Biomedical and Biotechnology,
Volume 5, Issue 2 , April 2008, , Pages 34-44
Abstract
Uncontrolled release of light non aqueous phase liquids (LNAPL) such as diesel, gasoline, fuel oils and lubricating oils from transporting vehicles, pipeline and underground storage tanks (UST) could lead to the migration of contaminants to the subsurface soil and ground water. There is a high interfacial ...
Read More
Uncontrolled release of light non aqueous phase liquids (LNAPL) such as diesel, gasoline, fuel oils and lubricating oils from transporting vehicles, pipeline and underground storage tanks (UST) could lead to the migration of contaminants to the subsurface soil and ground water. There is a high interfacial tension (IFT) between LNAPL molecules and water molecules that makes water a non-efficient cleaning material for removing LNAPL from the soil. Nowadays, surfactants (surface active agents) can promote the enhanced removal of LNAPL from the subsurface through mobilization and solubilization. Encouraging results were achieved from laboratory and field results. The aim of this study is to improve the clean up efficiency of surfactant-flooding for two different surfactants; Triton X-100 and Sodium Dodecyl Sulfate which are known as mobilizing and solubilizing surfactants, respectively, by adding alkaline (increasing pH) and foam producing substances. It is shown here that adding alkaline improves the performance of Triton X-100 in removing LNAPL from the contaminated soil by about 8 percent, but spoils the remediating capability of Sodium Dodecyl Sulfate by about 3 percent. Also, adding a foaming agent helps the surfactant solution in removing the LNAPLs out of the soil by more than 5 percent.
Biomedical and Biotechnology,
A. Rafie Lak; O. Vahidi
Volume 15, Issue 3 , September 2018, , Pages 34-52
Abstract
This paper presents using the fractional PImDn controller module which manipulates insulin infusion rate to maintain normoglycemia in subjects with type 1 diabetes. To prevent severe hypoglycemia, a conventional proportional controller is used to regulate glucagon infusion rate when the blood glucose ...
Read More
This paper presents using the fractional PImDn controller module which manipulates insulin infusion rate to maintain normoglycemia in subjects with type 1 diabetes. To prevent severe hypoglycemia, a conventional proportional controller is used to regulate glucagon infusion rate when the blood glucose levels fall below a threshold. Two sets of controller parameters are obtained and evaluated. For the first tuning set, clinical data from an oral glucose tolerance test taken from a group of healthy subjects are used to obtain the controller parameters such that it can mimic a real healthy pancreas. To obtain the second tuning set, the controller parameters are optimized through a sequential quadratic programming algorithm. Using the second tuning set, the in silico 2-hour postprandial test result and comparing it with the glucose concentration trajectory of the healthy subjects show that the controller performs well in returning the blood sugar levels into the glucose homeostasis while keeping the plasma insulin concentration within the acceptable physiological range. It is indicated that the manipulation of glucagon infusion rate is effective in hypoglycemia prevention if more aggressive controller settings are chosen or dysfunctional insulin infusion occurs.
M. Cheraghipoor; M. Zakeri
Abstract
Pearlescent pigments are a variety of pigments that can generate an optical pleasant appearance in the system because of the ability of easy parallel orientation of a large number of platelet-like particles. In the present work, the green pearlescent pigments based on mica (biotite) and mica-titania ...
Read More
Pearlescent pigments are a variety of pigments that can generate an optical pleasant appearance in the system because of the ability of easy parallel orientation of a large number of platelet-like particles. In the present work, the green pearlescent pigments based on mica (biotite) and mica-titania flakes covered with a thin film of nickel oxide were prepared with novel methods via the homogeneous precipitation of nickel acetate with sodium / potassium hydroxide, and in the presence of mica (biotite), titania, ammonium molybdate or mica-titania flakes. The synthesized pigments were characterized by means of X-ray diffractometery (XRD), Thermal Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and X-Ray fluorescence (XRF) analyses. By comparing the XRD pattern of synthesized pigments with the mica base pattern, it is clear that the structure of the support does not change due to the layering on these bases. As these layers are hydroxide, oxide and chloride compounds. The XRF analysis shows that the nickel compound is layered well on the mica at 8.823%. The quantity and quality of the produced pigments by methods 1 and 2 were approximately the same. Consequently, due to commercial savings, method 1 was recommended for the preparation of the metallic pearl pigments and mica was known as the best support for the production of the pearlescent pigments by the introduced methods. Furthermore, TGA/DSC curve showed that the introduced pigments were stable up to 200 ˚C. The results showed good chemical resistance and pearl luster effects for the produced pigments.
