Impacts of tower spacing on thermo-flow characteristics of natural draft dry cooling system

Multi-towers are widely introduced to the natural draft dry cooling system in power plants, and the geometrical layout of dry-cooling towers is a key issue to the thermo-flow characteristics of natural draft dry cooling system. Based on a representative two-tower design with vertically arranged heat exchanger bundles around the circumference, the air-side flow and heat transfer models of natural draft dry cooling system at the tower spacing to diameter ratios from 0.1 to 3 are developed and the velocity, pressure and temperature fields of cooling air in the absence and presence of ambient winds are presented. The mass flow rate and heat rejection of the two air-cooled heat exchangers at various wind speeds and in various wind directions are calculated. The correlations between the heat rejection of each tower and the tower spacing, wind speed and angle are obtained. The results show that the impacts of tower spacing on thermo-flow characteristics of natural draft dry cooling system depend on the wind speed and the arrangement of towers. The towers arranged in line are superior to those arranged in other patterns. When the tower spacing to diameter ratio is lower than unity, the conspicuous interaction between two towers will deteriorate the thermo-flow performances of natural draft dry cooling system. The results can contribute to the dry-cooling tower layout of natural draft dry cooling system in power plants.