Initial Droplet Size Distribution Research Articles

Particle morphology of alkali metal chloride salts in induction heating based pulsed spray drier: Experimental analysis and ANN prediction

Hygroscopic nature of alkali metal chloride salts makes attaining mono-sized dried particles from their aqueous precursor solution an engineering challenge for conventional co-current or counter-current spray driers. Conventional spray driers offer better thermal utilization in either the spray zone or dried particle zone depending on their configuration viz. co-current or counter-current, respectively. In this work, an alternative prototype named induction heating based pulsed spray drier (IH-PSD) is proposed to obtain dry alkali metal chloride salt powders with narrow particle size distribution. Laser diffraction analysis is carried out for initial droplet size distribution whereas scanning electron microscopy and sieve shaker analysis is carried out for studying the particle morphology and particle size distribution of dried powder for all the selected salts. The resultant particle properties emphasized in the present work are the dried particle to initial droplet diameter ratio and the wet basis moisture content. It has been observed that the ratio of mean volume diameter of dried particle to sauter mean diameter of initial droplet lies in the range of 0.4–3.6 meanwhile the wet basis moisture content of dried powder lies in the range of 1.4–3.6 for the selected salts. Artificial neural network (ANN) model is applied for inferring the influence of IHPSD process parameters on the above mentioned dried particle properties and satisfactory convergence with experimental values has been achieved.

Induction heating-based pulsed spray drier for dewatering of alkali metal halide salts: Numerical model and its experimental validation

Dewatering of alkali metal halide salts in conventional co-current or counter-current spray driers to obtain low moisture content and agglomeration in resultant dried powders is difficult owing to their hygroscopic nature. Co-current spray driers offer the advantage of good heat transport characteristics in spray zone while counter-current spray driers offer better thermal utilization throughout the drying chamber. In the present work, modified prototype of a conventional counter-current spray drier is developed to obtain both these advantages in the drying chamber by employing induction heating and mechanical pulsation techniques. After carrying out several experiments in this prototype viz. Induction heating-based pulsed spray drier (IH-PSD), the optimal process parameters are obtained which maximize thermal utilization throughout the drying chamber and minimize both moisture content and agglomeration in resultant dried powders of sodium and potassium halide salts. The initial droplet and final particle size distributions are obtained using laser diffraction analyzer and sieve shaker experiments respectively. An experimentally validated numerical model implemented using open-source computational solvers is utilized to obtain average drying rates in IH-PSD. It is observed that the average drying rate lies between 0.03 and 0.18 mg/s and 0.04 and 0.14 mg/s for sodium and potassium metal halide salts respectively.

Machine learning assisted characterisation and prediction of droplet distributions in a liquid jet in cross-flow

In this paper, an artificial neural network (ANN) is trained with large eddy simulation (LES) data to predict the droplet size distribution (DSD) from the primary atomisation of a liquid jet in gaseous cross-flow (JIC), in terms of the Weber number (We), momentum flux ratio (q) and density ratio. The JIC is simulated considering three We (250, 500, 1000), q (1, 5, 10), and density ratios (10, 100, 1000), respectively. The accuracy of the simulations is enhanced by including the injector geometry as well. The training data are obtained using LES with a stochastic fields transported-probability density function (PDF) method. We initially provide a physical analysis of the droplet distributions observed. We find that for lower density ratios, the resulting spray is mostly dominated by q, influencing the main mechanisms governing the break-up process, which change the DSD shape. This dual mechanism is not present when increasing the density ratio. In the second part of the work, we build an ANN model (based on a multi-layered perceptron) using the DSDs from the LES as a train-and-test dataset, to predict at the end the full DSD for the JIC given as input the three non-dimensional parameters. The DSD from the trained ANN is found to be a good fit for the range investigated, predicting both the stochastic nature and change in shape of the droplet populations upon varying the input parameters. The developed model is intended to enhance future simulations of secondary atomisation in Eulerian-Lagrangian frameworks by providing the initial DSDs.

