EFFECT OF MIXING ENERGY, MIXING TIME AND SETTLING TIME ON DISPERSION EFFECTIVENESS IN TWO BENCH-SCALE TESTING SYSTEMS

2008 ◽  
Vol 2008 (1) ◽  
pp. 651-656 ◽  
Author(s):  
Biplab Mukherjee
Keyword(s):  
Energy Dissipation ◽  
Size Distribution ◽  
Mixing Time ◽  
Tween 80 ◽  
Settling Time ◽  
Oil Droplets ◽  
Mixing Energy ◽  
Oil Dispersant ◽  
Dissipation Rates ◽  
Dispersed Oil

ABSTRACT Dispersion experiments were conducted in baffled-flask and paddle-jar mixing systems at five energy dissipation rates ranging from 4.8 × 10−4 to 1.6 × 10−1 J/kg-s. The objective of these experiments was to investigate the effects of mixing energy, mixing time, and settling time on dispersion effectiveness and size distribution of the chemically dispersed oil droplets. Two separate combinations of evaporatively weathered Mars crude oil premixed with dispersants differing in hydrophile-lipophile balance (HLB) (12 and 10) but having the same chemical composition (Tween 80 and Span 80 in dodecane) were used. Dispersion effectiveness increased with energy dissipation rate to a maximum and then leveled for all cases studied. In the baffled flask, dispersion effectiveness reached a maximum of 82 ± 5% irrespective of oil-dispersant combination. In the paddle jar, the maximum value of dispersion effectiveness was oil-dispersant specific, being at 87 ± 9% and 30 ± 11% for dispersant HLB 12 and 10, respectively. Mixing time did not seem to have a significant effect on dispersion effectiveness in comparison to the effects of energy dissipation rates and oil-dispersant combinations. The normalized volume distributions of the dispersed oil droplets were tri-modal in both systems, suggesting that multiple mechanisms of droplet formation occurred. The largest droplet mode disappeared from the size distribution in dispersions produced in the baffled flask when the mixing energy was >1.6 × 10−2 J/kg-s. A similar behavior was also observed in the paddle jar for the oil-dispersant combination of HLB 12, but not for HLB 10. Inclusion of a settling period of 20 minutes before collecting sample decreased the dispersion effectiveness in paddle jar but no significant changes were observed in the baffled flask system. The differences observed were due to the differences in the size distributions of the dispersed oil droplets generated in these two systems.

OIL DROPLET SIZE DISTRIBUTION AS A FUNCTION OF ENERGY DISSIPATION RATE IN AN EXPERIMENTAL WAVE TANK

2008 ◽  
Vol 2008 (1) ◽  
pp. 621-626 ◽  
Author(s):  
Zhengkai Li ◽  
Kenneth Lee ◽  
Thomas King ◽  
Michel C. Boufadel ◽  
Albert D. Venosa
Keyword(s):  
Energy Dissipation ◽  
Size Distribution ◽  
Dissipation Rate ◽  
Droplet Size Distribution ◽  
Breaking Waves ◽  
Energy Dissipation Rate ◽  
Wave Tank ◽  
Chemical Dispersant ◽  
Dispersed Oil ◽  
Dispersant Effectiveness

ABSTRACT The U.S. National Research Council (NRC) Committee on Understanding Oil Spill Dispersants: Efficacy and Effects (2005) identified two factors that require further investigation in chemical oil dispersant efficacy studies: 1) quantification of mixing energy at sea as energy dissipation rate and 2) dispersed particle size distribution. To fully evaluate the significance of these factors, a wave tank facility was designed and constructed to conduct controlled oil dispersion studies. A factorial experimental design was used to study the dispersant effectiveness as a function of energy dissipation rate for two oils and two dispersants under three different wave conditions, namely regular non-breaking waves, spilling breakers, and plunging breakers. The oils tested were weathered MESA and fresh ANS crude. The dispersants tested were Corexit 9500 and SPC 1000 plus water for no-dispersant control. The wave tank surface energy dissipatation rates of the three waves were determined to be 0.005, 0.1, and 1 m2/s3, respectively. The dispersed oil concentrations and droplet size distribution, measured by in-situ laser diffraction, were compared to quantify the chemical dispersant effectiveness as a function of energy dissipation rate. The results indicate that high energy dissipation rate of breaking waves enhanced chemical dispersant effectiveness by significantly increasing dispersed oil concentration and reducing droplet sizes in the water column (p <0.05). The presence of dispersants and breaking waves stimulated the oil dispersion kinetics. The findings of this research are expected to provide guidance to disperant application on oil spill responses.

