Loading...
Search for:
dispersed-phase
0.005 seconds
Total 21 records
Slip velocity in pulsed disc and doughnut extraction columns
, Article Chemical Industry and Chemical Engineering Quarterly ; Volume 17, Issue 3 , 2011 , Pages 333-339 ; 14519372 (ISSN) ; Jalilvand, H ; Outokesh, M ; Sharif University of Technology
2011
Abstract
In the present work, slip velocity has been measured in a 76 mm diameter pulsed disc and doughnut extraction column for four different liquid-liquid systems. The effects of operating variables including pulsation intensity and dispersed and continuous phase flow rates on slip velocity have been investigated. The existence of three different operational regimes, namely mixersettler, transition, and emulsion regimes, was observed when the energy input was changed. Empirical correlations are derived for prediction of the slip velocity in terms of operating variables, physical properties of the liquid systems, and column geometry for different regimes. Good agreement between prediction and...
Investigation of mass transfer coefficient under jetting conditions in a liquid-liquid extraction system
, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 29, Issue 1 , 2010 , Pages 1-12 ; 10219986 (ISSN) ; Omidkhah, M. R ; Bastani, D ; Saifkordi, A. A ; Sharif University of Technology
Abstract
In this research mass transfer coefficient under jetting regime in different directions (from dispersed to continuous and continuous to dispersed phase) has been studied using an experimental setup. n-Butanol-succinic acid-water with low interfacial tension has been selected as experimental chemical system. The effects of various parameters such as jet velocity, nozzle diameter and the height of the continuous phase above the nozzle, on mass transfer coefficient have been investigated. A correlation has also been derived in order to predict the mass transfer coefficient as a function of physical properties of both phases and aforementioned parameters. Based on the experimental results, mass...
Modeling of Water Injection into the Desuperheater of Steam Generator
, M.Sc. Thesis Sharif University of Technology ; Saidi, Mohammad Hasan (Supervisor)
Abstract
One of the most important equipment in a power station is desuperheater which its operation has effect on power station performance and efficiency.It is necessary to identify and evaluate the most important factors that have effect on its performance. Using desuperheater cause that the temperature of exhausting superheat steam of boiler decreases to the desired quantity. If the temperature of superheat steam is very high, it will cause burning of superheater pipes that is very dangerous.Steam is used for two purpose of power generating and operational process. Unfortunately these applications have different requirement. In power generating for maximizing efficiency, turbine needs high...
Study of Dispersed Phase Holdup and Slip Velocity in a Pulsed Disc and Doughnut Extraction Column
, M.Sc. Thesis Sharif University of Technology ; Outukesh, Mohammad (Supervisor) ; Torab Mostaedi, Meisam (Supervisor)
Abstract
Dispersed phase holdup has been measured in a 75 mm diameter pulsed disc and doughnut extraction column for three different liquid-liquid systems. The effects of operational variables such as pulsation intensity and dispersed and continuous phases flow rates on holdup have been investigated and found to be significant. The existence of three different operational regimes, namely mixer-settler, dispersion, and emulsion regimes, was observed when the energy input was changed. The results indicated that the characteristic velocity approach is applicable to this type of extraction column for analysis holdup in transition and emulsion regions. Empirical correlations are derived for prediction of...
Study on Continuous Phase Holdup in a Pulsed Disc and Doughnut Extraction Column by Radiotracer Technique
, M.Sc. Thesis Sharif University of Technology ; Outokesh, Mohammad (Supervisor) ; Tabasi, Mohsen (Supervisor) ; Mostaedi, M.T (Co-Advisor)
Abstract
The dispersed phase holdup is one of the important parameters in the design pulsed column and set the column diameter, height and characteristics of flooding and mass transfer. High efficiency and low space requirements of these columns cause is particularly in the nuclear industry, Due to the possible presence of radiation and the need for protection against radiation, considered and used. In this project, the dispersed phase holdup and mean residence time in a pulsed disc and donut column in a semi-industrial scale using radiotracer and shut down methods compared and presented for water-kerosene system. Also axial dispersion coefficient in the column using radiotracer methods is calculated...
