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991.
Hadiseh Khalilpourmeymandi Azadeh Mirvakili Mohammad Reza Rahimpour Alireza Shariati 《中国化学工程学报》2017,25(5):676-687
Nowadays, by the increasing attention to environment and high rate of fuel production, recycling of purge gas as reactant to a reactor is highly considered. In this study, it is proposed that the purge gases of methanol production unit, which are approximately15.018 t·h~(-1) in the largest methanol production complexes in the world, can be recycled to the reactor and utilized for increasing the production rate. Purge gas streams contain 63% hydrogen,20% carbon monoxide and carbon dioxide as reactants and 17% nitrogen and methane as inert. The recycling effect of beneficial components on methanol production rate has been investigated in this study. Simulation results show that methanol production enhances by recycling just hydrogen, carbon dioxide and carbon monoxide which is an effective configuration among the others. It is named as Desired Recycle Configuration(DRC) in this study. The optimum fraction of returning purge gas is calculated via one dimensional modeling of process and Response Surface Methodology(RSM) is applied to maximize the methanol flow rate and minimize the carbon dioxide flow rate. Simulation results illustrate that methanol flow rate increases by 0.106% in DRC compared to Conventional Recycle Configuration(CRC) which therefore shows the superiority of applying DRC to CRC. 相似文献
992.
Javad Safaei-Ghomi Alireza Hatami Hossein Shahbazi-Alavi 《Polycyclic Aromatic Compounds》2017,37(5):407-414
A concise and efficient method for the synthesis of 3,4,5-substituted furan-2 (5H)-ones was achieved through a three-component reaction of amines, dialkyl acetylene dicarboxylate, and aromatic aldehydes using nano-CdZr4(PO4)6 as catalyst under microwave irradiation. This method has several advantages such as, high efficiency, short reaction times, simple workup, and recyclability of the catalyst up to seven runs without considerable loss of activity. 相似文献
993.
Vahid Monfared 《SILICON》2017,9(3):339-345
A new analytical approach is proposed to analyze the steady state creep in a short fiber composite SiC/Al6061 (Silicon Carbide/Aluminum 6061) under axial load based on high order displacement functions. The creep behavior of the matrix is described by an exponential law, while the fibers behave elastically. The main originality and purpose of the present paper is to predict the creep behavior in the short fiber composite “Silicon Carbide/Aluminum 6061 using high order functions analytically. The paper is presented in order to prevent undesirable events, as well as controlling the creep deformation rate. Good agreements are found among available experimental methods, FEM and present analytical approach results. As a result, most behaviors have ascending behaviors with smooth gradients, and also are controllable. 相似文献
994.
Vahid Amirzadeh-Fotovat Yousef Hatefi 《International Journal of Applied Ceramic Technology》2019,16(4):1441-1449
In this work, the spark plasma sintering (SPS) of commercial yttria nanopowder is investigated. The SPS parameters such as sintering temperature, applied pressure, and dwell time are varied. Densification without grain growth occurring at occurred up to a sintering temperature of 1400°C and grain growth without further densification taking place at the higher temperature. The optimum sample was obtained at a temperature of 1400°C with a pressure of 70 MPa and dwelling time of 15 minutes. The highest relative density of 99.8% and the average grain size of 1.26 μm were obtained at 1400°C. The yttria ceramic annealed at 1200°C had the in-line transmission of 5%-70% and 70%-82% in the visible and infrared wavelength region, respectively. The measurements of hardness and fracture toughness characteristics of the transparent yttria ceramic showed 9.2 GPa and 2.24 MPa.m1/2, respectively. 相似文献
995.