Modeling and Simulation
M. Varmazyar; R. Mohamady; M. Bazargan
Volume 15, Issue 1 , February 2018, , Pages 35-48
Abstract
The Lattice Boltzmann Method is used to simulate the dynamics of droplet deformation in a channel flow under various conditions. The droplet behavior has been investigated under transient conditions. For cases where the droplet remains attached to the surface, the shape deformation of the droplet during ...
Read More
The Lattice Boltzmann Method is used to simulate the dynamics of droplet deformation in a channel flow under various conditions. The droplet behavior has been investigated under transient conditions. For cases where the droplet remains attached to the surface, the shape deformation of the droplet during crawling is captured. It has been shown that there is a limiting value for the droplet volume beyond which the critical shear rate remains almost constant and does not demonstrate much correlation with the size of the droplet. The predicted shapes of the droplet at various stages of deformation in the course of the flow by the current LBM code demonstrates more resemblance to the reported experiments than those obtained by a traditional CFD code. The effect of the droplet's initial volume and Reynolds number on the detachment and crawling processes are also investigated. The results are presented at various time steps to better demonstrate the droplet separation. Under the flow conditions investigated, wherever the Aniline droplet detaches, the entire droplet separates from the surface. For an Isoquinoline droplet however, once the main body is detached, a small part of the droplet remains attached to the surface in flows with low Reynolds numbers.
M. r. Talaghat; F. Shafiei
Volume 16, Issue 3 , September 2019, , Pages 37-57
Abstract
The main objective of this research is to analyze optimization and the thermal performance of circular porous fins with four different profiles, rectangular, convex, triangular and concave under fully wet conditions. In this research, a linear model was used for the relationship between humidity and ...
Read More
The main objective of this research is to analyze optimization and the thermal performance of circular porous fins with four different profiles, rectangular, convex, triangular and concave under fully wet conditions. In this research, a linear model was used for the relationship between humidity and temperature. Also, modeling is assumed one-dimensional and the temperature changes only in the direction of the radius of the fin. Moreover, the thermal conductivity and heat transfer coefficient are a function of porosity and temperature, respectively. The governing equations are solved using the Galerkin method and the finite difference method and the use of the Gauss-Seidel algorithm. In this study, the effect of different parameters including relative humidity, Darcy number and Rayleigh number and porosity on temperature distribution, fin efficiency, and fin effectiveness was investigated. The results showed that the efficiency, effectiveness, and heat transfer rate to the base for the rectangular profile is higher than other profiles. In this research, the Nelder-Mead algorithm is used for optimization. The results showed that to maintain optimal conditions, the ratio of thickness to fin length should be increased by increasing relative humidity or decreasing the Darcy number, Rayleigh number and porosity.
Reaction Engineering, Kinetics and Catalysts,
M. Ghashghaee; S. Shirvani; V. Farzaneh
Volume 15, Issue 2 , May 2018, , Pages 38-51
Abstract
Furfural is one of the most promising chemical platforms with bright perspective with respect to the production of biobased chemicals and fuels from lignocellulosic material. Globally, the majority of this biomass derived chemical is converted into furfuryl alcohol, a building block in polymers industry. ...
