Heat treansfere in bubble columns using tow diffirent column diameters

Dissertant

Naji, Ula Isam

Thesis advisor

Abid, Balasim Ahmad

University

University of Technology

Faculty

-

Department

Department of Chemical Engineering

University Country

Iraq

Degree

Master

Degree Date

2010

English Abstract

Bubble columns are preferred in many chemical and biochemical processes for gas liquid contacting due to their simplicity in design, operation and maintenance.

Solids, in some operations, are introduced into the bubble column as a third phase to enhance heat and mass transfer inside the bubble column.

The main object of this study is to investigate the effect of column diameter on the heat transfer coefficient, superficial gas velocity and gas holdup and bubble dynamics (bubble diameter and rise velocity).The heat transfer coefficient was measured for the air water system in bubble columns of two different diameters, 0.15 and 0.3m .The superficial gas velocity Ug, was varied in the range from (0.002-0.012) m / s, for the 0.15m while at 0.3m (0.0005-0.0025) m / s and the velocity common between two column diameters are(0.002-0.0035) m / s for the homogeneous flow regime.

The cause of this difference in velocities is the difference in the gas distributor for each column.

The liquid phase level was kept constant at 1m for the two columns and gas holdup was measured also.

From experimental data it was found that the heat transfer coefficient and gas holdup, increased with increasing superficial gas velocity.

Also the bubble diameter and bubble rise velocity increased too.

The experimental results emphasis significant influence of the column diameter on the hydrodynamics.

The experimental results of this research were compared with the Kist's (1963) correlation which applied for column diameter equal 0.29 m, for low superficial gas velocity (0.002-0.06)m/s and the common superficial gas velocity for two columns used in the experimental work is (0.002-0.0035)m / s which located between the superficial gas velocity of Kasts correlation : h/PlCplUg = 0.1 [(PlDcUg/ug)(U2g/gDc)(ulCpl/Kl)] The heat transfer coefficient showed the same tendency of increase but there is a difference between the theoretical and experimental values due to the different system used.

Heat transfer coefficient, bubble diameter and bubble rise velocity showed an increase with increasing column diameter, while gas holdup decreased with increasing column diameter.

Main Subjects

Physics

Topics

• Dynamics
• Bubble wrap

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305028