Numerical Investigation of Combustion of Cryogenic H2-O2 Propellant under Sub-Critical Condition
, M.Sc. Thesis Sharif University of Technology ; Mardani, Amir (Supervisor) ; Farshchi, Mohammad (Supervisor)
Abstract
The present work is concerned with numerical simulation of spray flame for rocket combustor (MASCOTTE A-10 test case at 10 bar pressure) based on cryogen gaseous hydrogen and liquid oxygen at specific condition. This liquid oxygen and gaseous hydrogen single element combustor experiment has been the focus of many numerical studies which is representative of combustion in rocket combustion chamber condition. The purposed strategy relies on hybrid Eulerian-Lagrangian framework that continuous phase is evaluated by Reynolds average Navier-stokes (RANS) equation with quick discretization method and dispersed phase of combustion chamber atmosphere is evaluated by discrete phase method (DPM). To...
Electrowetting induced droplet generation in T-junctions
, Article Journal of Heat Transfer ; Volume 143, Issue 5 , 2021 ; 00221481 (ISSN) ; Moosavi, A ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2021
Abstract
In this study, droplet generation in a T-junction fluidic channel device was studied by using electrowetting actuation with the consideration of different droplet forming regimes. For this purpose, the finite element method (FEM) was used to solve the unsteady Naiver-Stokes equation. In addition, the level set method was applied to capture the interface between two phases. It was shown that there was a good agreement between obtained data and other work during the process of droplet generation in the absence of electrowetting actuation which results in the decrease in the size of the droplet with increasing the velocity ratios. In the shearing regime, the effectiveness of electrowetting on...
Recovery of Uranium from the Waste of UCF Plant By Means of Solvent Extraction Method
, M.Sc. Thesis Sharif University of Technology ; Samadfam, Mohammad (Supervisor) ; Taghizadeh, Mohammad (Supervisor)
Abstract
During various stages of processing uranium in Isfahan’s UCF plant, liquid waste containing uranium compounds, is directed to evaporation lagoons. Gradually, a considerable amount of precipitation will form at the bottom of the lagoons. Since the concentration of uranium in evaporation ponds is relatively high, it seems that in addition to environmental issues, recycling uranium from existing pools is also economical. Uranium may be recovered from an aqueous solution by precipitation, solvent extraction and ion exchange. The solvent extraction is the best option for our purpose because of simple operation without increased consumption of heat or chemicals. It is also preferable when large...
Study of Effects of Operational Parameters on Flooding in Pertraction of Dysprosium in a Vertical Pulsed Packed Column
, M.Sc. Thesis Sharif University of Technology ; Bastani, Dariush (Supervisor) ; Safdari, Jaber (Supervisor) ; Raji, Maliheh (Co-Supervisor)
Abstract
Pulsed packed columns are among the most important devices used in liquid-liquid extraction, with wide application in petroleum and petrochemical industries, metal salt extraction, pharmaceutical industries, metallurgy, and other areas. Liquid-membrane technology is an alternative separation technique to the liquid-liquid extraction for the extraction and recovery of metal ions from aqueous solutions. There are three main types of liquid membranes: emulsion liquid membrane (ELM), Bulk Liquid Membrane (BLM), and Supported Liquid Membrane (SLM). Liquid emulsion membrane is one of the pertraction methods with phase dispersion. It is a three-phase dispersion system, consisting: external phase,...
Study of droplet behaviour along a pulsed liquid-liquid extraction column in the presence of nanoparticles
, Article Canadian Journal of Chemical Engineering ; Volume 91, Issue 3 , 2013 , Pages 506-515 ; 00084034 (ISSN) ; Bahmanyar, A ; Molavi, H ; Bastani, D ; Mozdianfard, M. R ; Bahmanyar, H ; Sharif University of Technology
2013
Abstract
In this article, droplet size and its distribution along a pulsed liquid-liquid extraction column, is studied where SiO2 nanoparticles with concentrations of 0.01, 0.05 and 0.1vol.% and different hydrophobicities are applied to the dispersed phase. Using ultrasonication, nanoparticles were dispersed in kerosene as the base fluid. Nanofluids' stability was ensured using a UV-vis spectrophotometer. Some 22,000 droplets were measured by photographic technique and results were compared with systems containing no-nanoparticles (Water-Acetic acid-Kerosene). Addition of nanoparticles changed the droplet shape from ellipsoidal to spherical. Also, there was a marked influence on droplet breakage and...