Read More
Furfural is one of the most promising chemical platforms with bright perspective with respect to the production of biobased chemicals and fuels from lignocellulosic material. Globally, the majority of this biomass derived chemical is converted into furfuryl alcohol, a building block in polymers industry. The vapor-phase hydrogenation of furfural over copper species dispersed on two types of silica (bulk-type and nano-sized) supports with or without chromium as a promoter was studied for the first time. The catalysts were synthesized via impregnation method and operated under mild hydrogenation reaction conditions. The results represented that the catalytic performance of the nano-sized silica-supported catalyst was better in terms of furfural conversion, furfuryl alcohol yield and selectivity than that of the bulk-type silica after 4 hours of operation. However, by incorporation of chromium as a promoter, the bulk-type silica-supported catalyst exhibited an improved performance during the whole run length (higher than 82% and 96% of furfural conversion and furfuryl alcohol selectivity, respectively).
Energy
M. Moaf; O. Alizadeh; A. R. pendashteh
Abstract
In this experimental investigation, the heat transfer and pressure drop of helical tubes with various helical diameters have been studied considering air injections. The tube was rested in vertical form and was put under the constant heat flux. The flow had a downward form and the air was injected into ...
Read More
In this experimental investigation, the heat transfer and pressure drop of helical tubes with various helical diameters have been studied considering air injections. The tube was rested in vertical form and was put under the constant heat flux. The flow had a downward form and the air was injected into the water stream outside the helical tube. According to the findings, air injection has a notable impact on the heat transfer coefficient of each helical tube. The results showed that employing air bubbles could increase the Nusselt Number by up to 14 %. To make an acceptable comparison among all states, the Cost Benefit Ratio (C.B.R.) factor was evaluated. The results showed that the pipes with bigger diameters had the best C.B.R. factor values. It means that the air injection in the tubes with larger diameters was more beneficial than in the tubes with smaller helix diameters. The best value was attained for the helix diameter of 18 cm and the VF of 0.33 with a C.B.R. factor of 0.84. Also, the worst value was 1.18 for a helix diameter of 10 cm.
Modeling and Simulation
M. rasteh
Volume 16, Issue 2 , June 2019, , Pages 41-56
Abstract
In this study, an Eulerian-Eulerian multi-fluid model (MFM) was used to simulate the segregation pattern of a conical fluidized bed containing ternary mixtures of equidensity TiO2 particles. Experimental 'freeze–sieving' method was employed to determine the axial mass fraction profiles of the ...
Read More
In this study, an Eulerian-Eulerian multi-fluid model (MFM) was used to simulate the segregation pattern of a conical fluidized bed containing ternary mixtures of equidensity TiO2 particles. Experimental 'freeze–sieving' method was employed to determine the axial mass fraction profiles of the different-sized particles, and validate the simulation results. The profiles of mass fraction for large, medium and small sized particles along the bed height during the simulation time indicated that the particles’ segregation can be predicted by CFD model. Effect of superficial gas velocity on segregation pattern was also investigated. It was shown that for U0=1.2Umf, partial segregation of large particles occurred, while for U0=1.6Umf, small and medium size particles also segregated and full segregation was achieved. By increasing U0 to 2Umf, mixing of different sized particles was increased and particles segregation was reduced. Therefore, it can be concluded that there was a critical velocity below which particles would segregate while above which their mixing increased.
Modeling and Simulation
M. Khajeh Amiri; A. Ghaemi; H. Arjomandi
Volume 16, Issue 1 , March 2019, , Pages 54-64
Abstract
In this work, zeolite 13X with porosity structure has been used as an adsorbent for adsorption of CO2 flue gas. The effect of operating conditions including pressure and time on adsorption capacity were investigated. The experiments conditions are constant temperature, the range of pressure 1 - 9 bar ...
Read More
In this work, zeolite 13X with porosity structure has been used as an adsorbent for adsorption of CO2 flue gas. The effect of operating conditions including pressure and time on adsorption capacity were investigated. The experiments conditions are constant temperature, the range of pressure 1 - 9 bar and the registration of adsorption capacity with passing of time. Experimental data were adjusted with adsorption isotherm models including two and three parameters isotherm. Also the process was studied in terms of kinetic models and after the implementation of the experimental data with kinetic models, the speed of this process equations were obtained. The best kinetic model for this process was selected first order equation. The results showed that adsorption capacity of 13X is 71.5 mg/g at pressure of 8 bars. Also the result indicate that 13x has high capacity at low pressures. With regard to achieved results for adsorption isotherm modeling, the adsorption isotherm followed of the three-parameter and among three-parameter models, Toth isotherm can be interpreted the process. Also the results of the fixed bed indicate a very high adsorbent selectivity to carbon dioxide adsorption and there was little oxygen and nitrogen adsorption.
