Coupling the organic/inorganic permeabilities in shale is fundamental. Simple treatments, including the arithmetic/geometric average methods, are problematic and can lead to large errors. More complicated methods can generate reasonable results but are much more expensive. In this work, a simple and accurate empirical model for the equivalent permeability of shale considering permeability contrast between organic and inorganic matter and TOC is established. Geometric explanation of the parameters in the model is also provided. Afterwards, model validation against numerical data demonstrates the accuracy of the model in all realistic scenarios. Moreover, model comparison with arithmetic/geometric average methods shows the superiority of the model in accurate calculation while keeping the form simple. Finally, the model is applied to liquid flow in shale, and the results are analyzed. The model is highly recommended for theoretical studies in shale gas/oil that need coupling of the organic and inorganic permeabilities, including single-phase and multi-phase flows.

Flotation is a density separation process which is influenced by physico-chemical interaction between a particle and a bubble. In biotechnology, it finds application in the solid-liquid separation of biomass. The process mechanism depends on the formation of stable microorganism-bubble-complexes by collision and adsorption. The difference in density of these complexes and the surrounding liquid medium causes them to rise to the liquid surface, where a foam develops. This microorganism enriched foam can then be removed. An economical comparison of the separation technologies centrifugation, cross-flow-filtration and flotation showed, that flotation is a financially and energetically interesting alternative process step for the harvest of microorganisms. In this work separation results with a model microorganism S. cerevisiae are presented. Experiments were conducted batch-wise in a 6L- laboratory dissolved air flotation setup, where bubble generation classically results from expanding air from supersaturated medium. Goal was the optimization of the flotation rate and the energy efficiency of the flotation process by adaptation of operational parameters, such as gas- and recycle flow rate and saturation pressure. Flotation models show proportional dependency between the flotation rate and the bubble size and bubble surface area flow rate. Therefore, the effect of operational parameters, such as saturation pressure, recycle and gas flow rate, on the bubble size and surface area flow rate was analyzed. The positive effect of an increasing bubble surface area was possible with increasing gas flow rate, recycle flow rate and saturation pressure. Decreasing bubble sizes were measured for increasing recycle flow rate and saturation pressure, meanwhile the contrary was the case with an increasing gas flow rate. Evaluation of the flotation rate and flotation energy efficiency showed, increasing the recycle flow rate and the saturation pressure both improved the flotation rate, but had low effect on the energy efficiency. Increasing the gas flow rate improved both flotation rate and energy efficiency. It is the most interesting operational parameter for enhancing the process efficacy.

To cope the challenges including the low areal energy density and interface engineering between electrode and electrolyte of quasi-solid-state supercapacitors. We herein demonstrate the rational design and synthesis of ion/electron dual-conductive carbon nanoflowers assembled by N,S co-doped two-dimension mesoporous nanosheets. Electronic density functional theory calculations suggest that the S doping could lead to an extra quantum capacitance and suppress the side reactions. The structure characterization suggests that the bigger S atoms could enlarge interlayer distance of carbon from 0.347 nm to 0.378 nm, accelerating ions diffusion kinetics. Consequently, the N,S-C nanoflowers deliver excellent electrochemical performances even the loading mass of N,S-C reaches 6.38 mg cm-2 owing to the good electrical conductivity and low charge transfer resistance. Furthermore, the a symmetrical quasi-solid-state supercapacitor is assembled and delivers a high specific capacitance of 52.5 F g-1 even at 13.5 mg cm-2 and a capacitance retention of 97.2% after 10000 cycles.

Transient gas-liquid flow dynamics in partially aerated square cross-sectioned bubble columns were studied using an Eulerian-Eulerian based large eddy simulation approach. The numerical model was validated with the interfacial closures evaluated for drag, lift and virtual mass forces. The simulation data showed good agreement with both numerical predictions and experimental measurements in the literature. The current model was also shown to be able to predict the global gas holdup in the bubble column up to a very high value. Further simulations were performed to study the influences of initial liquid phase height to width ratio and inlet area to column cross-sectional area ratio on the global gas holdup in the bubble column. The numerical results indicated that the global gas holdup increases linearly with the superficial gas velocity. Thus, an empirical multivariate regression model was proposed to predict the global gas holdup with an adjusted R-square value of 0.99.

