Thermal and hydrodynamic performance of a novel passive mixer ‘wavering coiled flow inverter’

Abstract This study explores the design of a novel passive mixer based on the concept of a coiled flow inverter (CFI) with an enhanced heat transfer efficiency. The proposed wavering coiled flow inverter (WCFI) was designed by inserting a 90° bend in halfway of the helical coils of equal arm lengths and wavering curvature radius. The hydrodynamics and thermal performance of the developed WCFI were than compared with helical coiled tube (HCT) and CFI with the same heat transfer areas (A t  = 0.062 m 2 and 0.157 m 2 ). Water was used as the working fluid in a range of Dean number from 8 to 1581. The designed WCFI, showed a 48% enhancement of the Nusselt number over an HCT with the same heat transfer area. Furthermore, the WCFI provided an 18% higher Nusselt number than the CFI due to the wavering curvature effects. Additionally, the friction factor data were practically comparable to that of the HCT. This study offers a preliminary investigation of the local and average heat transfer advantages of using a novel passive device WCFI. The present work may be significant, as it offers heat transfer augmentation via intensified geometrical design, without additional pressure drop.