Abstract: Abstract:The variation of working condition of aircooling system in direct aircooling unit can impact on the exhaust steam pressure and then impact on the unit output power. According to the structure parameters and the operation parameters of the 600MW supercritical direct aircooled unit of a power plant, using the ηNTU method, a mathematic model of aircooling system working condition variation analysis was established. The variation rules of the exhaust steam pressure depending on the inlet air temperature, the exhaust steam heat load and the face air velocity were analyzed respectively. The influences of above factors on the unit output power were analyzed too. According to the influencing rules, the adjustment strategy of the speed and the air volume of the air fan was proposed, which provides a theoretical reference for improving the operation efficiency of the aircooled unit.

Key words: Keywords:direct aircooling, working condition variation, power output of unit, exhaust steam pressure；exhaust steam heat load