W1/O/W2 compound droplets generation in a co-flowing microfluidic device with two-step structure was observed through experiments, and the formation process is quantitatively studied. Further the effects of the flow rates of all phases as well as the viscosity of W2 phase on the geometric size are extensively investigated. The results indicate that the outer diameter of compound droplets mainly depends on the flow rate and viscosity of external phase. The core water droplet diameter can be controlled by adjusting the flow rates of both inner and middle phases, and it is more sensitive to inner phase. Generally, the inner diameter of compound droplets is not only relative to the core droplet diameter, but also influenced by the encapsulated core water droplet number. Finally, a prediction correlation for dimensionless outer diameter with several dimensionless numbers is obtained. The results could provide an experimental basis for controllably preparing millimeter-scale monodisperse compound droplets.

Industrial denitrification catalyst monoliths are regularly tested in controlled lab-scale conditions to quantify their activity. As mass transfer phenomena occurring inside the channels of the monoliths have an important impact on the global denitrification kinetics, activity measurements must be conducted in well-known conditions in terms of sample geometry and gaseous flow regimes, among others. The lack of accurate mass transfer correlations for the complex flows at stake however prevents any accurate generalisation of the test results. In this paper, we propose a semi-empirical method for the quantification of contribution of mass transfer to the global denitrification kinetics for any given test bench. It is based on the experimental adjustment of mass transfer correlations presenting a suitable form. Mass transfer can therefore be decoupled from the intrinsic kinetics and large ranges of conditions can be covered by conducting a limited number of measurements.

Monoclonal antibodies (mAbs) are one of the most important class of therapeutic proteins. Their proteinaceous nature makes them labile towards aggregation, considered a critical quality attribute (CQA) as it affects safety and efficacy of a biotherapeutic product. Present study examines early stage aggregation behaviour of monoclonal antibodies experimentally. The process is also described using hybrid reaction and population balance model. Size exclusion chromatography and dynamic light scattering have been used to obtain kinetic parameters featuring in the mechanistic model. The aggregation process of two different mAbs in the presence of either acetate or citrate buffer is analysed at two temperatures. The rate of aggregation is found to be significantly influenced by the type of buffer medium (faster in citrate compared to acetate buffer). The enhanced aggregation in citrate buffer is attributed to the reduction in the net energy barrier for protein-protein interaction resulting in loss of stability of mAb species.

To high value-added utilization of waste polystyrene (PS) foam, an in-situ phase change material (PCM) encapsulation protocol was realized by using waste PS foam as a holding material for thermal energy storage with a shape-stabilization methodology. Mechanistic study suggested that the robust Lewis acid catalysed Friedel-Crafts reaction involved was the key to the success of this method owing to a simultaneous process of porous structure formation and PCM impregnation, by which the PCM encapsulation rate can attain to 68.7% without leakage. Lewis acid catalysts used in the process were able to be converted to their corresponding metal oxides via a simple alkali treatment, which not only diminished the tedious metal species isolation step but also made an external thermal conductivity enhancement that an utmost 61.0% thermal conductivity enhancement can be achieved compared with that of pristine paraffin wax. Additionally, the PCM composite preparation process can be facilely scaled up which strongly demonstrated its real application feasibility. Moreover, besides waste PS foam, other waste PS based materials were proven to be feasible towards PCM holding materials with the same approach.

Molten compositions in the CaO-K2O-SiO2 system relevant to woody biomass ash slags were simulated with molecular dynamics to extract structural characteristics. Multivariate analysis elucidated correlations of these structural characteristics with viscosity measurements. The simulations show SiO4/silicate tetrahedral units (STUs) diffusing slowly and forming flexible networks via oxygen bridges. The degree of STU polymerization varies linearly with the (K2O + CaO)/SiO2 ratio. Ca depolymerises stronger than K, but K diffuses quicker. Depolymerization and diffusion cause network disruptions and agitations that promote collective atomic mobility of the system. This imposes structural characteristics in the slag that correlate with viscosity. The inter-STU Si-O-Si angle narrows with decreasing viscosity, while the Si-O bond length of these bridges increases. Attributes related to atomic mobility, such as the variations in the Si-O-Si angle and the distance of nearest Si–Si pairs, also correlate with viscosity. The discussion provides insight into the connection between structural characteristics and viscosity.

