Research note
Transport Phenomena,
Volume 3, Issue 4 , October 2006, Pages 3-16
Abstract
> The motion and shape of a flattened drop and bubble through another continuous liquid phase (conveying phase) are investigated experimentally, using a narrow gap HeleShaw cell. Seven different liquid-liquid systems were tested. In all cases the continuous phase was the more viscous wetting phase. ...
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> The motion and shape of a flattened drop and bubble through another continuous liquid phase (conveying phase) are investigated experimentally, using a narrow gap HeleShaw cell. Seven different liquid-liquid systems were tested. In all cases the continuous phase was the more viscous wetting phase. A number of observations on the shape and motion of the elongated flattened drops are noted and discussed. In the capillaritydominated (Ca<1.69×10-6) region, the irregular shape of the discontinuous phase drops changed with time and position, and the drop velocity was much lower than that of the conveying phase. Three different shapes of stabilized elongated drops were observed at higher Capillary numbers. The conditions that lead to the appearance of stabilized elongated drops are discussed. The velocities of these stabilized elongated flattened drops were 2 to 4.7 times higher than that of the conveying liquid. A correlation to predict the elongated flattened drop shape as a function of the dimensionless parameters governing the system is developed based on the experimental results.
Full article
Thermodynamics,
Volume 3, Issue 4 , October 2006, Pages 17-22
Abstract
In this work the volume expansion for the binary systems of ethanol and toluene, as industrial organic solvents, in the presence of nearcritical and supercritical carbon dioxide, CO2, at a temperature range of 293 to 333 K has been meticulously measured. The effect of the temperature and pressure of ...
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In this work the volume expansion for the binary systems of ethanol and toluene, as industrial organic solvents, in the presence of nearcritical and supercritical carbon dioxide, CO2, at a temperature range of 293 to 333 K has been meticulously measured. The effect of the temperature and pressure of binary systems on volume expansion for organic solvents have also been investigated. It can be observed that by increasing the pressure of the system at a constant temperature, the volume of the liquid phase increases smoothly, while at higher pressures a sudden volume expansion can occur. The range of pressure that can lead to a sudden increase in the volume expansion of the liquid phase in each specified temperature can be reported as a proper condition in producing micro and nanoparticles. The experimental data for the volume expansion of organic solvents were modeled using the conventional cubic Peng Robinson equation of state. The Average Absolute Relative Deviation percent (AARD%) for the binary systems of ethanol + CO2 and toluene + CO2 were reported as 14.9% and 15.1%. As inferred, it is vital to develop a thermodynamic model with greater accuracy in order to correlate the volume expansion of the systems studied in this work at various conditions.
Full article
Modeling and Simulation
Volume 3, Issue 4 , October 2006, Pages 23-34
Abstract
"> In the present study the reaction kinetic and dynamic modeling of the reactor for syngas transformation into dimethyl ether using a mixture of a metallic oxides (CuO, ZnO, Al2O3), and an acidic component (γ-Al2O3) as the catalyst has been investigated. A combination of the Graff kinetic model ...
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"> In the present study the reaction kinetic and dynamic modeling of the reactor for syngas transformation into dimethyl ether using a mixture of a metallic oxides (CuO, ZnO, Al2O3), and an acidic component (γ-Al2O3) as the catalyst has been investigated. A combination of the Graff kinetic model for methanol synthesis and the Bercic model for methanol dehydration was correlated with the experimental results obtained in this study. Activity and kinetic measurements were carried out using a catalytic fixed bed micro reactor. The operating temperature range was 230-300 °C and the pressure was 8 barg. The experimental runs were performed applying a wide range of catalyst to feed ratios. A simple dynamic model for the reactor performance was developed and tested with the experimental data. The mean absolute deviation, concerning the data for the steady state conditions, was less than 8%.
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Separation Technology,
Volume 3, Issue 4 , October 2006, Pages 35-43
Abstract
Dialysis is a membrane based separation process in which the concentration gradient across the membrane is the driving force resulting in a flow of material from one side of the membrane to the other. In this study membranes (Accurel, Celgard, GVHP, PM30 and PTHK) with different pore sizes were employed ...
