Prediction of Particle Deposition Using a Simplified Particle Model in Fully Developed Channel Flow

In this study the Eulerian particle model was modified to predict the particle deposition rate in fully developed channel flow. The modified model is less complicated and has much lower computation time. The performance of the simplified model was examined by comparing the particle deposition rate in a vertical channel with the experimental data for fully developed channel flow available in the literature. The effects of turbophoretic force, thermophoretic force, electrostatic force, gravitational force, Brownian/turbulent diffusion, and the wall roughness on the particle deposition rate were examined. The predictions of the modified particle model were in agreement with the experimental data.     

Tie‐simplex based compositional space parameterization: Continuity and generalization to multiphase systems

A theoretical analysis is provided of the continuity of multiphase compositional space parameterization for thermal‐compositional reservoir simulation. It is shown that the tie‐simplex space changes continuously as a function of composition, pressure, and temperature, and this justifies the Compositional Space Adaptive Tabulation (CSAT) framework, in which a discrete number of tie‐simplexes are constructed, tabulated, and reused in the course of a simulation. The CSAT is extended for thermal‐compositional displacements for mixtures that can form an arbitrary number of phases. In particular, the construction is described of three‐phase tie‐simplex tables, and it is shown how the degeneration of multiphase regions can be accurately captured over wide ranges of temperature and pressure. Several challenging multiphase examples are used to demonstrate the accuracy and effectiveness of phase‐state identification using tabulated tie‐simplexes. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1684–1701, 2013     

CPFD flow pattern simulation in downer reactors

This study contributes with a computational fluid dynamic simulation based on the numerical solution of continuity and momentum balance equations in a three‐dimensional (3‐D) framework. The proposed down flow gas–solid suspension model includes a unit configuration and C_D drag coefficients recommended for these units. Computational particle fluid dynamics (CPFD) calculations using suitable boundary conditions and a Barracuda (version: 14.5.2) software allow predicting local solid densification and asymmetric “wavy flows.” In addition, this model forecasts for the conditions of this study higher particle velocity than gas velocity, once the flow reaches 1 m from the gas injector. These findings are accompanied with observations about the intrinsic rotational character of the flow. CPFD numerical 3‐D calculations show that both gas and particle velocities involve the following: (a) an axial velocity component, (b) a radial velocity component (about 5% of axial velocity component), and (c) an angular velocity component. The calculated velocity components and the rotational flow pattern are established for a wide range of solid flux/gas flux ratios. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1635–1647, 2013     

Novel PDMS‐based membranes: Sodium chloride and glucose permeability

Permeation of sodium chloride and glucose through polydimethylsiloxane‐poly(N‐isopropylacrylamide) (PDMS‐PNIPAAm) interpenetrating polymer networks (IPNs) of two different microstructures was investigated. We have successfully developed small‐molecule permeable IPNs, by modifying PDMS film structure. A group of PDMS films was prepared using conventional solvent casting (SC) method and another group produced by introducing oil, followed by SC and leaching the oil out (SCOL method). Scanning electron microscopy (SEM) and attenuated total reflection fourier transformer infrared (ATR‐FTIR) spectroscopy results confirmed the presence of PNIPAAm in the SC and SCOL IPNs. Results obtained from spectra of differential scanning calorimetry (DSC) showed that these IPNs had a phase transition temperature at about 32°C. Permeation measurements showed that the presence of PNIPAAm as the second phase in the IPN, improved the permeability of PDMS film. According to the results, maximum permeation coefficient was related to SCOL IPN containing 15.8% ± 0.3%PNIPAAm, at 23°C (5.98 × 10^?7 ± 7.93 × 10^?9 cm²/s for sodium chloride and 3.6 × 10^?7 ± 7 × 10^?9 cm²/s for glucose). These results suggested that these PDMS‐PNIPAAm IPNs with sodium chloride and glucose permeability may be further developed as ophthalmic biomaterials or corneal replacements. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Antimicrobial properties of treated cotton fabrics with non-toxic biopolymers and their dyeing with safflower and walnut hulls

Novel results were obtained by selection of chitosan treatment parameters on cotton fabrics to obtain antimicrobial properties against E. coli, gram-negative bacteria. Taguchi experimental design was used in this study and microbial reduction rate was considered as the response. The signal-to-noise and the analysis of variance (ANOVA) were used to find the optimum levels to indicate the impact of treatment parameters on antimicrobial properties. The antimicrobial behavior of the fabric against bacterium as a function of each parameter was plotted. A verification test was also performed to prove the validity of Taguchi technique for this study after the determination of parameters’ optimum levels. Also the effect of chitosan and the mordanting on the dyeing properties of cotton fabrics with natural dyes such as walnut hull and safflower was investigated by measuring the color strength (K/S values) of the treated and untreated substrates at various concentrations. The results revealed that the K/S of dyed chitosan-treated cottons increased compared to untreated samples. In addition, antimicrobial properties of natural-dyed treated and untreated fabrics were determined. Walnut hull and safflower have shown antimicrobial properties. Although dyeing the chitosan-treated fabric reduced its antimicrobial effects but the results showed that chitosan-treated cotton fabrics had excellent antimicrobial properties against E. coli. Applying Taguchi experimental design for treating cotton fabrics with chitosan and utilizing these native natural dyes have never been used elsewhere.     