Novel chloride-substituted octylphenoxy polyoxyethylene (COP20, polymerization degree: 20) was synthesized. Xanthan gum (XG) was then modified by using COP20 to produce XGP20. XGP20 could be expected to be applied in polymer flooding. Compared with XG, the XGP20 solutions exhibited lower interfacial tensions in additional to higher apparent viscosities and salt-thickening effect. Its critical micelle concentrations (CMC) were 0.3 g/L in water and 5 g/L NaCl at 30 °C, and the interface tension was 0.46 mN/m in the saline solution. Large associating structures formed in the XGP20 saline solution. The thermodynamic data of micellization revealed that the micelle formations were spontaneous from 30 to 50 °C. Both standard enthalpy and entropy increased clearly with temperature. Compared with XG, the resistance and residual resistance factors were evidently higher in 5.177 g/L salt for XGP20. Nuclear magnetic resonance images showed that the sweep efficiency of water was enhanced significantly after XGP20 polymer flooding.

Under certain conditions in preferred three-stream geometries, a non-Newtonian airblast atomization flowfield violently pulses (axially and radially) by self-generating and self-sustaining interfacial instability mechanisms. The pulsing is severe enough to send acoustic waves throughout feed piping networks. The most recent work on this system instructed that exothermic chemical reactions enhance this moderate Mach number atomization. Explored herein is the potential to further enhance reaction-assisted disintegration by independently superimposing both sinusoidal and randomized mass flow fluctuations of +/- 50% of the mean onto otherwise constant gas feed streams using surrogate models. Two nozzle geometries (low versus high prefilming distance) and multiple superimposed feed frequencies (ranging from below to above the naturally dominant tone) are considered for each gas stream, making twenty-one total long-running unsteady PLIC-VOF CFD models. Droplet size, plus nine other temporal measures, were considered for assessing atomizer performance in our energy production process. Results indicate that superimposed frequencies have potential to enhance chaotic atomization in a statistically significant manner. Depending on the geometry, the largest effect was about a 10% reduction in droplet size; however, some combinations experienced a droplet size increase. Only marginal differences were seen in the nine other measures, such as injector face heat exposure. In addition to the immediate industrial benefit from modulation, dramatic changes in acoustics were produced by imposed feed perturbations at frequencies lower than the natural tone. A detailed study of start-up flow reveals new mechanisms which explain performance differences.

Surface activity, foaming ability, and foam stability of SDS and salts mixtures are experimentally studied. It is shown that adding KCl or CaCl2 can increase the surface activity but decrease the foaming ability of SDS solution. The capacity to stabilize SDS foam decreases as KCl＞CaCl2＞NaCl. The SDS foam ageing is delayed due to the crystals blocked in the plateau borders and adsorbed on the surface of bubble films. When the SDS concentration is too high, the foam stability rises only if there are enough crystals in the plateau borders. The influence of crystal structure on foam stability has been investigated by using FESEM. The KDS crystals with lower random close-packing density stabilize SDS foam more efficiently than Ca(DS)2 crystals with higher random close-packing density. The understanding of this study is of great importance for the application of SDS foams in fire extinguishing and upstream petroleum industry.

In this paper two things are done. (1) It is shown that the concept of a direct energy cascade is possible to be violated under specific circumstances as a consequence of dissipation process which initially takes place at Taylor microscales of the inertial subrange. (2) This work predicts, for the first time, the existence of isotropic turbulence at length scales smaller than that of Kolmogorov scales and that it never decays with time as long as the fluid is in motion. It should be remarked that no comparison with experiments searching for the proposed length scales can be made at present.

This work aims to investigate the breakup dynamics of the low-density gas and liquid interface during bubble formation in a microchannel flow-focusing device. A high-contrast interface tracking method is developed. After the neck motion analysis in radial and axial directions, the time domain criterion between the liquid squeezing stage and the free pinch-off stage is proved to be two orders of magnitude less than the capillary time and is close to the viscous time of the liquid. Comparing to Nitrogen bubbles, the pinch-off point of Helium bubbles deflects downstream in viscous liquids and upstream in low surface tension liquids. Helium bubbles generate faster in viscous liquids and slower in low surface tension liquids. The power law exponents of thread diameter to the pinch-off remaining time in Helium experiments, which are larger than those in Nitrogen experiments, agree with previous studies in both ranges (1/3 to 1/2) and tendency.

