Materials synthesize and production
Mahdi Norouzi; Seyyed Ghorban Hosseini; Manoochehr Fathollahi; Seyyed Alireza Rezvan Leylan; sajjad ebrahimi; Azam Karimian
Abstract
Potassium superoxide tablets can be used in respiratory air regeneration systems within confined spaces such as spacecraft, submarines, coal mines and individual and collective masks. These tablets react with moisture and carbon dioxide in air and release oxygen. In this study, The effect of five parameters; ...
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Potassium superoxide tablets can be used in respiratory air regeneration systems within confined spaces such as spacecraft, submarines, coal mines and individual and collective masks. These tablets react with moisture and carbon dioxide in air and release oxygen. In this study, The effect of five parameters; the pressing pressure (0.5, 2, 4 and 5 bar), humidity (10, 15, 20, 25 %), Catalyst additives (CuSO4.5H2O, (Cu2(OH)3Cl2)2, CuO, TiO2), H2O Absorbent additives (SiO2, LiCl, CaO, SiO2.Al2O3) and CO2 Absorbent additives (LiOH, NaOH, KOH, Ca(OH)2) were investigated in four levels using the Taguchi method. The carbon dioxide absorption and Surface Erosion were selected as criteria for optimizing the performance of Potassium Superoxide tablets based on the analysis of variance and the optimal conditions of each were evaluated separately and simultaneously. The optimal conditions for the higher carbon dioxide absorption and smaller Surface Erosion include the Humidity of 15 %, pressing pressure of 4 bar, CuSO4.5H2O as the Catalyst, SiO2 as the H2O absorbent and Ca(OH)2 as the CO2 absorbent. Experiments performed in the performance test show that the optimized tablets in this study show a 28 % and 79 % increase in the carbon dioxide absorption compared to commercial tablets and pure potassium superoxide respectively. The results showed that the catalysts with copper cation had the greatest effect on the performance of the tablets.
M. yari; Gh. Moradi; M. Abdolmaleki; Sh. Bashiri
Abstract
Biodiesel, as a renewable and environmentally friendly fuel, is a feasible alternative to fossil diesel, which has gained great popularity in recent years. However, due to some undesirable properties such as higher viscosity, biodiesel must be blended with diesel in order to be utilizable in a diesel ...
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Biodiesel, as a renewable and environmentally friendly fuel, is a feasible alternative to fossil diesel, which has gained great popularity in recent years. However, due to some undesirable properties such as higher viscosity, biodiesel must be blended with diesel in order to be utilizable in a diesel engine. Therefore, a reasonable approach is required for predicting the diesel-biodiesel blend properties. This study tries to estimate two substantial properties of blend, i.e. kinemattic viscosity (KV) and cetane number (CN), through neural network (NN) and empirical models which use pure properties of biodiesel (kinematic viscosity, boiling point, evaporation point, flash point, pour point, heat of combustion, cloud point, and specific gravity) as independent variables. In this regard, a three-layer feed-forward network with varying input parameters, training algorithms, transfer functions, and hidden neurons has been examined to predict the KV and CN of the diesel-biodiesel blend. Besides, the prediction capability of thirty empirical equations is investigated to determine the top equations describing blend properties. The result reveals that an ANN with three input parameters of biodiesel concentration (%), the CN of biodiesel, and biodiesel cloud point has the best prediction quality of CN with an R-value of 0.9961. Moreover, NN estimates the KV of blend with the highest correlation coefficient of 0.9985. The results corresponding to empirical equations also indicate that fractional-exponential equations are the best describer of the CN and KV of blend with R-values of 0.9947 and 0.9980, respectively.
A. Alipour; R. Sotude.Gharebagh; M. Koksal; G. Kulah; R. Zarghami; N. Mostoufi
Abstract
The attrition of 300 µm natural zeolite particles was studied in a laboratory scale draft tube spouted bed (DTSB) and spout-fluid bed (DTSFB). It has been shown that the attrition rate decreases with time and reaches to an almost constant value. The results show that the prevailing attrition mechanism ...
