International Journal of Chemical Engineering The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Seed Oil of Morinda citrifolia L. as a Surfactant for Deinking Flotation Tue, 23 May 2017 00:00:00 +0000 Surfactants are essential in the pulp recovery process for the removal of ink on paper to be recycled. In order to create a “green” surfactant, seed oil was extracted from Morinda citrifolia L. by Soxhlet extraction for 4–8 h and its composition evaluated by gas chromatography-mass spectrometry (GC-MS). The total ion chromatogram (TIC) of fatty acids of Morinda citrifolia L. (FAMC) indicated that extraction yields the largest amount of unsaturated fatty acids (UFA), specifically C19H34O2 and C21H38O2, at 6 h. All FAMC fractions were evaluated for their suitability as a surfactant for deinking flotation. FAMC isolated after 6 h of extraction yields fatty acids that are the most suitable surfactants, as the fraction consists of mostly unsaturated fatty acids that show good interactions with the structure of common ink molecules. Our results show that the performance of the FAMC taken after 6 h of extraction approaches that of a synthetic surfactant (SS). The appropriate viscous force for deinking flotation was found to be 1.5–2.0 × 10−4 mg/mm s2 when the synthetic surfactant is used compared to 1.0–1.5 × 10−4 mg/mm s2 for FAMC. The higher intermolecular bonding strength in the synthetic surfactant-ink particle system requires higher viscous force. Trismawati Trismawati, I. N. G. Wardana, Nurkholis Hamidi, and Mega Nur Sasongko Copyright © 2017 Trismawati Trismawati et al. All rights reserved. Retracted: Oxygen Mass Transfer in an Aerated Stirred Tank with Double Impellers: A Generalized Correlation Including Spacing Impact Thu, 11 May 2017 00:00:00 +0000 International Journal of Chemical Engineering Copyright © 2017 International Journal of Chemical Engineering. All rights reserved. Investigation on the Transition Criterion of Smooth Stratified Flow to Other Flow Patterns for Gas-Hydrate Slurry Flow Tue, 02 May 2017 08:47:48 +0000 A stability criterion for gas-hydrate slurry stratified flow was developed. The model was based on one-dimensional gas-liquid two-fluid model and perturbation method, considering unstable factors including shear stress, gravity, and surface tension. In addition, mass transfer between gas and liquid phase caused by hydrate formation was taken into account by implementing an inward and outward natural gas hydrates growth shell model for water-in-oil emulsion. A series of gas-hydrate slurry flow experiments were carried out in a high-pressure (>10 MPa) horizontal flow loop. The transition criterion of smooth stratified flow to other flow patterns for gas-hydrate slurry flow was established and validated and combined with experimental data at different water cuts. Meanwhile, parameters of this stability criterion were defined. This stability criterion was proved to be efficient for predicting the transition from smooth to nonsmooth stratified flow for gas-hydrate slurry. Bohui Shi, Jiaqi Wang, Yifan Yu, Lin Ding, Yang Liu, and Haihao Wu Copyright © 2017 Bohui Shi et al. All rights reserved. Physicochemical Characterization of Representative Firewood Species Used for Cooking in Some Colombian Regions Tue, 18 Apr 2017 00:00:00 +0000 Socioeconomic conditions and the main firewood species used for cooking in three Colombian regions are studied in this work. The species collected were Cordia alliodora, Guazuma ulmifolia, Eucalyptus grandis, and Pinus patula. The used patterns of biomass and socioeconomic conditions of the selected regions were defined by means of secondary information. Firewood was physicochemically characterized and the species are compared with fossil fuels with regard to emissions of CO2, energy density, and costs. The studied regions require solutions to use firewood in eco-efficient systems, since in these rural regions people use biomass as an energy source. Studied firewood species are suitable to be gasified in fixed bed reactors due to their high volatile matter content (>80%) and low ash content (<1.8%). Pinus patula is the one with the highest fuel value index, mainly due to its low ash content (0.4%). The firewood consumption in advanced stoves has environmental advantages resulting from its low CO2 emissions: a cubic meter of Eucalyptus could replace 113 liters of kerosene or 120 m3 of natural gas for cooking applications. Hernán E. Díez and Juan F. Pérez Copyright © 2017 Hernán E. Díez and Juan F. Pérez. All rights reserved. Effect of Surfactants on Gas Holdup in Shear-Thinning Fluids Sun, 16 Apr 2017 09:37:30 +0000 In this study, the gas holdup of bubble