Pressure gradient in horizontal liquid-liquid flows

On the simulation of three-phase slug flow in nearly horizontal pipes using the multi-fluid model

The present study is aimed at an investigation of the pressure drop characteristics during the simultaneous flow of a kerosene-water mixture through a horizontal pipe of 0.025 m diameter. Measurements of pressure gradient were made for different combinations of phase superficial velocities ranging from 0.03-2 m/s such that the regimes encountered were smooth stratified, wavy stratified, three layer flow, plug flow and oil dispersed in water, and water flow patterns. A model was developed, which considered the energy minimization and pressure equalization of both phases.

Pressure Drop in Liquid‐liquid Two Phase Horizontal Flow: Experiment and Prediction

Dense nonaqueous phase liquids (DNAPLs) such as perchloroethylene, polychlorinated biphenyls, creosote mixtures, and many solvents and degreasers can be released into karst aquifers through sinkholes and sinking streams in quantities up to tanker car volumes. Although DNAPLs are easily injected into karst aquifers, discharge of the contaminants through springs may be significantly delayed depending on transport mechanism, storm water recharge, and storage sites within the karst aquifer. Storage sites include (1) the epikarst; (2) pools and depressions within underground streams; (3) incorporation of DNAPL within clastic sediments that are present in most conduits; (4) adsorption onto organic materials and onto manganese oxides, iron oxides, and other substrates; and (5) migration to depth within the fracture system. Effective transport of DNAPL contaminants during storm flow pulses requires the exceedance of thresholds best defined in terms of the conduit stream power. Movement of pooled DNAPL requires a boundary shear between the liquid and water flowing over it. DNAPL stored in clastic sediment bleeds out slowly or dissolves into surrounding pore water until storm pulses create a stream flow sufficient to flush the pore water, or possibly move the sediment pile itself. Under extreme flow conditions the entire sediment pile, including the DNAPL, can be entrained and ejected from the conduit system.

A Conceptual Model for DNAPL Transport in Karst Ground Water Basins

An accurate determination of the pressure gradient is required for efficient designing of oil and gas wells and pipe systems. Despite the recent improvements in accuracy of models and correlations developed for determining the pressure gradient, they are still incapable of estimating the pressure drop with desired accuracy. Therefore, a robust model is required to determine the pressure gradient precisely. Regarding high performance and great robustness of Artificial Neural Networks for solving science and engineering problems, this paper presents a Radial Basis Function Neural Network (RBF-NN) model to determine the pressure gradient. The model was developed over 994 experimental data sets which are covering a wide range of variables such as oil slip velocity, water slip velocity, pipe diameter, pipe roughness and oil viscosity. The model estimation indicated an average relative deviation of 0.92%, an average absolute relative deviation of 8.25% and an average correlation factor of 0.99. A comparison between the proposed model and the most prominent models and correlations illustrated that the RBF-NN model exclusively out-performs other models and correlations and the estimated values are in great agreement with the experimental data. At last, a sensitivity analysis was applied to clarify the effect of input parameters in estimated results.

H. Herm Stapelberg

Papers

The pressure loss and slug frequency of liquid-liquid-gas slug flow in horizontal pipes