Mean Drop Diameter Research Articles

Study of Drop Size Distribution in RTL Contactor

The present work studied the drop size distribution in the RTL contactor using two liquid-liquid systems, xylene-acetone-water and kerosene-acetone-water. Process variables studied were: rpm (10-50 min-1), continuous phase flow rate (4-12 l/h), dispersed phase flow rate (4-12 l/h), and concentration (0.1-0.5 mole/l). It was found that Sauter mean drop diameter (d32) decreased with increasing rpm and continuous phase flow rate, and decreasing dispersed phase flow rate and concentration. An empirical correlation, with a correlation coefficient equal to (92.6%), relating d32 with process variables was developed having the form:

Forecasting Sauter mean droplet size and examining the range of droplet sizes in a Tenova liquid–liquid extraction column

A new type of Tenova pulsed extraction column was introduced in 2017. It is the newest generation of pulsed columns. Due to the internal equipment of this column and the lack of moving parts and the simplicity and speed of repairs and maintenance, it has been the focus of researchers in recent years. No correlations for predicting the mean drop size and drop size distribution of the Tenova column have been reported. The Sauter mean drop diameter and drop size distribution are investigated for a Tenova pulsed column with a diameter and an active height of 7.4 and 73 cm, respectively. Three standard chemical systems of isobutyl acetate-water, isobutanol-water, and toluene-water have been used. The effects of pulse intensity, dispersed and continuous phase flow rates have been taken into account. In each experiment, 200–300 drops have been analyzed in a total of 10,000 drops. The investigation covered a spectrum of physical properties, notably surface tension (within a range of 1.75–36 mN/m). Operating conditions including pulse intensity (in the range of 0.2–2 cm/s) and the flow rate of continuous and dispersed phases (in the range of 8–30 L/h) have been investigated. Methods based on artificial intelligence (AI) such as multilayer perceptron neural networks and gene expression programming were combined with a dimensional analysis approach to provide a new approach to estimating the mean drop diameter (d32). Experimental results have been compared with the equations found by other researchers in similar columns. The variation of drop size distribution has also been experimentally obtained.Methods based on artificial intelligence (AI) such as multilayer perceptron neural networks and gene expression programming were combined with a dimensional analysis approach to provide a new approach to estimating the mean drop diameter (d32). Experimental results have been compared with the equations found by other researchers in similar columns. The variation of drop size distribution has also been experimentally obtained.

Micro Rain Radar and Radiometric Measurements to Unravel Contrasting Features of Rain Microstructure Below and Above the Boundary Layer

AbstractKa‐band Micro rain Doppler radar is an effective tool to investigate the profiles of precipitation microstructure in terms of the raindrop size distribution (DSD). The DSD parameters that vary appreciably with height are indicative of the associated atmospheric phenomena. Hence the present investigation endeavors to put light on the underlying physical processes responsible for the evolution of varied rain microstructure profiles using micro rain radar (MRR), and radiometric measurements complemented with re‐analysis outputs over an urban tropical location, Kolkata (22.57°N, 88.37°E), India. MRR unravels the prevalence of significant biases in the typical power law relationship (Dm = aRb) between rain rate (R) and mass‐weighted mean drop diameter (Dm) along the rain height, especially during intense convective rain events, above the atmospheric boundary layer (ABL). Consequently, an alternative empirical relation appropriate to account for the R‐Dm variability above the ABL is proposed. Further, radiometric measurements and re‐analysis outputs reveal that the presence of atmospheric instabilities coupled with wind shear impacts above the ABL contributes to the enhanced breakup of raindrops and the deviations in the usual R‐Dm relationship. Thus, the present study intends to highlight the applicability of ground‐based radar measurements over the tropics to devise quantitative precipitation algorithms for reliable rain estimates.

A new power-law model for μ–Λ relationships in convective and stratiform rainfall

Abstract. In this study, we take a closer look at the important issue of μ–Λ relationships in raindrop size distributions (DSDs) by conducting a systematic analysis of 20 months of data collected by disdrometers in the Netherlands. A new power-law model for representing μ–Λ relationships based on the double normalization framework is proposed and used to derive separate μ–Λ relationships for stratiform and convective rain events. The sensitivity of the obtained relationships to measurement uncertainty is studied by applying two different quality control filters based on the mass-weighted mean drop diameter (Dm) and liquid water content (LWC). Our results show that there are significant differences in μ–Λ relationships between convective and stratiform rainfall types. However, the retrieved relationships appear to be quite robust to measurement noise and there is good agreement with other reference relations for similar climatological conditions.

