Abstract
There is a growing number of proposed models for the estimation of the time needed to restart a
core annular flow line after shutting down, pertaining the improvement of core annular flow (CAF)
technology for transportation of high viscous oil. Existing restart time models tend to predict that
the flow line needs to be completely clean. However, this is practically not feasible. Firstly, this
work revisits the results of the flow pattern trends and pressure drop evolutions during the restart
of a core annular flow experiments. Based on the analyses of the transient pressure drop profiles,
deduction of a ‘realistic and economical’ re-start time, expressed as a function of the pressure
drop, has been made. This approach can be helpful in control engineering design of an efficient
and cost-effective re-start process of a core annular flow (CAF) line.