Showing papers on "Slug flow published in 2021"
TL;DR: In this article, a finite volume method was employed to numerically simulate two-phase flow by means of a finite-volume method and several decisive parameters including superficial gas velocity, channel surface wettability, and channel cross-section geometry were considered to find their effects on the liquid removal behavior.
31 citations
TL;DR: In this paper, the influence of mixing mechanism on the mass transfer performance under gas-liquid and liquid-liquid slug flow, in both continuous slugs and dispersed droplets, was investigated.
27 citations
TL;DR: Based on the online method, the absorption kinetics and mass transfer of CO2 in potassium carbonate solution in a serpentine minichannel are studied in this paper, where three flow patterns are observed: slug-bubbly flow, slug flow, and slug flow with precipitation of SiO2.
25 citations
TL;DR: In this paper, the authors investigated the two-phase occurrence state and fluid transport in shale inorganic calcite nanopores utilizing molecular dynamics simulation and found that the multilayer sticking flow (negative slip) of oil and water is observed.
23 citations
TL;DR: Recently, slug-flow crystallizers (SFCs) have been proposed for continuous manufacturing of colloidal quantum dots (QDs) despite the intriguing advantages of SFCs for controlled manufacturing of QDs as mentioned in this paper.
Abstract: Recently, slug-flow crystallizers (SFCs) have been proposed for continuous manufacturing of colloidal quantum dots (QDs). Despite the intriguing advantages of SFCs for controlled manufacturing of Q...
21 citations
TL;DR: In this paper, changes in the droplet formation mechanism and the law of droplet length in a two-phase liquid-liquid system in 400 × 400 μm standard T-junction microchannels were experimentally studied using a high-speed camera.
Abstract: In this study, changes in the droplet formation mechanism and the law of droplet length in a two-phase liquid–liquid system in 400 × 400 μm standard T-junction microchannels were experimentally studied using a high-speed camera. The study investigated the effects of various dispersed phase viscosities, various continuous phase viscosities, and two-phase flow parameters on droplet length. Two basic flow patterns were observed: slug flow dominated by the squeezing mechanism, and droplet flow dominated by the shear mechanism. The dispersed phase viscosity had almost no effect on droplet length. However, the droplet length decreased with increasing continuous phase viscosity, increasing volume flow rate in the continuous phase, and the continuous-phase capillary number Cac. Droplet length also increased with increasing volume flow rate in the dispersed phase and with the volume flow rate ratio. Based on the droplet formation mechanism, a scaling law governing slug and droplet length was proposed and achieved a good fit with experimental data.
20 citations
TL;DR: In this article, a review of the transition mechanics from spherical cap bubble flow to slug flow in vertical pipes is presented, where the bubble flow was split into subregions, bubbles and spherical cap bubbles and the mechanisms to classify them (i.e., bubble terminal velocity and cap bubble velocity) was analyzed.
19 citations
TL;DR: A comprehensive review of published experimental and numerical works in horizontal pipes, including a critical analysis of state-of-the-art parameters used to characterize the slug flow regime is provided in this article.
17 citations
TL;DR: In this article, a multiscale three-dimensional CFD model for simulation of two-phase gas-liquid flows with different interface length scales, with focus on slug flow pattern is presented.
17 citations
TL;DR: In this article, a small-scale air-water test loop is performed to investigate the flow-induced vibration behaviors of a flexible catenary riser conveying slug flow over a wide range of the gas-to-liquid flow rate ratios from 1.0 to 4.5.
17 citations
TL;DR: In this paper, a slug flow crystallizer for cooling crystallization with focus on enhanced product quality control in terms of narrow particle size distribution (PSD) was designed and characterized, where emphasis was put on slug flow stability while maintaining a convex shape of slugs to make use of the advantage of a narrow residence time distribution.