A theoretical and experimental investigation of batch oil-water gravity separation

Gravity separation of oil-water emulsions is an industrially crucial process. Mechanistic models for a batch separation process can immensely be beneficial by linking emulsion experimental characterization to optimal industrial equipment design. For this reason, a mathematical model for this process was developed, which considers droplets settling/rising due to buoyancy force, binary and interfacial coalescence of the droplets using a film drainage model, and formation of a homophase. Various models for the droplet slip velocity were compared, which exhibit similar predictions using the Kumar and Hartland model and Behzadi et al. model while different from the Zaki and Richardson model. Another crucial part of the model is the proper mathematical description for forming the dense-packed layer (DPL). This study proposes a new approach to improve the prediction for the DPL formation by introducing diffusion in the model as an advection-diffusion equation. Accordingly, a suitable closure model for effective diffusion coefficient was selected, ensuring physical volume fraction range (0−1) in the system. Finally, the proposed closure model was tuned using experimental data for a stabilized water in model oil emulsion. Experiments were performed by the NMR technique for a wide range of initial water volume fractions (20–60%). The model prediction agrees well with the experiments. In particular, simultaneous agreement with all cases having various initial volume fractions and droplet size distributions suggests that this model can be generalized and applied to a wide range of oil and water emulsions. Additionally, the developed model shows promise as it can ensure physical values for volume fractions.

Liquid-phase temperature in the SpraySyn flame measured by two-color laser-induced fluorescence thermometry and simulated by LES

In the SpraySyn burner (Schneider et al., 2019) a solution of metal salts in a combustible liquid is atomized in a two-fluid nozzle with molecular oxygen as dispersion gas to generate oxide nanoparticles via combustion synthesis. The flame is anchored by a methane (CH4)/oxygen (O2) premixed flat flame stabilized on a porous plate surrounding the spray nozzle. This burner features a standardized design with simple geometry, which provides well-defined boundary conditions for the simulation to support model development and the interaction between experiment and simulation. In this work, two-color laser-induced fluorescence (2cLIF) thermometry based on the fluorescence tracer coumarin 152 dissolved in ethanol is applied to provide temporally averaged but spatially resolved liquid-phase temperature maps. The operating conditions for the spray formation were modified by varying the injection rate and the dispersion gas flow. Liquid-phase temperatures were predicted by large-eddy simulation (LES), where the spray is modeled by a Eulerian-Lagrangian approach based on measured liquid droplet properties (initial liquid-phase temperature, droplet size, and velocity distribution). Droplet size and velocity were measured by phase-Doppler anemometry (PDA). Gas-phase turbulent combustion is modeled with the flamelet-generated manifold (FGM) approach. Droplet temperature distributions were provided by the simulation to assess the systematic measurement error caused by LIF-signal averaging. Experimental and simulated average liquid-phase temperature maps are compared. The simulation results were found to be in good agreement with the experiment by showing a suitable prediction of the droplet heat-up process within the experimentally probed spray region.

65 kHz picosecond digital off-axis holographic imaging of 3D droplet trajectory in a kerosene swirl spray flame

It is difficult to track fuel droplets in a swirl spray combustion field due to three-dimensional (3D) movement and turbulent flame influence. The present work carries out an experimental study to investigate and track the dispersed kerosene droplets in a swirl spray combustion field. RP-3 kerosene and air are mixed and burned in open space under different mixture ratios. Pulsed high-speed (65 kHz) digital off-axis holography with an equivalent pixel size of 9.3 μm is adopted to visualize and quantify the droplet size, 3D position and velocity. The measurement uncertainty of the technique is calibrated and discussed. The turbulent flame of hydrocarbon fuel causes some darker speckles in the morphology view, but droplet images are clear and the initial droplet size distribution at 1 mm downstream of the swirler is obtained. A particle tracking algorithm considering x, y and z with different locating errors and droplet diameter is proposed and applied to obtain droplet trajectory. Smoothed droplet trajectories are obtained through multi-frame tracking and trajectory regressing methods. From the perspective of the Lagrangian view, droplet momentum and size oscillation are also observed and discussed.

Droplet drying and whey protein denaturation in pulsed gas flow - A modeling study

Pulse combustion drying is a novel advanced drying technique that uses pulsating gas flow generated by intermittent combustion. The technique has been used for fine powder production from various materials, including heat sensitive materials such as foods and pharmaceuticals. In this study, denaturation of whey protein isolate (WPI) during drying in pulsated gas flow is investigated numerically. A mathematical model has been developed by coupling a single droplet drying model with a kinetic model of whey protein denaturation, both validated experimentally. To understand the influence of operating conditions on process dynamics and product properties, variations of initial droplet size, initial solid content, gas temperature, pulsation frequency, and gas velocity components are simulated. It is found that small droplets undergo drying and denaturation faster, and stay longer in the drying chamber. The influence of initial solid content is complex and depends on other variables. Gas pulsation has been shown to enhance drying with small reduction in final product activity. It also reduces the discrepancies in product quality and energy consumption in case of different initial droplet size distributions. The influence of frequency and velocity amplitude weakens at higher magnitudes of the same. Average flow velocity has a negligible effect on the properties of dried product, but it determines the droplet residence time. For WPI it is better to dry slowly at moderate temperatures than to dry faster at high temperatures, to prevent too much denaturation. It is also shown that employing pulsation is a better strategy than increasing temperature to enhance the drying process while preserving product quality. • Whey protein denaturation during droplet drying in pulsating flow is modelled. • Denaturation is faster at higher temperature, stronger pulsation, and smaller droplet size. • Small droplets stay longer in drying chamber, getting more dried and denatured. • Pulsation reduces quality differences due to different initial droplet size distributions. • Product quality is retained better by pulsating flow than by increasing temperature.

