Thermal performance of undulant narrow channel with skewed sinusoidal wall-waves and 45° ribs

This experimental study examines the properties of heat transfer, pressure drop and thermal performance factor (TPF) of a narrow undulant channel enhanced by skew sinusoidal wall-waves and 45° ribs. Detailed Nusselt number (Nu) distributions over the wavy ribbed channel wall are generated by the steady-state infrared thermography method and examined along with the accompanying pressure drop coefficient (f) in the test Reynolds number (Re) range of 800–9000. With references to the Nusselt numbers (Nu∞) and pressure drop coefficients (f∞) of smooth plain tube, the area-averaged heat transfer enhancement (HTE) ratios, pressure drop augmentations (f/f∞) and TPF for the tested undulant channel are compared with those obtained from other passive HTE devices. Empirical correlations evaluating the area-averaged Nusselt number (image) over the undulant ribbed channel wall and the pressure drop coefficients are generated to assist design activities using this newly devised HTE measure.