Numerical simulation of water spray for pre-cooling of inlet air in natural draft dry cooling towers

• Numerical investigation of inlet air cooling by water spray in NDDCTs was performed.
• Strong links identified between droplet size, air velocity, evaporation and trajectory.
• Pre-cooling of up to 8.1 °C predicted.
• The maximum evaporation was achieved with the smallest droplet size.

This paper presents a numerical investigation of inlet air pre-cooling with water sprays to enhance the performance in Natural Draft Dry Cooling Towers (NDDCT). A 3-D numerical model of a test channel was generated and the evaporation from a single spray nozzle was analyzed. The droplet evaporation and the resulting cooling of air were predicted for a range of inlet air conditions and spray characteristics. The results showed that up to 81% evaporation can be achieved for water droplets of 20 μm at a velocity of 1 m/s and that, droplet transport and evaporation strongly depend on droplet size and air velocity.