Abstract
In order to improve the boiler efficiency, latent heat recovery from the flue gas is very important concept. Condensation heat transfer on horizontal spirally finned tubes was investigated experimentally by using an actual flue gas from a natural gas boiler. The experiments were conducted at different steam mass concentrations of the flue gas and a wide range of tube wall temperature. The mass concentration was controlled with a steam injection into the flue gas. Fin efficiency at the condensation region was significantly lower than that at the dry region. The empirical correlation developed for a single-phase fluid was extrapolated to the condensation heat transfer region. The fin efficiency was evaluated with an equivalent heat transfer coefficient used as a first approximation. The heat and mass transfer behaviors on the spirally finned tubes were well predicted with the analogy correlation based on the empirical correlation.
