Current Issue : October - December Volume : 2015 Issue Number : 4 Articles : 5 Articles
Well-dispersed nanocrystalline MnCr2O4 was prepared by a salt-assisted combustion process using low-toxic glycine as fuel and\nMn(NO3)2 and Cr(NO3)3\n?9H2O as raw materials. The obtained products were characterized by X-ray Diffraction (XRD), Fourier\nTransform Infrared (FT-IR) spectroscopy, Raman spectroscopy, Transmission Electron Microscopy (TEM), and Scanning Electron\nMicroscopy (SEM). The fabrication process was monitored by thermogravimetric and differential thermal analysis (TG-DTA). The\nphase formation process was detected by XRD, and MnCr2O4 single phase with high crystallinity was formed at 700?C. TEM and\nSEM images revealed that the products were composed of well-dispersed octahedral nanocrystals with an average size of 80 nm.\nInert salt-LiCl played an important role in breaking the network structure of agglomerated nanocrystallites....
Y2O3:Eu3+ nanophosphors were prepared through combustion reaction under controlled condition of the fuel ethylenediaminetetraacetic\nacid (EDTA-Na2) and in the temperature range from 350 to 700?C. The products were characterized by X-ray diffraction\n(XRD), field emission scattering electron microscopy (FESEM), and energy dispersive spectroscopy (EDS). The results showed\nthat Y2O3:Eu3+ nanoparticles were successfully synthesized by combustion method at low temperature and in short reaction time.\nThe light-emitting ability of Y2O3:Eu3+ nanoparticles upon the electron excitation has been studied at the potentials 5, 10, and\n15 kV. The thermoluminescent glow curves have elucidated an intense peak at 117?C after UV exposure and at least two peaks at\n125 and 336?C with Gamma irradiation. Photoluminescent spectra of Y2O3:Eu3+ nanoparticles exhibited strong red luminescent\ncolor with highest sharp band at 612 nm under excitation in ultraviolet at 254, 394 and in visible at 465 nm. The dependence of\nphotoluminescent properties of Y2O3:Eu3+ nanoparticles on annealing temperature and concentration of Eu3+ was also studied....
Nanocrystalline La2Sn2O7 and La2Sn1.8Co0.2O7 with a phase-pure pyrochlore structure were synthesized by a hydrothermal\nmethod, and their catalytic activity was investigated for soot combustion. The as-synthesized catalysts presented relatively larger\nsurface area, and pore volume, which was benefit to the gas molecule diffusion in the reaction. A uniform spherical structure with\nparticle size of 200ââ?¬â??500 nm was found in SEM.The samples via hydrothermal route are more active for catalytic soot combustion,\nascribing to the spherical morphology, high surface area and improved oxygen mobility. After Co, the reducibility was improved\nand surface oxygen vacancy was produced, resulting in the enhanced activity and selectivity to CO2 formation....
The purpose of this paper is to investigate combustion characteristics for rotary\nengine via numerical studies. A 3D numerical model was developed to study the influence\nof several operative parameters on combustion characteristics. A novel rotary engine called,\nââ?¬Å?Leaf Spring Rotary Engineââ?¬Â, was used to illustrate the structure and principle of the engine.\nThe aims are to (1) improve the understanding of combustion process, and (2) quantify the\ninfluence of rotational speed, excess air ratio, initial pressure and temperature on combustion\ncharacteristics. The chamber space changed with crankshaft rotation. Due to the complexity\nof chamber volume, an equivalent modeling method was presented to simulate the chamber\nspace variation. The numerical simulations were performed by solving the incompressible,\nmultiphase Unsteady Reynolds-Averaged Navierââ?¬â??Stokes Equations via the commercial code\nFLUENT using a transport equation-based combustion model; a realizable K- ? turbulence\nmodel and finite-rate/eddy-dissipation model were used to account for the effect of local\nfactors on the combustion characteristics....
Thermogravimetric analysis was used to investigate oxy combustion of corncob and stover.The biomass samples were heated from\nambient temperature to 900?C at different heating rates of 10, 30, and 50 K/min. Both biomass samples showed similar weight loss\npatterns with three zones, corresponding to dehydration, devolatilization, and char combustion, but displayed different degradation\ntemperatures. Increasing heating rate was found to shift the degradation patterns to higher temperatures. Decomposition rates of\ncob and stover may have been influenced by their lignocellulosic composition.The kinetic parameters of the thermal degradation\nprocess were also determined and compared using the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods. Both methods\nwere found to give similar values and patterns of activation energy against conversion fraction. The average values were found to\nbe in similar magnitude to those reported in the literature, around 170 and 148 kJ/mol for cob and stover, respectively....
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