Abstract:
The present study aims to better understand liquid-liquid intermittent flow regimes under different
operational and flow conditions, such as flowrates of fluids, pipe inclination and fluid properties,
with a focus on the pipe inclination alternating between 0° and +5°. A 0.0254m diameter pipe
loop multiphase flow rig was utilised to conduct the experimental study. The fluids used for tests
were tap water (pw = 997kg/m ³ and μw = 1mPa.s under the normal temperature and pressure (i.e.
NTP, 15°C and 1atm) with an oil. Two different oils, EDM250 (p₀ = 811kg/m ³ and μw = 7mPa.s
under the NTP) and H100 (p₀ = 878kg/m ³ and μw = 423mPa.s under the NTP) were used for tests
to cover the variations in density and viscosity. It was found that less dense and viscous oils are
less likely to develop intermittent flow regimes than heavier oils. In addition, regardless of the oil
type present, intermittent flows are more likely to develop in a pipe with a higher degree of
upwards inclination. This is particularly more effective for lighter oils because the inclination
factor alters the angle between multiphase flow direction and gravity. This, in turn, aids the oil
phases to intrude into the water phase region to have a greater prospect of developing and
widening the relevant flow regimes envelopes such as slug and plug flows. Additionally, this
thesis also proposes a modified liquid-liquid flow regime grouping method based on the modified
Froude numbers. The proposed dimensionless parameter takes water hold-up variables into
consideration by defining the hydraulic diameter to coincide with each phase's gravitational and
inertial forces. Furthermore, correlations of pressure gradient and hold-up are also developed and
presented. The developed models are then implemented with a dimensionless scale-up protocol
to demonstrate scaling across laboratory experimental data generated from systems with different
pipe diameter sizes. Overall, the models developed show improved performance for grouping
flow patterns consistently, hence allowing for better prediction of liquid-liquid flow regimes that
transition between intermittent flows. The significant outcomes of this project are the following:
(1) evidence of intermittent flow regimes existing across a wide range of dual-incompressible
multiphase flow conditions, (2) the development of design charts for pipelines that consider the
prevention of intermittent flow regimes and (3) utilising the proposed hold-up and pressure
gradient correlations with a scale-up protocol to predict larger pipeline behaviours.