شبیه‌سازی هیدرودینامیکی بیورآکتور گاز-مایع همزن دار جهت بهینه‌سازی سرعت چرخش پروانه‌های-راشتون به کمک CFD

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده مهندسی نفت، گاز و پتروشیمی، دانشگاه خلیج فارس

2 گروه مهندسی شیمی، دانشکده مهندسی نفت، گاز و پتروشیمی، دانشگاه خلیج فارس، بوشهر

چکیده

در این تحقیق، تأثیر تغییرات سرعت چرخش پروانه راشتون درون بیورآکتور به منظور پخش مناسب هوا، بررسی نرخ کرنش برشی، شبیه‌سازی و بررسی شد. شبیه‌سازی انجام ‌شده با رویکرد چند فازی، مدل فاز پراکنده‌ صفر معادله، با کمک مدل اغتشاش K-Epsilon Standard، به‌‌ صورت پایا و سه‌بُعدی توسط مجموعه نرم‌افزاری ANSYS Products ورژن R3 2019 و نرم افزار Ansys CFX انجام گرفت. معادلات حاکم بر سیستم با روش حجم محدود برای کل سیستم محاسبه شد. به منظور تزریق مناسب هوا به درون بیورآکتور، از یک حلقۀ حباب‌ساز که در زیر پروانه قرار گرفته است، استفاده شد. نتایج به دست آمده نشان داد که افزایش سرعت چرخش پروانه می‌تواند به پخش بهتر هوا درون بیورآکتور کمک کند؛ اما از طرفی موجب افزایش نرخ کرنش برشی درون بیورآکتور می‌شود. همچنین، افزایش سرعت چرخش پروانه بیش از ۱۵۰ دور بر دقیقه موجب افزایش اغتشاش در مایع‌ شده و تأثیرات آن روی فاز گاز کاهش می‌یابد. علاوه بر این، با در نظر گرفتن سرعت چرخش پروانه و تأثیر آن بر روی میزان اختلاط فاز گاز و مایع، تنش درون مایع و نرخ متوسط انتقال جرم، می‌توان سرعت ۳۵۰ تا ۴۵۰ دور بر دقیقه را برای سرعت بهینه در نظر گرفت. در نهایت، مشخص شد که با افزایش سرعت چرخش پروانه نمی‌توان به اختلاط بهتر در بیورآکتور رسید و می‌بایست سرعت بهینه را مشخص کرد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Hydrodynamic simulation of stirred gas-liquid bioreactor for the optimization of the rotation speed of Rushton impellers using CFD

نویسندگان [English]

  • Pedram Nasehi 1
  • A. Azari 2
1 Faculty of Petroleum,, Gas and Petrochemical Engineering, Persian Gulf University
2 Faculty of Petroleum, Gas and Petrochemical Engineering, Persian Gulf University
چکیده [English]

In the present research, the effect of altering the rotational speed of the Rushton impeller inside the bioreactor was simulated and investigated for proper air distribution and changes in the shear stress rate. The simulation was performed using the multiphase approach of the zero-equation scattered phase model, via the K-Epsilon Standard perturbation model, in stable three-dimensional manner using ANSYS Products 2019 R3 and Ansys CFX software packages. The governing equations of the system were solved by the finite volume method for the entire system. To properly inject air into the bioreactor, a sparger ring was used under the impeller. The results revealed that increasing the impeller rotation speed could help better disperse the air inside the bioreactor. However, it also increases the shear stress rate inside the bioreactor. It was also shown that increasing the speed and getting more energy from it creates turbulence in the liquid. Additionally, its effect on the gas phase is reduced for the rotation speeds more than 150 rpm. Considering the rotation speed of the impeller and its effect on the mixing of gas-liquid phase, the intra-liquid stress and the average mass transfer rate, the speed of 350 to 450 rpm may be considered as the optimal speed. Finally, it was found that by increasing the rotation speed of the impeller, better mixing in the bioreactor could not be achieved and the optimal speed had to be determined.

کلیدواژه‌ها [English]

  • Computational Fluid Dynamics
  • Bioreactor
  • Rushton impeller
  • Gas-Liquid Bioreactor
  • K-Epsilon model
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