According to the recent researches, adding nanomaterial within the pure refrigerant can substantially enhance the heat transfer rate in phase change (boiling/condensing) flows. Therefore, for a given operating conditions, it is unclear whether the heat transfer is optimized at a certain mass fraction of nanoparticles. In the present study, an integrated analytical, and experimental approach was scrutinized to find the heat transfer optimization of flow condensation using nanorefrigerant. For the experiment, CuO nanoparticles were disperesed with varying mass fractions (0.5–3.5%) in the baseline refrigerant/oil (R600a/POE) to produce Nanorefrigerants (R600a/POE/CuO). The optimum nanomaterial concentration for maximum perfromance has been desiganted by a novel optimization method called two stage-Bayesian optimization (TS-BO), which replaces the expensive experimental process by a cheap surrogate model constructed by Kriging. It was proved that the optimum nanoparticle fraction is significantly depend on the mass velocity and vapor quality while at a fixed vapor quality, the optimum nanoparticle concentration increased with decreasing mass flux. The highest heat transfer enhancement was achieved by nanparticle concentrations of 1.5–2.2%.

Mixing downstream of a moving square cylinder placed inside a square section channel was analyzed experimentally and numerically at blockage ratio 2/5 and Reynolds 200. Three frequencies were considered for the prescribed sinusoidal, constant amplitude, cylinder motion: 0.5f0,1f0 and 2f0, where f0 stands for the frequency of the first instability of the wake in the unmoving cylinder case. Mixing was quantified by computing the downstream standard deviation of the distribution of virtual particles seeded behind the cylinder. Experimental PIV frames were used to evaluate mixing at the channel symmetry plane. Numerical streak-lines were used to compute mixing at the full section of the channel. The power required to move the cylinder was computed as well. It was found that maximum mixing efficiency combined with minimum motion power occurred for the frequency 1f0, proving that optimum mixing does not necessarily require high frequencies and/or high input power.

Pipelines are one of the most efficient methods to transport large quantities of natural gas from gas reserves to main markets. However, because of the unsteady nature of gas flow, the operation of pipelines is always dynamic. Furthermore, the uncertainties in demand and the fluctuation of gas composition also make the efficient operation of these dynamic processes challenging. This study addresses the problem of determining the optimal operation to minimize compression costs, while considering demand and gas composition uncertainties. A dynamic pipeline network model is developed with rigorous thermodynamic equations, allowing accurate calculation of gas compressibility factor at any temporal and spatial point. The supply gas composition and demand nodes flow rates are assumed to be uncertain. To deal with these uncertainties, a robust optimization algorithm is applied using back-off constraints calculated from Monte Carlo simulation. Through successive iterations, the algorithm terminates at a solution that is robust to a specified level of process variability with minimal cost. We show from the case studies that the formulated model and the algorithm can successfully address the problem with acceptable computational cost.

Vertical falling film with low Reynolds number (Re) is widely used, but the influence of surface waves on mass transfer is still unclear. This paper theoretically described the wave structure along the flow direction, and evaluating the enhancement on mass transfer during halide-solution/air absorption. The effects of flow viscosity, surface tension gradient, liquid/air convective heat transfer, film thickness and flow distance are considered. Model validation were performed by comparing with the data from literatures and our experiments. For practical use, empirical correlations of wavelength and amplitude are provided, using Re, Marangoni and Nusselt numbers as variables. Wavelength increases proportionally with liquid Re, and amplitude mainly increases with the flow distance. When Re increases from 20 to 60, wave amplitude and wavelength increase by 10% and 40%. The enhancement effect is determined by the wavelength and frequency, and is more obvious under conditions of large liquid concentration or small liquid Re.

The tortuosity of kerogen pore structures is a vital parameter in the quantification of the gas diffusion ability and production of shale reservoirs. In this study, we perform a molecular dynamics simulation on the gas diffusion in the molecular- and nano-scale pores of shale kerogen to evaluate the tortuosity of the kerogen pore structure to gas diffusion. A novel diffusion model is proposed to evaluate the tortuosity by considering gas adsorption affinity, transportation regime, and probe gas atomic size. The results indicate that the tortuosity of the kerogen pore structure to gas diffusion is not a constant; instead, it highly depends on the probe gas atomic size and gas adsorption ability. The diffusive tortuosity is overestimated when the effect of gas adsorption ability is ignored. We find that the electrical tortuosity is lower than the diffusive tortuosity. This confirms that the tortuosity is underestimated when considering a purely geometric effect.