Dispersed phase holdup in a pulsed disc and doughnut extraction column
, Article Brazilian Journal of Chemical Engineering ; Volume 28, Issue 2 , June , 2011 , Pages 313-323 ; 01046632 (ISSN) ; Jalilvand, H ; Outokesh, M ; Sharif University of Technology
2011
Abstract
Dispersed phase holdup has been measured in a 76 mm diameter pulsed disc and doughnut extraction column for three different liquid-liquid systems. The effects of operational variables such as pulsation intensity and dispersed and continuous phase flow rates on holdup have been investigated and found to be significant. The existence of three different operational regimes, namely mixer-settler, dispersion, and emulsion regimes, was observed when the energy input was changed. The results indicated that the characteristic velocity approach is applicable to this type of extraction column for analysis of holdup in the transition and emulsion regions. Empirical correlations are derived for...
The effect of dispersed phase salinity on water-in-oil emulsion flow performance: A micromodel study
, Article Industrial and Engineering Chemistry Research ; Volume 56, Issue 15 , 2017 , Pages 4549-4561 ; 08885885 (ISSN) ; Ayatollahi, S ; Rezaei, N ; Masihi, M ; Sharif University of Technology
American Chemical Society
2017
Abstract
In this work, the effect of brine salinity on water-in-oil emulsion flow performance in porous media is studied as it imposes a significant challenge to oil production in the petroleum industry. A crude oil sample from an Iranian oilfield and synthetic brine with different salinities (40-140 g/L salt) are used. The results show that the emulsion viscosity and interfacial tension increase slightly with salinity, while they do not considerably affect the flow behavior. The emulsion stability analysis shows that larger w/o emulsion droplets are formed for higher brine salinity, which potentially block more pore spaces through straining and interception mechanisms. This phenomenon resulted in...
Controlling the microscale separation of immiscible liquids using geometry: A computational fluid dynamics study
, Article Chemical Engineering Science ; Volume 220 , 2020 ; Mohammadi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this study, we numerically determined the performance of a microscale separator comprising a lateral and a main channel to separate a two-phase flow. It was aimed to conduct continuous phase through the lateral channel and dispersed phase through the main channel. The continuous and dispersed phases were modeled as incompressible Newtonian fluids with the corresponding interface tracked by the phase-field model. The dynamics, including pressure fluctuations in the separator, were further examined. It was mechanistically demonstrated how the geometry of the separator modulates the phase separation. Further examined were the influences of various geometrical parameters on the performance of...
Experimental modeling and uncertainty analysis of dispersed phase holdup at flooding in a pulsed disc-doughnut column, case study: Response surface methodology and Monte-Carlo simulation
, Article Progress in Nuclear Energy ; Volume 141 , 2021 ; 01491970 (ISSN) ; Ghaemi, A ; Hemmati, A ; Asadollahzadeh, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This study aims to investigate, optimize, and simulate the dispersed phase holdup at flooding conditions for the standard physical systems in a pulsed extraction column with the disc-doughnut configuration. The interaction impacts for operational parameters (pulse intensity and organic and aqueous phase velocities) and interfacial tension (systems type) were examined using the response surface approach. A novel correlation for the dependent parameter, namely holdup at flooding based on the quadratic model, was developed with the central composition design methodology. A desirable agreement between actual data and calculated data from the proposed model was observed because of the high...
The influence of nanoparticles on hydrodynamic characteristics and mass transfer performance in a pulsed liquid-liquid extraction column
, Article Chemical Engineering and Processing: Process Intensification ; Volume 50, Issue 11-12 , 2011 , Pages 1198-1206 ; 02552701 (ISSN) ; Khoobi, N ; Mozdianfard, M. R ; Bahmanyar, H ; Sharif University of Technology
Abstract
With respect to the influence of nanoparticles on mass transfer characteristics, limited number of studies available in the literature, deal primarily with gas-liquid systems. In this work, mass transfer performance and hydrodynamic characteristics including static and dynamic dispersed phase hold-ups of nanofluids have been investigated for pulsed liquid-liquid extraction column (PLLEC). The nanofluids used were prepared by dispersing SiO2 nanoparticles of 0.01, 0.05 and 0.1 volume percent with two different hydrophobicities in kerosene as base fluid using ultrasonication. UV-vis spectrophotometer was also used for evaluation of the nanofluids stability. The results were compared with...
