Heat transfer enhancement of Taylor–Couette–Poiseuille flow in an annulus by mounting longitudinal ribs on the rotating inner cylinder

This work experimentally investigates the heat transfer characteristics of Taylor–Couette–Poiseuille flow in an annular channel by mounting longitudinal ribs on the rotating inner cylinder. The ranges of the axial Reynolds number (Re) and the rotational Reynolds number (ReΩ) are Re = 30–1200 and ReΩ = 0–2922, respectively. Three modes of the inner cylinder without/with longitudinal ribs are considered. A special entry and exit design for the axial coolant flow reveals some interesting findings. The value of Nusselt number (Nu) is almost minimal at the inlet of the annular channel, and then sharply rises in the axial direction. The average Nusselt number image increases with Re. Nu increases rapidly with ReΩ at low Re (such as at Re = 30 and 60) but that the effect of ReΩ decreases as the value increases (such as at Re = 300–1200). The ratio image increases with ReΩ and exceed two at all Re and in the test modes. The heat transfer is typically promoted by mounting longitudinal ribs on the rotating inner cylinder, especially at Re = 300 and 600. When Re = 300 or 600 and ReΩ > 2000, the image of the system with ribs reaches around 1.4 times that of image (image in mode A). Under a given pumping power constraint (PRe3), the image of the system with ribs (modes B and C) generally exceeds that without ribs (mode A), while the difference between the values of image in modes B and A slowly falls as PRe3 increases. Additionally, mode B (with ribs) is preferred for high heat transfer when PRe3 < 4.5 × 1013 but mode C (with cavities on ribs) is optimal for high heat transfer when PRe3 > 4.5 × 1013.