Numerical simulation on synergetic optimization of non-equidistant fillings and non-uniform water distribution for wet cooling towers

Abstract

To improve the heat and mass transfer performance of large wet cooling towers, a synergetic optimization method of non-equidistant fillings and non-uniform water distribution was proposed in this paper. The impact of the optimization scheme on the cooling performance was studied for the cooling tower equipped for a 600 MW unit. Firstly, the fillings were divided into two zones, and the optimized inner fillings radius was obtained according to the different non-equidistant fillings patterns, namely the optimized radius dividing point in the filings zone. Then, the cooling performance variation under different non-uniform water distribution patterns was discussed based on this optimized radius dividing point. The simulation results showed that the synergetic optimization coupling the fillings and water-spraying zones improves significantly the uniformity of the air dynamic and temperature field. The water temperature drops and ventilation rate all increase firstly and then decrease with the increase of the water distribution ratio in the inner zone. Compared with the equidistant fillings layouts of 26 mm and 30 mm, after the synergetic optimization, the outlet water temperature drops increase by 0.21 ℃, 0.22 ℃, and the ventilation rate enhances by 6.68%, 1.13% respectively in the design condition, but 0.28 ℃, 0.31℃ and 7.03%, 1.53% in the typical operating condition in summer. Additionally, the evaporation loss all decreases by about 3.3% in the design condition by comparison with the equidistant fillings layouts of 26 mm and 30 mm, but increases in the typical operating condition in summer.