Current Issue : October - December Volume : 2017 Issue Number : 4 Articles : 5 Articles
Hydrocracking is a catalytic reaction process in the petroleum refineries for\nconverting the higher boiling temperature residue of crude oil into a lighter\nfraction of hydrocarbons such as gasoline and diesel. In this study, a modified\ncontinuous lumping kinetic approach is applied to model the hydrocracking\nof vacuum gas oil. The model is modified to take into consideration\nthe reactor temperature on the reaction yield distribution. The model is\ncalibrated by maximizing the likelihood function between the modeled and\nmeasured data at four different reactor temperatures. Bayesian approach\nparameter estimation is also applied to obtain the confidence interval of\nmodel parameters by considering the uncertainty associated with the measured\nerrors and the model structural errors. Then Monte Carlo simulation is\napplied to the posterior range of the model parameters to obtain the 95%\nconfidence interval of the model outputs for each individual fraction of the\nhydrocracking products. A good agreement is observed between the output\nof the calibrated model and the measured data points. The Bayesian approach\nbased on the Markov Chain Monte Carlo simulation is shown to be\nefficient to quantify the uncertainty associated with the parameter values of\nthe continuous lumping model....
We report the development of technology that may contribute to a reduction\nin greenhouse gas emissions and improve the energy efficiency of the CO2\ncapture process. Lithium ortho-silicate is a suitable solid sorbent for capturing\nCO2. This reversible chemical reaction is also applicable to chemical heat storage.\nThe absorption reaction characteristics of lithium ortho-silicate were\nstudied by a thermogravimetric method and a volumetric method that demonstrated\nthe influence of heat and mass transfer limitations in a packed bed\ndesigned to be as small as possible. We developed a method for measuring the\nabsorption reaction characteristics in the experiments. In the experiments, a\nconstant conversion fraction of 60% was observed. The reaction system was\nstable to repetition. The CO2 absorption rate depends on the CO2 pressure\nand reactor temperature. The absorption rate was determined at several reactor\ntemperatures when the conversion fraction was 0.3. In this study, the\nmaximum absorption rate was obtained at 670Ã?Å¡C. It was demonstrated that\nlithium ortho-silicate is suitable for use in a chemical heat storage system....
A stability criterion for gas-hydrate slurry stratified flow was developed. The model was based on one-dimensional gas-liquid two-fluid model and perturbation method, considering unstable factors including shear stress, gravity, and surface tension. In addition, mass transfer between gas and liquid phase caused by hydrate formation was taken into account by implementing an inward and outward natural gas hydrates growth shell model for water-in-oil emulsion. A series of gas-hydrate slurry flow experiments were carried out in a high-pressure (>10�MPa) horizontal flow loop. The transition criterion of smooth stratified flow to other flow patterns for gas-hydrate slurry flow was established and validated and combined with experimental data at different water cuts. Meanwhile, parameters of this stability criterion were defined. This stability criterion was proved to be efficient for predicting the transition from smooth to nonsmooth stratified flow for gas-hydrate slurry....
Investigations of the working processes in a gas turbine low-emission combustor operating on the synthesis gas, in which the\nprinciple of RQL (Rich-Burn, Quick-Mix, and Lean-Burn) combustion technology is realized, have been performed. Selected\nconcept of a gas turbine combustor can provide higher performance and lower emission of nitrogen oxides and demonstrates\nsatisfactory major key parameters. Obtained results and recommendations can be used for the gas turbine combustor operation\nmodes modeling, geometry optimization, and prospective power generation units design and engineering....
The development of electric and hybrid automobiles has gained momentum\nwith the growth of interest in the field of miniaturization of electrode materials.\nIn particular, technologies that improve the electrical property of stainless\nsteel, while maintaining corrosion resistance, are gaining interest in terms\nof maintaining specific resistivity. The study on metal doping in diamond-like\ncarbon coating is currently in progress to enhance the characteristics of conductivity\nand corrosion resistance with excellent properties such as corrosion\nresistance and lubrication coating. It is the process of using Cr arc with DLC\ncoating to actuate AEGD. The change of I(D)/I(G) (Graphite peak (G) and\ndisordered bond peak (D)) ratio and G-peak position in Cr-containing DLC\nfilm causes graphitization and thus lowers the basic electric resistance. Simultaneous\ninput of nitrogen gas leads to deposition of CrN by a specific ratio of\nCr and N in the DLC coating, and the nitrogen atoms replace hydrogen in\nbonding to increase the sp3 bond structure in the DLC film, in which CrN is\nnot deposited, to result in specific resistivity of a specific value or less....
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