steam condensation, air-cooled condenser, inclination, experiment
Experimental results for steam condensation in large, flattened-tube air-cooled condensers are presented. Capacity, void fraction, and steam-side pressure drop and heat transfer coefficient are measured, and visualization is performed simultaneously. Capacity and pressure drop results are discussed here. The condenser tube has an elongated-slot cross-section, with inner dimensions of 214 x 16 mm. The tube is 10.7 m long. Steam mass flux ranges from 6-10 kgm-2s-1, average air-side velocities were 1.8 and 2.2 m s-1, and steam condensation pressure ranges from 90-105 kPa. All tests are performed with a horizontal tube and co-current vapor and condensate flow. Three different profiles of cross-flowing air are tested: uniform air flowing upwards, non-uniform air flowing upwards, and uniform air flowing downwards. Reversing airflow direction from upwards to downwards is found to significantly increase condenser capacity. Capacity is also shown to increase with a non-uniform air-velocity profile in comparison to a uniform air-velocity profile. Both of these performance increases are shown to be the result of matching regions of maximum heat transfer coefficient on the air and steam sides. Reducing condensation pressure from 105 to 90 kPa is shown to have no effect on capacity, but is shown to increase steam-side pressure drop, due to an increase in steam velocity.