Liutex-based flow structure characterization in vibrating downhole hydrocyclone for oil-water-sand multiphase systems

Various chemical products are synthesized in processes using gas/liquid reactors with bubbly flows. Hence, there is a significant interest in a more efficient process design as well as in process intensification with a strong focus on this reactor class. However, the design of industrial gas/liquid reactors requires more detailed information about the flow structures and characteristics of two‐ or multiphase systems. The basic models for two‐fluid model simulations of dispersed gas/liquid flows in bubble columns at high gas fractions are presented.

Zahlreiche Produkte der chemischen Industrie entstehen in Gas/Flüssig‐Reaktoren mit Blasenströmungen. Entsprechend groß ist das Interesse daran, diese Reaktorklasse zu optimieren. Zur Auslegung industrieller Gas/Flüssig‐Reaktoren sind möglichst genaue Informationen über Strömungsstruktur und ‐verhalten des vorliegenden Zwei‐ oder Mehrphasensystems nötig. Die für die Simulationsgüte wesentlichen Modelle für die zwei‐fluid‐modell‐basierte Simulation disperser Gas/Flüssig‐Strömungen in Blasensäulen bei hohen Gasgehalten werden erläutert.

XRD, NMR, and DSC results indicate that both block poly(ethylene oxide-co-nylon 6) and poly(ethylene oxide-co-nylon 12) are separated, multiphase systems that include a well-defined polyamide crystalline phase, a polyamide amorphous phase, and a predominantly amorphous polyether phase. The DSC data suggest the existence of polyether-based crystallites in both cases. However, a polyether crystalline phase was not detected by XRD, indicating either that it is a minor component or that the crystallites are very poorly defined compared to the homopolymer. In addition, the NMR and XRD results reveal that the crystalline polyamide phase in both polymers adopts a structure (α or γ) similar to that found in the corresponding polyamide homopolymer

Mucoadhesive buccal films (MBFs) provide an innovative way to facilitate the efficient site-specific delivery of active compounds while simultaneously separating the lesions from the environment of the oral cavity. The structural diversity of these complex multicomponent and mostly multiphase systems as well as an experimental strategy for their structural characterization at molecular scale with atomic resolution were demonstrated using MBFs of ciclopirox olamine (CPX) in a poly(ethylene oxide) (PEO) matrix as a case study. A detailed description of each component of the CPX/PEO films was followed by an analysis of the relationships between each component and the physicochemical properties of the MBFs. Two distinct MBFs were identified by solid-state NMR spectroscopy: (i) at low API (active pharmaceutical ingredient) loading, a nanoheterogeneous solid solution of CPX molecularly dispersed in an amorphous PEO matrix was created; and (ii) at high API loading, a pseudoco-crystalline system containing CPX-2-aminoethanol nanocrystals incorporated into the interlamellar space of a crystalline PEO matrix was revealed. These structural differences were found to be closely related to the mechanical and physicochemical properties of the prepared MBFs. At low API loading, the polymer chains of PEO provided sufficient quantities of binding sites to stabilize the CPX that was molecularly dispersed in the highly amorphous semiflexible polymer matrix. Consequently, the resulting MBFs were soft, with low tensile strength, plasticity, and swelling index, supporting rapid drug release. At high CPX content, however, the active compounds and the polymer chains simultaneously cocrystallized, leaving the CPX to form nanocrystals grown directly inside the spherulites of PEO. Interfacial polymer-drug interactions were thus responsible not only for the considerably enhanced plasticity of the system but also for the exclusive crystallization of CPX in the thermodynamically most stable polymorphic form, Form I, which exhibited reduced dissolution kinetics. The bioavailability of CPX olamine formulated as PEO-based MBFs can thus be effectively controlled by inducing the complete dispersion and/or microsegregation and nanocrystallization of CPX olamine in the polymer matrix. Solid-state NMR spectroscopy is an efficient tool for exploring structure-property relationships in these complex pharmaceutical solids.

