Heat transfer in bubble columns for viscous liquid

مقدم أطروحة جامعية

al-Zuhairy, Muhammad Abd al-Husayn

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم الهندسة الكيمياوية

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2008

الملخص الإنجليزي

In recent years., bubble columns with highly viscous liquids are found in widespread applications in chemical and biotechnological processes especially in biochemical reactors and pollution treatment.

The heat transfer behaviour of bubble columns ot highly viscous liquids is different from that of the low viscosity liquids, due to the complex hydrodynamic parameters and their interactions.

Computational fluid dynamics (CFD) is a simulation tool, which uses powerful computer and applied mathematics to model fluid flow situations for the prediction of heat, mass and momentum transfer and optimal design in industrial processes.

In easy way, this method has beer, generalized for a wide range of scales bubble columns with various gas- liquid systems and low cost compared to the practical cost requirements.

A low Reynolds number k-z model has been developed for the prediction of fkwv pattern in bubble columns.

Specific attention has been given to the modeling near the wall.

Excellent agreement between predicted and experimental profiles of hold-up and velocity was observed for a wide range of column diameter 0.1

These data have been reported in different laboratories.

The near wall flow model was extended for prediction of heat transfer in the bubble column reactor.

GAMBIT 2.2.30 (preprocessor for FLUENT 6.2.16) is used to create three dimensional geometries of the bubble column as well as for its meshing.

The mode I was aIso success fully applied to manv different gas-liquid system, tor a range of liquid physical properties, including air-water, Air-Glycenne (2.8-240 mPa,s) Air- Carboxy Methyl Cellulose (CMC) (μL = 0.96-38 mPa.s) Nitrogen-Paratherm NF (μL= 5.3-19 mPa.s) Nitrogen-Glycol (μL= 2.9-23 mPa.s) New approach method has been developed to improve the prediction of axial liquid velocity near wall as function of experimental data for certain VG and gas-liquid system, in the superficial gas velocity range 0.01-0.1 m/s.

and mean correlation coefficient equal to 0.982, as : uL = Nw uL predicted - VG In [1- VG ÷ r / R] This method has been Reflected to predict heat transfer coefficient, by amending the temperature gradient obtained from (CFD) by the following relationship : Tr = 2 [uL ÷ uL predicted] Tr predicted Excellent agreement has been found between the CFD predictions values of heat transfer coefficient and the experimental data those found in literature, with mean percentage error 4.33 % for different system, used in this research.

The present observations and results pointed to that, the superficial gas velocity and the liquid viscosity arc the two main process variables that determine the heat transfer coefficient in the bubble column.

Therefore an attempt has been made to correlate an experimental data as empirical relation as : h = 6000VG 0.44 μL - 0.1.

التخصصات الرئيسية

الفيزياء

الموضوعات

• الفيزياء
• الميكانيكا
• الديناميكا الحرارية
• الديناميكا
• نظرية الكم
• الفقاعات الهوائية

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-305132