Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Hydrodynamics


Modeling of Single Channel Monolithic Reactor with The Single pass Flow Operation System

Lange; Zaidoon; A Al-Najar; Jenan; Adel; A. Shuhaib

Engineering and Technology Journal, 2010, Volume 28, Issue 11, Pages 2221-2236

In the following sections, the recent published studies on modeling and
simulation of monolith reactors were reviewed. Mass transfer, and reaction kinetics
were achieved by establishing mass, energy and momentum balance equations. The
model equations were solved simultaneously. Such a model can be useful for studying
the impact of changes of superficial gas and liquid velocities on reaction rate within
the slug flow regime. The reaction system used is the hydrogenation α–methyl styrene
(AMS) to cumene over a palladium on γ–alumina catalyst, It is a well known
system used to understand three-phase reactor performance under mass transfer
limited condition by the gas mass transfer through the liquid film at the catalyst
surface to the active sites. The effects of superficial gas and liquid velocities on
reaction rate were studied with the range of 10 cm/s ≤ UL ≤ 30 cm/s, and 10 cm/s
≤ UG ≤ 30 cm/s. The flow pattern for all these range of velocities was in the Taylor
flow pattern.

Scale Effects on the Hydrodynamics of Bubble Column

Farah S. Jameel; Mohammad F. Abid

Engineering and Technology Journal, 2009, Volume 27, Issue 10, Pages 2142-2164

The main object of this study is to investigate the influence of the column
geometric and operating variables ( i.e., column diameter, superficial gas velocity
and liquid viscosity) on the hydrodynamic parameter ( i.e. , gas holdup, bubble
dynamics and liquid phase axial dispersion coefficient ). The experimental data
obtained showed that the gas holdup increases linearly with superficial gas
velocity at both homogeneous and heterogeneous regimes but the rate of
increasing is slower at the heterogeneous one. The bubble rise velocity was found
to decrease with increasing superficial gas velocity until a transition point was
reached and after that the relationship was linearly increasing. It was observed
that with an increase in liquid phase viscosity and increase in column diameters, a
decrease in gas holdup and an increase in bubble size were obtained. It was
observed that increasing axial position led to an increase in bubble diameter and a
decrease in bubble rise velocity. Axial dispersion coefficient which is measured
by tracer response technique was found to increase with gas superficial velocity,
increases with column diameter, increases with axial position and decreases with
liquid viscosity. This work also presents a theoretical analysis that is used to
calculate the axial dispersion coefficient. The measured axial dispersion
coefficient was generally consistent with the predictions of the well established
correlations from the literature. The validity of the model was settled by
comparing its predication with the objective function of the well-Known empirical
correlation formulated by ( Hikita and Kikukawa , 1974) .The comparison shows
that the present model is statistically significant at a 95% confidence level by
using goodness – of – fit test .
Also a statstical analysis was performed to get a general correlation for the gas
holdup (εg) as a function of the parameters studied:
= 0.15325 Fr 0.29617 Ga 0.09223 Bo -0.0424 g e
Where the correlation coafficient ( R ) was equal to ( 0.957) and the absolute
error (3.5%).

Studies Pressure Drop of gas-Non-Newtonian Liquid Two Phase Flow in Bubble Column

Ali H. Jawad

Engineering and Technology Journal, 2009, Volume 27, Issue 7, Pages 1336-1350

An exclusive study has been done on experimental investigation of the two-phase flow
pressure drop in an air-non-Newtonian liquid (CMC solutions) system in bubble column.
The effects of gas and liquid flow rate on two-phase pressure drop have been illustrated.
Experiments in a 0.2-m diameter, 2.4-m-high bubble column were carried out to determine
the pressure drop. At the selected superficial velocities, two flow regimes were observed:
heterogeneous bubbling flow and heterogeneous churn turbulent flow, they were identified
through the slope changes in the plots of pressure drop and gas holdup. The pressure drop
did not seem to be affected by the superficial liquid velocity and it was increased as the
superficial gas velocity decreased or the CMC concentrations increased.

Hydrodynamics Of Two Phase Flow For Coalescing And Non Coalescing Systems

Thamer J. Mohammed; Mohammed F. Abid; Hiba M. Abdullah

Engineering and Technology Journal, 2009, Volume 27, Issue 3, Pages 481-495

This experimental study is aimed at investigating the effect of superficial gas
velocity, liquid phase properties and gas distribution on gas holdup, bubble
characteristics and drag coefficient in two-phase bubble column. Various liquids
covering a sufficiently broad range of viscosity and surface tension values were
employed, while the gas phase was atmospheric air. Aqueous glycerine solutions were
used to simulate the behavior of coalescing viscous liquids whereas aqueous alcohol
solutions were used to simulate the behavior of non-coalescing organic liquids. The
experimental results obtained with two different types of gas distributor in the
coalescence solutions and in non coalescence solutions were compared with data on
standard air–water system. A computerized conductivity probe system and high speed
digital camera were used for the systematic measurements of bubble size, velocity and
gas hold-up. Correlations based on dimensionless groups were proposed for the
prediction of gas holdup and drag coefficient in the homogeneous flow regime.