Transport Phenomena,
Volume 1, Issue 2 , July 2004, , Pages 19-27
Abstract
The present study attempted deriving and solving the falling- cylinder governing equations for power law model non-Newtonian fluids. Based on this theoretical study, a novel falling- cylinder rheometer (FCR) was designed and constructed to measure the Theological properties of non-Newtonian fluids. Different ...
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The present study attempted deriving and solving the falling- cylinder governing equations for power law model non-Newtonian fluids. Based on this theoretical study, a novel falling- cylinder rheometer (FCR) was designed and constructed to measure the Theological properties of non-Newtonian fluids. Different falling cylinders with predesigned densities were used to determine the apparent viscosity of polyvinyl alcohol (PVA) solutions in water with various concentrations. The results indicate that all PVA solutions obey the power law model with the power law index as well as the consistency index changing linearly with concentration. Increasing concentration of the solution decreases power law index, while enhances consistency index and apparent viscosity.
Separation Technology,
Volume 8, Issue 1 , January 2011, , Pages 20-30
Process Control and Engineering, Process Safety, HSE
Volume 3, Issue 2 , April 2006, , Pages 20-32
Separation Technology,
Volume 11, Issue 4 , October 2014, , Pages 21-30
Separation Technology,
Volume 4, Issue 1 , January 2007, , Pages 21-35
Abstract
Activated carbons are extremely versatile adsorbents for major industrial significance, especially for metal ions recovery from wastewaters. In this study, the activated carbon prepared from the hard shell of apricot stones, an agricultural solid, which was used for the gold recovery from gold-plating ...
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Activated carbons are extremely versatile adsorbents for major industrial significance, especially for metal ions recovery from wastewaters. In this study, the activated carbon prepared from the hard shell of apricot stones, an agricultural solid, which was used for the gold recovery from gold-plating wastewater is investigated. Activated carbon was produced by chemical activation with phosphoric acid. Recovery parameters such as adsorbent dose, the particle size of the activated adsorbent, pH and the agitation speed of mixing were studied. The equilibrium data fit well with the Freundlich isotherm model. A Langmuir isotherm model has been used to obtain thermodynamic parameters. The results showed that under the optimum operating conditions, more than 98 per cent of the gold was recovered by activated carbon after only 3 hours. It was found that the activated hard shell of apricot stones could be used as an effective adsorbent for gold recovery from wastewaters.
Biomedical and Biotechnology,
Volume 10, Issue 2 , April 2013, , Pages 22-32
Reaction Engineering, Kinetics and Catalysts,
Volume 9, Issue 2 , April 2012, , Pages 22-33
Thermodynamics,
Volume 9, Issue 3 , July 2012, , Pages 22-30
Separation Technology,
Volume 7, Issue 4 , October 2010, , Pages 22-28
Biomedical and Biotechnology,
M. Azizi; H. Ghourchian; F. Yazdian; F. Dashtestani
Volume 12, Issue 1 , January 2015, , Pages 22-29
Abstract
"> There has been considerable interest in developing albumin nanoparticles as drug delivery devices. Albumin is an important endogenous antioxidant due to its potential of acting as reactive oxygen species scavenger. On the other hand, toxicity of silver nanoparticles had been demonstrated on cancer ...
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"> There has been considerable interest in developing albumin nanoparticles as drug delivery devices. Albumin is an important endogenous antioxidant due to its potential of acting as reactive oxygen species scavenger. On the other hand, toxicity of silver nanoparticles had been demonstrated on cancer cell lines. In the present study, Ag NPs coated with BSA NPs were synthesized by silver nanoparticles which were coated with bovine serum albumin (BSA) via desolvation technique. The Ag NPs coated with BSA NPs formation was confirmed by UV-Vis spectroscopy and #_>ADF;;==@ Dynamic Light Scattering (DLS). Human breast cancer cells (MCF7 cells) were then cultured in the presence of the nanoparticles to evaluate the cytotoxicity of Ag NPs coated with BSA NPs by the MTT colorimetric technique. The antioxidant activities ofAg NPs coated with BSA NPs were evaluated in terms of their inhibition of autoxidation rate of pyrogallol as superoxide. The effect ofAg NPs coated with BSA NPs on MCF7 exhibit a dose-dependent toxicity for the cell tested and the viability of MCF-7 decreased to 50% (LD50) at the concentration of5 Ïg/mL. The IC50 value ofantioxidant activities ofAg NPs coated with BSA NPs were 8 µg/mL which demonstrated that Ag NPs coated with BSA NPs were good superoxide scavengers. In conclusion, our data show that Ag NPs coated with BSA NPs had antioxidant and anticancer activities in MCF-7 cells.