swarms in shear-thinning fluids was experimentally studied at superficial gas velocities ranging from 0.001 to 0.02 m·s−1. Carboxylmethyl cellulose (CMC) solutions of 0.2 wt%, 0.6 wt%, and 1.0 wt% with sodium dodecyl sulfate (SDS) as the surfactant were used as the power-law (liquid phase), and nitrogen was used as the gas phase. Effects of SDS concentration, rheological behavior, and physical properties of the liquid phase and superficial gas velocity on gas holdup were investigated. Results indicated that gas holdup increases with increasing superficial gas velocity and decreasing CMC concentration. Moreover, the addition of SDS in CMC solutions increased gas holdup, and the degree increased with the surfactant concentration. An empirical correlation was proposed for evaluating gas holdup as a function of liquid surface tension, density, effective viscosity, rheological property, superficial gas velocity, and geometric characteristics of bubble columns using the experimental data obtained for the different superficial gas velocities and CMC solution concentrations with different surfactant solutions. These proposed correlations reasonably fitted the experimental data obtained for gas holdup in this system. Shaobai Li, Siyuan Huang, and Jungeng Fan Copyright © 2017 Shaobai Li et al. All rights reserved. Investigations of a Gas Turbine Low-Emission Combustor Operating on the Synthesis Gas Wed, 05 Apr 2017 08:48:37 +0000 Investigations of the working processes in a gas turbine low-emission combustor operating on the synthesis gas, in which the principle of RQL (Rich-Burn, Quick-Mix, and Lean-Burn) combustion technology is realized, have been performed. Selected concept of a gas turbine combustor can provide higher performance and lower emission of nitrogen oxides and demonstrates satisfactory major key parameters. Obtained results and recommendations can be used for the gas turbine combustor operation modes modeling, geometry optimization, and prospective power generation units design and engineering. Serhiy Serbin and Nataliia Goncharova Copyright © 2017 Serhiy Serbin and Nataliia Goncharova. All rights reserved. Study on Carbonyl Emissions of Diesel Engine Fueled with Biodiesel Mon, 20 Mar 2017 00:00:00 +0000 Biodiesel is a kind of high-quality alternative fuel of diesel engine. In this study, biodiesel and biodiesel/diesel blend were used in a single cylinder diesel engine to study the carbonyl emissions. The result shows that carbonyl pollutants of biodiesel and biodiesel/diesel blend are mainly aldehyde and ketone compounds with 1–3 carbon atoms, and formaldehyde concentration is higher than 80% of the total carbonyl pollutants for biodiesel. The formaldehyde concentration peak is reduced with the increase of intake temperature (), intake pressure (), and exhaust gas recirculation (EGR) ratio and increased with the increase of compression ratio (). When excess air coefficient () is lower than 1.7, the formaldehyde concentration is increased with the increase of excess air ratio. When is higher than 1.7, the formaldehyde concentration is reduced with the increase of excess air ratio. The dilution of air can reduce formaldehyde concentration in the premixed flame of diesel effectively; however, it has less effect on biodiesel. Among the fuel pretreatment measures of adding hydrogen, CO, and methane, the addition of hydrogen shows the best effect on reducing formaldehyde of biodiesel. Ruina Li, Zhong Wang, and Guangju Xu Copyright © 2017 Ruina Li et al. All rights reserved. Removal of Reactive Anionic Dyes from Binary Solutions by Adsorption onto Quaternized Kenaf Core Fiber Wed, 08 Mar 2017 00:00:00 +0000 The most challenging mission in wastewater treatment plants is the removal of anionic dyes, because they are water-soluble and produce very shining colours in the water. In this regard, kenaf core fiber (KCF) was chemically modified by the quaternized agent (3-chloro-2-hydroxypropyl)trimethylammonium chloride to increase surface area and change the surface properties in order to improve the removing reactive anionic dyes from binary aqueous solution. The influencing operating factors like dye concentration, pH, adsorbent dosage, and contact time were examined in a batch mode. The results indicate that the percentage of removal of Reactive Red-RB (RR-RB) and Reactive Black-5 (RB-5) dyes from binary solution was increased with increasing dyes concentrations and the maximum percentage of removal reached up to 98.4% and 99.9% for RR-RB and RB-5, respectively. Studies on effect of pH showed that the adsorption was not significantly influenced by pH. The equilibrium analyses explain that, in spite of the extended