Evaluation of GPM DPR Rain Parameters with North Taiwan Disdrometers

Abstract Global precipitation demonstrates a substantial role in the hydrological cycle and offers tremendous implications in hydrometeorological studies. Advanced remote sensing instrumentations, such as the NASA Global Precipitation Measurement (GPM) mission Dual-Frequency Precipitation Radar (DPR), can estimate precipitation and cloud properties and have a unique capability to estimate the raindrop size information globally at snapshots in time. The present study validates the Level-2 data products of the GPM DPR with the long-term measurements of seven north Taiwan Joss–Waldvogel disdrometers from 2014 to 2022. The precipitation and drop size distribution parameters like rainfall rate (R; mm h−1), radar reflectivity factor (dBZ), mass-weighted mean drop diameter (Dm; mm), and normalized intercept parameter (Nw; m−3 mm−1) of the GPM DPR are compared with the disdrometers. Four different comparison approaches (point match, 5-km average, 10-km average, and optimal method) are used for the validation; among these four, the optimal strategy provided reasonable agreement between the GPM DPR and the disdrometers. The GPM DPR revealed superior performance in estimating the rain parameters in stratiform precipitation than the convective precipitation. Irrespective of algorithm type (dual- or single-frequency algorithm), sensitivity analysis revealed superior agreement for the mass-weighted mean diameter and inferior agreement for the normalized intercept parameter.

CFD-PB studies on effect of internals on specific interfacial area in a pulsed sieve plate columns

A CFD model coupled with population balance equations is developed to systematically study the effects of column internals on specific interfacial area generated in a pulsed sieve plate column (PSPC). The model has been validated against experimental data on holdup and Sauter mean drop diameter in laboratory scale PSPCs of different geometries. The column internals comprised of sieve plates with varying hole diameter, fractional open area and interplate spacing. Typically the standard sieve plate cartridge is characterised by sieve plates (3.2 mm diameter sieve holes with an fractional open area of 23%) placed 50 mm apart. A systematic response surface methodology has been adopted to determine the relative importance of these parameters on specific interfacial area. 3 factor 3 level Box Behnken design has been adopted. Specific interfacial area decreases with an increase in sieve hole diameter, interplate spacing and open area. Sieve hole diameter is found to be the most significant parameter affecting specific interfacial area. Important hydrodynamic variables like flow velocities in continuous and dispersed phases and how column internals affect them are also discussed.

Comparison of four radar profiling algorithms in the S‐band

AbstractRadar profiling algorithms are widely used for precipitation‐induced path‐attenuation correction. In this study, we investigate the impact of the four well‐known profiling algorithms on the efficacy of quantitative precipitation estimation retrievals. The first method, named the “simple PhiDP‐based method”, distributes precipitation‐induced path attenuation, or PhiDP (differential phase shift), of a rain segment to each radar gate according to radar reflectivity (Zh). The second one is a linear version of the ZPHI method derived from an approximate linear relationship between specific attenuation (Ah) and specific differential phase (KDP). The third one is a nonlinear version of the ZPHI that respects the nonlinearity of the Ah–KDP relationship. The fourth method is inspired from the self‐consistent method of Bringi. The two‐moment normalized raindrop size distribution (DSD) with two variables, scaled drop concentration and mean drop diameter , is used to represent natural variability of DSD. Two configurations are considered: a constant over a segment and a variable over a segment. The Ah, KDP, and rain intensity are estimated by the four profiling algorithms. The sensitivity of each algorithm to radar measurements uncertainty is also investigated. The evaluation of the estimates shows the following. First, for the range‐constant situation, the nonlinear ZPHI and the self‐consistent method yield the best estimates if the measurements errors are not considered. However, the nonlinear ZPHI and the self‐consistent method are significantly impacted by the Zh bias and the measurements noises respectively. Second, for the range‐variable situation, the self‐consistent method does not have a good performance even when radar measurements are accurate. The performance of the nonlinear ZPHI method is similar to the simple PhiDP‐based method, whereas the latter is immune to the Zh calibration error. These results suggest that the benefit of introducing in quantitative precipitation estimation algorithms can be significantly reduced if is not constant in reality and/or if the radar measurements are biased and noisy.

