CFD simulations on small natural draft dry cooling towers

The natural draft dry cooling tower (NDDCT) is believed to be the only cost-effective option for cooling system of geothermal power plants proposed by Queensland Geothermal Energy Centre of Excellence (QGECE). By reviewing literatures related to the design of NDDCT, the effect of crosswind on the cooling performance of NDDCT is not considered in contemporary design theories for cooling tower system. Practical operations on NDDCT showed that the crosswind larger than 1 m/s will have a profound effect on the performance and that cannot be neglected, especially for small size NDDCT. A study on the performance of a 15m-high natural draft dry cooling tower under different crosswind conditions is presented in this paper. CFD models (both 2D and 3D) based on porous media have been established for numerical simulations of the air dynamics and heat transfer inside and outside the cooling tower. The CFD results have been validated by comparing the results under no crosswind condition with those obtained in theoretical calculations (1D model). 3D CFD simulations showed that the total cooling capacity of the NDDCT is unfavourably affected by cross wind, and under certain conditions the heat rejection in the cooling tower can be reduced significantly. This trend matches the results of similar studies on large NDDCT found in open literatures well