The Fate of Dispersed Oil Under Ice: Results of JIP Phase 1 Program

2014 ◽  
Vol 2014 (1) ◽  
pp. 949-959
Author(s):  
CJ Beegle-Krause ◽  
Miles McPhee ◽  
Harper Simmons ◽  
Ragnhild Lundmark Daae ◽  
Mark Reed
Keyword(s):  
Literature Review ◽  
Water Column ◽  
Droplet Size ◽  
Fluorescent Dyes ◽  
Autonomous Underwater Vehicles ◽  
The Arctic ◽  
Formation Mechanisms ◽  
Oil Droplets ◽  
Mixing Energy ◽  
Dispersed Oil

ABSTRACT Ice infested waters pose unique challenges to preparedness and response for potential oil spills. An international team of researchers are working together to create a model to aid in evaluating use of dispersants in ice. The model will be designed to evaluate whether or not dispersed oil droplets formed under continuous or concentrated ice could resurface under the ice to form a significant accumulation within two days. The goal is to develop a tool to support contingency planning decisions with respect to dispersant use. Phase I of the project was to perform a literature review to develop recommendations to fill data gaps in the ice, current, and turbulence data needed to run a model. Phase II will include field work to collect data and model development and testing. The model will require information about the oil and dispersed oil droplet size distribution and water column information to predict mixing energy that could keep the oil droplets suspended. Droplet size distributions can be easily measured. The challenge is to provide representative information about the water column. We are evaluating several types of oceanographic observational technologies to collect data on under ice mixing energy such as fluorescent dyes, Turbulent Instrument Clusters (TICs), Autonomous Underwater Vehicles (UAVs), and Acoustic Doppler Current Profilers (ADCPs). From our review, we expect to be able to collect the required environmental parameters within reasonable cost and time. There are a variety of ice formation mechanisms and ice types in the Arctic and Antarctic. Bottom roughness and ice concentration play keys rolls controlling the amount of mixing energy available under the ice. Heavier ice concentrations absorb surface wave energy, which provides the mixing energy for open water dispersant operations. The literature review indicates that good measurements and a good turbulence closure model are key to obtaining good predictions. We are interested in feedback from the IOSC audience regarding our vision of framing the predictive model as an appropriate decision support tool for the Planning and Response Communities.

scholarly journals The Study of Carbon Recovery from Electrolysis Aluminum Carbon Dust by Froth Flotation

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 145
Author(s):  
Hesong Li ◽  
Jiaoru Wang ◽  
Wenyuan Hou ◽  
Mao Li ◽  
Benjun Cheng ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Mixing Time ◽  
Froth Flotation ◽  
Aluminum Electrolysis ◽  
Carbon Powder ◽  
Molten Salt Electrolysis ◽  
Carbon Recovery ◽  
Aluminum Smelting

A large amount of carbon dust is generated in the process of aluminum smelting by molten salt electrolysis. The carbon dust is solid hazardous waste but contains a large quantity of recyclable components such as carbon and fluoride. How to recycle carbon dust more effectively is a challenge in the aluminum electrolysis field. In this study, X-ray diffraction, scanning electron microscope, and other methods were used to analyze the phase composition of electrolytic aluminum carbon dust. The effects of particle size distribution of carbon dust, impeller speed, reagent addition, mixing time, and flotation time on the flotation recovery of carbon dust were studied. The optimal flotation conditions were obtained and the flotation products were analyzed. The results show that the optimal particle size distribution is 70% of particles below 200 mesh, corresponding to a grinding time of 11 min. The optimum speed of the flotation machine was to be between 1600 and 1800 r/min with the best slurry concentration of 20–30% and 5 min mixing time, and the collector kerosene was suitable for adding in batches. Under the above conditions, the recovered carbon powder with a carbon content of 75.6% was obtained, and the carbon recovery rate was 86.9%.

