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The pneumatic transport of fine ideally combustible coal dust to the burner furnace is an important process in coal fired power plants. The strongly swirling air phase responsible for the particle separation and transport in a coal pulverising mill was characterised experimentally and numerically. Measurements of the swirl velocity component were taken in a scaled laboratory model of the device and compared to CFD model. In particular, an evaluation of the turbulence models used to describe the flow was performed. The modified isotropic k-epsilon turbulence models (RNG k-ε and Realizable k-ε) were compared to the anisotropic Reynolds stress model (RSM) and their ability to predict the bulk flow structure present in the classifier was assessed. The experiments showed that the swirling flow structure, responsible for coarse-fine particle classification, has several flow regimes which are governed by the areas it is bounded by. The numerical model predictions generally corroborate the results. However, a distinction in performance between the three models can be made based on accuracy, solution generation time and numerical stability. The RSM model predicted both the trends and magnitude the most accurately when compared to the isotropic models. However, the Realizable k-epsilon model, with its relatively low solution generation time, shows potential when using CFD as a classifier design optimization tool. The investigation has given some insight on single phase classifier flow and suggests a design improvement based on the results. 相似文献
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Adebowale Martins Obalalu Lawal Lanre Adebayo Ilhami Colak Adebayo Olusegun Ajala Fatai Adisa Wahaab 《亚洲传热研究》2022,51(5):3951-3978
Minimizing entropy generation is a technique that helps improve the effectiveness of real processes by studying the associated irreversibility of system performance of nanofluid. This study examines the entropy generation analysis of electromagnetohydrodynamic radiative Casson flow induced by a stretching Riga plate in a non-Darcian porous medium under the influence of internal energy change, Arrhenius activation energy, chemical reaction, and melting heat transfer. The thermophysical features of the fluid are assumed constant in most of the literature. However, this current research bridges this gap by considering viscosity, conductivity, and diffusivity as temperature-dependent variables. Also, the exponential decaying Grinberg term is used as a resistive force in this investigation due to the electromagnetic properties of the Riga plate in the momentum conservation equation. Some suitable dimensionless variables are introduced to remodel the transport equations into unitless ones and then solved numerically by employing Galerkin Weighted Residual Method. Analyses reveal that the Casson parameter declines the fluid velocity, while the existence of the melting parameter has the opposite effect. Also, this article includes some future recommendations. 相似文献
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Fahad S. Al-Mubaddel Rawesh Kumar Mahmud Lanre Sofiu Francesco Frusteri Ahmed Aidid Ibrahim Vijay Kumar Srivastava Samsudeen Olajide Kasim Anis Hamza Fakeeha Ahmed Elhag Abasaeed Ahmed I. Osman Ahmed Sadeq Al-Fatesh 《International Journal of Hydrogen Energy》2021,46(27):14225-14235
The increasing alarm of global warming always draws interest in reactions like dry reforming of methane (DRM) where both global warming gases (CO2 and CH4) are converted into value-added chemical building blocks, such as syngas. Nickel catalyst active sites along with support acid-base profiles play a key role in DRM. Herein, xLa2O3+(100-x) Al2O3 (x = 0, 10, 15, 20%) supports are prepared and followed by NiO dispersion over the produced support by impregnation method. It was tested for DRM reaction and characterized with TGA, XRD, TEM, IR, Surface area and porosity measurement, H2-TPR, CO2-TPD and NH3-TPD techniques. Upon increasing the basic lanthana proportion in the acidic alumina support, the crystallinity of alumina and acidity of total support decline. Up to 15% Lanthana addition in support claims a low acid and rich basic surface including super basic sites (related to unidentate carbonates) which governed optimum catalytic performance 64% CH4 conversion, 79% CO2 conversion and H2/CO ~ 1 up to 460-min in time on stream test. 20% lanthanum oxide loading led to inferior performance due to rapid loss of surface area, pore-volume, pore diameter, acidity and medium basic strength sites. Fine-tuning of acid-base lanthana-alumina support with dispersed Ni species are a means for understanding DRM. 相似文献
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A flow deflection screen model is proposed and implemented to predict the influence of expanded metal screens on a turbulent wind tunnel flow. The screen model successfully predicted the mean velocity and turbulence distribution in the flow field downstream of different screen types and orientation in the wind tunnel flow. 相似文献
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An experiment study of the turbulent flow behind expanded metal screens has been carried out in a low‐turbulence wind tunnel using an X‐probe hot‐wire anemometer system. The expanded metal screens turn flow due to a complex array of vaned elements. The flow turning was found to vary accordingly with the dimensions of the strands that make up the screen. The turbulence generated by the screens decays at a rate proportional to the downstream distance to the power ‐ 5/7, consistent with studies in the literature of conventional screens types, and was found to scale with the thickness of the screen strands. The mean velocity, pressure drop and turbulence characteristics of expanded metal screens are presented. 相似文献
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Daniyan Ilesanmi Mpofu Khumbulani Daniyan Lanre Fameso Festus Oyesola Moses 《The International Journal of Advanced Manufacturing Technology》2020,107(11):4517-4530
The International Journal of Advanced Manufacturing Technology - Additive manufacturing technology involving the deposition of materials in successive layers provides a realistic possibility for... 相似文献
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