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.
Biomedical and Biotechnology,
M. Takapoui; M. Saadatmand; F. Ghobadi
Abstract
Numerous bone disorders and injuries, such as osteoporosis, are among the most prevalent and spreading types of human tissue injuries worldwide, and the available treatments for these injuries are often insufficient and inefficient. Nowadays a lot of attention has been paid to regenerative medicine, ...
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Numerous bone disorders and injuries, such as osteoporosis, are among the most prevalent and spreading types of human tissue injuries worldwide, and the available treatments for these injuries are often insufficient and inefficient. Nowadays a lot of attention has been paid to regenerative medicine, specifically tissue engineering because of its unique features. The extracellular matrix is a key component in tissue engineering because it must have specific properties to support cell survival and proliferation. Natural and synthetic polymeric hydrogels are among the materials commonly employed in tissue engineering. Because the extracellular matrix of bone is particularly mineralized and has a high elasticity, various nanoparticles are commonly utilized to improve the mechanical properties of polymeric hydrogels. In this study, first, we extracted the collagen type I from rat tail and characterized it with FTIR spectrum and self-assembly, second we synthesized the bioactive glass nanoparticles and characterized them with XRD and EDAX. Then we developed a polymeric collagen hydrogel (3 mg/ml) scaffold including bioactive glass nanoparticles (3 %wt) which increase the mechanical properties of the scaffold (103 pa elastic modulus) in comparison to collagen scaffold (0% wt nanoparticles) that it can be used for bone tissue engineering applications.
Energy
N. Gilani; S. Fallahdoost Moghadam; Ali Akbar Y.
Abstract
A hydrothermal method was used to synthesize different photoanodes for dye-sensitized solar cell (DSSC) applications. These photoanodes included WO3, TiO2, Graphene-TiO2, WO3-TiO2, and a nanostructure of Graphene-WO3-TiO2. The morphology of the nanoparticles was analyzed using scanning electron microscopy ...
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A hydrothermal method was used to synthesize different photoanodes for dye-sensitized solar cell (DSSC) applications. These photoanodes included WO3, TiO2, Graphene-TiO2, WO3-TiO2, and a nanostructure of Graphene-WO3-TiO2. The morphology of the nanoparticles was analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-vis), and Fourier-transform infrared spectroscopy (FTIR). The results demonstrated that the graphene-WO3-TiO2 nanostructure had a large surface area, providing more active sites for efficient conversion of solar energy. Notably, the DSSC incorporating the graphene-WO3-TiO2 nanoparticles electrode outperformed cells based solely on TiO2 and WO3, achieving a higher short-circuit current density of 7.5 mA.cm-2, an open-circuit voltage of 0.68 V, a fill factor of 0.46, and a power conversion efficiency of 2.4%. In contrast, the pure TiO2 and WO3 cells only achieved an efficiency of 0.88% and 0.69%, Respectively. The excellent electron mobility of the ternary nanostructure facilitated charge trapping and injection into the conductive substrate, reducing recombination. Additionally, the scattering effect of the WO3 nanorods and graphene enhanced light harvesting in the photoanode, leading to an increase in overall solar cell efficiency. These findings highlight the potential of the synthesized graphene-WO3-TiO2 nanostructure as a promising photoanode material for DSSC applications.
Separation Technology,
P. Valeh-e-Sheyda; Sh. Sarlak
Abstract
The increased demand of the world for energy and its reliance on fossil fuels ultimately contribute to the surge in the levels of carbon dioxide in the atmosphere. To achieve a green efficient carbon capture, a novel multi-component amine-amino acid solvent including methyldiethanolamine (MDEA), diisopropanolamine ...
