Effects of ambient winds on the thermo-flow performances of indirect dry cooling system in a power plant

Ambient winds are one of the key issues in the design and operation of indirect dry cooling system in a power plant. It is of benefit to the optimization of air-cooled heat exchangers and dry-cooling towers to investigate the impacts of ambient winds on the thermo-flow performances of indirect dry cooling system. Based on a representative 4 x 660 MW dry cooling power plant with the flue gas desulfurization and stack installed inside the dry-cooling tower, the physical and mathematical models of the air-side fluid and heat flows at various wind speeds and in various wind directions are developed. The velocity, pressure and temperature fields are presented, and the flow rate and heat rejection for the air-cooled heat exchangers and cooling towers are obtained by using CFD simulations. The results show that the fluid and heat flows of indirect dry cooling system are dominated by the wind induced and buoyancy driven air flows, which are the results of balance between the inertial force, and pressure, viscous and buoyancy forces. In the absence of ambient winds, the hot plume discharge experiences a reverse pressure gradient. The thermo-flow performances of indirect dry cooling system are deteriorated with increasing the wind speed at low wind speeds, but get improved at high wind speeds despite of the hot air penetration through parts of the air-cooled heat exchanger. The frontal finned tube bundles of air-cooled heat exchanger are superior to other finned tube bundles in thermo-flow performances. It will contribute to the proposal of measures against the adverse impacts of ambient winds for the indirect dry cooling system in a power plant. (C) 2012 Elsevier Masson SAS. All rights reserved.