Direct dry cooling system through hybrid ventilation for improving cooling efficiency in power plants

The thermo-flow performances of conventional air-cooled condenser (ACC) using mechanical ventilation are basically susceptible to ambient winds due to its geometrical flaws, so more attentions have been paid to weakening such unfavorable effects, but the hybrid ventilation has never been considered. Based on representative 2 x 600 MW power generating units, two types of hybrid ventilation direct dry cooling systems (HVDDCS) utilizing the buoyancy force from the cooling tower, circular-type and rectangular-type, are developed. Furthermore, the thermo-flow performances in three wind directions of 0, 45 and 90 are presented and compared with the conventional ACCs. The results show that the hot plume recirculation of the peripheral condenser cells for HVDDCS can be avoided, thus the inlet air temperature of air-cooled condensers is reduced. For circular HVDDCS, the reversed flows in upwind condenser cells are much weakened, leading to increased heat rejection and improved cooling performance in any case. In the wind direction of 0, the rectangular HVDDCS shows a superior performance to those in the wind directions of 45 and 90, so it is applicable to the region with a prevailing wind direction. The HVDDCS could be recommended for the potential engineering application thanks to its more energy efficient performance. (C) 2017 Elsevier Ltd. All rights reserved.