Performance improvement technique of natural draft dry cooling tower under ambient wind based on minimum mechanical energy dissipation

Abstract

The Natural draft dry cooling tower (NDDCT) performance decreases sharply under ambient winds. The drag reduction equation is introduced in paper to solve the flow field distribution inside NDDCT, which complies with the minimum mechanical energy dissipation and provides theoretical guidance for the baffle installation inside the NDDCT. Depending on the streamline distribution inside tower, the pressure drop between tower inlet and outlet can be reduced by 12.9 % to 76.9 % by installing the appropriate shape and size of deflectors inside the tower. The thermal behavior of NDDCT model, the two improved NDDCT model in reference, and the improved NDDCT model proposed in paper were compared under wind conditions. At a wind speed of 12m/s, the drag reduction model's drag coefficient was reduced by 10.9 %, and heat dissipation increased by 6.94 % compared to the NDDCT. Under high wind speed conditions, the improved model can greatly reduce the back pressure and coal consumption. At a wind speed of 16 m/s, the back pressure of unit is reduced by 3.29 kPa and the coal consumption is reduced by 1.71 g/(kW-h). Compared to the models mentioned in two references, it was determined that the improved NDDCT model reduces the negative impact of ambient wind on NDDCT mainly by reducing the resistance inside tower.