The identification of flow pattern is a basic and important issue in multiphase systems. Because of the complexity of phase interaction in gas-liquid two-phase flow, it is difficult to discern its flow pattern objectively. In this paper, we make a systematic study on the vertical upward gas-liquid two-phase flow using complex network. Three unique network construction methods are proposed to build three types of networks, i.e., flow pattern complex network (FPCN), fluid dynamic complex network (FDCN), and fluid structure complex network (FSCN). Through detecting the community structure of FPCN by the community-detection algorithm based on K -mean clustering, useful and interesting results are found which can be used for identifying five vertical upward gas-liquid two-phase flow patterns. To investigate the dynamic characteristics of gas-liquid two-phase flow, we construct 50 FDCNs under different flow conditions, and find that the power-law exponent and the network information entropy, which are sensitive to the flow pattern transition, can both characterize the nonlinear dynamics of gas-liquid two-phase flow. Furthermore, we construct FSCN and demonstrate how network statistic can be used to reveal the fluid structure of gas-liquid two-phase flow. In this paper, from a different perspective, we not only introduce complex network theory to the study of gas-liquid two-phase flow but also indicate that complex network may be a powerful tool for exploring nonlinear time series in practice.

It is known that the Eulerian-Lagrangian approaches for dispersive multiphase flows can simulate detailed flow structures with a much better spatial resolution than the Eulerian-Eulerian approaches. However, there are still unsettled problems regarding the calculation method for two-way interaction. Especially, numerical instability due to the dispersion's migration beyond computational mesh is a serious issue for accurate prediction of flow instability in multiphase systems as well as multiphase turbulent flows. This paper describes revised methods for calculating the continuous phase flow which is induced by the spherical dispersion's migration. Basic principle of the methods are of introduction of template functions which convert discrete mass and momentum sources of the dispersion to spatially continuous sources. Performance of Gaussian and sine wave's template functions are examined and good pridictionability of local two way interaction have been confirmed.

The design of industrial gas/liquid reactors such as bubble columns requires detailed information with respect to the flow structure and characteristics of two‐ or multiphase systems in the reactor. The contribution is focused on the evaluation of the simulation results obtained by model selection. The results are further compared with those reported in literature. The simulation has been performed with the CFD software OpenFOAM®. The main focus of the numerical simulation was set on capturing the characteristic process and design parameters of bubble columns.

We describe the use of low-coherence interferometry (LCI) for the structural characterization of nonuniform media with mesoscopic heterogeneities. The high sensitivity of LCI to the phase properties of scattered light makes it a suitable technique for the direct determination of size, concentration, and uniformity of heterogeneities in multi-phase systems. To demonstrate this, we examine using LCI to study a range of polystyrene microsphere suspensions with particle sizes ranging from 41 to 818 nm and concentrations from 0.25% to 10% by weight. The particle size and concentration information was extracted from the amplitude of the signal by using the theory of light scattering in nonuniform media. We have shown that the fluctuations in the unaveraged LCI signal may be utilized to extract additional information about system uniformity.

研究了重力跳动对液桥表面及内部流体流动的影响, 以期明确重力跳动对多相流体系统的作用效果. 理论研究表明, 当重力跳动作用于液桥时, 液桥反响频率的大小取决于液桥尺寸和物性参数; 实验研究显示重力跳动引入的液桥表面振动、液桥内部流动与温度振动之间存在着三角耦合关系; 数值模拟结果揭示了重力跳动作用于液桥时液桥内部流体的流动结构. 另外, 对理论、实验与数值模拟结果进行了对比验证, 得到了吻合一致的结果.

For years, conventional X-ray tomography has been used successfully to study the flow structures of vertical two-phase gas-solid flows. As a result, the different flow structures of downward- and upward-arranged currents have been described. The additional implementation of a dual-energy technique provides the opportunity to investigate multiphase (three phase) systems. The dual-energy technique makes use of the absorption coefficient which varies with the material and the X-ray energy, respectively. Applications in research are, e.g., suspension bubble columns or an injected liquid phase in a gas-solid fluidized bed. Therefore, implementations of computer tomography in process engineering are increasing.

Laser interferometry was used to investigate diffusive and convective mass transfer in a multicomponent fluid mixture with a liquid–liquid or liquid–gas interface. For this purpose, an immobile gas bubble or insoluble fluid droplet, having the shape of a short cylinder with a free lateral surface, was inserted into a thin liquid layer. In the case of non-uniform distribution of the dissolved surfactant component, the Marangoni convection near the drop/bubble was initiated by the surface tension inhomogeneities, depending on the surfactant concentration. The applied experimental techniques allowed us to study the structure and evolution of the convective flows and concentration fields in a liquid layer, which due to its small thickness were nearly two-dimensional. Making use of both the vertical and horizontal orientation of the liquid layer, we investigated the mass transfer process at different levels of the interaction between gravity and capillary forces. During the experiments, we detected new solutocapillary phenomena, which were found to be caused by oscillatory regimes of solutal convection occurring around air bubbles and chlorobenzene drops in heterogeneous aqueous solutions of alcohol with a vertical surfactant concentration gradient. The role of the oscillatory instability in the processes of drop saturation by the surfactant from its water solution and an inverse process of surfactant extraction from the drop into the surrounding homogeneous fluid (water) was determined. A reasonable explanation for the driving mechanisms of the discovered effects has been proposed.