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Dialysis is a membrane based separation process in which the concentration gradient across the membrane is the driving force resulting in a flow of material from one side of the membrane to the other. In this study membranes (Accurel, Celgard, GVHP, PM30 and PTHK) with different pore sizes were employed to characterise the transport of lithium ion in various (0.01, 0.1, 0.5, 1 and 2.5 w/v percent) initial feed concentrations via the dialysis process. This may be considered as a basis for wastewater treatment containing metal ions. The results show that low initial feed concentration causes less passage of ions through the membrane due to low driving force i.e. concentration gradient across the membrane. The investigation of the effect of membrane pore size on ion transport revealed that large pore size membranes provide less penetration of the metal ions through the membrane. These reproducible results, which are not expected, have been explained by the transport mechanism. Two types of mechanisms (extensive versus intensive) have been suggested for metal ion transport through different membranes. If the mechanism of ion transport is intensive, more ions pass through the membrane. Extensive mechanism results in lower ion transport through the membrane.
Full article
Modeling and Simulation
Volume 3, Issue 4 , October 2006, Pages 44-59
Abstract
"> Accurate prediction of the minimum miscibility pressure (MMP) in a gas injection process is crucial to optimizing the management of gas injection projects. Because the experimental determination of MMP is very expensive and time-consuming, searching for a fast and robust mathematical determination ...
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"> Accurate prediction of the minimum miscibility pressure (MMP) in a gas injection process is crucial to optimizing the management of gas injection projects. Because the experimental determination of MMP is very expensive and time-consuming, searching for a fast and robust mathematical determination of CO2-oil MMP is usually requested. This paper presents a new model based on a hybrid neural-genetic algorithm for predicting pure and impure CO2-oil MMP. The CO2-oil MMP of a reservoir fluid was correlated with the reservoir temperature, the composition of the oil, and that of the solution gas. The developed model is able to reflect the impacts on the CO2–oil MMP of the molecular weight of the C5+ fraction, reservoir temperature, and solution gas in the oil. The validity of this new model was successfully approved by comparing the model results to the calculated results for the common pure and impure CO2-oil MMP correlations. The new model yielded the accurate prediction of the experimental slim-tube CO2-oil MMP with the lowest mean absolute percentage error (MAPE), the standard deviation of error (SD), the root mean square error (RMSE), and the highest correlation coefficient among tested impure and pure CO2-oil MMP correlations. The results demonstrate that the hybrid neural-genetic model can be applied successfully and provide high accuracy and reliability for MMP forecasting.
Full article
Process Control and Engineering, Process Safety, HSE
Volume 3, Issue 4 , October 2006, Pages 60-75
Abstract
The spreading of a tracer in a bubbly two-phase grid-generated turbulent flow system is studied. In this work both particle image velocimetry (PIV) and planer laser-induced fluorescence (PLIF) are used to study the effect of the dispersed phase flow rate on the mixing characteristics of the tracer. The ...
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The spreading of a tracer in a bubbly two-phase grid-generated turbulent flow system is studied. In this work both particle image velocimetry (PIV) and planer laser-induced fluorescence (PLIF) are used to study the effect of the dispersed phase flow rate on the mixing characteristics of the tracer. The turbulent intensity of the continuous phase in the bubbly two-phase grid-generated turbulent flow is close to isotropic, and increasing the gas void fraction reduces the degree of non-isotropicity. The self-similarity of mean and RMS values of the cross-stream concentration distribution is observed. A new mathematical model is suggested to describe the self-similarity of the cross-stream profiles of the mean concentration based on two separate Gaussian curves into the central and outer region of the flow. The turbulent diffusivity is calculated using the Taylor hypothesis, which is based on the growth of the variance of the cross-stream profiles of the mean concentration, with a position along the direction of the flow. An increase in the void fraction does not affect the diffusivity of the superimposed distribution of the plume in the central region, however it did increase in the outer region.