Natural draft dry cooling tower (NDDCT) is an effective cooling technology which can be utilized in most of geothermal and concentrated solar thermal (CST) power plants. The experimental studies of the full scale cooling tower, especially the small size NDDCTs, are still not extensive. To fill this gap, Queensland Geothermal Energy Centre of Excellence (QGECE) at The University of Queensland has built a 20m high NDDCT. In this paper, the 1D analytical model and the 3D CFD model of this cooling tower were developed and its cooling performance was investigated at different ambient temperatures, hot water temperatures and velocities of cross wind. The result shows that the small size NDDCT is suitable for 2~3MW CST power plants. The cooling performance decreases with the increase in the ambient temperature and the decrease in the hot water temperature. In terms of the cross wind, the heat rejection ratio decreases with the increase of the cross wind velocity when cross wind velocity is low. However, when velocities of the cross wind become large enough, the heat dumped at the bottom of the tower can compensate some loss caused by cross wind. The results found in the present paper give reference for planed future experiments
