Full article
Modeling and Simulation
M.R zeynali; M. Nazari; S. Karimi; S. M. Seyedmohaghegh; S. Soltani
Volume 14, Issue 2 , 2017, Pages 3-16
Abstract
In this research samples of PVOH were synthesized at various reaction conditions (temperature, time, and amount of catalyst). First at 25˚C and 45˚C and constant catalyst weight samples of PVOH were prepared with different degree of hydrolysis at various times. For investigation of the effects of temperature, ...
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In this research samples of PVOH were synthesized at various reaction conditions (temperature, time, and amount of catalyst). First at 25˚C and 45˚C and constant catalyst weight samples of PVOH were prepared with different degree of hydrolysis at various times. For investigation of the effects of temperature, at times 20 and 40 min and constant weight of catalyst PVOH was prepared at various temperatures. Increasing the time and temperature of the hydrolysis reaction caused increasing degree of hydrolysis and reducing the molecular weight of the samples. Considering the variation of reaction condition, the effects of each parameter on molecular weight, degree of hydrolysis and conversion were investigated individually and also collective. Also, by an artificial neural network method, using experimental results (temperature, time and catalyst amount as input and conversion, degree of hydrolysis and molecular weight as output) a network by Levenberg-Marquardt (LM) back propagation with tan-sigmoid transfer function was established. Finally, the established model presented a good prediction capability and enabled us to predict the output in terms of arbitrary in puts. PVOH is an important polymer and prediction its properties during production significantly improves the quality of the products. Neural network technique is used to model the chemical processes to predict the behavior of the process. In this research we investigated the effects of various processing parameters on the properties of PVOH.
Full article
Modeling and Simulation
I. Omidi; M. Kalbasi
Volume 14, Issue 2 , 2017, Pages 17-32
Abstract
The performance of the solid acid fuel cell by CsH2PO4 electrolyte was analyzed using the present model of the electrochemical reaction and transport phenomena, which are fully coupled with the governing equations. Development of such a model requires creating the three-dimensional geometry and its mesh ...
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The performance of the solid acid fuel cell by CsH2PO4 electrolyte was analyzed using the present model of the electrochemical reaction and transport phenomena, which are fully coupled with the governing equations. Development of such a model requires creating the three-dimensional geometry and its mesh grid, discretization of momentum, mass and electric charge balance equation and solving the equations based on the information of electrical and electrochemical models in different areas of the cell consisting of porous electrodes, gas channels, and the solid parts like the current collector. The model equations were solved employing a finite elements technique solver of cell potential. Different parameters including current density (i), cell potential (V), cell power and concentration distribution of hydrogen, oxygen and water vapor have been investigated in this study. Also, the effect of different voltages on the concentration distribution of all the mentioned species through the cell length are taken into account. Comparing the polarization curve values with the experimental results shows a good agreement between the computed and experimental values (Maximum error is less than 4%). The results showed that there is a noticeable difference between H2, O2 and H2O concentration through the cell length subjected to various voltages. This difference was more apparent at lower voltages due to higher current density and higher consumption of species. The polarization curve is well consistent with the model and experimental data which verify the present simulation results.
Full article
Modeling and Simulation
E. Pashai; M. R. Dehghani; F. Feyzi
Volume 14, Issue 2 , 2017, Pages 33-47
Abstract
Varnish and sludge formation are considered as one of the most common problems in lubrication and hydraulic systems. In order to simulate the condition of sludge formation, base stock lubricant (Group 1 API) has been selected and exposed to heat in a laboratory setup. Sludge formation process accelerated ...
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Varnish and sludge formation are considered as one of the most common problems in lubrication and hydraulic systems. In order to simulate the condition of sludge formation, base stock lubricant (Group 1 API) has been selected and exposed to heat in a laboratory setup. Sludge formation process accelerated in the laboratory scale and solid liquid equilibrium data were extracted. Then solid-liquid equilibrium has been modeled using SAFT equation of state through sludge formation. The results for prediction of sludge formation showed that the absolute average deviations between experimental and theoretical results were less than 1.4%. The calculated results for solubility coefficient of the oxidation byproducts from SN100 (solvent neutral Group I) base stock in fresh (un-oxidized) oil were in good agreement with the experimental data, and average deviation between calculated and experimental data was less than 6.5%. The amount obtained for binary interaction parameter K_ij was – 0.0447. It is shown that SAFT equation of state has the capability of solid liquid equilibrium.
Full article
Transport Phenomena,
P. Goodarzi; V. Mohebbi
Volume 14, Issue 2 , 2017, Pages 48-58
Abstract
Understanding the kinetics of gas hydrate formation is essential to model and predict the hydrate formation (or dissociation) process. In the present paper, we investigated the formation of pure propane gas hydrate as a former gas. In this regard, several experiments were conducted to measure the rate ...
