Heat transfer and pressure drop characteristics during the in-tube cooling process of carbon dioxide in the supercritical region

Abstract In this study, experiments were performed on air heater samples with three different shapes (chevron, wave and dimple type) to reduce theplumes from cooling towers. The tests were conducted for a range of frontal air velocities of 1~3 m/s and water flow rate 0.19~0.33 kg/s. The results showed that the heat transfer rate increased with increasing air velocity or water flow rate. The air-side pressure drop also increased with increasing air velocity. At the same frontal air velocity, the highest heat transfer rate was obtained for the chevron sample (1.5~1.7 times compared to that of the plate sample), followed by the dimple, wave and plate samples. The heat transfer rate per unit power consumption was also 15 % larger than that of the dimpl