Experimental Studies on Two-Phase Flow with a Novel Slotted Plate Internal in an Air Pulsed Column

ABSTRACT A novel air pulsed column plate internal featuring plates having concentric circular slots of fixed width (3 mm) is conceptualized, tested, and compared against standard sieve plate internal for counter-current two-phase flow. This new plate design (slotted plates) offers significant intensification in terms of specific interfacial area by as much as ~ 50% vis-à-vis standard sieve plates. The studies are carried out in a 3 inch diameter air pulsed column with tap water as the continuous phase and 30% (v/v) tributyl phosphate in dodecane as the dispersed phase. A high-speed imaging system is used to quantify the state of dispersion and obtain drop size distribution along with Sauter mean drop diameter. The effects of pulsing velocity, dispersed phase velocity and continuous phase velocity on dispersed phase holdup, drop size and consequentially specific interfacial area have been systematically studied for both internals. In all cases, slotted plates are characterized by generation of smaller drops and a higher holdup leading to significant improvement in specific interfacial area. Previously reported correlations for estimating dispersed phase holdup and Sauter mean diameter in pulsed sieve plate columns are found to be inadequate for slotted plate internals. Therefore, new correlations for prediction of holdup and drop diameter have been proposed for the new plate design.

Experimental modeling of mean drop size and dispersed phase holdup in rotating disc contactors, using RSM

In this study, the behavior of hydrodynamic parameters was investigated in agitated columns including Asymmetric rotating disc contactor (ARDC), Perforated rotating disc contactor (PRDC), Oldshue–Rushton column (ORC), and Kuhni. The effects of various parameters, including rotor speed (rpm), dispersed and continuous phase velocities, interfacial parameters, and type of RDCs on the dispersed phase holdup and Sauter mean drop diameter were studied. The response surface methodology (RSM) based on the central composite design (CCD) approach was applied for the experimental modeling of three standard systems including toluene-water, butyl acetate-water, and butanol-water. Results showed that the enhancement of rotor speed and dispersed and continuous phase velocities would enhance the dispersed phase holdup. PRDC showed the least enhancement of dispersed phase holdup compared to the other three columns. Our investigation demonstrated that Sauter mean droplet diameter decreased with the rotor speed increase, and this declining trend is more appreciable in ORC and Kuhni columns. Additionally, by increasing dispersed phase velocity in the four columns, the droplet size in the ORC column is larger than the columns. However, by increasing continuous phase velocity, subtle changes in droplet size was observed. Based on the experimental data, new correlations have been presented to predict Sauter mean drop diameter and dispersed phase holdup for agitated columns by analysis of variance (ANOVA). The coefficient of determination (R2) was obtained to be 0.9612 and 0.9495 for Sauter mean drop diameter and dispersed phase holdup, respectively, indicating a good correlation between the predicted and observed values of the models.

A comparative study on emulsification in the presence of a nanoclay (Pickering emulsion) or a surfactant using high intensity mixing

The study explored the potential of using a nanoclay, Laponite RD, as a stabilizing agent in comparison to a surfactant, Tergitol TMN6, at dispersed phase volume fractions of 10–50% vol. An ultrasonicator was employed as an energy intensive device; covering a specific power input range of ∼ 36–52 W kg− 1. In both cases, final dispersions obtained could be considered stable over the period of ageing tests for 3 months as comparable drop size distributions were obtained although there were some differences in the rheology at the highest dispersed phase concentration. Whilst surfactant stabilized emulsions were of Newtonian behavior, Pickering emulsions stabilized with the nanoclay exhibited non-Newtonian behavior, which may be a desirable feature of the final product- certainly one that requires attention in design and scale up. Kinetics of breakup studied through the evolution of the Sauter mean diameter prior to reaching an equilibrium value on the basis of energy density have shown the breakup process being faster with the Pickering emulsions although the equilibrium drop diameters were larger. Overall, with emulsions stabilized using a surfactant, Sauter mean drop diameters could be as low as 240 nm, regardless of the dispersed phase volume fraction, drop sizes were larger with Pickering emulsions which depended on the dispersed phase concentration.

