R. Parvizsedghy; M. Alibolandi; S. M. Sadrameli
Abstract
Vegetable oils are proved as valuable feedstocks in the biofuel production. Some common issues of cracking of vegetable oils–as an effective method for the biofuel production- are related to the glycerol decomposition during the cracking process. Transesterification, which can remove glycerol from ...
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Vegetable oils are proved as valuable feedstocks in the biofuel production. Some common issues of cracking of vegetable oils–as an effective method for the biofuel production- are related to the glycerol decomposition during the cracking process. Transesterification, which can remove glycerol from vegetable oil molecules, is performed before the thermal cracking to adjust the problems. This study has been aimed at surveying the efficiency of transesterification and the thermal cracking integration to produce bio-gasoline and bio-oil from castor oil. In transesterification, methanol as alcohol and KOH as catalyst were used, and the catalyst concentration, reaction temperature, and alcohol to oil ratio were effective variables. Statistical studies demonstrated the interactions among parameters and the yield of the methyl ester production as 96.7 % under the optimized conditions. Results showed that in the thermal cracking two parameters, of the feed flowrate and temperature, influenced the product yield significantly without any interaction. Under the optimum conditions, to maximize the bio-gasoline production, 28 % of bio-gasoline and 88.6 % of bio-oil were produced. The lack of acrolein, as a toxic component, the negligible amount of the generated water in the product, the high octane number, the significant amount of the heat of combustion of bio-gasoline, and being in criteria of standard gasoline as per ASTM D4814 for the distillation curve and RVP of bio-gasoline, were the great advantages of the cracking of the transesterified caster oil. Therefore, the bio-gasoline produced via the thermochemical conversion of castor oil could be used as a fuel for spark-ignition engines or as an octane enhancer with gasoline, i.e., by adding 10 % of bio-gasoline to the refinery gasoline, the octane number increased from 95 to 105.
M. r. Talaghat; F. Shafiei
Volume 16, Issue 3 , Summer 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 ...
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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.
Modeling and Simulation
A. Abdi; M.Sh Izadkhah; A. Karimi; M. Razzaghi; H. Moradkhani
Volume 15, Issue 3 , Summer 2018, , Pages 82-93
Abstract
A three-layer artificial neural network (ANN) model was developed to predict the remained DO (deoxygenation) in water after DO removal with an enzymatic granular biocatalyst (GB), based on the experimental data obtained in a laboratory stirring batch study. The effects of operational parameters such ...
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A three-layer artificial neural network (ANN) model was developed to predict the remained DO (deoxygenation) in water after DO removal with an enzymatic granular biocatalyst (GB), based on the experimental data obtained in a laboratory stirring batch study. The effects of operational parameters such as initial pH, initial glucose concentration and temperature on DO removal were investigated. On the basis of batch reactor test results, the optimum value of operating temperature, glucose concentration and pH were found to be 30oC, 80 mM and 7, respectively. After back-propagation training, the ANN model was able to predict the remained DO with a tangent sigmoid function (tansig) at hidden layer with 7 neurons and a linear transfer function (purelin) at the output layer. The linear regression between the network outputs and the corresponding targets were proven to be satisfactory with a correlation coefficient of 0.995 for three model variables used in this study.
Reaction Engineering, Kinetics and Catalysts,
I. Khosrozadeh; M.R. Talaghat; A.A. Roosta
Volume 15, Issue 2 , Spring 2018, , Pages 52-64
Abstract
Catalytic naphtha reforming is one of the most important processes in which, low quality naphtha is converted into high octane motor gasoline. In this study, a mathematical model was developed and was used for investigation the effect of temperature, pressure, hydrogen to hydrocarbon ratio on the octane ...
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Catalytic naphtha reforming is one of the most important processes in which, low quality naphtha is converted into high octane motor gasoline. In this study, a mathematical model was developed and was used for investigation the effect of temperature, pressure, hydrogen to hydrocarbon ratio on the octane number, the yield of product and the undesirable phenomena of coke deposition in a semiregenerative catalytic reforming unit. The result of the model was compared to the plant data to verify the model accuracy. Then, the model was used to find the optimal condition for the maximum value of octane number and yield of product and the minimum value of coke deposition. The optimum condition of the process is estimated using genetic algorithm optimization method as an efficient optimization method. In the optimal condition, the octane number and the yield of the product are improved 0.3% and 1.23% respectively, and the coke deposition is reduced 2.1 %.
