International Journal of Engineering
Volume:26 Issue: 8, Aug 2013

The gelatin/gum Arabic microcapsules encapsulating peppermint oil were prepared by complex coacervation using tannic acid as hardening agent. The effects of various parameters, including concentration of wall material, core material, tannic acid and tween80 were investigated on particle size and encapsulation efficiency. For statistical evaluation of the parameters, Taguchi method has been used. The size of prepared spherical microcapsules was 19-66 micrometers. The results showed that, particle size increased with increasing core and wall concentration and decreased with increasing Tannic acid and Tween80 concentration. The efficiency increased by increasing the core and wall concentration, Tannic acid and Tween80 concentration had no effect on efficiency. Maximum efficiency of 82% was under optimal conditions: 4% wall material, 5% core material, 0.75% tannic acid and 0.02% tween80. The release of microcapsules was investigated in gastric and intestinal fluid. The microcapsules were release most of the core material in simulated gastric fluid (pH 1.2).

This study reports the purification and biochemical characterization of thermostable and acidic-pH-stable α-amylase from Bacillus sp. Iranian S1 isolated from the desert soil (Gandom-e-Beryan in Lut desert, Iran). Amylase production was found to be growth associated. Maximum enzyme production was in exponential phase with activity 2.93 U ml-1 at 50°C and pH 5. The enzyme was purified by isopropanol sedimentation, ion-exchange chromatography on DEAE cellulose DE-52 and gel filtration on Sephadex G-100. The enzyme was purified to homogeneity with purification fold 98.9 with 25% yield and specific activity 375.9 U mg-1 of protein. The molecular weight of purified α-amylase was estimated to be 70 KDa by SDS-PAGE. The enzyme remained stable in a wide range of temperature and pH between 30°C- 110°C and 3-9, respectively. Assayed with soluble starch as substrate, the enzyme displayed optimal activity at 90°C and pH 5. The purified α-amylase was acid- and thermo-stable with novel properties making it suitable for many industrial purposes.

Nanofluids are suspensions of nanoparticles in the base fluids, a new challenge for thermal sciences provided by nanotechnology. In this paper, the tested fluids are prepared by dispersing the Al and Cu into water at three different concentrations such as 500, 1000 and 2000 ppm. Thermal conductivities of these fluids are measured experimentally by thermal property analyzer i.e. KD2 Pro by using KS-1 sensor needle as this needle is preferred for low viscosity fluids. Experimental results show that thermal conductivity of nanofluids are higher than the base fluid and Thermal conductivity of Cu/Water nanofluid is more than Al/Water nanofluid, because of the Cu thermal conductivity is more in comparison with Al thermal conductivity. In addition, a comparison is made between the experimental results of thermal conductivity and the results calculated using models presented for predicting them. Results showed that classic thermal conductivity models are failed to predict nanofluids thermal conductivity, but novel models that consider the effects of temperature have more acceptable results and9% difference is found between experimental results and Xei model for Cu/water nanofluid.

The most important pollutants in wastewater are heavy metal ions. In this paper, the effects of various parameters such as pH, contact time, initial concentration, and temperature on the adsorption of Cu (II) by nanochitosan (NCS) was investigated in batch experiment. Nanochitosan was prepared based on ionic gelation and charac­terized by means of Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) analysis. Maximum uptake of Cu (II) was recorded at pH=6. Equilibrium data for Cu (II) were fitted well by Langmuir adsorption model with maximum adsorption capacity of 33.33 mg/g at 25°C. The obtained data showed that kinetically proceeded according to pseudo second-order model. It was concluded that NCS had great potential to remove Cu (II) ions from the aqueous solutions at various concentrations of metal ions.

The forced convective heat transfer (CHT) coefficient of a particular nanofluid, Al2O3 nanoparticles-ethylene glycol (EG) mixture, was investigated experimentally in a double-pipe heat exchanger. The nanofluid Nusselt number for different nanoparticles’ concentrations as well as various operating temperatures was measured to be increased up to 23.7% using 1.0% wt of nanoparticles. The significance of this work as novelty are the 22-screening design was used to investigate the effect of factors and the results emphasized that increasing nanoparticles’ concentration has higher effect on the CHT coefficient enhancement of nanofluid. The comparison of experimental results and semi-empirical correlations’ results was done and it was shown considerable deviations for high operating temperatures and nanoparticles as nanostructure concentrations.

Removal of Fe (II) from aqueous media was investigated using chitosan as the adsorbent in both batch and continuous systems. Batch experiments were carried out at initial concentration range of 10-50 mg/L and temperature range of 20–40˚C. In batch experiments, maximum adsorption capacity of 28.7 mg/g and removal efficiency of 93% were obtained. Adsorption equilibrium data were well-fitted with Langmuir-Freundlich model and the model parameters were recovered. In column study, experiments were performed in a fixed bed of chitosan operated at continuous up-flow mode and constant temperature of 25˚C. Sharp breakthrough curves were observed at high flow rates, high inlet metal concentrations and low bed heights. Breakthrough curves were analyzed by physical models such as Thomas and Yan’s models as well as Artificial Neural Network (ANN) method. Compared to physical models, simulation of dynamic behaviour of the system using Back Propagation Artificial Neural Network (BP-ANN) demonstrated high coincidence between experimental and predicted breakthrough curves. The FTIR spectrum of chitosan before and after adsorption process demonstrated that hydroxyl and amino groups are the main functional groups involved in the binding of iron ions.