Effects of Air Pollution on Rainfall Microphysics Over the Yangtze River Delta

AbstractHerein, the raindrop size distribution (DSD) and rainfall microphysics characteristics are investigated at multiple stations within the Yangtze River Delta (YRD) under two air pollution conditions. Raindrop data from 14 Thies Clima Laser Precipitation Monitor disdrometers spanning approximately 2 years were employed together with corresponding air pollution data. Rain gauge data and several types of meteorological data were also used. The DSD characteristics were found to vary across the YRD; thus, we compiled DSD‐based demarcations between convective rain and stratiform rain at each site. During summer, the average mass‐weighted mean drop diameter parameter value was higher by a mean 20%, and the average normalized intercept parameter value was lower by a mean 12% in polluted atmosphere conditions for both convective rain and stratiform rain, as well as for different rainfall intensity classes. The differences in atmospheric conditions between clear and polluted air conditions partially account for the uncertainties in the DSD characteristics. Air pollution resulted in uncertainty in the shape parameter‐slope parameter relationship and in the rainfall kinetic energy‐rainfall intensity (KE‐R) relationship. The air pollution index can be integrated into the KE‐R relationship to improve the KE simulation accuracy. In addition, air pollution causes some uncertainty in the radar reflectivity‐rainfall intensity (Z‐R) relationship, while the acceptable deviation of the Z‐R relationship did not significantly impact the accuracy of rainfall simulations. This study improves our understanding of DSD and provides a comprehensive overview of the relationship between air pollution and rainfall microphysics for a typical urban agglomeration area.

Experimental investigation on drop size distribution and mean drop size in an L-shape pulsed packed extraction column

In this study, the mean drop diameter and drop size distribution have been investigated in a pilot plant of a new type of extraction column entitled “L-shaped pulsed packed extraction column” by using two liquid systems of toluene/acetone/water and n-butyl/acetone/water in the presence of mass transfer in two directions. The effects of operational variables, physical properties and mass transfer direction have been considered on the dispersed drop size. It is found that the mean drop diameter and drop size distribution is significantly affected by the pulsation intensity and interfacial tension of liquid system. However, the phases flow rates and mass transfer direction have a weaker impact. Furthermore, it is observed that the mean drops diameter in the horizontal and vertical sections of the used column have mostly the same size and it is considered as a significant advantage. Finally, new correlations are proposed to accurately predict the mean drop size and drop size distribution. Good agreement between predictions and experiments was found for all operating conditions, chemical systems and mass transfer direction that were investigated.

Influence of Reduced Anthropogenic Activities on Rain Microphysical Properties and Related Atmospheric Parameters Over an Urban Tropical Location

This letter reveals the prevailing scenario of raindrop size distribution (DSD) in terms of mass-weighted mean drop diameter ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D_{m}$ </tex-math></inline-formula> ) over a tropical metropolis, Kolkata (22.57°N, 88.37°E), India, in a contrasting aerosol environment that occurred during the COVID-19 pandemic in the absence of usual human activities. In the premonsoon months (March–May), the probability of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D_{m}$ </tex-math></inline-formula> values exceeding 2 mm has increased in 2020, indicating the dominance of large raindrops, compared to the years 2017–2019. Increased number densities of larger drops have influenced the drop fall velocity spectrum as measured by a laser precipitation monitor in terms of the percentage occurrence of high-velocity small drops (superterminal) and low-velocity large drops (subterminal) for both convective and stratiform precipitations. As measured from a Ka-band microrain Doppler radar, the mean melting layer altitude during stratiform rain has decreased by ~800 m during the premonsoon of 2020 compared to 2017–2019. According to the ERA-5 reanalysis data, changing rain microphysical characteristics are related to decreasing zero-degree isotherm height and reduced wind shear.

Long-Term Impact of Continental and Maritime Airflow on Aerosol Environment and Rain Microstructure Near Land–Sea Boundary

The present study deals with the interplay of multiple atmospheric processes in changing the microphysical properties of precipitation during the pre-monsoon season (March–May) using the long-term experimental data of raindrop size distributions (DSDs) spanning over 15 years (2005–2019) obtained at an urban tropical location, Kolkata (22.57°N, 88.37°E), near the land–sea boundary. The changing pattern of air mass flows from the maritime and continental region, which contribute to the formation of precipitation processes, has been responsible for the varying characteristics of rain. Changes in raindrop sizes are related to aerosol properties, cloud features, temperature, and relative humidity that change mass-weighted mean drop diameter ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D_{m}$ </tex-math></inline-formula> ) differently in low and high rain rate regimes. <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D_{m}$ </tex-math></inline-formula> has shown an increasing trend over time for low rain rates (< 15 mm/h), but a decreasing trend for high rain rate regimes (≥15 mm/h). An increase (decrease) in mean temperature (relative humidity) below the atmospheric boundary layer (< 1.6 km) has enhanced the evaporation of small raindrops and altered rain microphysical features. Based on satellite observations, it has been found that the increasing aerosol optical depth (AOD) has been accompanied by an increase in cloud effective radius (CER), resulting in the anti-Twomey effect, which is due to the dominance of maritime influence over continental activities. Because of the predominant maritime activities, sea salt aerosols have a greater presence, causing an increase in CER, which consequently prevents raindrops from becoming large enough before they fall, thereby reducing <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D_{m}$ </tex-math></inline-formula> at high rainfall rates.