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The attrition of 300 µm natural zeolite particles was studied in a laboratory scale draft tube spouted bed (DTSB) and spout-fluid bed (DTSFB). It has been shown that the attrition rate decreases with time and reaches to an almost constant value. The results show that the prevailing attrition mechanism under the conditions of this work is the surface abrasion which occurs due to the collisions between particles. It has been found that increasing the cone angle from 30º to 60º in the DTSB, causes a decrease in the extent of attrition. In addition, by increasing the spouting air velocity and the height of the entrainment zone in the DTSB, the extent of attrition increases due to a more energetic collision between particles as well as the increased circulation rate of solids. Increasing the auxiliary air velocity in the DTSFB increases the rate of attrition. A comparison between the attrition in the DTSB and DTSFB has been conducted and has indicated that applying the auxiliary air flow causes up to a 6 % increase in the extent of attrition. An empirical correlation is derived for evaluating the extent of the attrition in the DTSB and DTSFB. This empirical correlation is in good agreement with the experimental data.
A. Etemadi; R. Alizadeh; M. Sirousazar
Abstract
Water and solid effective diffusivities and shrinkage were correlated for finite hollow cylinder-shaped apple samples during the candying operation in the osmotic solution. Experiments were conducted in the sucrose solution as an osmotic agent at different temperatures (i.e., 40, 50, and 60 °C) and ...
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Water and solid effective diffusivities and shrinkage were correlated for finite hollow cylinder-shaped apple samples during the candying operation in the osmotic solution. Experiments were conducted in the sucrose solution as an osmotic agent at different temperatures (i.e., 40, 50, and 60 °C) and at a constant concentration of 55 °Brix. The effective diffusivities of water and solid were calculated by fitting the water loss and solid uptake experimental data to Fick’s second law and fractional calculus method, considering the shrinkage of the samples during the candying process. The obtained results exhibited that the volume of the apples reduced linearly by increasing the water loss. For above conditions of the candying process, water effective diffusivities with Fick second law were determined in the range of 3.7×10−10 m2/s–8.73×10−10 m2/s, and those with fractional calculus method were in the range of 2.75×10−10 m2/s–6.98×10−10 m2/s. The results indicated that the coefficient of determination for the fractional calculus method was more than the coefficient of determination for the Fick model. The value of the empirical parameter α for the Non-Fickian diffusion model was always higher than unity, meaning that the dehydration process had a super-diffusive mechanism.
Environmental Engineering,
A. Es,Hagi; H. Hazrati
Abstract
The membrane bioreactor (MBR) is a combination of biological and membrane systems. It utilizes advanced technologies in the treatment of various types of wastewater, having unique advantages such as the high-quality effluent and improved efficiency. The primary limiting factor for the utilization of ...
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The membrane bioreactor (MBR) is a combination of biological and membrane systems. It utilizes advanced technologies in the treatment of various types of wastewater, having unique advantages such as the high-quality effluent and improved efficiency. The primary limiting factor for the utilization of this bioreactor is the membrane fouling phenomenon, which increases operational costs. In this study, four membrane bioreactors were used, with the first MBR (R1) serving as the control bioreactor. In the second MBR (R2), an adsorption process was employed, while in the third (R3) and fourth MBR (R4), in addition to the adsorption process, the electrochemical process was applied with voltages of two and one volts respectively. For the four bioreactors, the percentages of the Chemical Oxygen Demand (COD) were recorded as 86%, 91.2%, 90.7%, and 95.3% respectively. The levels of the total Extracellular Polymeric Substances (EPS) in R1, R2, R3, and R4 were about 260, 155, 177, and 98 mg/gVSS respectively. The R4 exhibited significantly lower EPS (98 mg/gVSS) compared to R1 (260 mg/gVSS), possibly due to the adsorption of EPS by nanoparticles and its subsequent removal during the electrochemical process. The role of voltage was evident in R3, where the higher voltage (2V) resulted in the less removal of EPS (155 mg/gVSS) compared to the same in R4 (98 mg/gVSS). The study found that the values of the Soluble Microbial Products (SMP) for R4, R3, R2, and R1 were about 15, 65, 55 and 139 mg/L respectively. Particularly in the most effective MBR, R4, where the addition of the zeolite adsorbent alongside metal ions demonstrated the best performance in the removal of SMP.
Separation Technology,
P. Abbasi; K. Shayesteh; V. Vahidfard; M.J. Khani
Abstract
The cementation reaction of Ni-Cd occurs on the surface of zinc powder, and the Ni-Cd ions in the zinc sulfate solution (make-up) change into a solid metal deposit during the process. The primary purpose of this study is to evaluate the effect of the particle size of zinc powder on the operational parameters ...