Effect of poly (propylene-g-maleic anhydride) on the morphological, rheological, and mechanical properties of PP/HDPE blend
, Article Journal of Thermoplastic Composite Materials ; Volume 22, Issue 5 , 2009 , Pages 519-530 ; 08927057 (ISSN) ; Abdi Valami, M ; Khak, M ; Sharif University of Technology
2009
Abstract
In this study, the morphological, rheological, and mechanical properties of PP/HDPE blend compatibilized with poly (propylene-g-maleic anhydride) were studied. Necessary blends were prepared using a counter current twin-screw extruder. The blend composition ranged from 10 to 50 wt% of dispersed phase (HDPE) and compatibilizer (MAPP) with two Concentration ranges 10, 20 wt% were used for PP/HDPE (80/20) blend with respect to the dispersed phase (HDPE). The results of morphological studies shows a droplet dispersion morphology in the composition to 50wt% HDPE content, which indicates that HDPE forms a dispersed phase and PP forms a continuous phase in these composition region. Addition of the...
The performance of pulsed scale-up column for permeable of selenium and tellurium ions to organic phase, case study: Disc and doughnut structure
, Article Chemical Engineering and Processing - Process Intensification ; Volume 157 , 2020 ; Torkaman, R ; Torab Mostaedi, M ; Asadollahzadeh, M ; Sharif University of Technology
Elsevier B.V
2020
Abstract
A research investigation of the overall mass transfer coefficients, holdup and mean drops of dispersed phase as well as slip and characteristic velocities were carried out in the pulsed scale-up column with disc and doughnut structure for extraction of tellurium and selenium from a hydrochloric acid medium with TBP extractant. The impact of operating conditions containing the pulse intensity, inlet aqueous and solvent phase velocities have been studied on the mass transfer rates, and the special column characteristic. By considering the reactive extraction situations, modified models were derived for predicting of holdup, d32, and slip velocity in this extractor. The axial diffusion model...
Exact hydrodynamic description of pilot plant Oldshue-Rushton contactor: a case study with the introduction of selenium and tellurium into reaction system
, Article International Journal of Environmental Analytical Chemistry ; 2020 ; Torkaman, R ; Torab Mostaedi, M ; Asadollahzadeh, M ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
In this paper, the hydrodynamic behaviour of the chemical reaction system (selenium, tellurium, and TBP) was interpreted in the Oldshue-Rushton extraction column. The optimum operating parameters for extracting the selenium and tellurium from chloride medium were carried out by using the batch experiments. The feed acidity of 5 molar and solvent phase with 20% (v/v) TBP in kerosene were optimised to examine the hydrodynamic parameters of the mentioned column. The impacts of operating variables such as rotor speed, inlet aqueous phase velocity, and inlet solvent phase velocity on the dispersed phase hold-up, mean drop size, slip velocity, drop size distribution, and extraction rate were...
Three-dimensional simulation of hydrodynamics in a rotating disc contactor using computational fluid dynamics
, Article Chemical Engineering and Technology ; Volume 32, Issue 1 , 2009 , Pages 93-102 ; 09307516 (ISSN) ; Hedayat, N ; Ziyari, A ; Kazemzadeh, M ; Shafiee, M ; Sharif University of Technology
2009
Abstract
The 3D simulation of the hydrodynamic behavior of a rotating disc contactor (RDC) by means of computational fluid dynamics (CFD) was investigated for the n-butanol-succinic acid-water (BSW) system. For the two-phase liquid-liquid flow, the velocity distribution of the continuous phase and drop size distributions were determined using the k-ω turbulence model in conjunction with the Eulerian-Eulerian approach and MUSIG model. In this system in which the holdup of the dispersed phase is low, the continuous phase velocity was computed by simultaneously solving the Navier-Stokes equations beside the different models of turbulence. The motions of the dispersed phase was calculated while...
Numerical simulation of vortex engine flow field: One phase and two phases
, Article Journal of Thermal Science ; Volume 18, Issue 3 , 2009 , Pages 226-234 ; 10032169 (ISSN) ; Saemi, S. D ; Saidi, M. H ; Sharif University of Technology
2009
Abstract
Aiming at improving efficiency in combustion systems, the study on droplet behavior and its trajectory is of crucial importance. Vortex engine is a kind of internal combustion engine which uses swirl flow to achieve higher combustion efficiency. One of the important advantages of designing vortex engine is to reduce the temperature of walls by confining the combustion products in the inner vortex. The scopes of this investigation are to study vortex engine flow field as well as effective parameters on fuel droplet behavior such as droplet diameter, droplet initial velocity and inlet velocity of the flow field. The flow field is simulated using Reynolds Stress Transport Model (RSM). The...