Different Ratios Of Oxygen Research Articles

Combination Effect of in-Situ Combustion and Exhaust Gases Recirculation on 1D Combustion Tube: Numerical Approach

ABSTRACT Despite the widespread use of renewable and green energy, the demand for fossil fuels is also rising due to increasing global energy demand. Therefore, unconventional solutions, with safe environmental impacts, are being pursued to solve this problem. Instead of getting rid of the exhaust gases in the surroundings, one solution might be to inject them with the oxidizer into the oil reservoir, to initiate an in-situ combustion (ISC) process to enhance oil recovery. A numerical study of a 1-D combustion tube has been conducted and validated to simulate the in-situ combustion process using enriched air as the oxidizer. The effects of injecting exhaust gases with the oxidizer are studied. Different ratios of oxygen to nitrogen are used in the enriched air as well as different ratios of exhaust gases. If enriched air which is mostly oxygen, i.e. 95% O2 +5%N2, is used, it is found that replacing 10% of the enriched air with exhaust gases can increase the oil recovery factor (ORF) from 94.7% to 94.9% and replacing 20% can improve oil recovery to 95.1%. For another enriched air, 60% O2 +30% N2, it is found that replacing portions of the enriched air with exhaust gases will reduce the oil recovery factor. In all previous cases, it was found that replacing the proportions of enriched air with exhaust gases reduces the amount of fuel burned and increases hydrogen production.

Magnetron sputtered TiO2 with metal NPs for plasmonic applications

This work is aimed at finding the optimal technological modes for the deposition of TiO2 films by reactive magnetron sputtering for use as a photoactive material in plasmonic applications. The structural and optical parameters of films obtained at different ratios of oxygen in a mixture of working gases were studied. On the basis of the obtained experimental results, a numerical simulation of the spectral characteristics of the TiO2 / NP structure of the metals silver and gold was carried out.

Influence of Cold Atmospheric Pressure Plasma on Pea Seeds: DNA Damage of Seedlings and Optical Diagnostics of Plasma

Cold atmospheric pressure plasma treatment is currently being explored as an alternative way to improve the germination and growing parameters of plant seeds. However, it is important to pay attention to the effect of plasma treatment on DNA damage of the seeds as well as detailed characteristics of plasma composition and parameters. The aim of this work was to study the DNA damage of plasma-treated pea seeds (Pisum sativum L.) and plasma parameters such as the chemical composition of plasma gaseous compounds and plasma radiation. Seeds were treated with plasma using the diffuse coplanar surface barrier discharge generated in different working gases (ambient air, nitrogen, oxygen and different mixtures of oxygen and nitrogen) at atmospheric pressure and at 60 s, 180 s and 300 s exposure times. DNA damage was studied using the single cell-gel electrophoresis called the comet assay and the plasma parameters were investigated by Fourier transform infrared spectroscopy and optical emission spectroscopy. Experiments in different ratios of oxygen and nitrogen were realized in order to understand the reaction mechanism between the ambient air plasma and the treated seeds. Based on our results, ambient air plasma appears to be the most advantageous for the plasma treatment due to no significant DNA damage because of the proper combination of plasma composition in combination with water vapor present in ambient air.

Formation of NO in High-Temperature N2/O2/H2O Mixtures: Re-evaluation of Rate Coefficients

A re-evaluation of the flow reactor experiments of Abian et al. (Abian, M.; Alzueta, M. U.; Glarborg, P. Formation of NO from N2/O2 Mixtures in a Flow Reactor: Toward an Accurate Prediction of Thermal NO. Int. J. Chem. Kinet. 2015, 47, 518−532, DOI: 10.1002/kin.20929) is presented. In these experiments, nitrogen oxide formation was measured at atmospheric pressure in the temperature range of 1700–1810 K using several mixtures containing different ratios of oxygen, nitrogen, and water vapor. On the basis of the mechanism of Abian et al., the two most important reaction steps for NO formation (reaction R1, NO + N = N2 + O; reaction R2, N2O + O = 2 NO) were identified by local sensitivity analysis. For the optimization of the Arrhenius parameters of these reaction steps, 25 data points measured by Abian et al., two direct rate coefficient measurements (73 data points), and one theoretical calculation were used. The obtained mechanism with the optimized Arrhenius parameters (reaction R1, A = 1.176 × 1010 cm3 ...

Tantalum oxide film deposited by vacuum cathodic arc plasma with improved electrochromic performance

Inorganic solid-state electrochromic devices (ECDs) based on tantalum oxide (Ta2O5) as ion conductor layer were fabricated by vacuum cathodic arc plasma (CAP) deposition. This work focuses on key factor of fabricating Ta2O5 film deposited by CAP through four different ratios of oxygen and argon. Our results show that refractive index mostly decreased with increasing oxygen flow rate. Refractive index of 1.9 was achieved for Ta 2O5 film with O2/Ar = 2.4 which provided high ion conduction pathways through a highly porous structure. We also observed higher ionic conductivity σi=3.5×10−6Scm−1 for Ta2O5 film at O2/Ar = 2.4 which enhanced ion's mobility for ECDs causing rapid coloring/bleaching phenomenon. As a result, excellent optical density and rapid response times were observed in fabricated device with an area of 20 cm2, exhibiting optical density of 0.63 (@550 nm) and transmittance variation T = 50% (@550 nm) with the bleaching time= 5 s and transmittance variation T = 50% (@550 nm) with the coloring time = 13 s.