Observations of Small-Scale Turbulence and Energy Dissipation Rates in the Cloudy Boundary Layer

2006 ◽  
Vol 63 (5) ◽  
pp. 1451-1466 ◽  
Author(s):  
Holger Siebert ◽  
Katrin Lehmann ◽  
Manfred Wendisch
Keyword(s):  
Boundary Layer ◽  
Energy Dissipation ◽  
Wind Velocity ◽  
Turbulence Theory ◽  
Horizontal Wind ◽  
Inertial Subrange ◽  
Intermittent Flow ◽  
Small Scale ◽  
Dissipation Rates ◽  
Wide Range

Abstract Tethered balloon–borne measurements with a resolution in the order of 10 cm in a cloudy boundary layer are presented. Two examples sampled under different conditions concerning the clouds' stage of life are discussed. The hypothesis tested here is that basic ideas of classical turbulence theory in boundary layer clouds are valid even to the decimeter scale. Power spectral densities S( f ) of air temperature, liquid water content, and wind velocity components show an inertial subrange behavior down to ≈20 cm. The mean energy dissipation rates are ∼10−3 m2 s−3 for both datasets. Estimated Taylor Reynolds numbers (Reλ) are ∼104, which indicates the turbulence is fully developed. The ratios between longitudinal and transversal S( f ) converge to a value close to 4/3, which is predicted by classical turbulence theory for local isotropic conditions. Probability density functions (PDFs) of wind velocity increments Δu are derived. The PDFs show significant deviations from a Gaussian distribution with longer tails typical for an intermittent flow. Local energy dissipation rates ɛτ are derived from subsequences with a duration of τ = 1 s. With a mean horizontal wind velocity of 8 m s−1, τ corresponds to a spatial scale of 8 m. The PDFs of ɛτ can be well approximated with a lognormal distribution that agrees with classical theory. Maximum values of ɛτ ≈ 10−1 m2 s−3 are found in the analyzed clouds. The consequences of this wide range of ɛτ values for particle–turbulence interaction are discussed.

Experimental Measurement of Oil Droplets Size and Velocity Above the Rotor/Stator in a Rotary Compressor

2021 ◽  
Author(s):  
Puyuan Wu ◽  
Jun Chen ◽  
Paul E. Sojka ◽  
Yang Li ◽  
Hongjun Cao
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Outer Region ◽  
Droplet Size Distribution ◽  
Rotary Compressor ◽  
Discharge Process ◽  
Oil Droplets ◽  
Lower Cavity ◽  
Lubricant Oil ◽  
Rolling Piston

Abstract Hundreds of millions of Air conditioning (AC) systems are produced each year. Many of them, especially small AC appliances, use rotary compressors as the system’s heat pump due to their simple structure and high efficiency in a small system. Lubricant oil is used in the rotary compressor to lubricate the moving parts, such as the crankshaft and the rolling piston, and to seal the clearance between the sliding parts, e.g., the clearance between the rolling piston and the cylinder, and the vane and the cylinder. As the compressed refrigerant vapor is discharged from the cylinder through the discharge port, part of lubricant oil in the cylinder would be carried by the vapor and atomize into small droplets in the lower cavity during the discharge process, which is complicated and highly-coupled. Some of these oil droplets would ultimately be exhausted from the compressor and enter other parts in the system, reducing the compressor reliability and deteriorating the heat transfer of the condenser and the evaporator in the system. Our previous research studied the atomization of the lubricant oil during the discharge process in the compressor’s lower cavity. However, the oil droplets’ behavior downstream of the lower cavity is unknown. Thus, studying the oil droplets’ behavior after passing through the rotor/stator can help understand how the rotor/stator would affect the droplet size distribution and movement, thus controlling the flow rate of escaped oil droplets. In this study, a hot gas bypass test rig is built to run a modified rotary compressor with sapphire windows right above the rotor/stator. The oil droplets’ size distribution and movement along the radial direction are obtained at the shaft’s rotating frequency of 30 and 60 Hz by shadowgraph. It is found that droplet size at 30 and 60 Hz varies little in the inner region of the rotor/stator clearance and would increase sharply above the clearance and keep increasing in the outer region of the clearance. More importantly, droplet velocity has a downward velocity component at the inner region and an upward velocity component at the outer region of the rotor/stator clearance. With the result of droplet size distribution and droplet velocity above the rotor/stator, we propose the model of the oil droplet’s path above the rotor/stator, which can be understood as the coupling of a swirling jet and a rotating disk.