Novel Water-in-Oil Emulsions for Co-Loading Sialic Acid and Chitosan: Formulation, Characterization, and Stability Evaluation.

This study was designed to co-load sialic acid (SA) and chitosan in a water-in-oil (W/O) emulsion and investigated its characterization and stability. Emulsions were prepared using two different oils (olive oil and maize oil) and polyglycerol polyricinoleate (PGPR) alone or in combination with lecithin (LE) as emulsifiers. The results revealed that the aqueous phase of 5% (w/v) SA and 2% (w/v) chitosan could form a stable complex and make the aqueous phase into a transparent colloidal state. Increasing the concentration of PGPR and LE presented different effects on emulsion formation between olive oil-base and maize oil-base. Two stable W/O emulsions that were olive oil-based with 1.5% (w/v) PGPR+ 0.5% (w/v) LE and maize oil-based with 2% (w/v) PGPR+ 0% (w/v) LE were obtained. Initial droplet size distribution curves of the two stable emulsions displayed unimodal distribution, and the rheological curves displayed the characteristics of shear thinning and low static shear viscosity. Moreover, the storage stability showed that there was no significant change in droplet size distribution and Sauter mean diameter of the emulsions at room temperature (25 °C) for 30 days. These results indicated that the W/O emulsions could effectively co-load and protect sialic acid and chitosan and thus could be a novel method for increasing the stability of these water-soluble bioactive compounds.

A short review of vapour droplet dispersion models used in CFD to study the airborne spread of COVID19

The use of computational fluid dynamics (CFD) to simulate the spread of COVID19 and many other airborne diseases, especially in an indoor environment needs accurate understanding of dispersion models. Modelling the transport/dispersion of vapour droplets within the atmosphere is a complex problem, as it involves the motion of more than one phase, as well as the interphase interactions between the phases. This paper reviews the current canon of research on dispersion modelling of vapour droplets by looking at three specific aspects: (i) physical definition/specification of the initial droplet size distribution; (ii) physics of evaporation/condensation models and (iii) transport equations (with molecular/turbulent dispersion models) to describe the movement of the vapour droplets as they propagate through the air. This review found that the state of modelling implements a wide range of models which shows variances in results thus leading to a state where it is difficult to know which model is most accurate. The authors suggest that further studies in this direction should focus on developing a principle set of equations by benchmarking the previously developed models to establish model uncertainty of the previously developed models with reference to a fixed theoretical model and be compared under identical conditions. However, it must be noted that due to the complex nature of microdroplet evaporation and dispersion coupled with the unpredictable way droplet size distributions are produced, current experimental methodologies that are available to validate such simulations, such as particle image velocimetry, are still not robust enough to provide detailed data to verify minute aspects of the simulations.

A systematic approach to calibrate spray and break-up models for the simulation of high-pressure fuel injections

A novel calibration methodology is presented to accurately predict the fundamental characteristics of high-pressure fuel sprays for Gasoline Direct Injection (GDI) applications. The model was developed within the Siemens Simcenter STAR-CD 3D CFD software environment and used the Lagrangian–Eulerian solution scheme. The simulations were carried out based on a quiescent, constant volume, computational vessel to reproduce the real spray testing environment. A combination of statistic and optimisation methods was used for spray model selection and calibration and the process was supported by a wide range of experimental data. A comparative study was conducted between the two most commonly used models for fuel atomisation: Kelvin–Helmholtz/Rayleigh–Taylor (KH–RT) and Reitz–Diwakar (RD) break-up models. The Rosin–Rammler (RR) mono-modal droplet size distribution was tuned to assign initial spray characteristics at the critical nozzle exit location. A half factorial design was used to reveal how the various model calibration factors influence the spray properties, leading to the selection of the dominant ones. Numerical simulations of the injection process were carried out based on space-filling Design of Experiment (DoE) schedules, which used the dominant factors as input variables. Statistical regression and nested optimisation procedures were then applied to define the optimal levels of the model calibration factors. The method aims to give an alternative to the widely used trial-and-error approach and unveils the correlation between calibration factors and spray characteristics. The results show the importance of the initial droplet size distribution and secondary break-up coefficients to accurately calibrate the entire spray process. RD outperformed KH–RT in terms of prediction when comparing numerical spray tip penetration and droplet size characteristics to the experimental counterparts. The calibrated spray model was able to correctly predict the spray properties over a wide range of injection pressure. The work presented in this paper is part of the APC6 DYNAMO project led by Ford Motor Company.