Polycarboxylate adsorption on coal surfaces and its effect on viscosity of coal-water slurries

It is extremely important to reveal the adsorption behavior of polycarboxylate (PC) on coal to improve the performance of PC and even enhance its fabrication and preparation. In this work, three kinds of low rank coal with different ratios of oxygen to carbon (O/C) were employed to prepare coal-water slurries and analyze performances. Apparent viscosities of the slurries were tested. The contact angle and adsorption of PC dispersant on coal were measured. It is observed that the viscosity reduction of CWS is dependent on the saturated adsorption of PC on coal. The order of viscosity reduction is same with the hydrophilicity/hydrophobicity of the PC on the coal surfaces, which corresponds well with the ratio of O/C in coal. So the future dispersant should be designed to improve its adsorption on coal according to the ratio of O/C in coal. Moreover, using a Scanning Electron Microscopy-Energy Dispersive Spectrometer, and zeta potential analysis, we demonstrate the morphology of PC dispersant on coal and clarify further the mechanism of the efficient PC dispersant. Extra dosage of the PC will prevent relative movement between coal particles thus increasing the viscosity of CWSs. So, it is quite necessary to control the proper dosage of the PC dispersant on the basis of the adsorption values in the slurry processing.

Effect of the Gas Composition at the Electrical Explosion of Wires on the Nanopowders Properties

In this paper we present the study results of nanopowders properties produced by electrical explosion of wires in argon-oxygen and argon-air mixtures with different ratios of oxygen and air (0.5-30 vol. %). The products of aluminum, titanium and copper wires explosions were studied. The effect of the synthesis conditions on the metal content in the nanoparticles and their phase, chemical and size composition is discussed. The oxygen addition of 10-30 vol. % leads to a reduction in the metal content in the particles and to the formation of metals oxide. The small additives of reactive gases (< 2 vol. %) into the inert gas in the discharge chamber can be used for production of metal powder.

Violet–blue–green emission and shift in Mg-doped ZnO films with different ratios of oxygen to argon gas flow

Mg-doped ZnO films were deposited using radio frequency reactive magnetron sputtering at different ratios of oxygen to argon gas flow. The crystal structures, surface morphology and optical properties of Mg-doped ZnO thin films were analyzed. The results indicated that three main emission peaks located at 400, 440 and 483nm were observed in Mg-doped ZnO films. Violet peak at 400nm and blue peak centered at 440nm shifted to 392nm and 422nm, respectively, as the ratio of oxygen to argon gas flow is increased. The spectra shift mechanism was discussed, which would be caused by small amount of Zn nanoparticles in Mg-doped ZnO films. The electrons on the Zn conduction band will go across the interface for energy equilibration, and then transition to Zn vacancies and the top of the valence band, which may cause spectra shift.

Morphological and optical characteristics of nanocrystalline TiO2 thin films by quantitative optical anisotropy and imaging techniques

TiO2 thin films were prepared by dc reactive sputtering with different ratios of oxygen to argon. The optical characteristics of the films were studied by birefringence imaging and optical anisotropic analysis using MetriPol. A clear trend of aggregation and structural variation of TiO2 nanoparticles in the films can be seen using MetriPol optical anisotropic imaging. It was found that the optical characteristics of the TiO2 thin films depend on the ratios of O2/Ar during sputtering of the films. The optical anisotropies are closely related to the structural feature of TiO2 nanoparticles. Variation trends of TiO2 film structures and optical characters have also been confirmed by FESEM observations and refractive index.

Formation of acicular ferrite and influence of vanadium alloying

The effect of vanadium microalloying in promoting a tough, acicular ferrite microstructure in C-Mn steels has been investigated. The microstructure obtained consisted of fine interlocking ferrite plates and was indistinguishable from acicular ferrite developed in steel weld metals, apparently from the intragranular nucleation of ferrite at inclusions. A number of variables were examined in high purity experimental steels including composition and heat treatment conditions, and related to a metallographic examination of the microstructure by high resolution micro-analytical transmission electron microscopy and surface analysis. A comprehensive study of the inclusions in the steels, containing different ratios of oxygen and nitrogen concentration, did not find any significant evidence that inclusion assisted nucleation was the sole determining factor in producing acicular ferrite. Moreover, no evidence could be found to relate vanadium alloying to significant vanadium nitride precipitation, either separately, or associated with the inclusions. Thus, in the present steels, any possible alternative influence of vanadium on intragranular ferrite nucleation is not obscured by effects associated with the inclusion population. The vanadium concentration appeared to be the most important influence in developing an acicular ferrite microstructure in these experimental steels, and this is not inconsistent with previous reports in the literature of a beneficial 'vanadium effect'. Evidence for vanadium segregation in the microstructure was found, which may be related to the effect of vanadium in encouraging the formation of acicular ferrite. Even when there is good evidence that inclusions are responsible for intragranular ferrite nucleation (as, for example, in steel weld metals), a 1 :1 inclusion-ferrite relationship has been difficult to establish. Thus, even an inclusion activated nucleation theory is likely to require additional intragranular ferrite formation without inclusion assistance, such as sympathetic or autocatalytic nucleation, and this could be reflected in the present study by vanadium atom clustering facilitating an alternative intragranular ferrite nucleation mechanism.

Characterization of Flame Grown Diamond Films by Luminescence and EPR

ABSTRACTFlame grown diamond films, depending on the growth conditions may present various amounts of diamond like carbon (DLC) besides the diamond phase. A correlation of the morphology with the secondary electron emission, cathodoluminescence, photoluminescence, EPR and Raman data is presented for samples grown using in different ratios of oxygen and acetylene.