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The cementation reaction of Ni-Cd occurs on the surface of zinc powder, and the Ni-Cd ions in the zinc sulfate solution (make-up) change into a solid metal deposit during the process. The primary purpose of this study is to evaluate the effect of the particle size of zinc powder on the operational parameters of cementation, such as the quantity of the zinc powder used, the reaction temperature, and the contact time. These parameters are influential on cost reduction as well as the manufacturing rate of zinc ingot. Results indicated that providing that the zinc powder, -325 mesh, is used, the consumption of zinc powder used in the industry can be reduced by an average of 40%. It was also confirmed that the best times for the cementation of Ni-Cd for all studied sizes were 75 and 60 minutes respectively. The Ni and Ca were removed in -325 mesh to the optimal values at 85℃ and 65℃ respectively. By optimizing the evaluated parameters, the concentrations of Ni and Cd impurities were obtained at the lowest possible and acceptable levels for transferring the make-up solution to the electrolysis stage.
S. Faramarzi; A.H Oudi; S. Azimi; Y. Davoodbeygi
Abstract
Methanol is an important industrial chemical, and its synthesis and purification units are among the most widely used processes in the field of energy. The two-column separation unit of methanol has been analyzed from the thermodynamic and energy points of view in the present study. The simulation has ...
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Methanol is an important industrial chemical, and its synthesis and purification units are among the most widely used processes in the field of energy. The two-column separation unit of methanol has been analyzed from the thermodynamic and energy points of view in the present study. The simulation has been done by Aspen Hysys V11 and the SRK equation has been regarded as the most appropriate equation of state (EOS) for this simulation with the mean relative error (MRE) of 2 %. Then, the design of the heat exchanger network (HEN) has been calculated using the Aspen Energy Analyzer V11. Both distillation towers have been analyzed using pinch technology. As a result, the amount of hot and cold utilities used has been LP=1.482×〖10〗^8, MP=1.57×〖10〗^4, and Air =1.423×〖10〗^8, respectively. Besides, the total heating and cooling target of the process has been 1.482×〖10〗^8 and 1.423×〖10〗^8, accordingly. Then, the 〖∆T〗_min (minimum allowable temperature difference between hot and cold currents) and its effect on the annual cost have been investigated. The optimum value 〖∆T〗_min is determined to have better-operating conditions and to meet the design of the HEN economically. Reducing 〖∆T〗_min increases operating costs and reduces energy costs.
Modeling and Simulation
M. Moghadasi; M. Moraveji; O. Alizadeh
Abstract
Ejectors offer a cost-effective and practical solution for recovering flare gases, thereby reducing greenhouse gases. Improving the entrainment rate of the secondary fluid can enhance ejector performance. The objective of this research is to identify the optimal ejector geometry to maximize the absorption ...
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Ejectors offer a cost-effective and practical solution for recovering flare gases, thereby reducing greenhouse gases. Improving the entrainment rate of the secondary fluid can enhance ejector performance. The objective of this research is to identify the optimal ejector geometry to maximize the absorption rate of the secondary fluid. Computational fluid dynamics is used to evaluate a two-phase ejector. Geometric parameters such as throat diameter and length, nozzle diameter, and converging and diverging angles impact the absorption rate of the secondary fluid. Using a multi-objective genetic algorithm, the optimal values for each parameter are obtained. The results show that reducing the throat length and angle of the converging section, as well as nozzle diameter, leads to increased absorption. In contrast, the throat and angle of the divergent section increase absorption. Additionally, energy efficiency is investigated under basic and optimized geometries. The findings reveal that increasing the soak range does not necessarily enhance energy efficiency.
Energy
Z. Rahimi-Ahar; M. Sadegh Hatamipour
Abstract
Humidification-dehumidification (HD) desalination has been identified as a sustainable, reliable, and energy-efficient technology for producing freshwater on a small scale. VP-HD systems operated at one-stage, multi-stage, and multi-feeding vacuum humidification-over atmospheric pressure dehumidification ...