Influence of the component composition of extinguishing fluids on the droplet distribution in an aerosol cloud

The key challenge in the process is to reliably predict the droplet size distributions of extinguishing liquids after they cover the distances from the drop/spray point to the flame combustion area when using aircraft, sprinkler systems, or high-altitude ground spraying systems. It is sensible to perform a comparative analysis of changes in the size of droplets of typical fire extinguishing composition free-falling or sprayed in a gas medium from a variable altitude. We used the compositions typical of fire-extinguishing systems: bishofite and fire-extinguishing agent solutions, bentonite suspension, foamer emulsion, and water. The variation rate of the average, minimum and maximum sizes of droplets in the aerosol composition was recorded. Experiments were performed with varying spray height and initial droplet size distribution to show significant differences in the resulting droplet size distribution of suspensions, emulsions and solutions. Conditions were established, in which the droplet distribution for different extinguishing compositions remains comparable.

Consideration of Initial Cloud Droplet Size Distribution Shapes in Quantifying Different Entrainment‐Mixing Mechanisms

AbstractEntrainment‐mixing process significantly affects cloud micro/macrophysics and the evaluation of aerosol indirect effects. However, it is still an open question as to how to quantify entrainment‐mixing mechanism for broad cloud droplet size distributions (CDSDs). Here, CDSDs with different spectral widths are used to initialize the Explicit Mixing Parcel Model to address this problem, and microphysical properties are compared for different CDSD widths. For relatively broad CDSDs, as the number concentration and liquid water content decrease, the volume‐mean radius and mean radius increase, which is opposite to the scenario for relatively narrow CDSDs and the homogeneous/inhomogeneous conceptual model. For the relatively broad CDSDs, such relationships could be mistaken as inhomogeneous mixing with subsequent ascent in analysis of the conventional microphysical mixing diagram. This then causes traditional homogenous mixing degrees to be unrealistically negative and not applicable for relatively broad CDSDs. New measures are introduced to explicitly account for the effect of CDSD spectral shapes on quantifying entrainment‐mixing mechanism. The new measures yield reasonable ranges of values that conform to the dynamical measures such as the Damköhler and transitional scale numbers, and their temporal variation can be explained physically. This study extends the measures of homogeneous mixing degrees from narrow to broad CDSDs, and sheds new light on the consideration of CDSD shapes in parameterizations of entrainment‐mixing mechanism.

Longitudinal drift behaviors and spatial transport efficiency for spraying pesticide droplets

Pesticide spraying for crop protection is to obtain adequate coverage on the target surfaces with a minimum of off-target waste. Understanding the spatial behaviors of spray droplets is critical to regulate pesticide deposition. Here, we investigated the droplet interaction behaviors in the dense region and the transport efficiency of pesticide droplets in the dispersed region. The trajectories were tracked with the discrete phase method verified by the wind tunnel experiment. In the dense region near the nozzle, coalescence between droplets smaller than 150 μm and the larger ones can obviously improve the initial droplet size distribution. The reduction in the proportion of easily drifted droplets, contributed by droplet coalescence, can significantly increase droplet deposition onto the target region. When droplets are gradually dispersing, the critical drift height is proposed and clarified by recognizing the falling distance where the mass transport efficiency begins to reduce rapidly. Once the actual spray height exceeds the critical drift height, narrowing the initial relative span of droplets will not facilitate the pesticide transport efficiency, even aggravating the drift loss. The evaporation losses of droplets smaller than 150 μm are more sensitive to the air temperature and relative humidity. The findings of droplet drift behaviors offer insights into pesticide spraying and also provide a strategy for drift regulation.