Langmuir model failure to describe the data in the binary system, it is better than the Jain and Snoeyink model in describing the adsorption behavior of binary dyes onto QKCF. Also, the pseudo-second-order model was better to represent the adsorption kinetics for RR-RB and RB-5 dyes on QKCF. Intidhar Jabir Idan, Siti Nurul Ain Binti Md. Jamil, Luqman Chuah Abdullah, and Thomas Shean Yaw Choong Copyright © 2017 Intidhar Jabir Idan et al. All rights reserved. Mesoporous (Ta, Nb)3W7 Modified with Stearic Acid Used as Solid Acids for Esterification Tue, 07 Mar 2017 08:40:02 +0000 Mesoporous solid acids Ta3W7 and Nb3W7 were prepared from TaCl5 and NbCl5 with WCl6 in the presence of stearic acid (SA) via a sol-gel method, respectively. For comparison, mesoporous Ta3W7-P123 mixed oxides and mesoporous Nb3W7-P123 mixed oxides were synthesized in the same way. The catalysts were characterized through TGA, XRD, SEM, TEM, BET, and NH3-TPD. Experimental results showed that Ta3W7-SA and Nb3W7-SA exhibited several advantages such as higher activity, shorter preparation period, lower cost, stronger acid sites, and higher surface area, which had potential to be used as mesoporous heterogeneous catalysts in biodiesel production. Fei Chang, Rui Wang, Quan Zhou, Hu Pan, and Heng Zhang Copyright © 2017 Fei Chang et al. All rights reserved. Enhancement of Methane Concentration by Removing Contaminants from Biogas Mixtures Using Combined Method of Absorption and Adsorption Mon, 06 Mar 2017 06:39:34 +0000 We report a laboratory scale combined absorption and adsorption chemical process to remove contaminants from anaerobically produced biogas using cafeteria (food), vegetable, fruit, and cattle manure wastes. Iron oxide (Fe2O3), zero valent iron (), and iron chloride (FeCl2) react with hydrogen sulfide (H2S) to deposit colloidal sulfur. Silica gel, sodium sulfate (Na2SO4), and calcium oxide (CaO) reduce the water vapour (H2O) and carbon dioxide (CO2). It is possible to upgrade methane (CH4) above 95% in biogas using chemical or physical absorption or adsorption process. The removal efficiency of CO2, H2S, and H2O depends on the mass of removing agent and system pH. The results showed that Ca(OH)2 solutions are capable of reducing CO2 below 6%. The H2S concentration was reduced to 89%, 90%, 86%, 85%, and 96% for treating with 10 g of FeCl2, (with pH), Fe2O3, , and activated carbon, respectively. The H2O concentration was reduced to 0.2%, 0.7%, 0.2%, 0.2%, and 0.3% for treating raw biogas with 10 g of silica gel and Na2SO4 for runs R1, R2, R3, R4, and R5, respectively. Thus, given the successful contaminant elimination, the combined absorption and adsorption process is a feasible system for biogas purification. Muhammad Rashed Al Mamun and Shuichi Torii Copyright © 2017 Muhammad Rashed Al Mamun and Shuichi Torii. All rights reserved. Modelling the Evaporation Rate in an Impingement Jet Dryer with Multiple Nozzles Thu, 02 Mar 2017 00:00:00 +0000 Impinging jets are often used in industry to dry, cool, or heat items. In this work, a two-dimensional Computational Fluid Dynamics model is created to model an impingement jet dryer with a total of 9 pairs of nozzles that dries sheets of metal. Different methods to model the evaporation rate are studied, as well as the influence of recirculating the outlet air. For the studied conditions, the simulations show that the difference in evaporation rate between single- and two-component treatment of moist air is only around 5%, hence indicating that drying can be predicted with a simplified model where vapor is included as a nonreacting scalar. Furthermore, the humidity of the inlet air, as determined from the degree of recirculating outlet air, has a strong effect on the water evaporation rate. Results show that the metal sheet is dry at the exit if 85% of the air is recirculated, while approximately only 60% of the water has evaporated at a recirculation of 92,5%. Anna-Lena Ljung, L. Robin Andersson, Anders G. Andersson, T. Staffan Lundström, and Mats Eriksson Copyright © 2017 Anna-Lena Ljung et al. All rights reserved. Coalbed Methane Production System Simulation and Deliverability Forecasting: Coupled Surface Network/Wellbore/Reservoir Calculation Tue, 31 Jan 2017 06:07:50 +0000 As an unconventional energy, coalbed methane (CBM) mainly exists in coal bed with adsorption, whose productivity is different from conventional gas reservoir. This paper explains the wellbore pressure drop, surface pipeline network simulation, and reservoir calculation model of CBM. A coupled surface/wellbore/reservoir calculation architecture was presented, to coordinate the gas production in each calculation