Modelling and mass transfer studies in liquid liquid systems
This thesis describes an investigation into the formation of a laminar liquid jet
and its disintegration into droplets in another immiscible liquid. Measurements
on jet length, jet diameter and drop diameter are reported. It was found that
the diameter of the jet can expand or contract depending upon the nozzle
diameter, nozzle velocity and physical properties of the phases. A
mathematical model was developed in this investigation to predict the jet
diameter at varying distances from the nozzle tip. The results showed good
agreement with the corresponding experimental values.
In liquid-liquid systems an understanding of drop size distribution is important
because this affects interfacial area, relative velocity and mass transfer
coefficients. An investigation has been carried out to determine the effects of
drop diameter, drop velocity and concentration driving force. on the mass
To reduce the error in determining the interfacial area inherent in calculation
of drop size distributions in liquid-liquid contactors, Das's technique for the
production of monosized droplets was employed using waterlacetic acid /
kerosene system available in the laboratory. To highlight the effect of drop
diameter on mass transfer, a spray column containing kerosene as the
continuous phase was used. The total flow of the dispersed phase was kept
constant while diameter of drops was varied. The results showed that the mass transfer coefficient increases with the increase in drop diameter and
drop velocity. These results were analysed and it is concluded that it is the
change in drop velocity that effects the values of mass transfer coefficient.
To further investigate this behaviour a ternary system
(Toluene/Methanol/Water) was employed. The dispersed phase in the form of
a drop (Distilled water) is introduced and the drop extracts methanol from the
continuous phase, the drop diameter increases and the density decreases.
When the density of the drop becomes less than that of the continuous phase
the drop becomes stationary and then starts to rise.
For the extraction of methanol using drops of distilled water as the dispersed
phase, the mass transfer initially is high this amount reduces with time and
approaches a steady state. A discussion of the results is presented in terms of
drop velocity. As the drop diameter increases, drop velocity decreases and
value of mass transfer coefficient decreases.