Abstract
The accurate prediction of pressure loss for two-phase slug flow in pipes with a simple and powerful methodology has been desired. The calculation of pressure loss has generally been performed by complicated mechanistic models, most of which require the iteration of many variables. The objective of this study is to optimize the previously proposed simplified slug flow model for horizontal pipes, extending the applicability to turbulent flow conditions, i.e., high mixture Reynolds number and near horizontal pipes. The velocity field previously measured by particle image velocimetry further supports the suggested slug flow model which neglects the pressure loss in the liquid film region. A suitable prediction of slug characteristics such as slug liquid holdup and translational velocity (or flow coefficient) is required to advance the accuracy of calculated pressure loss. Therefore, the proper correlations of slug liquid holdup, flow coefficient, and friction factor are identified and utilized to calculate the pressure gradient for horizontal and near horizontal pipes. The optimized model presents a fair agreement with 2191 existing experimental data (0.001 ≤ μL ≤ 0.995 Pa∙s, 7 ≤ ReM ≤ 227,007 and −9 ≤ θ ≤ 9), showing −3% and 0.991 as values of the average relative error and the coefficient of determination, respectively.
Highlights
Gas-liquid, two-phase slug flow in pipes is a commonly observed flow pattern in many industries such as petroleum, chemical, nuclear, ocean engineering, power plant, etc
The understanding and prediction of pressure loss have great importance, while it is usually complicated since the calculation process requires the iteration of many variables
Brito et al [9] proposed a simplified pressure gradient model derived from Equation (7)
Summary
Gas-liquid, two-phase slug flow in pipes is a commonly observed flow pattern in many industries such as petroleum, chemical, nuclear, ocean engineering, power plant, etc. The slug flow pattern has a repeating cycle of liquid slug body and liquid film region, coming with the fluctuation of pressure loss (see Figure 1). Based on the visual observations by Dukler and Hubbard [1], the slug has higher kinetic energy than that of the liquid film [2]. This intermittency can cause mechanical vibrations in the pipe with high structural loads threatening the stability of the system. The understanding and prediction of pressure loss have great importance, while it is usually complicated since the calculation process requires the iteration of many variables.
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