Preliminary Numerical Evaluation of Temperature Fluctuation in Two Different Converging Mixing-Tee Junctions

MLNG-Tiga of Bintulu decided to change their aging mixing-tee configuration in one of their natural gas regenerative heat cycle piping.In the original converging T-junction, hot gas is flowed in the main pipe with cold gas intersecting midway, resulted in thermal mixing.Even though the new design still utilized the concept of converging T-junction, the hot and cold gas are routed to collide with each other before exiting as mixed gas.Since the thermal mixing efficiency is not known, the relative performance of these two mixing-Tee could not be evaluated.The present study focused on the evaluation of thermal mixing of two different T-junctions, namely an intersecting Tee and a colliding Tee, both operated within limited parameters, with the intention to understand the thermal performance.The influence of different configurations of inlets and outlet was investigated numerically using the standard K-ε turbulence model with Liquified Natural Gas (LNG) as the working fluid.Literature survey revealed that a lot of research on T-junction has been conducted on geometric factors such as diameter ratios and different fluid properties, surprisingly, a comparative study on the effects of different flow configuration is yet to be found.The present research showed that due to different impact configurations, the colliding tee offered better thermal mixing compared to the intersecting tee, resulting in higher level of turbulent.Consequently, colliding tee will experience higher temperature fluctuation at 0.25D downstream of the mixing intersection, with possibility of shortening of its service life. © 2023, Institute of Technology PETRONAS Sdn Bhd.