Effects of the geometric parameters on the thermal-hydraulic performance of the wavy tubes

This research presents details of heat and fluid flow inside the wavy tubes with circular cross-sections at laminar regime under the Reynolds numbers in the range of 100 and 1000. To enhanced visualization, effects of non-dimensional geometric parameters such as the wave amplitude (H/D) varying between 0.1 and 0.5 and the wavelength (P/D) varying from 4 to 6 on the heat transfer process and flow nature are investigated in detail. The obtained results are validated against the available data in the literature. It is concluded that due to development of the centrifugal forces inside the wavy passage, a pair of Dean vortices appearances within the tube. The size of these vortical structures is strongly affected by the Reynolds number and geometric parameters of the wavy tube. On the other hand, at all Reynolds numbers under consideration, increasing the H/D and P/D enhances and diminishes the rate of heat transfer between the fluid flow and tube wall, respectively. Moreover, it is demonstrated that at low Reynolds numbers, the pressure drop penalty outweighs the heat transfer enhancement. It is found that the maximum thermal-hydraulic performance occurs in the case of H/D = 0.5, P/D = 6, and Re = 1000 with 42%.