Separation Technology,
Mo. H. Almasvandi; M. Rahimi
Volume 14, Issue 4 , Autumn 2017, , Pages 17-31
Abstract
This paper reports the results of experimentally removing ammonia from synthetically prepared ammonia solution using a micro scale mixing loop air stripper. Effects of various operational parameters (such as: pH, air flow rate, wastewater flow rate and initial ammonia concentration) were evaluated. By ...
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This paper reports the results of experimentally removing ammonia from synthetically prepared ammonia solution using a micro scale mixing loop air stripper. Effects of various operational parameters (such as: pH, air flow rate, wastewater flow rate and initial ammonia concentration) were evaluated. By increasing the pH from 10 to 12.25 the amount of KLa increased from 0.26 to 0.73 hr-1. A considerable enhancement, about 150%, can be found for KLa by changing the air flow rate from 280 to 700 mL/min under fixed condition. The wastewater flow rate can also the value of KLa from 0.22 to 0.59 hr-1. The values of KLa increased only about 20% by changing the initial concentration of ammonia in the range between 50 and 500 mg/L. The results showed that improving in air stripping using microchannel was successfully carried out with enhancing overall volumetric mass transfer coefficient (KLa) and providing higher mass transfer capabilities compared with other types of strippers, even for lower amounts of used air. The enhancement of mass transfer is happened by efficient mixing induced by the employed microchannel. It has been demonstrated that wastewater flow rate and air flow rate have significant effects on KLa. The optimal stripping conditions and mathematical modeling for ammonia removal and the relation between the parameters were determined using Response Surface Methodology (RSM) with Central Composite Design (CCD) method. The results demonstrate the advantages the proposed system over convention stripper types.
Biomedical and Biotechnology,
Arezou Soroushnia; Fariba Ganji; Seyed Mojtaba Taghizadeh
Volume 13, Issue 4 , Autumn 2016, , Pages 1-13
Abstract
Desmopressin acetate is a potent synthetic peptide hormone. A more acceptable route of Desmopressin acetate is a potent synthetic peptide hormone. That is administered via parenteral, intranasal, and oral routes. A more acceptable route of administration with potentially good bioavailability could be ...
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Desmopressin acetate is a potent synthetic peptide hormone. A more acceptable route of Desmopressin acetate is a potent synthetic peptide hormone. That is administered via parenteral, intranasal, and oral routes. A more acceptable route of administration with potentially good bioavailability could be offered by transdermal delivery. The present work reports on the development of water-in-oil (w/o) microemulsions for the transdermal administration of desmopressin acetate. A water-in-oil nano/submicron emulsions for transdermal administration of desmopressin developed. Its skin penetration profiles determined using Franz-diffusion cell. Pseudo-ternary phase diagrams for emulsion regions constructed. Effects of hydrophilic-lipophilic balance (HLB), ratio of surfactants and co-surfactant mixture to oil phase (Smix/oil), and ratio of surfactants to co-surfactant (S/Cs) on skin flux evaluated. Skin flux was increased when S/Cs and Smix/oil were decreased, and HLB was increased. Optimized formulation was obtained as: HLB=8, S/Cs=3 and Smix/oil=5.4, with average particle size of 69nm. The optimized nano/submicron emulsions increased desmopressin skin flux 4.45 fold relative to drug solution.
Modeling and Simulation
M Omidifar; S Shafiei; H Soltani
Volume 13, Issue 3 , Summer 2016, , Pages 63-77
Abstract
In modern refineries, hydrogen is widely used for the production of clean fuels. In this paper, a new method is presented in order to use hydrogen more effectively in refineries. This new method is based on combination of linear programming with imperialist competitive algorithm (ICA) in order to optimize ...