Crystallization fouling models for heat transfer surfaces are indispensable to provide reliable prediction of fouling behavior that would, in turn, facilitate the optimal design and operation of heat exchangers. Nonetheless, most previous models exclude surface properties in terms of surface energy and its components despite many studies confirmed otherwise. In this study, a general fouling model is developed which includes surface energy and its components. Primarily, the surface properties are incorporated into the work of adhesion. Thereafter, these properties, via a force balance, are corresponded to the shear strength of deposit in terms of removal rate. The model predicts that the shear strength of CaSO4 deposit and its adhesion on various coatings would be decreased up to 66% and 91% compared to the untreated surface, respectively. Finally, the validity of the proposed model is examined against the experimental results of CaSO4 crystallization fouling which resulted in good agreement.

The wave characteristics of the turbulent falling liquid film in the development region along the vertical Perspex plate were studied by using an Ultrasonic Doppler Velocimetry (a non-intrusive technique). The instantaneous thickness of the falling film at the center of the plate with axial distance ranges from 50 mm to 1300 mm was measured and the Rel (the liquid film Reynolds number) ranges from 2.28×103 to 1.43×104. The results show that the mean thickness, wave frequency and amplitude increase while the growth rate decreases with the increase of Rel. The Probability Density Function of the liquid film instantaneous thickness tends to an approximately normal distribution with increasing Rel. Furthermore, the Plateau-Rayleigh instability can cause the breakup of the liquid film surface and resist the increase of the liquid film thickness, which results in the fluctuation range of the liquid film approximate to a fixed value when the Rel＞1.20×104.

Kinetic model is significant for disclosing the oxygen permeation process through mixed ionic-electronic conducting (MIEC) membranes. However, current kinetic models are only applicable for certain materials. As a result, it is difficult to select a proper model to compare kinetic parameters of different membranes. In this paper, based on the dependence of oxygen vacancy concentration on oxygen partial pressure in the bulk of MIEC membrane, an extending of Zhu’s model was established for extensive MIEC membranes by revising one assumption in the original model. La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) membranes with different thickness and coated/uncoated LSCF catalyst layers and La0.7Sr0.3CoO3-δ (LSC) membrane were chosen to verify the correctness of the extended model. The fitting results of LSCF and LSC are reasonable and exclusive compared to the original model and Xu-Thomson’s model. In a word, the extended model can be applied to various MIEC materials.

A practical potential equation for mercury was developed, by incorporating the long-ranged interaction and multi-body effects into the temperature-dependent dispersion parameters, to describe the thermodynamic properties of the liquid-vapour equilibrium and adsorption in carbonaceous materials. The collision diameter (σ) decreases and the well depth of interaction energy (ε) increases with temperature, with the product σ6ε (a measure of attraction) decreasing with temperature. The critical temperature derived from this model, 1745K, agrees well with the experimental value of 1751K, and the wetting temperature of mercury on graphite was found to be 1600K, supporting the fact that mercury does not wet carbon under ambient conditions. Furthermore, it was illustrated with mercury can fill ultrafine graphitic slit pores, whose widths less than 0.7nm, under ambient temperatures, because of the enhancement of the solid-fluid potential and the strong intermolecular interactions, and the simulation results qualitatively agree well with experimental data.

This paper focus on the effects of electrohydrodynamic (EHD) on bubble dynamic characteristics generated on a submerged capillary in ethanol under non-uniform electric field, using high-speed photography and with a particular interest in the effect of electrical Bond number (BoE) on the bubble behaviors. The obtained results ranges of BoE from zero to 5.52 and Weber number (We) from 0.0006 to 0.1365 show that the bubble formation process associated with three stages at the low electric field strengths, including the nucleation, stable growth and necking stages, while the stable growth stage is absent for the high field strengths. With the increase of both We and BoE, the bubble period and waiting times are shortened rapidly, while the frequency is accelerated remarkably. The bubble dynamic behavior, which is characterized by the bubble volume and curvature radius, depends primarily on the BoE, and the increase in the We slightly raises the bubble volume and curvature radius at the departure time. Furthermore, it is found that with the increasing of BoE, bubbles coalescence evidenced at high We is weakened and eventually disappeared. Nevertheless, this phenomenon has the tendency to subsequently reappear at the higher We and BoE.

