To investigate the effect of water spray and crosswind on the effectiveness
of the natural draft dry cooling tower (NDDCT), a three-dimensional model has
been developed. Efficiency of NDDCT is improved by water spray system at the
cooling tower entrance for high ambient temperature condition with and
without crosswind. The natural and forced heat convection flow inside and
around the NDDCT is simulated numerically by solving the full Navier-Stokes
equations in both air and water droplet phases. Comparison of the numerical
results with one-dimensional analytical model and the experimental data
illustrates a well-predicted heat transfer rate in the cooling tower.
Applying water spray system on the cooling tower radiators enhances the
cooling tower efficiency at both no wind and windy conditions. For all values
of water spraying rate, NDDCTs operate most effectively at the crosswind
velocity of 3m/s and as the wind speed continues to rise to more than 3 m/s
up to 12 m/s, the tower efficiency will decrease by approximately 18%, based
on no-wind condition. The heat transfer rate of radiator at wind velocity 10
m/s is 11.5% lower than that of the no wind condition. This value is 7.5% for
water spray rate of 50kg/s.
CFD analysis of pre-cooling water spray system in natural draft dry cooling towers