Nozzle arrangement study for pre-cooling the inlet air of natural draft dry cooling tower under crosswinds

Abstract

Crosswind affects the airflow fields of the natural draft dry cooling towers (NDDCTs), thus the spray zones for pre-cooling the inlet air of the NDDCT might be different from no crosswind. Therefore, a 3-D model of pre-cooled NDDCT under crosswind was established by Fluent 16.2 to investigate the feasible zone of nozzle spray of a 120 m high NDDCT based on the behavior of the droplets. Six nozzle heights, nine nozzle radiuses and four spray angles were simulated for the NDDCT application within the crosswind speeds of 0∼10 m/s. The evaporation percentage of droplets higher than 99% and the maximum effective evaporation ratio are selected as the criterion for the feasible zone of nozzle arrangement. Simulation finds that: (1) the nozzle arrangement height should be set at 7 m when the crosswind speed is 0 m/s, and it should be set at 9 m when the crosswind speeds are 2 m/s, 4 m/s,6 m/s, 8 m/s and 10 m/s, respectively. (2) The feasible spray angles of nozzles are 0°and 90° at the crosswind speeds of 0∼4 m/s and 6∼10 m/s, respectively. (3) The nozzle radiuses are 0∼41.5 m at crosswind speed of 0 m/s, they are 0∼21.5 m at the crosswind speed of 2 m/s, and they are 0∼16.5 m when the crosswind speeds are 4 m/s, 6 m/s, 8 m/s and 10 m/s, respectively based on the above feasible heights and spray angles. The results will provide a guidance for nozzle design of spray pre-cooled NDDCT under crosswinds.