Transport Phenomena,
Volume 5, Issue 1 , January 2008, , Pages 22-33
Abstract
Synthesis of heat exchanger networks (HENs) is inherently a mixed integer and nonlinear programming (MINLP) problem. Solving such problems leads to difficulties in the optimization of continuous and binary variables. This paper presents a new efficient and robust method in which structural parameters ...
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Synthesis of heat exchanger networks (HENs) is inherently a mixed integer and nonlinear programming (MINLP) problem. Solving such problems leads to difficulties in the optimization of continuous and binary variables. This paper presents a new efficient and robust method in which structural parameters are optimized by genetic algorithm (G.A.) and continuous variables are handled due to a modified objective function for maximum energy recovery (MER). Node representation is used for addressing the exchangers and networks are considered as a sequence of genes. Each gene consists of nodes for generating different structures within a network. Results show that this method may find new or near optimal solutions with a less than 2% increase in Hen annual costs.
Modeling and Simulation
Volume 2, Issue 2 , April 2005, , Pages 22-36
Abstract
n this work, computational fluid dynamics of the flow behavior in a cold flow of fluidized bed is studied. An improved finite volume based finite element method has been introduced to solve the two-phase gas/solid flow hydrodynamic equations. This method uses a collocated grid, where all variables are ...
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n this work, computational fluid dynamics of the flow behavior in a cold flow of fluidized bed is studied. An improved finite volume based finite element method has been introduced to solve the two-phase gas/solid flow hydrodynamic equations. This method uses a collocated grid, where all variables are located at the nodal points. The fluid dynamic model for gas/solid two-phase flow is based on the two fluid model where both phases are continues and fully interpenetrating. For the gas and solid phases the Navier-Stokes equation based on the concept of local average is obtained. Results are verified against experimental data reported in the literature.
Transport Phenomena,
Volume 9, Issue 1 , January 2012, , Pages 23-32
Modeling and Simulation
Volume 6, Issue 1 , January 2009, , Pages 23-39
Biomedical and Biotechnology,
Volume 5, Issue 4 , October 2008, , Pages 23-32
Abstract
Phenolic acids constitute a major group of pollutants which are recalcitrant to common biological treatment. In this study synthetic wastewater containing a mixture of p-coumaric and p-hydroxybenzoic acids was evaluated for photo-Fenton pretreatment. The changes in biodegradability (ratio of biochemical ...
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Phenolic acids constitute a major group of pollutants which are recalcitrant to common biological treatment. In this study synthetic wastewater containing a mixture of p-coumaric and p-hydroxybenzoic acids was evaluated for photo-Fenton pretreatment. The changes in biodegradability (ratio of biochemical oxygen demand to total organic carbon (TOC)) and mineralization (TOC removal) were monitored. While there was a significant biodegradability enhancement during the photo-Fenton process, there was little mineralization (less than 6%) taking place over the course of oxidation. Longer oxidation time did not further improve the pretreatment; rather it decreased the biodegradability of the solution through complete mineralization of the biodegradable intermediates. Resin fractionation of treated solutions indicated an increase in the hydrophilic fraction and a decrease in the hydrophobic fraction. Indeed, there was a clear and direct correlation between the hydrophilic nature of the organics and the biodegradability of the solution, indicating that hydrophilic compounds are more biodegradable. The formation of aldehydes further supported the links between biodegradable and hydrophilic compounds
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%.
Reaction Engineering, Kinetics and Catalysts,
Volume 1, Issue 1 , April 2004, , Pages 23-28
Reaction Engineering, Kinetics and Catalysts,
Volume 8, Issue 4 , October 2011, , Pages 24-33
Modeling and Simulation
Volume 2, Issue 1 , January 2005, , Pages 24-33
Abstract
A new model to calculate heat eddy diffusivity in separating and reattaching flows based on modification of constant Prt is proposed. This modification is made using an empirical correlation between maximum Nusselt number and entrance Reynolds number. The model includes both the simplicity of Prt=0.9 ...
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A new model to calculate heat eddy diffusivity in separating and reattaching flows based on modification of constant Prt is proposed. This modification is made using an empirical correlation between maximum Nusselt number and entrance Reynolds number. The model includes both the simplicity of Prt=0.9 assumption and the accuracy of two-equation heat-transfer models. Furthermore, an appropriate low Reynolds number k — e model is adopted for calculation of eddy viscosity. The model is used for prediction of Nusselt number distribution at various ranges of Reynolds number and expansion ratio. The numerical results are compared with available experimental data in the literature and have shown good agreement. The CPU time for the present model is about 33% less than that of two-equation heat-transfer model.
