H-LS, using Froude number, N-Fr, viscosity number, N-mu, and inverse viscosity number, N-f. Some of these correlations show physically inconsistent behavior when tested against each flow parameter due to relying on regression analysis without considering the effect of each flow parameter included in these numbers.This work analyzes the performance of these numbers and provides guidelines for the selection of the correct combination of non-dimensional numbers. Our analyses indicate that the N-mu is not suitable for revealing the effect of liquid viscosity on H-LS; instead it reveals the effect of mixture velocity due to its dominant effect. Also, the product of the N-Fr and N-mu, both with positive exponents, is unsuitable for correlating H-LS with liquid viscosity. This combination results in a decrease in H-LS with increasing liquid viscosity, contradicting the experimental observations. Furthermore, the product of the N-Fr and N-f, both with positive exponents, results in a decrease in H-LS with increasing pipe diameter, opposing experimental findings reported in the literature. Finally it is concluded that the most suitable combination for correlating H-LS is the product of the N-Fr with a positive exponent, and the N-mu with a negative exponent.