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Understanding the kinetics of gas hydrate formation is essential to model and predict the hydrate formation (or dissociation) process. In the present paper, we investigated the formation of pure propane gas hydrate as a former gas. In this regard, several experiments were conducted to measure the rate of hydrate formation under various pressures (410 to 510 kPa) and temperatures (274 K to 277 K) in a controlled temperature stirred reactor. It was observed that propane consumption rate can be assumed constant with time. Mass transfer approach was used to estimate the mass transfer coefficient in the gas-liquid contact area as a function of pressure and temperature. Results indicated that mass transfer approach can predict the kinetics of propane hydrate formation. In other word, it is reasonable to assume that this process is a mass transfer limited phenomena and the mass transfer in the liquid side the gas-liquid contact area controls the hydrate growth.
Full article
Separation Technology,
M. Delavar; Gh. Bakeri; M. Hosseini
Volume 14, Issue 2 , 2017, Pages 59-73
Abstract
In this study, novel polycarbonate-titanium oxide nanotubes (PC-TNT) ultrafiltration mixed matrix membranes (MMMs) were fabricated for decontamination of Cd2+ and Cu2+ metal ions from aqueous solution. The weight percent of TNTs in the polycarbonate membrane matrix was changed from 0 to 15. The synthesized ...
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In this study, novel polycarbonate-titanium oxide nanotubes (PC-TNT) ultrafiltration mixed matrix membranes (MMMs) were fabricated for decontamination of Cd2+ and Cu2+ metal ions from aqueous solution. The weight percent of TNTs in the polycarbonate membrane matrix was changed from 0 to 15. The synthesized neat PC membrane and PC-TNTs MMMs were characterized with respect to structural morphology and hydrophilicity using scanning electron microscopy (SEM) and water contact angle, respectively. The effects of TNTs loadings on the pure water flux, mean pore size, porosity and water contact angle of fabricated membranes and Cd2+ and Cu2+ heavy metal ion rejection were also studied. By increasing the loading of TNTs nanoparticles in the membrane matrix, the membrane mean pore size tended to increase, while the porosity decreased. Also, the increase in TNTs loading resulted in an increase in membrane water flux which was mainly attributable to the enhancement in mean pore size and partly caused by the decreased contact angle value (more hydrophilic). Of all the membranes studied, it was found by UF experiments that PC-TNT MMM was the most efficient material in heavy metal ions removal due to the superior adsorption capacity of TNTs material. The generic results revealed that TNTs material can be favorite candidates for MMMs preparation in order to be conveniently used in the Cd2+ and Cu2+ heavy metal ions decontamination from polluted water resources.
Full article
Polymer Engineering and Technology,
M. Fasihi; R. Arabzadeh; M.R. Moghbeli
Volume 14, Issue 2 , 2017, Pages 74-82
Abstract
The aim of this study was to improve the adhesion performance of plasticized polyvinyl chloride (PVC) coatings on steel substrates by using nanoparticles. For this purpose, the PVC plastisol with different concentration of nano-silica was prepared and applied to bond steel joints. The adhesive strength ...
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The aim of this study was to improve the adhesion performance of plasticized polyvinyl chloride (PVC) coatings on steel substrates by using nanoparticles. For this purpose, the PVC plastisol with different concentration of nano-silica was prepared and applied to bond steel joints. The adhesive strength of the joints was determined by single-lap shear test. Moreover, mechanical properties and microstructure of coating were investigated. The addition of 1wt% nano-silica to plastisol dramatically increased the lap shear strength up to 4-fold, which was an outcome of compatibilizing effect of silica. Young's modulus and tensile strength of plasticized PVC were slightly increased by adding nanoparticles, as well. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) exhibited higher inclusion size in the coating having higher silica volume which was attributed to the agglomeration of nanoparticles. In the following, the effect of plasticizer composition on the adhesion strength by replacing some part of dioctyl phthalate (DOP) plasticizer with more polar oil, epoxidized soybean oil (ESO), was examined. Although adding ESO improved the lap shear strength of the neat coating, its effect on the properties of the coatings containing silica was negligible.
Research note
Reaction Engineering, Kinetics and Catalysts,
S. A. Hosseini
Volume 14, Issue 2 , 2017, Pages 83-90
Abstract
Two Cu-Co and Co3O4 oxides were synthesized by the conventional sol-gel auto-combustion and their physical-chemical properties were characterized by XRD, FTIR, SEM, TPR and XPS. The XRD results indicated that copper-cobalt oxide appeared in a mixture form of Cu0.15Co2.85O4 spinel and CuO phases, whereas ...
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Two Cu-Co and Co3O4 oxides were synthesized by the conventional sol-gel auto-combustion and their physical-chemical properties were characterized by XRD, FTIR, SEM, TPR and XPS. The XRD results indicated that copper-cobalt oxide appeared in a mixture form of Cu0.15Co2.85O4 spinel and CuO phases, whereas the cobalt oxide exhibited in the pure form of Co3O4 spinel. The FTIR approved the formation of the spinel structure in the both samples. The SEM results showed that both oxides are as nanoparticles. Application of the same synthesis conditions for both samples let to obtain samples with different purity. The results of temperature program reduction (TPR) revealed that Cu-Co nano oxide is more reducible at lower temperatures. The copper-cobalt oxide exhibited the higher activity that the Co3O4 in catalytic combustion of toluene, which is explained by its higher reducibility at the reaction conditions and by a possible synergistic effect between Cu-Co oxide and CuO particles.