Gas-solid fluidization technology has been commercialized in many industrial applications since its implementation in the fluid catalytic cracking process in the early 1940s, however, the understanding of the complex hydrodynamics of gas-solid flow inside fluidized beds is still far from satisfactory due to its dynamic and multiscale nature, especially, the critical role played by mesoscale structures. In recent decades, computational fluid dynamics (CFD) has become an important toolkit in understanding the physics of complex gas-solid flow and then for the scale-up, optimization and design of gas-solid fluidized bed reactors. This article presented a pedagogical and comprehensive review to the Navier-Stokes order continuum theory for CFD simulation of the hydrodynamics of gas-solid fluidization, without taking the effects of heat and mass transfer as well as chemical reactions into consideration. A concise introduction to the methods for multiscale CFD simulation of gas-solid fluidization was firstly provided, which include direct numerical simulation, (coarse-grained) discrete particle method, kinetic method, continuum method and mesoscale-structure-based multiscale method. The underlying postulates of homogeneous continuum theory that assume the structure inside each computational cell is (nearly) homogeneous were then examined, followed by an overview of the constitutive relationships available in literature, including the particle phase stress models, the interphase drag models and the models for particle-wall interactions. The importance of mesoscale structures that take the form of gas bubbles and/or particle clusters and streamers in the quantification of the hydrodynamics of gas-solid flows was then addressed, and the explicit resolution (or highly resolved) method and implicit modeling method for quantifying the effects of mesoscale structures in continuum modeling of gas-solid fluidization were highlighted. Coarse grid simulation of large scale fluidized beds with proper mesoscale, sub-grid scale or turbulent models for constitutive relationships were then reviewed, focusing on the filtered method, turbulence modelling and heterogeneity-based method where the energy-minimization multi-scale (EMMS) based method is a representative. Finally, the scope for the further research areas is described.

Although superwetting filtration membranes have been widely used, they suffer from the disadvantages of lower flux and membrane fouling caused by the nanoscale pore size. Herein, a laminated cellulose aerogel/membrane composite with large pore size is fabricated via combining facile freeze-drying and hydrophobic modification using cellulose fibers as building blocks. An ultrathin silanization coating layer on cellulose fibers surface is constructed via directly coupling alkoxysilane and endows the composite with excellent superhydrophobicity (161o) and superoleophilicity (0o). Upon contact with a water-in-oil emulsion, the aerogel layer causes the micrometer-sized water droplets to coalesce. The coalesced water droplets are then repelled by the membrane layer with large pore size, achieving ultrafast gravity-driven separation with high separation efficiency (99.5%) and separation flux (12890 L m−2 h−1). Moreover, the composite exhibits ease to cycle and good usability. The outstanding performance of composite highlights its potential applications in the field of oil related industry.

An adaptive algorithm was developed to handle some multiphase situations where outlet information is included in results or multiple inlets/outlets are implemented while only flow rates through inlets/outlets are known. This algorithm includes a first-order expanded Bernoulli equation and a mixed approximation algorithm. The expanded Bernoulli equation offers an initialization value for a concerned object for subsequent approximation processes. The mixed approximation algorithm completes final convergence via iteration and correction. The executed code was successfully compiled into a commercial computational fluid dynamics software. To test the algorithm, a series of corresponding experiments were performed. Three key parameters including the validity of the initialization condition from the expanded equation, convergence efficiency and reliability were evaluated and discussed. The results show that this boundary condition could accomplish the desired functions and maintain errors lower than 15% compared to experimental data, and in less rigorous applications, the error may be approximate to 5%.