period until the balance of surface/wellbore/reservoir. This coupled calculation method was applied to a CBM field for predicting production. The daily gas production increased year by year at the first time and then decreased gradually after several years, while the daily water production was reduced all the time with the successive decline of the formation pressure. The production of gas and water in each well is almost the same when the structure is a star. When system structure is a dendritic surface system, the daily gas production ranked highest at the well which is the nearest to the surface system collection point and lowest at the well which is the farthest to the surface system collection point. This coupled calculation method could be used to predict the water production, gas production, and formation pressure of a CBM field during a period of time. Jun Zhou, Guangchuan Liang, Tao Deng, Shiwei Zhou, and Jing Gong Copyright © 2017 Jun Zhou et al. All rights reserved. Systematic Prioritization of Sensor Improvements in an Industrial Gas Supply Network Tue, 31 Jan 2017 00:00:00 +0000 The paper analyzes the impact of the sensor reading errors on parameters that affect the production costs of a leading US industrial gas supply company. For this purpose, a systematic methodology is applied first to determine the relationship between the system output and input parameters and second to identify the assigned input sensors whose readings need to be improved in a prioritized manner based on the strength of those input-output relationships. The two main criteria used to prioritize these sensors are the decrease in production costs and the decrease in production costs’ volatility obtained when the selected sensor’s precision is improved. To illustrate the effectiveness of the proposed approach, we first apply it to a simplified version of the real supply network model where the results can be readily validated with the simulated data. Next, we apply and test the proposed approach in the real supply network model with historical data. Onur Babat, Ali Esmaili, Joshua D. Isom, Camilo Mancilla, and Luis F. Zuluaga Copyright © 2017 Onur Babat et al. All rights reserved. Route Optimization of Pipeline in Gas-Liquid Two-Phase Flow Based on Genetic Algorithm Thu, 19 Jan 2017 09:18:11 +0000 This paper describes the problems in route optimization of two-phase pipelines. Combining the hydraulic calculation with route optimization theory, this paper establishes an automatic route optimization model and adopts the general genetic algorithm (gGA) and steady-state genetic algorithm (ssGA) to solve the model, respectively, gets the optimal route, and discusses the influence of parameters setting to the result. This algorithm was applied in determining pipelines routes in coalbed methane gathering and transporting system in Shanxi Province, China. The result shows that the algorithm is feasible, which improves the hydraulic properties by reducing the pressure drop along the line while the pipeline length is still acceptable. Jun Zhou, Guangchuan Liang, Tao Deng, and Jing Gong Copyright © 2017 Jun Zhou et al. All rights reserved. Optimal Design of a Solar Desalination Unit with Heliostats Mon, 16 Jan 2017 09:36:10 +0000 The objective is to improve the yield of a solar desalination cell using concentration of solar rays by means of automatically controlled heliostats. The vertical cell is orientated towards the north. It is mainly composed of two plates; the one being heated by the solar rays reflected by the mirrors is used for evaporation of a falling water film; the other one is used for water vapor condensation. Each heliostat consists of an altitude-azimuth mount having two degrees of freedom and supporting a plane mirror. The heliostat permanently follows the sun trajectory and reflects the solar rays on the cell by means of automatic control implemented in a control card based on a microcontroller. Model predictive control allows us to maximize the distilled water production. M. Abidi, S. Ben Jabrallah, and J. P. Corriou Copyright © 2017 M. Abidi et al. All rights reserved. Effects of Thermal Radiation on Mixed Convection Flow of a Micropolar Fluid from an Unsteady Stretching Surface with Viscous Dissipation and Heat Generation/Absorption Thu, 01 Dec 2016 07:25:16 +0000 A numerical model is developed to examine the effects of thermal radiation on unsteady mixed convection flow of a viscous dissipating incompressible micropolar fluid adjacent to a heated vertical stretching surface in the presence of the buoyancy force and heat generation/absorption. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The model contains nonlinear coupled partial differential equations which have been converted into ordinary differential equation by using the similarity transformations. The dimensionless governing equations for this investigation are solved by Runge-Kutta-Fehlberg fourth fifth-order method with shooting technique. Numerical solutions are then obtained and investigated in detail for different interesting parameters such as the local skin-friction coefficient, wall couple stress, and Nusselt number as well as other parametric values such as the velocity, angular velocity, and temperature. Khilap Singh and Manoj Kumar Copyright © 2016 Khilap Singh and Manoj Kumar. All rights reserved. Numerical Simulation on Structure Optimization of Liquid-Gas Cylindrical Cyclone Separator Wed, 30 Nov 2016 12:54:35 +0000 With the further development of oilfield, liquid-gas separation has become an essential problem. Cylindrical cyclone separators are popular in the industrial process due to the advantage that they are simple, compact, and inexpensive to manufacture. In this paper, a three-dimensional turbulence model including Reynolds stress model was established to describe the mixture flow field in the separator. Through the numerical simulation, the separation efficiency was investigated under different parameter cases such as separator length, gas phase outlet diameter, and inlet shape. It can be indicated from the simulation results that the separation efficiency decreases with the increase of the separator length, and the separation efficiency increases firstly and then decreases with the increase of the gas phase outlet diameter as well as the liquid phase outlet. Furthermore, the rectangular inlet is more suitable than the circular inlet with the separation efficiency changing from 66.45% to 79.04%. In the end, the optimal geometrical structure was presented with separation efficiency of 86.15%. Peng Chang, Tian Hu, Li Wang, Sen Chang, Tianjing Wang, and Yueshe Wang Copyright © 2016 Peng Chang et al. All rights reserved. Biosorption and Diffusion Modeling of Pb(II) by Malt Bagasse Tue, 22 Nov 2016 13:48:13 +0000 The removal of Pb(II) from water by biosorption processes onto malt bagasse was investigated and the kinetic and thermodynamic parameters were obtained; additionally a diffusion modeling was proposed. The characterization of malt bagasse was performed by FTIR and SEM/EDS. The experiments were conducted in batch system and an experimental design based response surface methodology was applied for agitation speed and pH optimization. The kinetics of biosorption followed pseudo-second-order model and the temperature of the process affected the biosorption capacity. Isotherm models of Langmuir, Freundlich, and Elovich were applied and the Langmuir model showed better fit and the estimated biosorption capacity was 29.1 mg g−1. The negative values obtained for and positive values of confirm, respectively, the spontaneous and endothermic nature of the process. The diffusion modeling was performed based on experiments in the absence of agitation to investigate the influence of the biosorbent on the sorption process of Pb(II) ions. Klaiani B. Fontana, Giane Gonçalves Lenzi, Erica R. L. R. Watanabe, Ervin Kaminski Lenzi, Juliana A. M. T. Pietrobelli, and Eduardo S. Chaves Copyright © 2016 Klaiani B. Fontana et al. All rights reserved. Comparison of the Accuracy and Performance of Different Numbers of Classes in Discretised Solution Method for Population Balance Model Tue, 22 Nov 2016 12:00:42 +0000 One way of solving population balance model (PBM) in a time efficient way is by means of discretisation of the population property of interest. A computational grid, for example, ( is the volume of particle in class ), could be used to classify the particles in discretisation techniques. However, there are still disagreements in the appropriate number of classes divided by the grids. In this study, the different numbers of classes for solving PBM were compared in terms of accuracy and performance to describe the particle size distribution (PSD) from the flocculation of activated sludge. It is found that the simulated PSDs are similar to the experimental data for all the geometric grids , and there is no obvious difference among the values of calibrated parameter, ratio of breakage rate coefficient and collision efficiency, for each velocity gradient. However, the simulation results with less error could be obtained with larger number of classes, and more computational times, which show exponential relationship with the number of classes, are needed. Considering numerical accuracy and efficiency, the classes 35 or a geometric grid with factor 