Unraveling the initial flash boiling spray formation at the same superheated index achieved by altering ambient pressure and fuel temperature independently

When fuel is injected into a combustion chamber where the ambient pressure is lower than the saturation pressure of the fuel, flash boiling occurs. Recently, the flash boiling phenomenon has been investigated by many researchers due to its improved atomization performance on the spray. Recent engineering studies about flashing jet behaviors have correlated the macroscopic structure of flash boiling sprays solely as a function of ambient-to-saturation pressure ratio (Pa/Ps) regardless of fuel temperature, ambient pressure, and even fuel types. However, it is questionable if a superheated condition, which is achieved either by increasing the fuel temperature Tf(Ps) or decreasing the ambient pressure (Pa), would generate identical spray characteristics. In this research, a comparative study was conducted for various Pa/Ps conditions to unravel how the effect of increasing fuel temperature and decreasing ambient pressure to achieve a certain superheated condition appears differently on the flash boiling spray characteristics. To do this, first, bubble growth rates were predicted through the Rayleigh-Plesset equation. Then, the initial dispersion angle and droplet size distribution were analyzed using an X-ray imaging technique. The prediction results of the Rayleigh-Plesset equation showed that the bubble growth rate can be higher in the increased Tf case compared to the decreased Pa case at the same superheated indices. X-ray images revealed that the case of increasing Tf caused larger initial flow dispersion and smaller droplet sizes. These indicated that increasing Tf and decreasing Pa could generate different spray characteristics in particular conditions that need to be paid attention for the spray characterization.

Analysis of the Impact of Typical Severe Thermal Hydraulic Condition on the Evolution of Droplet Characteristics in a Spray: the Numerical Simulation

Numerical simulation has been widely applied in the research of spray systems during a severe nuclear plant accident. In order to improve the predictive accuracy of the calculation, the impact of the thermal hydraulic conditions on the development of the spray have been examined by the researchers. The current study presents the influence of the initial droplet distribution at the injection point of a full cone spray. By comparing the velocity of the droplets of different sizes with the experimental results, a reasonable initial droplet size distribution is suggested. Discussions are also performed to explain the divergence between the experiments and the numerical simulation.

Transport of Oil Droplets in the Upper Ocean: Impact of the Eddy Diffusivity

AbstractThe transport of oil droplets following a surface oil spill was investigated using a uniform vertical eddy diffusivity model and the K‐profile parameterization model, which assumes a maximum K value at 1/3 depth of the mixed layer. The initial droplet size distribution was obtained based on the Delvigne and Sweeney (1988, https://doi.org/10.1007/s13131‐013‐0364‐7) model. Using a uniform eddy diffusivity Kave, an exact analytical solution was used to produce the transient and steady state profile of the concentration of droplets of all sizes. It was found that the concentration at the surface is proportional to the droplet rise velocity and inversely proportional to Kave. Thus, small droplets (smaller than 100 μm) do not persist at the water surface. It was found that K‐profile parameterization produces smaller concentrations at the water surface than the uniform K model. The impact of waves was introduced into the K‐profile parameterization model through a roughness height, zo, that is comparable to the wave height. The investigation herein reveals that the Delvigne and Sweeney approach, commonly used in oil spill modeling, is not sufficient to predict the oil droplet size distribution, and that one needs to use a vertical eddy diffusivity to accurately predict the transport in the following hours and days. A new dimensionless formulation was provided to generalize the results, and showed that transport depends on three major parameters, the water friction speed, the mixed layer depth, and the droplet diameter.

Large eddy simulation of high pressure spray with the focus on injection pressure

This paper presents a detailed numerical analysis of diesel engine spray structure induced by the Engine Combustion Network (ECN) Spray A at different injection pressures. The non-reacting simulations are performed using OpenFOAM where an Eulerian–Lagrangian model is adopted in the large eddy simulation (LES) framework. Effects of the LES mesh resolution as well as the spray model parameters are investigated with the focus on their impact on spray structure as the injection pressure varies. The predicted liquid and vapour penetration lengths agree well with the measurements at different injection pressures. The mixture fraction is well captured for the injection pressure of 100 and 150 MPa while a slight deviation from the measurements is observed for the injection pressure of 50 MPa near the nozzle. The parametric analysis confirms that the LES mesh resolution has significant effects on the results. A coarser mesh leads to higher liquid and vapour penetration lengths where the deviation from the measurements is larger, resulting in the highest error at the lowest injection pressure. As the mesh size increases, the droplet size distribution becomes narrower, its pick moves to the smaller droplet size and the probability of droplets with higher temperature increases. On the other hand, with increasing the mesh size, the carrier gas velocity decays slower and its radial dispersion decreases. It is found that the droplet characteristics are more affected by the mesh resolution when the injection pressure is the lowest while the opposite is true for the carrier phase. The number of Lagrangian particles also affects the droplet characteristics and the fuel-air mixing but their effects are not as significant as the mesh size. The results become less sensitive to the number of Lagrangian particles as the pressure injection decreases. Finally, the importance of the initial droplet size distribution is investigated, confirming its impact is marginal, particularly on the liquid length. It is observed that the initial droplet size is only important at very close to the nozzle and its impact on the spray structure becomes quickly insignificant due to the high rates of breakup and evaporation. This trend is consistent at different injection pressures.

