Investigation on feasible zone of nozzle spray for pre-cooling the inlet air of natural draft dry cooling tower

Nozzle spray pre-cooling the inlet air can improve the thermal performance of natural draft dry cooling towers (NDDCTs). Nozzle arrangement is of great importance for achieving good performance improvement with minor water consumption. To this end, a 3-D model of spray pre-cooled NDDCT was established using FLUENT 16.2, aiming to investigate the feasible zone of spray pre-cooling of the NDDCT with three nozzles based on the behavior of the spray water droplets. Twelve nozzle heights, twelve nozzle radiuses and three spray angles are simulated for a 120 m-high NDDCT application. The evaporation percentage higher than 99.0 % is the nozzle's feasible position where the droplets can be almost completely evaporated. Simulation finds that: (1) the nozzle arrangement height should be set at 3 - 13 m. The evaporation percentage of droplets is less than 99.0 % at a height of 2 m and thus this height is not recommended. (2) The feasible arrangement radiuses of nozzles are different with their heights. The feasible arrangement radiuses of nozzles at the heights of 3 m, 4 - 5 m, 6 m, 7 8 m and 9 - 13 m are 35 - 44 m, 30 - 44 m, 35 - 44 m, 40 - 45 m and 45 - 50 m, respectively. (3) Spray angles of 90 degrees are suitable in the low-height zone with the radiuses of 30 - 44 m. Spray angles of 0 degrees, 45 degrees, or 90 degrees with a radius of 45 m are suitable for the middle-height zone. Spray angles of 0 degrees, 45 degrees, or 90 degrees with a radius of 50 m are suitable in the high-height zone.