1.6, aligning with the Fibonacci sequence , is recommended for the particles in the size range of 5.5~1086 μm. Zhenliang Li, Zhien Zhou, Sheng Zhang, and Hongqiang Jiang Copyright © 2016 Zhenliang Li et al. All rights reserved. Batch and Continuous Flow Adsorption of Phenolic Compounds from Olive Mill Wastewater: A Comparison between Nonionic and Ion Exchange Resins Tue, 23 Aug 2016 17:04:17 +0000 The goals of this work were (i) to compare two anion ion exchange resins (IRA958 Cl and IRA67) and a nonionic resin (XAD16) in terms of phenolic compounds adsorption capacity from olive mill wastewater and (ii) to compare the adsorption capacity of the best resin on columns of different length. The ion exchange resins performed worse than nonionic XAD16 in terms of resin utilization efficiency (20% versus 43%) and phenolic compounds/COD enrichment factor (1.0 versus 2.5). The addition of volatile fatty acids did not hinder phenolic compounds adsorption on either resin, suggesting a noncompetitive adsorption mechanism. A pH increase from 4.9 to 7.2 did not affect the result of this comparison. For the best performing resin (XAD16), an increase in column length from 0.5 to 1.8 m determined an increase in resin utilization efficiency (from 12% to 43%), resin productivity (from 3.4 to 7.6 ), and phenolics/COD enrichment factor (from 1.2 to 2.5). An axial dispersion model with nonequilibrium adsorption accurately interpreted the phenolic compounds and COD experimental curves. Davide Pinelli, Aurora Esther Molina Bacca, Ankita Kaushik, Subhankar Basu, Massimo Nocentini, Lorenzo Bertin, and Dario Frascari Copyright © 2016 Davide Pinelli et al. All rights reserved. Parametric Analysis of a High Temperature PEM Fuel Cell Based Microcogeneration System Thu, 23 Jun 2016 10:53:05 +0000 This study focuses on performance analysis of a 1  microcogeneration system based on a high temperature proton exchange membrane (HT-PEM) fuel cell by means of parametric investigation. A mathematical model for a system consisting of a fuel processor (steam reforming reactor and water-gas shift reactor), a HT-PEM fuel cell stack, and the balance-of-plant components was developed. Firstly, the fuel processor performance at different fuel ratios and equivalence ratio was examined. It is shown that high fuel ratios of 0.9–0.95 and equivalence ratios of less than 0.56 are suitable for acceptable carbon monoxide content in the synthetic gas produced. Secondly, a parametric study of the system performance at different fuel and equivalence ratios using key system operating parameters was conducted. Steam-to-carbon ratio, stack operating temperature, and anode stoichiometry were varied to observe the changes in the microcogeneration system. The analysis shows that the system can reach electrical and cogeneration efficiencies of 30% and 84%, respectively. Myalelo Nomnqa, Daniel Ikhu-Omoregbe, and Ademola Rabiu Copyright © 2016 Myalelo Nomnqa et al. All rights reserved. Exergetic Optimization of Power Generation Systems Thu, 09 Jun 2016 08:58:22 +0000 Pouria Ahmadi, Halil S. Hamut, Ahmadreza Ghaffarizadeh, Pedram Hanafizadeh, and Esmaiil Ghasemisahebi Copyright © 2016 Pouria Ahmadi et al. All rights reserved. Studies of Adsorption of Heavy Metals onto Spent Coffee Ground: Equilibrium, Regeneration, and Dynamic Performance in a Fixed-Bed Column Sun, 05 Jun 2016 11:25:01 +0000 Equilibrium and dynamic adsorption of heavy metals onto spent coffee ground (SCG) were studied. The equilibrium adsorption of Cd2+, Cu2+, and Pb2+ in a batch system was modeled by an ion-exchange model (IEM) based on an ion-exchange of heavy metals with calcium and protons bonded to active sites on SCG surface. The maximum amount of adsorbed metal ions obtained using the IEM was 0.12, 0.21, and 0.32 mmol/g of Cd2+, Cu2+, and Pb2+, respectively. Regeneration of SCG was evaluated using citric acid, calcium chloride, and nitric acid. The observed trend of desorption efficiency through four adsorption-desorption cycles was HNO3 > CaCl2 > C6H8O7. The effect of process variables such as flow rate and bed height during the dynamic adsorption was evaluated. Moreover, the applicability of a mass transfer model based on external mass transfer resistance, axial dispersion, and ion-exchange isotherm was evaluated, and the results were in good agreement with the experimental data for the adsorption in SCG packed column. The sensitivity analysis of the model parameters showed that axial dispersion coefficient is the most significant parameter in the dynamic simulation. The results obtained showed the potential of SCG as a low-cost material for wastewater metal removal in continuous