For the condenser in a 135 MW direct air-cooling condenser system in Northwest China

the effect of solar radiation on the operation of the condenser system was investigated theoretically.Based statistical data over a period of 21 years (1979 to 2000)

the monthly averaged midday solar radiation was obtained

and its effect on the heat load and back pressure were investigated based on the constant turbine outflow and monthly average day temperature of enviroment.The variation of azimuthal angle has little effect on the monthly average heat load from the solar radiation.The monthly average heat load from the solar radiation increases in a 5-month period (January to May)reaching 371.75 kW in May and then decreasing.The changing trend is consistent with that of the monthly average day sunshine time.For the azimuthal angle of 0°

the back pressure increases over a 7-month period (January to July)at the same environmental temperature

with the maximum increment reaching 0.2097 kPa in July

and then decreases over a 5-month period (August to December）.The changing trend is consistent with that of the monthly average day temperature of environment

and the back pressure is significantly affected by the environmental temperature.