Experimental investigation of water-nitrogen flow in microchannel with high aspect ratio (with the 20 µm gap)

This study is devoted to the experimental investigation of two-phase water-nitrogen flow in the slit microchannel with a gap of 20 µm and a width of 10 mm. The technology of microchannel fabrication has been developed and described in detail. Experiments were conducted in adiabatic conditions. Using a modified schlieren system, four flow patterns have been observed and described: jet, bubble, churn, and annular. Flow pattern map was plotted according to obtained patterns. Moreover, a two-phase pressure drop was measured. Dependencies between two-phase pressure drop and superficial liquid and gas velocities have been investigated.

Void Fraction and Flow Pattern of R-290 in A Horizontal Evaporator: Effects of Pipe Diameter and Cooling Capacity

Void fraction and flow pattern play important roles in the performance of evaporator in an air conditioning system. In this paper, the behaviors of void fraction and flow pattern of refrigerant R-290 in a horizontal evaporator are discussed. To simplify the analysis, the evaporator was divided into 10 segments. The void fraction was calculated based on the refrigerant flow quality and the flow pattern was determined on the basis of superficial gas and liquid velocity plotted in the flow pattern map. The calculation was carried on air conditioning machines with nominal capacities of 2.64 kW, 3.62 kW, and 5.28 kW using the evaporator pipe diameters of 3/8 in and 5/16 in. Generally, the lower evaporating temperature results in the higher void fraction, higher gas superficial velocity, and lower liquid superficial velocity. For all ranges of evaporator diameter and cooling capacity, annular flow is found to be the dominant flow pattern. The wavy flow is only found in the lower cooling capacity and larger evaporator diameter. Meanwhile, the slug flow occupies 16.7% to 25.8% of evaporator segment.

Flow Pattern Map of Flow Boiling in a Rectangular Channel Filled with Porous Media

A flow visualization study was carried out for flow boiling in a rectangular channel filled with and without metallic random porous media. Four main flow patterns are observed as intermittent slug-churn flow, churn-annular flow, annular-mist flow, and mist flow regimes. These flow patterns are clearly classified based on the high-speed images of the channel flow. The results of the flow pattern map according to the mass flow rate were presented using saturation temperatures and the materials of porous media as variables. As the saturation temperatures increased, the annular-mist flow regime occupied a larger area than the lower saturation temperatures condition. Therefore, the churn flow regime is narrower, and the slug flow more quickly turns to annular flow with the increasing vapor quality. The pattern map is not significantly affected by the materials of porous media.

Liquid-Liquid Flow Pattern Prediction Using Relevant Dimensionless Parameter Groups

Accurate predictions of flow patterns in liquid-liquid flow are critical to the successful design and operation of industrial and geo-energy systems where two liquids are jointly transported. Unfortunately, there is no unified flow pattern map, because all published maps are based on limited ranges of dimensional parameters. Dimensional analysis was performed on oil-water horizontal flows, to obtain some relevant dimensionless parameter groups (DPG) for constructing flow pattern maps (FPM). The following combinations of DPG were used: (i) the ratio of mixture Reynolds number to Eötvös number versus water fraction, (ii) the ratio of Weber number to Eötvös number versus water fraction, (iii) the mixture Froude number versus water fraction, (iv) the water Froude number versus oil Froude number, (v) the ratio of gravity force to viscous force versus water fraction. From twelve published experimental studies, 2696 data points were gathered and analysed covering a variety of flow patterns including stratified, stratified mixed, dispersed oil in water, dispersed water in oil, annular and slug flows. Based on the performed analysis, it was found that flow patterns could occupy more than one isolated region on the DPG-based flow pattern map. None of the combinations of DPG can mark out all the considered flow patterns, however, some combinations of DPG are particularly suitable for marking out the regions associated with some flow patterns.

Integrated application of flow pattern map for long-term gas lift optimization: a case study of Well T in Indonesia

Gas lift optimization has been a classic problem since its inception. The problem with currently practiced optimization, the gas lift performance curve (GLPC), was the sole requirement for exhaustive calculation that has to be performed every time changes to the reservoir are acknowledged. The approach of mechanistic modeling has been proven to be a powerful tool to complement the analysis of GLP curves, especially in complex, multi-well gas lift system. This publication offers a new approach in modeling the progression of flow pattern map (FPM) in case of reservoir pressure decline. The findings presented in this publication encourage the hypothesis that FPM can be used with minimum alteration should there be any changes in reservoir pressure.

Application of Mechanistic Modeling for Gas Lift Optimization: A General Scaling Curve for Variations of Tubing Size to Optimum Gas Injection

Gas Lift is currently held as one of the most prominent method in artificial lift, proudly operated flawlessly in hundreds of oil wells in Indonesia. However, gas lift optimization is still governed by the exhaustive Gas Lift Performance Curves (GLPC). This practice, albeit as established as it should be, does require repetitive calculations to be able to perform in life of well operations. Therefore, a new approach is introduced based on the mechanistic modeling. This research highlights the application of fundamental mechanistic modeling and its derivative, the Flow Pattern Map (FPM) for quick estimation of optimum injection gas rate, accompanied by a novel correction factor to account changing tubing sizes. It is hoped that this approach can be beneficial in developing a multitude of gas lift wells with changing tubing sizes.

Probabilistic approach of a flow pattern map for horizontal, vertical, and inclined pipes

A way to predict two-phase liquid-gas flow patterns is presented for horizontal, vertical and inclined pipes. A set of experimental data (7702 points, distributed among 22 authors) and a set of synthetic data generated using OLGA Multiphase Toolkit v.7.3.3 (59 674 points) were gathered. A filtering process based on the experimental void fraction was proposed. Moreover, a classification of the pattern flows based on a supervised classification and a probabilistic flow pattern map is proposed based on a Bayesian approach using four pattern flows: Segregated Flow, Annular Flow, Intermittent Flow, and Bubble Flow. A new visualization technique for flow pattern maps is proposed to understand the transition zones among flow patterns and provide further information than the flow pattern map boundaries reported in the literature. Following the methodology proposed in this approach, probabilistic flow pattern maps are obtained for oil–water pipes. These maps were determined using an experimental dataset of 11 071 records distributed among 53 authors and a numerical filter with the water cut reported by OLGA Multiphase Toolkit v7.3.3.