ارزیابی عملکرد یک رآکتور بستر سیال با بررسی هیدرودینامیک و خصوصیات گرمایی ذرات جامد مختلف

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده مهندسی مکانیک، دانشگاه گیلان، رشت، ایران

2 گیلان*مهندسی مکانیک

چکیده

نرخ انتقال حرارت بالا به عنوان یکی از مزایای مهم رآکتورهای بستر سیال به فرآیندهای هیدرودینامیکی بستر وابسته است. در این تحقیق پارامترهای مهم هیدرودینامیکی از جمله حداقل سرعت شناوری، افت فشار، ارتفاع بستر و وضعیت بستر از نظر تشکیل حباب و رژیم جریان به صورت آزمایشگاهی و عددی بررسی گردید. مدل اویلری دو سیالی به همراه تئوری انرژی جنبشی جریان دانه‌ای و دو مدل درگ مختلف گیداسپا و سایملال-اوبراین در شبیه‌سازی عددی حاضر به کار گرفته شد. نتایج نشان داد که با استفاده از مدل درگ گیداسپا در حل عددی، حداقل سرعت شناوری با خطای تقریبی 8/13 درصد و ارتفاع بستر با متوسط خطای 9 درصد نسبت به کار آزمایشگاهی قابل پیش‌بینی است. به منظور بررسی تأثیر خصوصیات ذرات بر توزیع دمای بستر سیال‌های حبابی، ذرات جامد مختلف با چگالی و ضرایب پخشندگی گرمایی متفاوت مورد بررسی قرار گرفتند. در نهایت برای اثبات مزیت استفاده از رآکتورهای بستر سیال برای دریافت هوای گرم مورد نیاز در واحدهای صنعتی، توزیع دما و ارتفاع یک رآکتور بستر سیال حبابی و کانال ساده‌ی دما ثابت در شرایط یکسان مقایسه گردید. نتایج نشان داد که دمای هوای خروجی از یک رآکتور بستر سیال حبابی تقریباً 28 درجه سلسیوس بیشتر از کانال ساده‌ی مشابه است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Performance Evaluation of a Fluidized Bed Reactor by Studying the Hydrodynamics and Thermal Properties of Different Solid Particles

نویسندگان [English]

  • Soodeh Torfeh 1
  • Ramin Kouhi Kamali 2
1 Department of Mechanical Engineering, University of Guilan, Rasht, Iran
چکیده [English]

High heat transfer rate as one of the important advantages of fluidized bed reactors is attributed to hydrodynamic mechanisms. In this research the important hydrodynamic parameters such as minimum fluidization velocity, pressure drop, bed height, bubble formation and flow regime were investigated experimentally and numerically. The two-fluid model coupled with the kinetic theory of granular flow and two different drag models of Gidaspow and Syamlal-O'Brien were applied in the present simulation. The results showed that by using the Gidaspow drag model in numerical solution, the minimum fluidization velocity with an approximate error of 13.8% and the bed height with an average error of 9% are predictable in comparison with the experiments. In order to investigate the effects of particles properties on temperature distribution of a bubbling fluidized bed, several solid particles with different densities and thermal diffusivities were investigated. Finally, to demonstrate the advantages of fluidized beds to receive the required hot air in industrial units, temperature distribution and required height of a bubbling fluidized bed reactor were compared with a similar constant surface temperature simple channel. The results showed that the outlet air temperature of a bubbling fluidized bed is about 28 degrees Celsius higher than a similar simple channel.

کلیدواژه‌ها [English]

  • Gas-solid fluidized bed
  • two-fluid model
  • hydrodynamic behavior
  • thermal diffusivity coefficient
  • temperature distribution
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