SIMULTANEOUS EFFECTS OF WATER SPRAY AND CROSSWIND ON PERFORMANCE OF NATURAL DRAFT DRY COOLING TOWER by

To investigate the effect of water spray and crosswind on the effectiveness of the natural draft dry cooling tower, a 3-D model has been developed. Efficiency of nat-ural draft dry cooling tower 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 natural draft dry cooling tower is simulated numerically by solving the full Navier-Stokes equations in both air and water droplet phases. Comparison of the numerical results with 1-D analytical model and the experimental data illustrates a well-predicted heat trans-fer rate in the cooling tower. Applying water spray system on the cooling tower ra-diators enhances the cooling tower efficiency at both no wind and windy conditions. For all values of water spraying rate, natural draft dry cooling tower operate most effectively at the crosswind velocity of 3 m/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 veloc-ity 10 m/s is 11.5 % lower than that of the no wind condition. This value is 7.5 % for water spray rate of 50 kg/s. Key words: natural draft dry cooling tower, water spray, wind, power plan