systems. N. E. Davila-Guzman, F. J. Cerino-Córdova, M. Loredo-Cancino, J. R. Rangel-Mendez, R. Gómez-González, and E. Soto-Regalado Copyright © 2016 N. E. Davila-Guzman et al. All rights reserved. Exergy and Exergoenvironmental Analysis of a CCHP System Based on a Parallel Flow Double-Effect Absorption Chiller Wed, 25 May 2016 09:22:02 +0000 A combined cooling, heating, and power (CCHP) system which produces electricity, heating, and cooling is modeled and analyzed. This system is comprised of a gas turbine, a heat recovery steam generator, and a double-effect absorption chiller. Exergy analysis is conducted to address the magnitude and the location of irreversibilities. In order to enhance understanding, a comprehensive parametric study is performed to see the effect of some major design parameters on the system performance. These design parameters are compressor pressure ratio, gas turbine inlet temperature, gas turbine isentropic efficiency, compressor isentropic efficiency, and temperature of absorption chiller generator inlet. The results show that exergy efficiency of the CCHP system is higher than the power generation system and the cogeneration system. In addition, the results indicate that when waste heat is utilized in the heat recovery steam generator, the greenhouse gasses are reduced when the fixed power output is generated. According to the parametric study results, an increase in compressor pressure ratio shows that the network output first increases and then decreases. Furthermore, an increase in gas turbine inlet temperature increases the system exergy efficiency, decreasing the total exergy destruction rate consequently. Ali Mousafarash Copyright © 2016 Ali Mousafarash. All rights reserved. Exergy and Environmental Impact Assessment between Solar Powered Gas Turbine and Conventional Gas Turbine Power Plant Mon, 23 May 2016 11:50:04 +0000 Recuperator is a heat exchanger that is used in gas turbine power plants to recover energy from outlet hot gases to heat up the air entering the combustion chamber. Similarly, the combustion chamber inlet air can be heated up to temperatures up to 1000 (°C) by solar power tower (SPT) as a renewable and environmentally benign energy source. In this study, comprehensive comparison between these two systems in terms of energy, exergy, and environmental impacts is carried out. Thermodynamic simulation of both cycles is conducted using a developed program in MATLAB environment. Exergetic performances of both cycles and their emissions are compared and parametric study is carried out. A new parameter (renewable factor) is proposed to evaluate resources quality and measure how green an exergy loss or destruction or a system as a whole is. Nonrenewable exergy destruction and loss are reduced compared to GT with recuperator cycle by 34.89% and 47.41%, respectively. Reductions in CO2, , and CO compared to GT with recuperator cycle by 49.92%, 66.14%, and 39.77%, respectively, are in line with renewable factor value of around 55.7 which proves the ability of the proposed green measure to evaluate and compare the cycles performances. Ali Rajaei, Hasan Barzegar Avval, and Elmira Eslami Copyright © 2016 Ali Rajaei et al. All rights reserved. An Improved Empirical Fuel Cell Polarization Curve Model Based on Review Analysis Mon, 16 May 2016 14:19:16 +0000 Based on a review analysis of empirical fuel cell polarization curve models in the literature, an improved model that can predict fuel cell performance with only measured current-voltage data is developed. The fitting characteristics of this new model are validated by fitting bench test data and road test data. In the case of bench test data, a comparison of the new model and two representative models is conducted, and the results show that the new model presents the best fitting effects over a whole range of current densities. Moreover, the fitted ohmic resistances derived from the new model show good agreement with the measured values obtained through a current interruption test. In the case of using road test data, the new model also presents excellent fitting characteristics and convenience for application. It is the author’s belief that the new model is beneficial for the application-oriented research of fuel cells due to its prominent features, such as conciseness, flexibility, and high accuracy. Dong Hao, Jianping Shen, Yongping Hou, Yi Zhou, and Hong Wang Copyright © 2016 Dong Hao et al. All rights reserved. Performance Assessment of a Hybrid Solar-Geothermal Air Conditioning System for Residential Application: Energy, Exergy, and Sustainability Analysis Thu, 12 May 2016 13:07:03 +0000 This paper investigates the performance of