Abstract: A slug flow crystallizer for cooling crystallization with focus on enhanced product quality control in terms of narrow particle size distribution (PSD) was designed and characterized. Emphasis was put on slug flow stability while maintaining a convex shape of slugs to make use of the advantage of a narrow residence time distribution. Measurements of the latter one showed plug-flow-like behavior for the liquid and solid phase independent of the operating conditions within the range investigated. A tube-in-tube temperature concept led to smooth cooling from 50 to 31 ° C avoiding supersaturation peaks. Seeded cooling crystallization of aqueous l- alanine solution successfully led to reproducible product PSDs avoiding secondary nucleation. Thereby the crystals’ median diameter was increased by 240 μ m. Within a residence time of 10.5 min only, a relative process yield of approximately 83% was achieved. To identify optimized operating conditions for narrow PSD and reduced agglomeration, the effect of total volume flow rate, slug length, and cooling rate on the PSD and agglomeration degree was quantified. A high flow rate (40 mL min − 1 ) and a high cooling rate (3.6 K min − 1 ) reduced agglomeration to its minimum and shifted the size distribution of single crystals without its broadening by in average 90 μ m.
01 Jun 2021
TL;DR: In this article, the influence of a sudden expansion on the upstream behavior of the horizontal gas-liquid slug flow was analyzed using a non-intrusive video technique on a 40 mm ID pipe with and without a sudden enlargement of aspect ratio σ = 0.444.
Abstract: The purpose of this work is to analyze the influence of a sudden expansion on the upstream behavior of the horizontal gas-liquid slug flow. Measurements were made on a 40 mm ID pipe with and without a sudden enlargement of aspect ratio σ = 0.444. The experiments were carried out with two-phase air-water mixture. The slug lengths and frequencies were measured using a non-intrusive video technique. Upstream the sudden enlargement, it was observed that the mixture velocity has no influence on slug length. The variation of slug frequency is found proportional to the liquid superficial velocity for the two cases within this study. It was also observed that the behavior of the slug length and frequency was affected by the presence of the sudden enlargement. The comparison of the results obtained with various empirical correlations available in the literature showed that the latter are not worthwhile in the case where singularity is installed.
TL;DR: Wang et al. as mentioned in this paper investigated the diversity of two-phase flow pattern in coal seam fracture and their controlling factors, and found that the flow pattern can be bubbly, stratified, slug, wavy, annular-mist and mist flow under different combinations of gas and liquid flow rates.
TL;DR: In this article, the authors link the flow characteristics inside a newly designed outside-in-liquid (OIL) atomizer with the spray stability and quality by flow visualization and digital image processing.
TL;DR: In this article, a physically based method to derive well-posed instances of the two-fluid momentum transport equations from first principles is presented, based on the variational principles of field theory, namely the Hamilton principle and the virtual power principle.
Abstract: A physically based method to derive well-posed instances of the two-fluid momentum transport equations from first principles is presented. The basic tools used in this endeavor are the variational principles of field theory, namely, the Hamilton principle and the virtual power principle. The state of the two-fluid flow is represented by the superficial velocity and the drift flux, instead of the average velocities of each fluid. This generates the conservation equations of the two principal motion modes naturally: the global center-of-mass flow and the relative velocity between fluids. Well-posed equations can be obtained by modeling the storage and exchange of kinetic energy in fluctuations structures induced by the interaction between fluids, like wakes and vortexes. In this way, the equations can be regularized without losing in the process the kinetic instabilities responsible for flow-patterns formation and transition. A specific case of vertical air–water flow is analyzed showing the capability of the present model to predict the formation of the slug flow regime as a train of solitons.
TL;DR: In this paper, the effects of fluid rheology on the operation range, bubble length and bubble shape are presented, showing that they can be well described by the effective viscosity.
TL;DR: In this paper, the authors used the four-sensor conductivity probe for upward bubbly and slug flow in a 25.4 mm ID pipe to improve the interfacial area transport equation model in the bubbly to slug transition flow.
TL;DR: In this paper, a two-dimensional acoustic pressure numerical model is established to investigate the ultrasonic pulse transmission behavior between the wall-gas and wall-liquid interface, and an RBF neural network is constructed for online flow pattern identification.
TL;DR: In this article, the effect of inlet disturbance on laminar to turbulent transition in a finite length square duct is considered at bulk Reynolds number Re = 2260 and Re=µ1540, to which a novel spatiotemporal disturbance is introduced through a narrow banded region at the inlet of the square duct.
