Steam condensation heat transfer coefficient in large, flattened-tube steam condensers

摘要

Steam condensation heat transfer coefficient (HTC) in a large, flattened tube with variable heat flux,wall temperature and inclination angle is determined experimentally. The condenser tube is that usedin air-cooled condensers for power plants. The steel tube has an elongated-slot cross section withinner dimensions of 216 × 16 mm. Vapor and liquid flow concurrently through a 5.7 m long air-cooledconditioning section, and HTC is determined in a 0.12 m long water-cooled test section.. Tubeinclination angle is varied from 0 – 25° downwards. The long conditioning section creates conditionsin the test section that mimic the conditions in an operating condenser – allowing for realisticdevelopment of flow regime and void fraction. HTC is then determined in the water-cooled section.Quality in this section ranges from 0 – 0.75. A visualization section allows determination of flowregime and void fraction. The flow is found to be stratified for all conditions. HTC is found to increaseby 6-10 times along the condenser height.