CFD modeling of the creaming zone of batch gravity separation with coalescence

Gravity separation of liquid-liquid dispersions is present in many industrial applications, and it involves the complex governing mechanisms of creaming and coalescence in concentrated mixtures. The aim of this work is to model the laminar creaming zone of batch gravitational separation with coalescence using CFD tools. The numerical results were compared to the experimental decay curves of bottle tests. The initial DSD representation by the population balance model was obtained with the Gauss-Legendre Quadrature. The number of velocity groups and the application range of the drag modifier showed to be a function of the initial DSD profile and polydispersity, respectively. The coalescence models evaluated were the constant coalescence efficiency, the critical approach velocity and the film drainage for a deformable partially mobile interface. The coalescence models parameters were calibrated for a determined initial condition (phases volume fraction and droplet size distribution (DSD)) and then applied for different initial conditions. All models were able to model the separation of all initial conditions with the same calibrated parameters, although the drainage model did not need to be calibrated. This suggests that when employed in the modeling of a continuous separator, these can be calibrated by the decay curves of bottle tests.

CFD–PBM simulation of two-phase flow in a pulsed disc and doughnut column with directly measured breakup kernel functions

The pulsed disc and doughnut column (PDDC) is a widely used type of liquid–liquid extraction equipment. Both the research and design of this type of equipment require in-depth knowledge of the dispersed phase droplet size distribution (DSD). The coupling of computational fluid dynamics (CFD) and population balance model (PBM) has exhibited a significant potential for predicting the DSD by considering droplet breakage and coalescence. In the present work, the CFD–PBM simulation is adopted to predict the DSD, and to investigate local liquid–liquid flow behaviors in a square-sectioned PDDC. The empirical correlations of the breakup kernels, which are based on our previous work [Hao Zhou et al., Direct measurement of droplet breakage in a pulsed disc and doughnut column. AIChE Journal, 2017, 63(9), 4188–4200], are implemented in the CFD code. For comparison, the kernel functions obtained by Coulaloglou and Tavlarides [Coulaloglou and Tavlarides. Description of interaction processes in agitated liquid–liquid dispersions. Chemical Engineering Science, 1977, 32, 1289–1297] are also tested. The class method with the fixed pivot technique is utilized to solve the population balance equations. The droplet size distribution predicted by the CFD–PBM simulation combined with the kernel functions that we have previously determined experimentally are observed to be more precise than those of Coulaloglou and Tavlarides. Accordingly, the CFD–PBM simulation results with the kernel functions of our proposed correlations are used to investigate the liquid–liquid flow behaviors in the PDDC. The influences of droplet size range and initial droplet size distribution at the dispersed phase inlet in the predicted DSD are discussed. The hydraulic performance of simulation results agrees well with experimental data. Local flow behaviors are illustrated to depict the typical flow characteristics of PDDC. The simulation results suggest that CFD–PBM method with the proposed PBM kernel functions is a promising approach for the simulation of liquid–liquid flow in the PDDC.

Effects of emulsion properties on demulsification of the phosphoric acid–tributyl phosphate (W/O) emulsion by hydrocyclone

ABSTRACTIn this study, the effects of emulsion properties on demulsification of the phosphoric acid–tributyl phosphate (W/O) emulsion by hydrocyclone were investigated. The droplet size distributions were measured pre and post demulsification. The demulsification performance was evaluated by calculating the average droplet size difference. The results showed that increasing kerosene addition in the oil phase improved demulsification efficiency. As the maximum amount of kerosene added in the oil phase, average droplet size difference could reach about 43 µm. In each composition, as the stirring rate increased from 3000 to 7000 r/min, the effect of initial droplet size distribution on demulsification by hydrocyclone was not obvious. A model for predicting average droplet size difference was established by dimensional analysis method. By comparing the experimental data with calculated ones, this model is available.