Dimensional characteristics of wind effects on the performance of indirect dry cooling system with vertically arranged heat exchanger bundles

Abstract

Ambient winds play a crucial role in the operation of indirect dry cooling system in power plants, so it is of use to study the wind effects on the thermo-hydraulic performances of various cooling deltas and sectors in the air-cooled heat exchanger and overall indirect dry cooling system. On the basis of a typical indirect dry cooling system with heat exchanger bundles outside, the computational models of air-side fluid and heat flows coupled with the performances of the circulating water and exhaust steam are developed. The velocity, pressure and temperature fields of cooling air at various wind speeds are presented and the air mass flow rate, inlet air temperature as well as the heat rejection for each cooling delta, each sector are calculated, by which the outlet water temperature of the air-cooled heat exchanger and the back pressure of turbine are obtained. The results show that the cooling deltas suffer from different actions of ambient winds and the conspicuous dimensional characteristics of wind effects on the thermo-hydraulic performances of indirect dry cooling system are presented. The performances of upwind cooling deltas are superior to those at the rear, and they are all better than the side ones. At high wind speeds, the side cooling deltas and sectors get improved in thermo-hydraulic performances to an extent as the wind speed increases, but the performances of the backward ones are deteriorated seriously due to the obstacle of high pressure converting from the strong ambient winds. There exists a critical wind speed, at which the air flow rate is lowest and the outlet water temperature of air-cooled heat exchanger reaches its maximum, the indirect dry cooling system performance is most deteriorated, resulting in an unfavorable turbine back pressure. The study of wind effects on the indirect dry cooling system performances is helpful to the design of air-cooled heat exchangers and dry-cooling towers.