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In modern refineries, hydrogen is widely used for the production of clean fuels. In this paper, a new method is presented in order to use hydrogen more effectively in refineries. This new method is based on combination of linear programming with imperialist competitive algorithm (ICA) in order to optimize the hydrogen distribution network. In this new approach, optimization is performed in two levels. In one level the hydrogen network layout is proposed by ICA and in the other level the total annual cost and utility are optimized by the linear programming. Thus, the minimum cost and the optimal configuration of the hydrogen distribution network are obtained. Finally, to illustrate the application of this method two cases are studied.
Petroleum and Reservoir Engineering
A. Mohammadi Doust; M. Rahimi; M. Feyzi
Volume 13, Issue 1 , Winter 2016, , Pages 3-19
Abstract
In this study, response surface methodology (RSM) based on central composite design (CCD) was applied for investigation of the effects of ultrasonic waves, temperature and solvent concentration on viscosity reduction of residue fuel oil (RFO). Ultrasonic irradiation was employed at low frequency of 24 ...
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In this study, response surface methodology (RSM) based on central composite design (CCD) was applied for investigation of the effects of ultrasonic waves, temperature and solvent concentration on viscosity reduction of residue fuel oil (RFO). Ultrasonic irradiation was employed at low frequency of 24 kHz and power of 280 W. The results showed that the combination of ultrasonic waves and solvent injection caused to further reduce of viscosity. To obtain optimum conditions and significant parameters, the results were analyzed by CCD method. In this method, maximum viscosity reduction (133 cSt) was attained in ultrasonic irradiation for 5 min, temperature of 50 °C and acetonitrile volumetric concentration of 5 % by means of experimental and three dimensional response surface plots. The kinematic viscosity decreased from 494 cSt to 133 cSt at the optimum conditions. In addition, a multiple variables model was developed by RSM which the second-order effect of ultrasonic irradiation time was significant on viscosity reduction of FRO. Finally, a comparison between the RSM with artificial neural network (ANN) was applied. The results demonstrated that both models, , were powerful to predict of kinematic viscosity of RFO. The results demonstrated that both models, RSM and ANN, with R2 more than 0.99 were powerful to predict kinematic viscosity of RFO.
Process Control and Engineering, Process Safety, HSE
Volume 6, Issue 4 , Autumn 2009, , Pages 27-33
Abstract
In low-temperature processes, heat rejected from separation columns is removed by refrigeration systems to heat sinks (reboilers & pre-heaters), process streams, other refrigeration streams, or external utilities. The need for efficient utilization and recovery of energy in sub-ambient gas separation ...
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In low-temperature processes, heat rejected from separation columns is removed by refrigeration systems to heat sinks (reboilers & pre-heaters), process streams, other refrigeration streams, or external utilities. The need for efficient utilization and recovery of energy in sub-ambient gas separation processes is still challenging. Performance and reliability of Simulated Annealing (SA) for simultaneous design and optimization of such systems has been investigated previously. In this work, the effect of different refrigerants satisfying a set of process cooling duties at different temperatures is addressed. Cost reduction can be realized by encompassing both effective screening of heat-integrated separation columns and selecting the best refrigerants. A 29.7% cost savings has been shown through a case study. Afterwards, a comprehensive thermodynamic analysis has been carried out on achieved solutions to verify the accuracy of existing shortcut models and robustness of optimized structure. It has been shown that exergy analysis using two different approaches (i.e. stream wise and unit operation wise) are the same, which indicate the accuracy of the used models. Moreover, we have indicated that both utility costs and exergy losses can be considered as an objective function when optimizing the designs.
Modeling and Simulation
Volume 5, Issue 3 , Summer 2008, , Pages 29-39
Abstract
An industrial ethane thermal cracking reactor was modeled assuming a molecular mechanism for the reaction kinetics coupled with material, energy, and momentum balances of the reactant-product flow along the reactor. To carry out the multi-objective optimization for two objectives such as conversion and ...
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An industrial ethane thermal cracking reactor was modeled assuming a molecular mechanism for the reaction kinetics coupled with material, energy, and momentum balances of the reactant-product flow along the reactor. To carry out the multi-objective optimization for two objectives such as conversion and ethylene selectivity, the elitist non-dominated sorting genetic algorithm was used. The Pareto optimum set was obtained successfully and finally the effect of the decision variable was discussed.
Transport Phenomena,
Volume 5, Issue 1 , Winter 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 1 , Winter 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 ...
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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]