NUMERICAL INVESTIGATION OF NONUNIFORM SPRAY EFFECT ON THE COOLING PERFORMANCE OF A LARGE-SCALE COOLING TOWER

To study the effect of water spray layout on the cooling performance of a natural draft wet cooling tower (NDWCT), a three-dimensional (3D) numerical model was developed and validated. The design working conditions for one large-scale NDWCT were adopted to analyze the effect of nonuniform spray, by which the water mass flow rate in the tower outer zone was greater than that in the tower inner zone. By numerical simulation, the distributions of the air velocity and water temperature inside NDWCT could be computed and analyzed in detail. Comparing the distributions of the air velocity and water temperature between the uniform spray and nonuniform spray, it could be found that the effect of the nonuniform spray rested with the special working conditions. When the rate of air mass flow through the tower is high, the air flow field dominates the heat and mass transfer, and then the effect of the nonuniform spray is insignificant. When the rate of air mass flow through tower is low, the effect of the nonuniform spray is positive and obvious. Compared with the uniform spray, the nonuniform spray cools the water in the tower inner zone sufficiently, and then improves the cooling performance of NDWCT. Besides, the effect of the nonuniform spray on the tower is also impacted by ambient crosswinds.