Petroleum and Reservoir Engineering
Volume 7, Issue 4 , October 2010, , Pages 29-41
Process Control and Engineering, Process Safety, HSE
Volume 1, Issue 1 , April 2004, , Pages 29-46
Biomedical and Biotechnology,
Volume 1, Issue 2 , July 2004, , Pages 29-37
Abstract
Immobilization of Lipase produced from Rhizomucor miehei on HDPE fine powder was investigated. As compared to an aqueous system, immobilization in a non-aquous organic medium such as n-hexane was not successful and caused enzyme denaturation. Prewetting the support with ethanol increased the immobilized ...
Read More
Immobilization of Lipase produced from Rhizomucor miehei on HDPE fine powder was investigated. As compared to an aqueous system, immobilization in a non-aquous organic medium such as n-hexane was not successful and caused enzyme denaturation. Prewetting the support with ethanol increased the immobilized protein and enzyme activity as much as 31% and 34%, respectively. The maximum immobilized activity was obtained at the isoelectric pH of 4-5. The enzyme was suspected to have competition and/or interaction with other protein entities on the surface. Immobilization of the enzyme onto the support seems to be via shear sensitive weak physical adsorption. Proper duration of mixing was found to be around 6 minutes. Longer periods of shaking led to enzyme desorption, thereby reducing the immobilized activity. Neither efficiency nor stability was improved using glutaraldehyde as a cross-linking agent despite the fact that in some occasions, protein loading of the support was improved. This suggests the possible effect of glutaraldehyde on enzyme denaturation in these conditions. At optimum conditions, immobilized enzyme activity was enhanced almost 6-folds increasing from 8 units (per 0.5 ml of the enzyme liquor) to about 45.8 units (when 0.5 ml was immobilized on one gram of support).
Transport Phenomena,
S. Abbasi; S. M. Zebarjad; S. H. NoieBaghban; A. Youssef; M. S. Ekrami-Kakhki
Volume 12, Issue 1 , January 2015, , Pages 30-40
Abstract
In this paper, we report for the first time, thermal conductivity behavior of nanofluids containing decorated MWCNTs with different amount of TiO2 nanoparticles. TEM image confirmed that the outer surface of MWCNTs successfully decorated with TiO2 nanoparticles. The results of thermal conductivity behavior ...
Read More
In this paper, we report for the first time, thermal conductivity behavior of nanofluids containing decorated MWCNTs with different amount of TiO2 nanoparticles. TEM image confirmed that the outer surface of MWCNTs successfully decorated with TiO2 nanoparticles. The results of thermal conductivity behavior of nanofluids revealed that the thermal conductivity and enhancement ratio of thermal conductivity of MWCNTsTiO2 at different amount of TiO2 nanoparticles are higher than those of TiO2 and MWCNTs nanofluids. Temperature and weight fraction dependence study also shows that the thermal conductivity of all nanofluids increases with temperature and weight fraction. However, the influence of temperature is more significant than that of weight fraction. We also found that decreasing amount ofTiO2 nanoparticles which introduce the outer surface of MWCNTs leads to the augmentation of thermal conductivity of nanofluids containing MWCNTs-TiO2.
Reaction Engineering, Kinetics and Catalysts,
Volume 11, Issue 4 , October 2014, , Pages 31-39
Reaction Engineering, Kinetics and Catalysts,
Volume 9, Issue 3 , July 2012, , Pages 31-47
Reaction Engineering, Kinetics and Catalysts,
Volume 8, Issue 1 , January 2011, , Pages 31-37
Modeling and Simulation
Volume 2, Issue 1 , January 2005, , Pages 31-54
Abstract
General modeling and optimization of syngas production via noncatalytic autothermal partial oxidation of methane are carried out using our developed scientific software which was based on the minimization of total Gibbs energy. In this work, a novel application of the direct search and Newton-Raphson ...