A quantitative characterization of the degree of agglomeration of the particles in multi-phase polymer alloy systems has been carried out. A numerical agglomeration distribution function and its 4 moments were calculated from SEM photographs using computer image analysis. In a model alloy system of PC/MBS a good correlation between the degree of agglomeration of the MBS and of the impact strength has been obtained. In PBT/PC alloys, the effect of mixing conditions in the heating rolls on the distribution of particle diameter, ligament thickness between particles and degree of agglomeration have been examined. A similar analysis has been carried out on on the PBT/PC alloys mixed with an extruder. The results showed that increasing agglomeration of the dispersed phase (PC) reduced the impact strength when the matrix was composed of high molecular weight PBT.

The treatment and analysis of small-angle X-ray scattering data are reviewed with specific concern for the glass science. The studies detail the characterization of the submicroscopic structure existing in terms of two-phase particulate systems, multiphase particle systems, non-particulate systems, including those of fractal surfaces, and the application of small-angle X-ray scattering to the examination of the intermediate-range order of glasses. The methods developed are illustrated by small-angle X-ray scattering and anomalous small-angle X-ray scattering results obtained from optical filter glass, glass produced by the sol–gel technique, optical colorless glass inclining to opalescence, porous glass and single-phase phosphate glass.

The mechanism of the meso-scale structure in multi-scale reaction systems in the bubble columns is of great significance in chemical engineering. A typical analytical method to investigate the mechanism for the regime transitions of the flow in the sys-tem is through the EMMS(energy-minimization-multi-scale) model. In the EMMS model, by introducing the stability condition to reflect the idea of ‘compromise-in-competition between dominant mechanisms’, the researchers can transform the multiple objectives(energy consumptions) problem(MOP) in the system into a single objective problem(SOP) to be optimized. In our previous works, we formulated the multi-objective problem(MOP) in the gas-liquid system as a noncooperative game between the tendencies of small and large bubbles. Since there are two players and three free variables, the problem arises to distribute appropriate strategies to the players. Based on this idea, we have build two different game models by two different ways of strat-egy distribution. They showed different systems states at GNE while the first game model seemed to agree with the prediction of EMMS model on the transition regime. In this paper, we will give some explanations on these findings. We will show that the optimal point of the SOP in EMMS model differs with the GNE of the fitst game model actually. This reveals the complexity of the multi-phase reaction systems and implies that the mechanism of the meso-scale structure is absolutely not naive and needs more further investigation.

ABSTRACTContinuous mixing and dispersing process flows produced by scraped surface heat exchangers (SSHE) in food technology influence the microstructure of multiphase food systems and hence desired quality aspects (e.g. specific texture properties and temperature resistance). Such process flows in general depict non‐Newtonian fluid behavior. To explain and optimize the structuring mechanism of food systems (due to mixing and dispersion) treated in such process apparatus the knowledge of the local flow behavior is necessary.In this paper a scraped surface apparatus with special narrow annular gaps including two wall scraper blades is chosen as model process (scraped surface heat exchanger (SSHE)). To get optimizing criteria in the SSHE for mixing and dispersion of shear‐thinning fluids which include structuring components, a numerical particle tracking method (NPT) was developed and used to investigate local flow behavior for various scraper blade geometries and rotational velocities. The flow fields considered are received from numerical flow simulations (finite volume method (FVM)), which have been validated with experimental velocity field measurements (digital‐particle image velocimetry method (D‐PIV)). Besides the flow field and pressure contours, values of elongational and shear rates (as components of the deformation rate tensor, causing flow structuring contributions) are compared along characteristic particle tracks in order to get a quantitative information on the mechanical history which is experienced by the structuring units. Related flow structuring contributions are defined in terms of elongational and shear energy dissipation, integrated over the particle residence times along the tracks. Hence the effects of the rotational velocity ω, the scraper blade angle β and the scraper blade gap rs on the flow structuring contributions are discussed and suggestions of SSHE geometries for food processing are given.