This paper examines the fluid dynamics of a pilot–scale high–pressure homogeniser using large–eddy simulation. The mixer consists of a non–planar elliptic jet released into a confined cylindrical chamber. The simulated results are validated by comparing mean quantities with published experimental data. The evolution of the shear layers in the jet near–field shows a localised region of high turbulent energy dissipation rate in the major plane, whereas in the minor plane the dissipation rate is of smaller magnitude and spreads over a wider region. The validity of the turbulence isotropy assumption, typically made in dispersed–phase modelling, is examined. Energy spectra exhibit an amplification close to the nozzle at frequencies associated with vortex shedding. Kolmogorovs classical 2/3 scaling in the second–order structure functions is found to be overshadowed by vortex shedding, resulting in steeper slopes in the jet near–field, where the rate of energy dissipation assumes the largest value in the mixer.

Brazilian pre-salt reservoirs represent the discovery of large amounts of light oil, but at high pressures and containing high concentration of CO2. Proper parameter estimation procedures are essential to perform more accurate predictions of their thermodynamic properties. Therefore, two new methodologies for such calculations have been implemented here: by applying simultaneously VLE and LLE to the metric; and by handling water content in dew point conditions. Utilizing the Cubic-Plus-Association (CPA) EoS, they were employed to obtain new parameters for water. Also, new parameters were obtained for H2O + CO2 mixtures, whose average absolute deviation in water content at high pressures fell from 24% to 3% compared to previous publications. The same procedure was performed for other aqueous mixtures containing H2S and light hydrocarbons. Finally, this study has been applied into a natural gas compressing simulation with CO2, studying streams properties comparing the parameters obtained in this work with the literature.

The paper presents an assessment of turbulence models in dispersed bubbly flows based on an analysis of their application to uniform and uniformly sheared homogeneous turbulence. This analysis leads to the development of a five-equation model where the total turbulent fluctuations in bubbly flow is submitted to a double decomposition: First, the turbulent fluctuations are split into Shear-Induced-Turbulence (SIT) and Bubble-Induced-Turbulence (BIT) components. Secondly, The BIT contribution is split into two components corresponding to non-dissipative pseudo-turbulent part and dissipative turbulent part produced by local shear in bubble’s wake. Consequently, the total turbulent energy is split into three contributions : two dissipative quantities kt and ks produced respectively by gradient of mean velocity in the liquid phase and by local shear in bubble’s wake both are described by their modeled transport equations as well as their dissipation rates εt and εs; and a non-dissipative component kp attributed to fluctuations of potential flow around bubbles described by its modeled transport equation. This model was implemented in CFD code and validated in homogeneous bubbly turbulence situations. The numerical results show a satisfactory agreement with experimental data of turbulence.

A set of rate laws for hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and aromatic hydrosaturation (AHS) of diesel was established to describe ultra-deep HDS in the sulfur concentration range from more than 10,000 ppm to below 10 ppm. High throughput experiments in micro-packed bed reactors with 2 mm inner diameter were conducted using NiMo/Al2O3 catalyst at temperatures from 300 °C to 360 °C, a pressure range of 4.4 MPa to 7.4 MPa, and liquid hourly space velocity (LHSV) between 0.75 h-1 and 12 h-1. To establish the rate laws, the sulfur content is divided into two regions, and the inhibition effects of H2S, nitrogen compounds, aromatics and the virtually refractory compounds was included. All kinetic parameters were estimated by combining genetic algorithm and least square regression to fit experimental data well. Finally, an appropriate operation interval of such reactor was obtained by using the developed model.

A diffusion model of gas hydrate dissociation into ice and gas is presented, which allows us to simulate the self-preservation effect of gas hydrates. This model takes into account that the forming ice layer has a porous structure that changes during the process of gas hydrate dissociation. Three problems of gas hydrate dissociation into ice and gas were considered separately: the dissociation of a spherical gas hydrate particle, the dissociation of a cylindrical gas hydrate, and the dissociation of a flat gas hydrate layer. For each problem, a solution in the framework of a quasi-stationary approximation is obtained. From the comparison of the calculated data with the available experimental data on the kinetics of dissociation of a powdery methane hydrate into ice and methane, the molecular diffusion coefficient of methane in ice and the diffusion coefficient of methane through the system of pores in the forming ice layer were estimated. Based on this estimation, an explanation of the anomalous preservation thermal regime of methane hydrate is provided.

