Investigation on the spray strategy for the inlet air pre-cooling of natural draft dry cooling tower under typical crosswind

Abstract

Spray pre-cooling technology is an effective way to promote the thermal performance of natural draft dry cooling tower (NDDCT) during high temperature periods. This paper aims to explore the spray strategy of different nozzle arrangements with low water consumption on the thermal performance of NDDCT under typical crosswind of 4 m/s, which is the most frequent wind speed. A 3-D model of a 120 m high NDDCT pre-cooled with nozzle spray was developed using Fluent 16.2. Half of the NDDCT model was simulated due to its symmetry structure. Four cases of spray strategies to incompletely saturate the tower airflow and three cases of spray strategies to fully saturate the tower airflow were extensively studied. The results show that: (1) the seven spray strategies to incompletely/fully saturate the tower airflow all improve the thermal performance of the NDDCT; (2) the heat rejection rate of the half NDDCT by case 8 is the highest as 73.32 MW while the heat rejection increment per unit water flowrate by case 3 is the highest as 1.39 MJ/kgw. The trade-off between the performance improvement of the NDDCT and water consumption should be considered during the design of the spray pre-cooled NDDCT under crosswind.