a ground source heat pump that is coupled with a photovoltaic system to provide cooling and heating demands of a zero-energy residential building. Exergy and sustainability analyses have been conducted to evaluate the exergy destruction rate and SI of different compartments of the hybrid system. The effects of monthly thermal load variations on the performance of the hybrid system are investigated. The hybrid system consists of a vertical ground source heat exchanger, rooftop photovoltaic panels, and a heat pump cycle. Exergetic efficiency of the solar-geothermal heat pump system does not exceed 10 percent, and most exergy destruction takes place in photovoltaic panel, condenser, and evaporator. Although SI of PV system remains constant during a year, SI of GSHP varies depending on cooling and heating mode. The results also show that utilization of this hybrid system can reduce CO2 emissions by almost 70 tons per year. Yasser Abbasi, Ehsan Baniasadi, and Hossein Ahmadikia Copyright © 2016 Yasser Abbasi et al. All rights reserved. Synthesis, Spectral Characterization, and Antibacterial and Antifungal Studies of PANI/V2O5 Nanocomposites Sat, 30 Apr 2016 13:45:43 +0000 The present study deals with the synthesis and characterization of nanocrystalline vanadium pentoxide (V2O5) nanoparticles and their antibacterial and antifungal activity on Staphylococcus aureus and Aspergillus niger, respectively, by agar diffusion method. The metal oxide has been synthesized by employing the sol-gel method, polyaniline (PANI) has been synthesized by chemical oxidation, and PANI/V2O5 composites have been synthesized by in situ polymerization method with different ratios (10, 20, 30, 40, and 50 weight%) of V2O5 in PANI. The newly prepared composites were characterized by FTIR and powder X-ray diffraction (P-XRD) techniques and are found to be formed of PANI/V2O5 nanocomposites, and also the compounds showed moderate antibacterial and antifungal activity. Chakradhar Sridhar B, Nagesh Gunvanthrao Yernale, and M. V. N. Ambika Prasad Copyright © 2016 Chakradhar Sridhar B et al. All rights reserved. Biodiesel Production by Reactive Flash: A Numerical Simulation Thu, 28 Apr 2016 09:17:10 +0000 Reactive flash (RF) in biodiesel production has been studied in order to investigate steady-state multiplicities, singularities, and effect of biodiesel quality when the RF system approaches to bubble point. The RF was modeled by an index-2 system of differential algebraic equations, the vapor split () was computed by modified Rachford-Rice equation and modified Raoult’s law computed bubble point, and the continuation analysis was tracked on MATCONT. Results of this study show the existence of turning points, leading to a unique bubble point manifold, , which is a globally stable flashing operation. Also, the results of the simulation in MATLAB® of the dynamic behavior of the RF show that conversion of triglycerides reaches 97% for a residence time of 5.8 minutes and a methanol to triglyceride molar flow ratio of 5 : 1. Alejandro Regalado-Méndez, Sigurd Skogestad, Reyna Natividad, and Rubí Romero Copyright © 2016 Alejandro Regalado-Méndez et al. All rights reserved. Natural Polymer of Iraqi Apricot Tree Gum as a Novel Corrosion Inhibitor for Mild Steel in 1 M HCl Solution Sun, 24 Apr 2016 15:35:07 +0000 Corrosion inhibition of mild steel in 1 M hydrochloric acid using Iraqi apricot tree gum Arabic as natural polymer was studied. The weight loss method was used to predict the efficiency of the inhibitor on corrosion of mild steel in a temperature range of 17–40°C. The FTIR result of natural polymer revealed that the C=O and O-H groups were found in the structure of the natural polymer. The results of weight loss method showed that the inhibition efficiency (%) increased with the increase in both the natural polymer concentration and the temperature; therefore, chemical adsorption mechanism was suggested in this system. The different mathematical models of the adsorption isotherms were studied and the results revealed that natural polymer was found to obey Temkin, Langmuir, and Freundlich adsorption isotherm. The activation energy of adsorption, enthalpy of adsorption, and entropy of adsorption were obtained for different concentrations of natural polymer (0, 0.1, 0.2, and 0.3 g/L) and the results showed that the thermodynamic properties decreased with the loading of a natural polymer. Gibbs free energy of adsorption results was a minus value that led to the conclusion of the spontaneous adsorption of the natural polymer in this system. I. M. Alwaan and Fouad Kadhim Mahdi Copyright © 2016 I. M. Alwaan and Fouad Kadhim Mahdi. All rights reserved.