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Mar 14, 2021

Combined operation mode of sub-critical W-flame boiler and coal mill optimized numerical simulation

The flow, combustion, heat transfer and NO_x emission characteristics of a 600 MW subcritical W-flame boiler were numerically simulated under different combined operation modes of coal mills, and compared with the measured results. The results show that the combustion, average residence time, burnout rate, NO_x emission characteristics and temperature distribution near the side wall of pulverized coal particles in the furnace have different effects on the combined operation mode of pulverized coal. In the combustion efficiency of give attention to two or more things, screen superheater section of fly ash carbon content and flue gas temperature of entrance at the same time, compared with six coal mill run at the same time, 5 coal mill run, shut down near the side wall of the coal mill is beneficial to reduce NO_x emission concentration, to achieve the emission reduction, at the same time under the wing wall and side wall area chamber of a stove or furnace slagging significantly reduce.

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Mar 18, 2021

Preparation and characterization of magnetic graphene oxide nanocomposite (GO-Fe3O4) for removal of strontium and cesium from aqueous solutions

Magnetic graphene oxide nanocomposites (M-GO) were successfully synthesized by partial reduction co-precipitation method and used for removal of Sr(II) and Cs(I) ions from aqueous solutions. The structures and properties of the M-GO was investigated by X-ray diffraction, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometer (VSM) and N₂-BET measurements. It is found that M-GO has 2.103 mg/g and 142.070 mg/g adsorption capacities for Sr(II) and Cs(I) ions, respectively. The adsorption isotherm matches well with the Freundlich for Sr(II) and Dubinin–Radushkevich model for Cs(I) and kinetic analysis suggests that the adsorption process is pseudo-second-ordered.

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Mar 24, 2021

Earthquake response control of ground soft storey

In the present study, friction damper, an energy dissipating passive device is explored to reduce the response of open ground storey building under lateral loading due to earthquake. This damper is installed in the selected bays of open ground storey so that the response is reduced. The masonry infill wall is macro-modeled in the form of compression only diagonal members. Three different types of bracing system were installed along with Pall friction damper – single diagonal tension – compression brace with friction damper, tension only cross brace with friction damper and chevron brace with friction damper were modeled using Wen’s plastic link element in SAP2000. G+4 storey buildings were analyzed using nonlinear time history analysis. The storey displacement and inter-storey drift for all the cases were compared in the study.

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Mar 29, 2021

Wolfram Mathematica, exact solutions for heat transfer methods applied to extrusion processes

Computer programs for the solution of everyday problems are very common because of the speed with which results can be obtained, which by traditional methods would be very laborious and especially those in which the solutions take repeated calculations. The work intends to demonstrate how, through programming, applying the exact solution method, fast and precise results can be obtained on similarities and differences between different geometries in heat

transfer, which demonstrate the behavior, according to parameters, under equal conditions (geometric properties, diameters, lengths, thicknesses, volumes) and physical properties (thermal conductivity, specific heat and density), appreciating how they influence results such as cooling times, production according to the physical properties and design of the equipment, consumption rates, core and surface temperatures and others, according to the plastic pipe extrusion method, necessary in production processes that require constant monitoring.

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Apr 3, 2021

Thermodynamic stability diagram of the copper/water/amylxanthate flotation system

The purpose of this work was to obtain the thermodynamic stability diagram that characterizes the copper/water/amylxanthate flotation system, as part of the theoretical foundation necessary for the analysis of the copperion flotation process with the flotation collector reagent potassium amylxanthate. From the system of fundamental chemical reactions and with the help of the Medusa software, the Eh-pH diagram was obtained, in which the stability zones of the different chemical species are defined and it is established that in the pH range from 4 to 13, the xanthogenic species of copper(I) and (II) coexist, whose ratio decreases with the increase of pH.

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Apr 10, 2021

Integrating optical and microwave satellite observations for high resolution soil moisture estimate and applications in CONUS drought analyses

In this study, optical and microwave satellite observations are integrated to estimate soil moisture at the same spatial resolution as the optical sensors (5km here) and applied for drought analysis in the continental United States. A new refined model is proposed to include auxiliary data like soil texture, topography, surface types, accumulated precipitation, in addition to Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) used in the traditional universal triangle method. It is found the new proposed soil moisture model using accumulated precipitation demonstrated close agreements with the U.S. Drought Monitor (USDM) spatial patterns. Currently, the USDM is providing a weekly map. Recently, “flash” drought concept appears. To obtain drought map on daily basis, LST is derived from microwave observations and downscaled to the same resolution as the thermal infrared LST product and used to fill the gaps due to clouds in optical LST data. With the integrated daily LST available under nearly all weather conditions, daily soil moisture can be estimated at relatively higher spatial resolution than those traditionally derived from passive microwave sensors, thus drought maps based on soil moisture anomalies can be obtained on daily basis and made the flash drought analysis and monitoring become possible.

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