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The increased demand of the world for energy and its reliance on fossil fuels ultimately contribute to the surge in the levels of carbon dioxide in the atmosphere. To achieve a green efficient carbon capture, a novel multi-component amine-amino acid solvent including methyldiethanolamine (MDEA), diisopropanolamine (DIPA), and Arginine (ARG) was designated for CO2 absorption in a T-microreactor. The potential absorption of the aqueous solutions of the desired mixed amines has been assessed through the CO2 absorption percentage (AP) and the total volumetric gas-phase mass transfer coefficient (TGMTC) over a wide range of gas flow rate (60-240 mL/min), solvent flow rate (2-6 mL/min), under three mixing concentrations of MDEA: DIPA: ARG (28:8:4), (28:6:6), and (28:4:8)) wt%. The research findings demonstrate an increment of 31% in CO2 absorption percentage by reducing DIPA to 4 wt% and raising the arginine concentration to 8 wt% in ternary amine solutions. Additionally, the highest mass transfer coefficient was achieved at 38.06 (kmol/m3.h.kPa) utilizing the aqueous solution of MDEA+DIPA+ARG (28+4+8) wt%.
Modeling and Simulation
A. Das; N. Azimi
Abstract
This research presents the performance of bladeless wind turbines. It also familiarizes readers with the phenomenon of eddy current, which serves as the foundation for bladeless turbines. In this direction, these kinds of bladeless turbines have been designed, modeled, and simulated. Firstly, a two-dimensional ...
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This research presents the performance of bladeless wind turbines. It also familiarizes readers with the phenomenon of eddy current, which serves as the foundation for bladeless turbines. In this direction, these kinds of bladeless turbines have been designed, modeled, and simulated. Firstly, a two-dimensional vibrational movement of the cylinder with a natural frequency of 2 Hz was modeled at Re = 51000. Additionally, it was noted that the values of the displacement amplitude, and lift coefficient are in the 0.8, and 1-1.5 ranges, respectively. After that, using 2D simulation, the impacts of two different geometries, horizontal and vertical ellipsoids, on displacement amplitude are examined. Investigations were conducted on important factors such as lift coefficients and displacement amplitude, as well as the vortex flow pattern formed behind these shapes. It was discovered that the vertical ellipsoid shape had the maximum values for the height of the displacement amplitude, and lift coefficient. The most important factor influencing this type of geometry's performance was examined in the following, namely the dimensionless Reynolds number, which ranges from 15000 to 90000. It was determined that the intended geometry exhibits a larger displacement response as the Reynolds number increases.
Separation Technology,
M. Abdollahi; Sh. Fatemi; M. Fakhroleslam; A.R. Sadri
Abstract
Vacuum swing adsorption (VSA) for CO2 capture has attracted much research effort due to the development of the novel CO2 adsorbent materials. In this work, three adsorbents (MAF-66, AC and CMS) were used to capture CO2 by VSA process from flue gas and their performances were compared. Adsorption equilibrium ...
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Vacuum swing adsorption (VSA) for CO2 capture has attracted much research effort due to the development of the novel CO2 adsorbent materials. In this work, three adsorbents (MAF-66, AC and CMS) were used to capture CO2 by VSA process from flue gas and their performances were compared. Adsorption equilibrium and kinetics data were extracted from recent works. A four step VSA cycle was employed to evaluate the performance of adsorbents for CO2 capture with the molar feed composition of CO2:N2 at 15:85% . Simulations of VSA units with two columns and different adsorbents were carried out. Some operating conditions such as total feed flowrate, feed composition, feed pressure, temperature and vacuum pressure were considered fixed and then the effect of the adsorbent mass was investigated on the recovery and productivity. The simulation showed that recovery and productivity decreased with increasing amount of adsorbent . In addition, the required amount of each adsorbent to reach to the purity of 99.5% was calculated. The modeling results predicted that the VSA process using MAF-66, CMS and AC adsorbents would need 1.25, 3.19 and 8.2 gr of adsorbent, respectively, to reach the N2 purity of 99.5%. According to the other parameters such as recovery, productivity and energy consumption, MAF-66 performed as the best adsorbent.
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.