Bio-based lubricants are an attractive class of products, gaining more attention in the recent years. The production of bio-based lubricants starting from vegetable oils derivates (e.g. epoxidized) and alcohols is gaining relevance among the various synthetic routes. Brøensted acids are normally used to promote the oxirane ring opening reaction, obtaining interesting products depending on the branching and chain length of the alcohol molecule. The use of homogeneous catalysts leads to evident drawbacks that could be overcome by replacing them with heterogeneous catalysts. Clays can be considered good candidates as they show reasonable acidity and are characterized by high availability and low price. In the present paper, the use of TONSIL EX 2166 was demonstrated to be a good candidate for the synthesis of bio-lubricant bases in the presence of 2-butanol. A kinetic model was proposed to describe the physical and chemical phenomena occurring in the reaction network.

Interest of Clathrate hydrates for industrial applications is rising. While numerous studies can be found on carbon capture or desalination, this effort investigates thermodynamics of the combined process using cyclopentane (CP) as second guest molecule. This document provides numerous equilibrium data of mixed CP/CO2 hydrates in presence of salt (NaCl, KCl) under differents concentrations. Final dissociation points are collected, as well as intermediate dissociation points in presence of hydrates. While the first provide equilibrium data, the others are not at equilibrium. Indeed, Results show that, in presence of salts, several crystallization events occur in the system. Consequently, multiple hydrate structures could be formed in the bulk, such as pure CO2 hydrates and mixed CO2/CP hydrates Finally, van der Waals and Platteeuw approach has been used and furnishes results within 0.4K uncertainty compared to this work and within 0.5K compared to literature. Besides, thermodynamic consistency of data has been evaluated.

In this paper, a study on the generation of foam in the presence of nanoparticles in porous media using microfluidics is reported. Drainage and co-injection tests were carried out and monitored with a high-speed camera. Convolutional neural network model was applied to quantify foam texture over time, efficiently. Microscopy images show a generation process characterized by early snap-off, followed by lamella-division, and finally leave-behind. In the presence of nanoparticles, the latter stage is delayed due to resistance to drainage imparted by capillary forces within the liquid films. Moreover, a general relationship between the generation rate and the pressure gradient, which resembles the classical constitutive equation for foam generation, i.e., rg∝∇Pα, could be formulated. This indicates that the generation of a foam in the presence of partially hydrophobic nanoparticles and anionic surfactant, used for strong foam formation, follows the same mechanism of a foam stabilized only with surfactant.

This paper is devoted to large eddy simulations of a turbulent flow in an un-baffled stirred tank reactor with vortex effect. The work aims at providing reference solutions regarding the hydrodynamics and the different mixing regions. Such data serve in modelling the precipitation process that takes place in many chemical engineering applications. The numerical study is performed by the open source TrioCFD code that employs a discontinuous front-tracking algorithm to solve the free surface at the top of the reactor. A sufficiently converged mesh has been identified from a sensitivity analysis where a convergence at the same order of the employed numerical scheme has been recorded. The quality of the resolved fields confirm that the performed LES is good and that the mesh size is almost of the Taylor turbulent micro-scale order. The converged statistical fields have shown a good agreement with both the theoretical models and the experimental measurements.

We report a joint experimental, numerical and theoretical study of particle residence times in a novel vortex-based vessel for thermal processing of suspended particles. The tracer pulse-response method, in which the particle phase itself is employed as the tracer, is used to measure the particle residence time distribution (RTD) within a laboratory-scale model of a class of Solar Expanding Vortex Receiver-Reactor (SEVR). The operating parameters of particle size, gas volumetric flow rate and inlet velocity were systematically varied to assess their influence on the particle RTD and to determine the mechanisms controlling the behaviour of the two-phase flow in the SEVR. The particle RTD behaviour is also described by a compartment model consisting of a small plug flow reactor followed by a series of two interconnected continuously-stirred tank reactors (CSTRs).

The electrical capacitance tomography (ECT) is a promising measurement technique, which tries to reconstruct the permittivity distribution in a measurement domain by solving an inverse problem. Low quality images narrow the applicability of the technique. To address the challenge, a new cost function, which considers model deviation and measurement noises, is devised to model the ECT reconstruction problem. The soft thresholding method and the fast-iterative shrinkage thresholding technique (FIST) are embedded into the iterative split Bregman (ISB) method to solve the devised objective functional. The numerical and experimental results indicate that the proposed ECT imaging technique not only mitigates the ill-posed nature, but also improves the reconstruction quality.