Experimental investigation on spray and ignition characteristics of plasma actuated bluff body flameholder

Stable combustion of aero-engines and ramjet combustors is greatly dependent on the quality of atomization. It is quite difficult to achieve wider ignition boundary and good combustion performance under low pressure and low temperature airflow, because the quality of fuel atomization is comparative bad and there is no enough surface area for fuel droplets to mix with surrounding air and evaporate. Internal mechanism of how plasma assisted ignition on spray performance in model aero-engine combustors and ramjet combustors remains not clear. In this study, a novel plasma-actuated bluff-body flameholder is proposed to help improve the quality of fuel atomization and thus enhance the ignition performance and stable combustion of original bluff-body flameholder. Spray and atomization properties of aviation kerosene (RP-3) were investigated under various operating conditions including inlet pressure, inlet temperature and gliding arc plasma actuation. A rotating arc discharge plasma column could be formed during the high-voltage tungsten electrode and the fins of bluff-body flameholder. Macroscopic as well as microscopic spray properties was analysed through simultaneous LIF/MIE technique along with particle/droplet image analysis (PDIA) system. Flame ignition limit at different inlet temperature was conducted under combustor inlet Mach number of 0.2. Results show that mean drop diameters were decreased with increase of inlet temperature and inlet pressure. Gliding arc plasma actuation help fuel injected from bluff-body flameholder breakup into smaller droplets and improve uniformity of fuel spray through heating and transport effect. With actuation of gliding arc plasma, Sauter mean diameter (SMD) was minished by 13%∼20% at inlet pressure of 30 kPa, while droplet uniformity index was increased by around 21.8%. Due to better fuel atomization quality together with more active components generated by gliding arc plasma, flame ignition limit of bluff-body flameholder was obviously extended by about 13%∼30%. The gliding arc plasma was verified to promote fuel droplets atomization and to achieve homogeneous distribution under low temperature and pressure, which is beneficial to wider flame ignition and stabilization boundary.

Orographically Modified Ice-Phase Precipitation Processes During the Olympic Mountains Experiment (OLYMPEX)

AbstractOver mountainous terrain, windward enhancement of stratiform precipitation results from a combination of warm-rain and ice-phase processes. In this study, ice-phase precipitation processes are investigated within frontal systems during the Olympic Mountains Experiment (OLYMPEX). An enhanced layer of radar reflectivity (ZH) above the melting level bright band (i.e., a secondary ZH maximum) is observed over both the windward slopes of the Olympic Mountains and the upstream ocean, with a higher frequency of occurrence and higher ZH values over the windward slopes indicating an orographic enhancement of ice-phase precipitation processes. Aircraft-based in situ observations are evaluated for the 01-02 and 03 December 2015 orographically-enhanced precipitation events. Above the secondary ZH maximum, the hydrometeors are primarily horizontally oriented dendritic and branched crystals. Within the secondary ZH maximum, there are high concentrations of large (&gt; ~2 mm diameter) dendrites, plates, and aggregates thereof, with a significant degree of riming. In both events, aggregation and riming appear to be enhanced within a turbulent layer near sheared flow at the top of a low-level jet impinging on the terrain and forced to rise above the melting level. Based on windward ground sites at low-, mid-, and high-elevations, secondary ZH maxima periods during all of OLYMPEX are associated with increased rain rates and larger mass-weighted mean drop diameters compared to periods without a secondary ZH maximum. This result suggests that precipitation originating from secondary ZH maxima layers may contribute to enhanced windward precipitation accumulations through the formation of large, dense particles that accelerate fallout.

