Heat transfer enhancement inside a constant temperature pipe via clockwise and counter-clockwise twisted triangle turbulators, applicable in IC engine system

This study investigated the impact of innovative clockwise and counter-clockwise twisted triangle-shaped turbulators on thermal-fractional parameters within a constant surface temperature pipe. One of the key features of this turbulator is its unique geometry, which combines the characteristics of twisted tape and louvered strip turbulators. This design allows for the simultaneous generation of radial and swirling flows within the pipe. The effects of various parameters such as twist angles between 60 and 270°, pitch distances from 0 to 10 mm, and different twisting direction sequences were studied. The findings indicate that increasing the twist angle up to 270° simultaneously enhances the Nusselt number and friction factor. However, while the thermal enhancement factor (TEF) increases with a twist angle up to 120°, it begins to decline at angles greater than 120°. Additionally, the results show that increasing the pitch distance up to 5 mm yields improvements in both heat transfer and TEF; however, beyond this distance, both parameters start to decrease. Moreover, the use of this turbulator can increase heat transfer by as much as 4.45 times compared to a smooth pipe. The maximum TEF achieved is 2.66, which occurs with a configuration of three clockwise and three counterclockwise triangle-shaped turbulators at a twist angle of 120° and a pitch distance of 5 mm.