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Humidification-dehumidification (HD) desalination has been identified as a sustainable, reliable, and energy-efficient technology for producing freshwater on a small scale. VP-HD systems operated at one-stage, multi-stage, and multi-feeding vacuum humidification-over atmospheric pressure dehumidification arrangements can be the recent modifications of an HD system. The present study offers a theoretical investigation and experimental verification of two VP-HD systems, encompassing both sub-atmospheric pressure humidification and over-atmospheric dehumidification. Two designs are evaluated, one comprising a three-stage humidification setup and the other featuring a three-feeding one-stage humidification apparatus. The results show which design has better performance than previous conventional and variable pressure HD systems. The parametric analysis reveals that an upsurge in freshwater generation is observed with an increase in air temperature, feed salinity, and a decrease in humidifier pressure. Additionally, an optimal water-to-air ratio is identified. The study further highlights that multi-stage humidification yields better results concerning freshwater productivity and specific power consumption. Three-stage humidification is found to be the most efficient in terms of freshwater production and specific power consumption, achieving the highest values of 1.93 L h-1 m-2 and 0.21 kWh L-1, respectively. The agreement between theoretical and experimental outcomes is deemed satisfactory.
Modeling and Simulation
ehsan salehi; Golara Nikravesh; Masoud Mandooie
Abstract
Metal-organic frameworks have emerged as extended-network, tunable, crystalline hydrogen storage adsorbents. The uptake of H2 on Zn4O-based MOFs with different linkers was studied in the current work. The binding energies, consecutive binding energy and step energy of H2-adsorption on MOF-177, MOF-200 ...
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Metal-organic frameworks have emerged as extended-network, tunable, crystalline hydrogen storage adsorbents. The uptake of H2 on Zn4O-based MOFs with different linkers was studied in the current work. The binding energies, consecutive binding energy and step energy of H2-adsorption on MOF-177, MOF-200 and a newly defined MOF (NEW-MOF) have been calculated on different possible sorption sites, using DFT/Dmol3/PBE. The linkers have the same benzene ring in center, but different numbers of phenyl rings, including 3, 6 and 9 phenyl rings in MOF-177, MOF-200 and NEW-MOF around the center ring, respectively. Our study results showed that the binding energy of the H2 molecules with the linker NEW-MOF was -4.165 kcal/mol, more negative than those obtained for MOF-177 (-3.276 kcal/mol) and MOF-200 (-3.438 kcal/mol). The obtained thermo-favorability may be attributed to the less steric hindrance for adsorption of H2 on the MOF with the larger linker. Step energy results showed that the linkers of MOF-177, MOF-200 and NEW-MOF could adsorb 7, 9 and 12 number of H2 molecules, respectively. Results also disclosed adsorbed moles of H2 per 1×1×1 unit cell of the MOFs decreases with increasing the linker length according to the order of 0.263 (for MOF-177), 0.16 (for MOF-200) and 0.137 (for NEW-MOF), mainly due to reduced packing density of the active sites in the MOFs with larger linkers. The most negative binding energy was also tabulated for the perpendicular approaching of H2 molecules to the node of the central phenyl ring with the bonding distance of 3.19 Å from the linker.
Reaction Engineering, Kinetics and Catalysts,
Abdullah Irankhah; Sepideh Ghafoori; atieh ranjbar
Abstract
In the present work, the effect of synthesis method (simultaneous impregnation and coprecipitation) and copper to nickel active phases loading were investigated in Ni-Cu-Al catalysts. The water/ethanol molar ratio of 6 and gas hourly space velocity (GHSV) of 20000 hr-1 were used in all the experiments. ...
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In the present work, the effect of synthesis method (simultaneous impregnation and coprecipitation) and copper to nickel active phases loading were investigated in Ni-Cu-Al catalysts. The water/ethanol molar ratio of 6 and gas hourly space velocity (GHSV) of 20000 hr-1 were used in all the experiments. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) techniques. The catalytic activity results revealed that 13Ni-6Cu/γ-Al2O3 impregnated catalyst was more active than co-precipitated one (13NiO-6CuO-81Al2O3) in the same amount of compositions of active metals and Al2O3, but by increasing the active phases (Cu and Ni) loading in co-precipitated catalysts (24NiO-31CuO-45Al2O3, 31NiO-24CuO-45Al2O3, 40NiO-15CuO-45 Al2O3 and 47NiO-8CuO-45Al2O3), they achieved a better performance than 13NiO-6CuO-81Al2O3 catalyst. The 40NiO-15CuO-45Al2O3 catalyst showed 99% ethanol conversion, as well as 303 hydrogen yield and 4% CO selectivity at 470oC. SEM images revealed agglomerated particles for the samples with high Al2O3 content and with increasing the active phase content in the catalyst the particle sizes decreased. The 40NiO-15CuO-45Al2O3 showed smallest particle size among the catalysts.