The purpose of this study is to develop a mathematical model for studying the magnetic field effect on blood flow through an axially non-symmetric but radially symmetric atherosclerotic artery. Herschel-Bulkley equation has been taken to represent the non-Newtonian character of blood. The response of magnetic field, stenosis height, shape parameter on velocity, volumetric flow rate in stenotic section and wall shear stress at the surface of stenosis are revealed analytically and graphically.

In this paper, experimental data and numerical results of heat transfer from a heated rotating disk in still air are presented over a large range of inclination angles and a dimensionless correlation is developed for forced, natural and mixed convection. The measured Nusselt number over the rotating disk is compared with the numerical results. The goal of the present research is to develop a semi empirical correlation in the familiar classical form for a rotating disk at any arbitrary inclination angle over a wide range of rotational Reynolds numbers. The results show that the local Nusselt number does not change dramatically with inclination angle.

The energy absorbing capability is one of the most important aspects of crushing behavior of a structure subjected to axial impact. In this paper, a simple practical method is introduced to enhance the crushing behavior of this kind of structure. The axial impact of metallic energy absorbing thin-walled tubes with special shaped cross-section is simulated using LS-DYNA software. The effect of change in the corners bluntness of non-circular metallic thin-walled tubes on their energy absorbing capability has been studied. Moreover, the mean crushing force, the maximum deformation, and the mass specific energy absorption (MSEA) of the tubes were compared. Results show that the energy absorbing capability can be significantly improved by choosing proper bluntness of the corners for quasi-triangle- and quasi-square shaped tubes. Furthermore, results show an improvement in the energy absorbing capability of quasi-square shaped tubes even in comparison with circular one.

Zirconia-nickel functionally graded materials were obtained by powder metallurgy technique. The microstructure, residual stress, fracture toughness and Vickers hardness were investigated. Mixed-mode fracture response of YSZ /Ni functionally graded materials was examined utilizing the three point bending test and finite element method (Cosmos/M 2.7). The results show that the stress intensity factors (KI, KII) for the FGM are less than those for non-graded composite (NGCs) under mixed mode loading conditions. There are some local perturbations in the crack propagation paths of the FGM and NGC specimens. Most of local perturbations exhibit in the layers with high Ni content such as the layers with 30%, 40% and 50% Ni, respectively. The local perturbations are believed to be caused by the local heterogeneity of the microstructure. The residual stress (maximum tensile stress) of the NGC (YSZ/50%Ni) was 122 MPa and was in agreement with the published paper.

This study is applied Lattice Boltzmann Method to investigate the natural convection flow utilizing nanofluids in a concentric annulus. A numerical strategy presents for dealing with curved boundaries of second order accuracy for both velocity and temperature fields. The fluid between the cylinders is a water-based nanofluid containing different types of nanoparticles: copper (Cu), alumina (Al2O3), titanium oxide (TiO2) and silver (Ag). The nanofluid is a two component mixture modeled as a single-phase incompressible fluid with the different thermophysical properties. This investigation compared with other experimental and found to be in excellent agreement. Result shows The type of nanofluid is a key factor for heat transfer enhancement. In this study the highest values of percentage of heat transfer enhancement are obtained when using silver nanoparticle.

Experimental test are carried out on a semi-heavy duty Motorsazan MT4.244 agricultural engine at various loads in order to evaluate performance and emissions of DI diesel engine using the blends of diesel fuel with 5%, 10%,15%,20%, 30%(by volume) Castor oil and pure diesel fuel separately. The result show that maximum decreasing of PM emission is 73.2% and is observed in B15 at 50%load and the maximum increasing of BSFC and NO are 10.7% and 15.6% than that of the diesel fuel and are observed in B30 at 50% load and B20 at 50% load respectively. The results show that in B15 at 25% load, NO and PM emissions decreases 6% and 64% respectively and BSFC increases 1.5%.

In this study, the overall performance of air PV/T, based on energy and exergy analysis has been investigated. Two combinations of air PV/T, which consist of unglazed and glazed air PV/T, are considered. Thermal analysis and numerical calculations were carried out, and the performance parameters of the system for the climate conditions of Kerman were studied. The results are presented in graphs and some parameters such as electrical, thermal and overall energy and exergy efficiencies of these two combinations, have been compared. The results show higher thermal and overall energy efficiencies of glazed PV/T, whereas, higher electrical and overall exergy efficiencies of unglazed one were observed. The overall energy efficiency of glazed and unglazed systems are about 66% and 52%, respectively. Also, the overall exergy efficiency for unglazed and glazed systems is between 11.2-11.6% and 10.5-11.1% respectively.

With progress in mineral processing technologies, particle size classification equipment has also been changed to satisfy the needs of modern plants. Accordingly, design, manufacturing and utilizing of banana screens in mineral processing plants have led to increased screening efficiency at industrial scale. Banana screen is an important invention occurred in past decade which increases screening capacity. These screens are made of several screening segments with different slopes. Despite of frequent use of banana screens in industry, their control and optimization has been limited due to lack of fundamental knowledge about the screening process. Using numerical simulation is an effective method to overcome such limitations in design and optimization studies. Discrete element method (DEM) is a numerical approach which computes particles interactions and their movements. In this paper, the results of modeling and simulation of particles movement and classification in banana screens using DEM method in PFC3D software environment is presented. Hence, DEM simulation of a three-segment banana screen was done to study the effect of design and operating variables on classification. To validate our DEM simulation, the results obtained in this study were compared with the previous results reported in literature. The comparisons show the correctness of authors DEM simulation.