Application of Artificial Intelligence and Gamma Attenuation Techniques for Predicting Gas–Oil–Water Volume Fraction in Annular Regime of Three-Phase Flow Independent of Oil Pipeline’s Scale Layer

To the best knowledge of the authors, in former studies in the field of measuring volume fraction of gas, oil, and water components in a three-phase flow using gamma radiation technique, the existence of a scale layer has not been considered. The formed scale layer usually has a higher density in comparison to the fluid flow inside the oil pipeline, which can lead to high photon attenuation and, consequently, reduce the measuring precision of three-phase flow meter. The purpose of this study is to present an intelligent gamma radiation-based, nondestructive technique with the ability to measure volume fraction of gas, oil, and water components in the annular regime of a three-phase flow independent of the scale layer. Since, in this problem, there are several unknown parameters, such as gas, oil, and water components with different amounts and densities and scale layers with different thicknesses, it is not possible to measure the volume fraction using a conventional gamma radiation system. In this study, a system including a 241Am-133Ba dual energy source and two transmission detectors was used. The first detector was located diametrically in front of the source. For the second detector, at first, a sensitivity investigation was conducted in order to find the optimum position. The four extracted signals in both detectors (counts under photo peaks of both detectors) were used as inputs of neural network, and volume fractions of gas and oil components were utilized as the outputs. Using the proposed intelligent technique, volume fraction of each component was predicted independent of the barium sulfate scale layer, with a maximum MAE error of 3.66%.

Thermodynamic Analysis of the Transition Between Slug and Annular Flow in Minichannels

Heat transfer mechanism during flow boiling of fluids in small channels differs significantly depending on whether two-phase flow is in slug or annular regime. Understanding of the transition conditions between homogeneous slug flow and annular two-phase flow is an important topic for mini- and microchannel heat exchangers performance optimization. The current study focuses on the analysis of thermodynamic equilibrium conditions of two neighboring two-phase flow regimes. In both flow patterns the total energy is equal at specific mass flux and vapor quality and those values can be used to mark the transition conditions.

Steady and Unsteady Simulations for Annular Internal Condensing Flows in a Channel

This paper highlights: (i) numerical methods developed to solve annular/stratified internal condensing flow problems, and (ii) the assessed effects of transverse gravity and surface tension on shear driven (horizontal channels) and gravity driven (inclined channels) internal condensing flows. A comparative study of the flow physics is presented with the help of steady and unsteady computational results obtained from the numerical solutions of the full two-dimensional governing equations for annular internal condensing flows. These simulations directly apply to recently-demonstrated innovative condenser operations which make the flow regime annular over the entire length of the condenser. The simulation algorithm is based on an active integration of our own codes developed on MATLAB with the standard single-phase CFD simulation codes available on COMSOL. The approach allows for an accurate wave simulation technique for the highly sensitive shear driven annular condensing flows. This simulation approach employs a sharp-interface model and uses a moving grid technique to accurately locate the dynamic interface by the solution of the interface tracking equation (employing the method of characteristics) along with the rest of the governing equations. The 4th order time-step accuracy in the method of characteristics has enabled, for the first time, the ability to track time-varying interface locations associated with wave phenomena and accurate satisfaction of all the interface conditions — including the more difficult to satisfy interfacial mass-flux equalities. A combination of steady and unsteady simulation results are also used to identify the effects of transverse gravity, axial gravity, and surface tension on the growth of waves. The results presented bring out the differences within different types of shear driven flows and differences between shear driven and gravity driven flows. The unsteady wave simulation capability has been used here to do the stability analysis for annular shear-driven steady flows. In stability analysis, an assessment of the dynamic response of the steady solutions to arbitrary instantaneous initial disturbance are obtained. The results mark the location beyond which the annular regime transitions to a non-annular regime (experimentally known to be a plug-slug regimes). The computational prediction of heat-flux values agree with the experimentally measured values (at measurement locations) obtained from relevant runs of our in-house experiments. Also, a comparison between the computationally predicted and experimentally measured values regarding the length of the annular regime is possible, and will be presented elsewhere.