Abstrakt Wind and increase in air temperature are among the most important environmental factors that have the greatest impact on the performance of the Heller tower with natural convection. In this research, the thermal behavior of a Heller-type dry cooling tower and the effect of changing the geometry of the tower (cylindrical, convergent-divergent and hyperbolic models) and the effect of increasing the height of the tower (cylindrical models with elevation of 120, 130 and 135 m) on its performance when wind blows with different velocities has been considered. The results of this simulation show that the geometric shape of the tower with wind at different speeds results in different thermal performance of the cooling towers. The use of convergent-divergent or hyperbolic towers when the wind blows at 8 and 12 m /s increases thermal performance of the tower by about 10%, while in the case of no wind, the best performance belong the cylindrical model. Also, increasing the height of the tower a cylindrical tower in no-wind condition will increase the thermal performance of the cooling tower by about 5 percent for a tower with a height of 130 and 135 meters. Also, the result of this study show that when we decreasing the angle of delta, the performance of cooling tower has been increased. It means with decrease 10 degree of angle between radiators and by 26 delta addition around the tower, the thermal performance of cooling tower increase 11 percent. In addition, the characteristic equation for different towers is extracted and the effect of changing the initial temperature difference (ITD) on thermal performance of the tower is proposed. Key Word ITD, Dry Cooling Tower, Heat dissipation, Increasing the height, Tower geometry, delta angle