کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
154549 456843 2016 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Effect of superficial gas velocity on the particle temperature distribution in a fluidized bed with heat production
ترجمه فارسی عنوان
اثر سرعت گاز سطحی بر توزیع دمای ذره در بستر سیال با تولید حرارت
کلمات کلیدی
تختهای مایع گاز جامد، مدل عنصر گسسته، تولید گرما، شبیه سازی عددی، پلیمریزاسیون الفین
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
چکیده انگلیسی


• We present a systematic CFD-DEM study of fluidized beds with heat production.
• These models can provide information on the particle temperature distribution.
• The effect of the superficial velocity on the heat transfer coefficient is minor.

The heat transfer behavior of particles and gas in an olefin polymerization fluidized bed was numerically analyzed using an in-house developed 3-D computational fluid dynamics discrete element model (CFD-DEM). First the implementation of the model was verified by comparing simulation results with analytical results. A constant volumetric heat production rate was implemented in the particle energy equation to mimic the heat production due to the polymerization reaction. It was found that the probability density function (PDF) of the particle temperature becomes more homogeneous with increasing superficial gas velocity. Furthermore, instantaneous snapshots of the thermal driving force (the difference between the single particle temperature and bed-average gas temperature, Tp−) for different heat production rates provide detailed insight in the particle temperature distribution inside the fluidized bed. The time- and bed-averaged particle convective heat transfer coefficient, which was calculated by Gunn׳s correlation, was found to be independent of the superficial gas velocity. This is explained by the fact that the relative velocity of gas and particles in the emulsion phase, where most of the particles and gas interact, is hardly influenced when increasing the gas superficial velocity. From the spatial distribution of Nusselt number, it becomes apparent that the high heat transfer regions are found in the wake of rising bubbles, whereas low heat transfer rates are found in the clouds of the bubbles.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Engineering Science - Volume 140, 2 February 2016, Pages 279–290
نویسندگان
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