Environmental Engineering,
Azadeh Hemmati; Hayede Nafasi; Fatemeh aghamohammadi; Ali Afrous
Abstract
Constructed wetlands have been increasingly used as an effective method for removing heavy metals from wastewater. This study aimed to investigate the combined effect of sawdust and Hydraulic Retention Time (HRT) on the performance of vertical-flow constructed wetlands cultivated with Phragmites Australis ...
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Constructed wetlands have been increasingly used as an effective method for removing heavy metals from wastewater. This study aimed to investigate the combined effect of sawdust and Hydraulic Retention Time (HRT) on the performance of vertical-flow constructed wetlands cultivated with Phragmites Australis to remove Pb and Co from oily wastewater. To this end, nine barrels were used to construct the wetlands, which were filled with coarse gravel, polluted soil, and varying percentages of sawdust (0%, 20%, and 40%). Phragmites Australis cuttings were then cultured inside the barrels and irrigated with heavy metal-contaminated oily wastewater for three different hydraulic retention times (5, 10, and 15 days). After the vegetation period, plant, soil, and wastewater samples were collected and analyzed for Co and Pb concentrations, from which transfer factor (TF), bioconcentration factor (BCF), and removal efficiency (%) were derived. Results showed that while both Pb and Co removal efficiencies were affected by HRT and sawdust, the removal efficiency of Pb (36.66%) was higher than that of Co (30.83%). TF<1 and was not affected by HRT and sawdust, but the effect of HRT and sawdust on increasing BCF was significant. However, Phragmites Australis demonstrated suboptimal performance in the uptake and transfer of metals from root to stem.
Modeling and Simulation
Yaser Kazemi; Abdullah Irankhah
Abstract
Most of the reactions that occur in microreactors take place on the surface, so it is important to keep the reactants close to the reactive wall. One effective technique in this field is single-phase hydrodynamic focusing. However, this method has a drawback: a high percentage of reactants penetrate ...
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Most of the reactions that occur in microreactors take place on the surface, so it is important to keep the reactants close to the reactive wall. One effective technique in this field is single-phase hydrodynamic focusing. However, this method has a drawback: a high percentage of reactants penetrate into the sheath fluid. To address this issue, the concept of two-phase hydrodynamic focusing is introduced in this study. The main idea is to use a highly viscous sheath fluid to create a barrier against reactant penetration into the sheath flow. To demonstrate the effectiveness of this method, a 3D numerical simulation was performed with an irreversible second-order reaction. The results show that two-phase hydrodynamic focusing increases reaction rates, particularly in downstream regions where the Sherwood number can increase by several orders of magnitude with the use of a highly viscous sheath of liquid. Additionally, it was observed that the use of two-phase hydrodynamic focusing improves efficiency, which is defined as the ratio of solute in the sample flow to the total solute in each cross-section.
Thermodynamics,
Gabriela Lisa; Iuliana Bîrgăuanu; Catalin Lisa; Alexandra Bargan; Silvia Curteanu
Abstract
This paper evaluates the following properties: surface tension and refractive index in an area of composition influenced by component miscibility, four temperatures: 293.15, 303.15, 313.15 and 323.15 K and atmospheric pressure (0.1 MPa), for binary and ternary systems of benzyl alcohol, n-hexanol and ...
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This paper evaluates the following properties: surface tension and refractive index in an area of composition influenced by component miscibility, four temperatures: 293.15, 303.15, 313.15 and 323.15 K and atmospheric pressure (0.1 MPa), for binary and ternary systems of benzyl alcohol, n-hexanol and water, less studied in the literature. There was an increase in surface tension with increasing temperature for the n-hexanol-water binary system and the ternary system. Given that the refractive index is determined much easier and with a lower consumption of substances than the surface tension, in this paper the statistical processing of experimental data with multiple linear regression method (MLR) was applied and the following model was obtained: exc= 478.5+101.514⸱X1+58.389⸱X2+ 47.083⸱(T/273.15)-416.897⸱n. It correlates the excess surface tension (exc) with the composition (X1 and X2), the normalized temperature and the refractive index (n). Modelling with neural networks was also performed. The multilayer perceptrons (MLP) neuronal model (4:20:12:1) performs better than the MLR model, but the advantage of the latter is that it provides a mathematical expression that can be easily used by chemical engineers to predict excess surface tension based on experimental measurements of refractive index.