Abstract: Laminar to turbulent flow transition in a finite length square duct has been carried out by imposing novel spatiotemporal finite amplitude inlet disturbance on the laminar flow. The present direct numerical simulation study demonstrates the effect of inlet disturbance on laminar to turbulent transition. A laminar flow in a finite length square duct is considered at bulk Reynolds number Re = 2260 and Re = 1540, to which a novel spatiotemporal disturbance is introduced through a narrow banded region at the inlet of the square duct. The puff (transition) and slug (turbulent) flow dynamics indicate the laminar to turbulent transition in a square duct. Disturbance introduced at Re = 2260 laminar flow propagates downstream, giving puff and slug flow phenomena similar to pipe flows. However, at Re = 1540, inlet disturbance shows only a puff-like structure. The four vortex mean secondary flow is observed in a puff region, while the conventional eight vortex is observed in the slug region. The coherent structures of the transition (puff) flow show the presence of dual-type hairpin structures. The turbulent kinetic energy spectrum indicates conventional −5/3 spectra for slug flow and −2 energy spectra for puff flow. Thus, in this paper, it is shown that the puff and slug characteristics of laminar to turbulent transition in a square duct are similar to that of a circular duct. It is also shown that the novel inlet disturbance through a narrow banded region captures the dynamics of laminar to turbulent transition in a square duct.
TL;DR: In this article, a snapshot proper orthogonal decomposition (snapshot POD) with an additional mode coupling algorithm is employed, which provides an energy-ranked mode basis of the underlying coherent structures.
TL;DR: In this paper, the authors evaluated the effect of density, viscosity, and surface tension on the flow regime map of two-phase gas/liquid flow in pipes and showed that the flow patterns and transition boundaries were affected by fluid properties.
TL;DR: In this article, the authors identify the flow structure in an air-lifted pump-bubble generator system by using experimentally obtained differential pressure signals, and the results indicate that the water movement mechanism in the riser pipe could be divided into three regions, namely fixed liquid, locally moving liquid and fully moving liquid, depending on the supplied superficial air velocity.
TL;DR: In this article, a gas-liquid phase-change model was adopted to study the characteristics of two-phase flow and heat transfer, and three types of wettability surfaces (hydrophilic, hydrophobic, and gradient Wettability) were explored under different mass fluxes with subcooling inlet and constant heat flux conditions.
TL;DR: In this article, the authors present an experimental system for slug-flow tubular crystallization that employs a spatial temperature profile and directed noncontact ultrasonication to induce primary nucleation to enable the generation of a wide variety of crystal size distributions.
Abstract: Continuous slug-flow tubular crystallization has been explored by several research groups in academia and industry as a way to produce crystals while having low capital equipment costs In this crystallization type, slugs of slurry and gas consecutively travel through a tube, with a high degree of mixing and temperature uniformity within each slug This article presents an experimental system for slug-flow tubular crystallization that employs a spatial temperature profile and directed non-contact ultrasonication to induce primary nucleation to enable the generation of a wide variety of crystal size distributions The crystal size distributions are compared for data collected from a full-factorial experimental design (27 experiments in total) to predictions from a population balance model that includes the effects of ultrasonication on primary nucleation This population balance model for tubular crystallization is the first that incorporates the effects of ultrasonication and dissolution on the crystal size distribution The crystal size distributions are reasonably consistent with the model, within 20% prediction error, for all experiments in which the spatial temperature profile is monotonically decreasing and at low to moderate supersaturation Potential causes for weaker agreement for other experiments are discussed
TL;DR: Based on the image processing technique, the decay law and swirl length of swirling gas-liquid flow induced by a vane-type swirler in a vertical pipe is experimentally and theoretically studied in this paper.
TL;DR: In this article, vertically upward steam-water two-phase flow has been carried out in a single-side heated narrow rectangular channel with a gap of 3mm, and the experimental data has been compared with other flow pattern maps and transition criteria.
TL;DR: In this article, selective extraction of zinc from sulphate effluents containing zinc, cadmium and manganese by liquid-liquid extraction with a capillary microreactor operating in the slug flow regime was investigated.
TL;DR: In this paper, the enhanced flow boiling heat transfer of HFE-7100 in wavy copper microchannel heat sink was experimentally studied, which was fabricated with the picosecond laser technique.
TL;DR: In this paper, the effect of the gas-liquid phase separation caused by seawater boiling on the carbonate crack dissolution process was investigated using the lattice Boltzmann (LB) method at the pore scale.