Read More
General modeling and optimization of syngas production via noncatalytic autothermal partial oxidation of methane are carried out using our developed scientific software which was based on the minimization of total Gibbs energy. In this work, a novel application of the direct search and Newton-Raphson methods was introduced to apply to optimization of a complex chemical reaction. Sensitivity analysis was done to investigate the effect of several parameters on the quality of syngas and the production yield. The acceptable concentrations of CO2 and H2O injected into the methane feed are optimized in the specified temperature and pressure range, while H2/CO ratio in the product stream is set to remain at 1.5 or 2, methane slip in the syngas is less than 1.5% and the non-endothermic conversion area of reaction prevail, simultaneously. This facilitates monetizing CO2 in the petrochemical and steel industries. The output from this software is comparable both with the experimental results, cited in Ref [1] , and with that from ASPEN PLUS in simulating the experiments mentioned in Ref [2]
Modeling and Simulation
Volume 10, Issue 2 , April 2013, , Pages 33-54
Transport Phenomena,
Volume 9, Issue 1 , January 2012, , Pages 33-39
Thermodynamics,
Volume 9, Issue 4 , October 2012, , Pages 33-48
Separation Technology,
Volume 5, Issue 4 , October 2008, , Pages 33-38
Abstract
Membrane technology is one of the few non-pollutant choices when selecting a treatment process. A membrane with suitable pore size can remove almost all pollutants without using any chemicals. In this research, chromium, zinc and lead were removed from synthetic wastewater by a membrane bioreactor. The ...
Read More
Membrane technology is one of the few non-pollutant choices when selecting a treatment process. A membrane with suitable pore size can remove almost all pollutants without using any chemicals. In this research, chromium, zinc and lead were removed from synthetic wastewater by a membrane bioreactor. The results showed that by using a membrane bioreactor, the COD removal efficiency was increased in all conditions in comparison with that of an activated sludge process system. According to the test results, in the case of having heavy metals; Chromium with a concentration below 50 mg/l , the removal efficiency was shown to be about 95% and at these concentrations, chromium has no toxic effect on micro-organisms. However, the Activated Sludge Process showed poor removal efficiency in the case of having zinc. But when ASP was used in conjunction with the membrane, the removal efficiency was increased to 76%. Membrane showed an improvement of efficiency from 44% to 65% in the case of having 50 mg/ l of lead.
Thermodynamics,
Volume 3, Issue 2 , April 2006, , Pages 33-51
Modeling and Simulation
Volume 9, Issue 2 , April 2012, , Pages 34-42
Polymer Engineering and Technology,
Volume 8, Issue 4 , October 2011, , Pages 34-42
Transport Phenomena,
Volume 5, Issue 1 , January 2008, , Pages 34-50
Abstract
"> In this research an extensive literature search into the mechanism of cavitation dynamics and its consequences was conducted. A cavitation venturie rig was designed and constructed, and the cavitation number was checked mathematically. A new camera technique was developed to capture the cavitation ...
Read More
"> In this research an extensive literature search into the mechanism of cavitation dynamics and its consequences was conducted. A cavitation venturie rig was designed and constructed, and the cavitation number was checked mathematically. A new camera technique was developed to capture the cavitation cloud. Carbon steel (AISI 1020), stainless steel (AISI 304 and 316), ferritic alloy steel (B1274), brass (C27000), phosphor bronze (C51000) and aluminum bronze (C60800) test pieces were prepared and tested in the venturie tube. Aluminum bronze was the most and carbon steel the least resistant of these alloys, the measured mechanical properties could not systematically be correlated with cavitation resistance. The microscopic examinations showed that cavitation induced plastic deformation had caused the misalignment of polishing lines. A field study into the susceptibility of an Iranian sugar cane company’s centrifugal pumps showed that deviation from the manuals hydraulic settings caused cavitation and that the gray cast iron had a poor resistance. Besides the venturie tube, other configurations were considered, of which an oil industry choke valve was constructed and examined for cavitation.