Computational fluid dynamics approach for energy savings evaluation in core annular flow of a horizontal T-pipe

The application of core annular flow (CAF) has become an interesting solution in transporting heavy oil through pipeline because of its energy reduction and cost efficiency. At the same time, the CAF in pipe with hydraulic fittings and the problem of unstable CAF are the part of some big issues in using CAF techniques. This study intended to investigate the energy saving of CAF in horizontal T-pipe with symmetrical flow and diameter of 50 mm for oil and water system using CFD approach. Pressure reduction and power consumption were computed as the parameters to measure the energy saving of the flow system. The result of this study showed significant energy reduction of CAF with 94% of pressure drop reduction, for transporting the same amount of oil, when comparing to the traditional single phase oil flow. On the other hand, the intersection of the T-pipe was considered as critical region that promoting the change of flow direction and disturbing the existing CAF pattern. Thus, this study also proposed the strategy for returning the CAF during the process of oil transportation without stopping or restarting the flow operation. The geometry of the T-pipe was modified to facilitate the additional water injection at the intersection as a strategy to get back the CAF pattern. Consequently, the modified T-pipe with certain velocity of additional water injection was recorded to give important improvement of CAF application in terms of more stable CAF and higher pressure drop reduction (98%) compared to oil transportation without lubrication. This study also recorded the values of power reduction factor that indicating the cost of power consumption to transport the oil could be saved more than 80% than single phase oil transportation. (c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The application of core annular flow (CAF) in transporting heavy oil through pipelines has shown potential in reducing energy consumption and improving cost efficiency. However, the presence of hydraulic fittings and the instability of CAF pose challenges. This study investigated the energy-saving potential of CAF in a horizontal T-pipe with symmetrical flow and proposed a strategy for maintaining CAF during oil transportation. The results showed significant energy reduction and pressure drop with CAF compared to traditional single phase oil flow. The modified T-pipe with additional water injection improved the stability of CAF and further reduced pressure drop and power consumption.