scholarly journals EFFECTS OF SONICATION ON SIZE DISTRIBUTION AND ENTRAPMENT OF LYNESTRENOL TRANSFEROSOME

2020 ◽  
pp. 245-247
Author(s):  
ISKANDARSYAH ISKANDARSYAH ◽  
CAMELIA DWI PUTRI MASRIJAL ◽  
HARMITA HARMITA
Keyword(s):  
Drug Delivery ◽  
Particle Size ◽  
Size Distribution ◽  
Time Variation ◽  
Transdermal Drug Delivery ◽  
Entrapment Efficiency ◽  
Tween 80 ◽  
Sonication Time ◽  
Size Evaluation ◽  
Edge Activator

Objective: The aim of this study was to develop transferosome vesicles for the transdermal drug delivery of lynestrenol.Methods: The lynestrenol transferosome vesicle was made by encapsulating the drug in a variation of phosphatidylcholine and Tween 80 by the thinlayerhydration method. The resulting transferosome vesicles were modified with a time variation of 30, 60, 90, and 120 min, and sonication variationswere paused and not paused. Particle size evaluation, polydispersity (PDI), and entrapment efficiency (%EE) were carried out on the variation ofsonication time.Results: The evaluation results showed that sonication without pauses showed better %EE and particle size than sonication with pauses andincreasing concentration of Tween 80 (edge activator). The %EE increased, and particle size decreased with increasing sonication time; PDI of vesicleswas heterogeneous with increasing sonication time. The %EE in formulas F1 and F2 after 120 min was 73.06% and 76.06% (paused) and 80.40% and82.97% (without paused). The particle size of formula F1 and F2 after 120 min 575.4 nm and 471.6 nm (paused) and 524.1 nm and 434.7 nm (withoutpaused). The PDI formulas of F1 and F2 after 120 min were 0.69 and 0.763 (paused) and 0.84 and 0.59 (without paused).Conclusion: Based on the results of the transferosome vesicle characteristics, it was shown that the optimal vesicle composition for packaginglynestrenol was vesicles that were composed of phosphatidylcholine and Tween 80 without pauses and could potentially be used as a transdermaldrug delivery system.

scholarly journals Hydrodynamics and Mass Transfer Analysis in BioFlow® Bioreactor Systems

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1311 ◽  
Author(s):  
Marian Kordas ◽  
Maciej Konopacki ◽  
Bartłomiej Grygorcewicz ◽  
Adrian Augustyniak ◽  
Daniel Musik ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Mixing Time ◽  
Mass Transfer Rate ◽  
Mass Transfer Process ◽  
Mixing Process ◽  
Stirred Tanks ◽  
Mixing Energy ◽  
Biotechnological Processes ◽  
Liquid Transfer ◽  
Mathematical Relationships

Biotechnological processes involving the presence of microorganisms are realized by using various types of stirred tanks or laboratory-scale dual-impeller commercial bioreactor. Hydrodynamics and mass transfer rate are crucial parameters describing the functionality and efficiency of bioreactors. Both parameters strictly depend on mixing applied during bioprocesses conducted in bioreactors. Establishing optimum hydrodynamics conditions for the realized process with microorganisms maximizes the yield of desired products. Therefore, our main objective was to analyze and define the main operational hydrodynamic parameters (including flow field, power consumption, mixing time, and mixing energy) and mass transfer process (in this case, gas–liquid transfer) of two different commercial bioreactors (BioFlo® 115 and BioFlo® 415). The obtained results are allowed using mathematical relationships to describe the analyzed processes that can be used to predict the mixing process and mass transfer ratio in BioFlo® bioreactors. The proposed correlations may be applied for the design of a scaled-up or scaled-down bioreactors.

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