Numerical investigation of the enhanced heat transfer characteristics in dimpled enhanced tube to shell-and-tube lube oil heat exchangers

The lubricating oil heat exchanger plays a critical role in the lubricating oil system of an aero-engine. In order to enhance its heat transfer efficiency, a novel design featuring a shell-and-tube heat exchanger with disk-and-doughnut baffles and spiral dimple tubes (SDDD-STHX) is designed. Computational fluid dynamics is employed to compare this innovative design with the traditional smooth tube heat exchanger (STDD-STHX). The computational results reveal that the SDDD-STHX exhibits an approximately 11% lower average shell-side pressure drop compared to the STDD-STHX. Moreover, the tube-side heat transfer coefficient of the SDDD-STHX is about 12% higher than that of the STDD-STHX. Furthermore, across a range of inlet mass flow rates from 0.4 to 1.5 kg/s, it is observed that the SDDD-STHX demonstrates an approximately 7.6% higher heat transfer coefficient per unit pressure drop in its shell section when compared to the STDD-STHX.