Copper-phthalocyanine and nickel nanoparticles as novel cathode catalysts in microbial fuel cells 总被引:1,自引:0,他引:1
Mostafa Ghasemi Wan Ramli Wan Daud Mostafa Rahimnejad Majid Rezayi Amin Fatemi Yaghoob Jafari M.R. Somalu Alireza Manzour 《International Journal of Hydrogen Energy》2013
In this study, four different catalysts (i.e., carbon black, nickel nanoparticle (Ni)/C, Phthalocyanine/C and copper-phthalocyanine/C), were tested in a two-chamber Microbial Fuel Cell (MFC) and their performances were compared with Pt as the common cathode catalyst in MFC. The characterization of catalysts was done by TEM, XPS and EDX and their electrochemical characteristics were compared by cyclic voltammetry (CV) and Linear Sweep Voltammetry (LSV). The results proved that copper phthalocyanine and nickel nanoparticles are potential alternatives catalyst for Pt. Even copper-phthalocyanine generated power is almost the same as Pt. The CV and LSV results reported high electrochemical activity of these catalysts. The maximum power density and coulombic efficiency was achieved by copper-phthalocyanine/C as 118.2 mW/m2 and 29.3%. 相似文献
996.
Gas–solid flow in a pipe with different configurations (vertical, horizontal, and inclined positions) is studied experimentally. Air with temperature around 170°C and sand particles with mean diameter of 253 μm are used as gas and solid mediums, respectively. Effects of different parameters (pipe slope and solid particles feed rate) are studied on heat transfer rate between gas and solid particles. The Nusselt number decreases at lower solids feed rate in a dilute regime of the mixture; however, it increases at higher solids feed rates. Furthermore, results show that a higher Nusselt number takes place at the angles closer to 45 degrees. 相似文献
997.
Poly(vinylphosphonic acid) (PVPA) was synthesized by free radical polymerization of vinylphosphonic acid (VPA) in different solvents. Bromotrichloromethane as a chain transfer agent (CTA) was used in some experiments to control molecular weight of the PVPA. The effects of solvent type and initiator and CTA concentrations on the microstructure, molecular weight and stereoregularity of the resulting PVPA was extensively investigated by FTIR, 1HNMR, 31PNMR and elemental analysis. Polymers with a number-average molecular weight (Mn) in the range of 1550 to 42,190 gmol?1 were prepared. High molecular weight PVPA with Mn of 42,190 gmol?1 was obtained from aqueous solution polymerization of VPA with initiator/monomer molar ratio of 0.16/100 at 80°C. Molecular weight decreased with increasing the concentration of initiator and CTA. 1HNMR spectra were used to investigate tetrad sequences for the methylene protons of PVPA, from which stereochemical information of the polymer chain was obtained. Tetrad sequences were also calculated by Bernoullian probabilities. Moreover, the percent of head-to-head and tail-to-tail irregularities of the resulting PVPA were obtained to be in the range of 16.6–58% depending on the reaction conditions. The PVPA synthesized in acetic anhydride as a solvent had highest amount of the irregularities due to the high reaction rate, which does not allow controlling the structure. Furthermore, due to the importance of PVPA in the proton exchange membranes (PEMs), the effects of molecular weight and temperature on the acidity and titration behavior of PVPA polyelectrolyte were investigated. It was found that molecular weight has no significant effect on the acidity and dissociation of protons at operational conditions of degree of dissociation lower than 0.5. It was also found that by increasing the temperature, pH values were decreased, meaning that dissociation of protons and consequently the proton conductivity of PVPA membranes can be affected by temperature. Titration behavior of PVPA also showed that the PVPA has a behavior similar to a monoprotic acid. 相似文献
998.
A pore network study of evaporation from the surface of a drying non‐hygroscopic porous medium 下载免费PDF全文
Alireza Attari Moghaddam Abdolreza Kharaghani Evangelos Tsotsas Marc Prat 《American Institute of Chemical Engineers》2018,64(4):1435-1447
The phenomena occurring at the surface of a porous medium during drying in the capillary regime are investigated by pore network simulations. The impact of the formation of wet and dry patches at the surface on the drying rate is studied. The simulations indicate an edge effect characterized by a noticeable variation of saturation in a thin layer adjacent to the porous surface. Also, the results indicate a significant nonlocal equilibrium effect at the surface. The simulation results are exploited to test Schlünder's classical model which offers a simple closure relationship between the evaporation rate and the degree of occupancy of the surface by the liquid. In addition to new insights into the surface phenomena, the results open up new prospects for improving the continuum models of the drying process. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1435–1447, 2018 相似文献
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