Application of artificial neural network for vapor liquid equilibrium calculation of ternary system including ionic liquid: Water, ethanol and 1-butyl-3-methylimidazolium acetate

A feed forward three-layer artificial neural network (ANN) model was developed for VLE prediction of ternary systems including ionic liquid (IL) (water+ethanol+1-butyl-3- methyl-imidazolium acetate), in a relatively wide range of IL mass fractions up to 0.8, with the mole fractions of ethanol on IL-free basis fixed separately at 0.1, 0.2, 0.4, 0.6, 0.8, and 0.98. The output results of the ANN were the mole fraction of ethanol in vapor phase and the equilibrium temperature. The validity of the model was evaluated through a test data set, which were not employed in the training case of the network. The performance of the ANN model for estimating the mole fraction and temperature in the ternary system including IL was compared with the non-random-two-liquid (NRTL) and electrolyte non-random-two-liquid (eNRTL) models. The results of this comparison show that the ANN model has a superior performance in predicting the VLE of ternary systems including ionic liquid.     

The joint reaction of methanol and i-butane over the HZSM-5 zeolite

The effects of i-butane addition to methanol in MTP reaction were investigated over an in-house prepared HZSM-5 catalyst. It was observed that, propylene yield would be enhanced when i-butane fed to the reactor along with methanol. The rising growth of the propylene yield continued to peak on till the balance in thermal condition established. Similar trends have been observed when water was added to the mixture. The effect of WHSV with fixed water composition on product distribution was also studied. The optimum point where the highest amount of propylene yielded was shown to be high depended upon the temperature and residence time.     

Synthesis of Molybdenum Oxide Nanohybrids as Efficient Catalysts in Oxidation of Alcohols

Novel layered materials based on molybdenum oxide have been synthesized using three amino-carboxylate ligands; terephetalic acid, p-aminobezoic acid and diaminobenzene. On the basis of X-ray diffraction, scanning electron microscopy, thermogravimetry, and infrared results, the insertion of organic ligands into the interlayer space of molybdenum oxide has been proposed. Moreover, the influence of organic guests on the oxide structure and also their catalytic performance are discussed. Furthermore, fabrication of the nanostructured molybdenum oxide is achieved by calcinations of these hybrid materials at 600 °C. Somewhat oriented nanoplatelets are viewed with different catalytic activity.     

Polypropylene cellulose‐based composites: The effect of bagasse reinforcement and polybutadiene isocyanate treatment on the mechanical properties

Using bagasse fiber as the reinforcing filler and polypropylene as the thermoplastic matrix polymer, a reinforced composite was prepared, and its mechanical properties examined as a function of the amount of compatibilizing agents used. In the sample preparation, four levels of fiber loading (10, 20, 30, and 40 wt %), three levels of polybutadiene isocyanate (PBNCO) content (0, 2, and 4 wt %) and two levels of maleated polypropylenes (MAPP) content (0 and 3 wt %) as compatibilizing agents were used. The tensile properties of the composites improved as the fiber loading and the compatibilizing agents increased, but the impact strength was significantly decreased. The mechanical study revealed that the positive effect of compatibilizing agents on interfacial bonding. The composites treated with PBNCO showed superior tensile and impact properties than those without treatment. The findings indicated that bagasse as agro‐waste material is a valuable renewable natural resource for composite production and could be utilized as a substitute for wood in composite industries. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of Iron sulfate as electrolyte additive on plasma electrolytic oxidation of aluminum alloy

This study has been carried out to investigate the incorporation of Iron(II) sulfate as an additive of electrolyte on formed AA1010 aluminum alloy, using plasma electrolytic oxidation method in silicate-based electrolytes containing Iron(II) sulfate. In order to fabricate nanocomposite coating, silicon nitride nanopowder was added to electrolyte. The effects of iron(II) sulfate additive on the voltage-time trend, microstructure, compositions, wear, and corrosion resistances of PEO coatings were investigated. In addition, current density and concentration of additive were studied as parameters that were effective on coating. Results showed that although FeSO₄ enters to the coating structure, but it does not develop a new phase. The corrosion and wear behavior of coated samples with FeSO₄ indicate an improvement as compared to those without additive.