Effect of cross-slot configuration in microfluidics on o/w emulsification at high throughput

The Liquid–liquid dispersion process is experimentally investigated to manufacture oil-in-water emulsion working at high flowrates in the cross-slot type of microfluidics. Two cross layouts, namely symmetric and asymmetric configurations, are compared via characterizing the droplet size and size distribution. Automated granulometry is implemented on the images taken by microscopy observations of the emulsion samples. High-speed shadow photography is carried out to discover the continuous- and dispersed-phase flow interactions in the vicinity of the collision region. The results show that the designed microsystems present great potential in terms of fabricating fine oil droplets distributed in the final emulsion. The arithmetic averaged diameter is less than 10 μm at all tested flow conditions and the minimum mean diameter reaches 3.9 μm at the highest energy consumption case. Because of the higher shear stress and more intensified interaction, the symmetric geometry of the cross-slot is beneficial to create fewer amounts of large droplets and dispersing the oil phase more uniformly at the same hydrodynamic conditions, especially in the low Reynolds flow case in this study. As the flowrate is enhanced, the disparity between them is diminished due to the instability inside the channel reaching a high level. The mean drop diameter for both systems is capable to be scaled with the emulsion velocity-based Weber number. The detrimental effect of the symmetric configuration is that the energy required to burst the dispersed streams is relatively a little higher than with asymmetric one.

Hydrodynamic behavior of standard liquid-liquid systems in Oldshue–Rushton extraction column; RSM and ANN modeling

This study aims at evaluating the dispersed phase holdup and Sauter mean drop diameter (d32) of three liquid-liquid systems in an Oldshue–Rushton pilot column. The systems include butanol–water, n-butylacetate–water, and toluene–water with a wide range of interfacial tension. Two modeling approaches of response surface methodology (RSM) and artificial neural network (ANN) are employed. Four independent factors, including rotation rate (N: 60-240 rpm), continuous phase velocity (Vc: 0.499-0.997 mm/s), dispersed phase velocity (Vd: 0.499-0.997 mm/s), and interfacial tension (σ: 1.75-36 mN/m) are taken into account to investigate their individual and interaction impacts. Two correlations for both responses are developed according to the composite central design (CCD) method in RSM modeling. A python-based code, an open-source project NetHub, is utilized to apply a Multi-Layer Perceptron (MLP) algorithm in ANN modeling to find the best network structure with minimum mean square error (MSE) and maximum coefficient of determination (R2). The high prediction accuracy of both developed models is confirmed by the R2 values of 0.9975 and 0.9905 for RSM and ANN modeling, respectively. The optimum network structure contained four layers with 15, 20, 10, and 2 neurons at each layer, respectively, achieving the minimum MSE value of 0.0023.

Response surface methodology study of dispersed phase holdup and mean droplet size in a perforated rotating disc contactors (PRDC)

ABSTRACT This research aims to optimize the influential hydrodynamic parameters in liquid-liquid extraction columns for three different systems of butanol–water, n-butylacetate–water, and toluene–water recommended by the European Federation of Chemical Engineering. The operating conditions of rotor speed, continuous phase, and dispersed phase velocities and two responses of the dispersed phase holdup of dispersed phase and Sauter mean drop diameter are considered to examine their interaction effects in a perforated rotating disc contactor (PRDC) pilot plant by response surface methodology (RSM). A desirable consistency between the predicted and experimental data was observed due to an R2 value higher than 0.99. The maximum dispersed phase holdup and minimum Sauter mean drop diameter (d32 ) were obtained at 0.117 and 0.599 mm, respectively. The results pointed out that the rotor speed is the most substantial variable in the studied responses.

Drop sizes and its distribution in jet-driven liquid–liquid mixing column: substantial application for the liquid–liquid extraction process

The present work reports the study of drop size distribution, drop aspect ratio, and interfacial area in a liquid–liquid jet-driven mixing column. Four different liquids, i.e., kerosene, diesel, 1-decanol, and paraffin, are used as dispersed phases and water as the continuous phase. The effect of the jet velocity, the volume fraction of the dispersed phase, and the physical properties of a liquid mixture such as density, viscosity, and surface tension are studied on the drop size distribution and drop aspect ratio. The column diameter of 0.37 m and nozzle diameter of 0.005 m were used. The velocity of the jet is varied between 0.68 m/s–1.71 m/s. It is observed that the drop size decreases as the volume fraction of the dispersed phase and jet velocity increases. Drop size distribution is found to follow the Log-logistic drop size distribution function. The aspect ratio is close to unity for a small drop, and it decreases as the drop size increases. The increase in the Eötvös number leads to a decrease in the aspect ratio. The correlation for the drop aspect ratio is proposed in terms of the Reynolds and Eötvös numbers in the ranges of 0.061 <Re < 342.59, 0.004 <Eo < 1.166, and (−4.756) < log10 (Mo) < (−9.171), respectively. Interfacial area of drop enhances with an increase in the dispersed volume phase and jet velocity. Empirical correlation is developed to predict Sauter mean drop diameter, drop aspect ratio, distribution function parameters, and interfacial area based on operating variables and physical properties of the system.