steam condensation, air-cooled condenser, inclination, modeling
A thermo-hydraulic model for calculating capacity, heat transfer coefficient and void fraction of an inclined air-cooled steam condenser is presented. The condenser tube has an elongated-slot cross-section, with inner dimensions of 214 x 16 mm. The tube is 10.7 m long. The model is for downward inclination angles from 0-90o, with co-current vapor and condensate flow. The cooling air is in cross flow. This model is developed based on existing models for inclined, stratified-flow condensation models. These have been adapted to the current geometry and conditions for the development of the current model. The model couples both air- and steam-side behavior in order to accurately resolve the variation in heat transfer coefficients, temperature difference, and heat flux. On the steam side, the model is for stratified flow, and separates the flow into two sections: a falling film along the wall, and an axially-flowing condensate river along the tube bottom. The axially-flowing condensate river is modeled using open-channel-flow theory. Air-side heat transfer coefficient is determined from a combination of empirical correlation and CFD. The model and experimental results show agreement within 10% in capacity (both local and overall) and overall heat transfer coefficient for all tube inclinations.