Modeling and Simulation
Volume 9, Issue 4 , October 2012, , Pages 25-32
Modeling and Simulation
Volume 11, Issue 3 , July 2014, , Pages 26-36
Modeling and Simulation
B. Abbasi Souraki; R. Hasanzadeh
Volume 12, Issue 2 , April 2015, , Pages 26-36
Abstract
> In this paper, extraction of starch and protein from potato during leaching in a batch extractor, using distilled water as the solvent, was investigated. The experiments were carried out by soaking bulk of infinite slab shape potato samples in distilled water in a temperature and agitation controlled ...
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> In this paper, extraction of starch and protein from potato during leaching in a batch extractor, using distilled water as the solvent, was investigated. The experiments were carried out by soaking bulk of infinite slab shape potato samples in distilled water in a temperature and agitation controlled batch extractor at the three temperatures of 30, 45 and 55ºC. A mathematical model was developed for prediction of mass transfer during the leaching process, by defining a partition factor (K) as the ratio of the concentration on the surface of the body to that in the bulk of solution. Diffusion coefficients of the solutes and moisture were obtained by fitting the experimental data of solute loss and moisture gain to the first six terms of the series solution of the mathematical model by using a non-linear regression analysis. The diffusivity values for starch, protein and moisture were evaluated between 0.273u10-10 and 1.577u10-10 m2/s, with adjustment parameter R2 values in the range of 0.941 to 0.986 and mean relative error (MRE) values between 0.092 and 0.356, respectively. Results showed that the proposed model could be used for explaining the diffusion of solutes and moisture into the potatoes, during the leaching process, with acceptable degree of goodness.
Transport Phenomena,
Volume 6, Issue 3 , July 2009, , Pages 26-45
Abstract
ewline"> Dispersion of heavy gases is considered to be more hazardous than the passive ones because it takes place more slowly. When the gas is accidentally released at ground level or where there are many obstacles in the area it is considered to be a heavy gas. In this paper, based on the extensive ...
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ewline"> Dispersion of heavy gases is considered to be more hazardous than the passive ones because it takes place more slowly. When the gas is accidentally released at ground level or where there are many obstacles in the area it is considered to be a heavy gas. In this paper, based on the extensive experimental work of McQuid and Hanna, the model was tested against two types of experiments: A simple experiment “Thorney Island” and a complex experiment “Kit Fox” in order to validate CFD code. In order to accomplish this validation the multiphase approach was employed. Also, the vertical temperature gradient in the atmosphere was investigated. The investigation of wind speed was done taking factors such as time, height and direction into consideration. In order to reduce the number of elements in the computational domain, a combination of 2D and 3D geometry was utilized. The results showed that the wind inlet correction, as well as the temperature gradient, had a significant influence on gas concentration records.
Reaction Engineering, Kinetics and Catalysts,
A. Irankhah; M. Jafari; M. Mahmoudizadeh
Volume 14, Issue 1 , March 2017, , Pages 26-39
Abstract
Methanol steam reforming plays a pivotal role to produce hydrogen for fuel cell systems in a low temperature range. To accomplish higher methanol conversion and lower CO production, the reaction was catalyzed by CuZnFe mixed oxides. Various ratios of Fe and Cu/Zn were coprecipitated in differential method ...
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Methanol steam reforming plays a pivotal role to produce hydrogen for fuel cell systems in a low temperature range. To accomplish higher methanol conversion and lower CO production, the reaction was catalyzed by CuZnFe mixed oxides. Various ratios of Fe and Cu/Zn were coprecipitated in differential method to optimize the CuZnFe structure. The sample containing 45Cu50Zn5Fe (Wt. %) revealed its maximum methanol conversion of 98.4 % and CO selectivity of 0.78 % with operating conditions of gas hourly space velocity of 18000 h-1 and steam to carbon ratio of 1.3 at 270 °C. The synthesized catalysts were analyzed by powder X-ray diffraction, N2 adsorption/desorption, temperature programmed reduction, scanning electron microscopy techniques. The results revealed that the prepared samples presented mesoporous structure with different pore size depending on the Cu/Zn/Fe ratios. The results showed that increase in Fe loading to 20 Wt. % empowered methanol conversion and decreased CO selectivity. Moreover, the optimized catalyst activity was kept constant during 17 h time on stream. Besides, operating conditions of gas hourly space velocity and steam to carbon ratios were evaluated.
Materials synthesize and production
Volume 10, Issue 3 , July 2013, , Pages 27-38