At low ambient temperature in winter

when the unit's heat load is low

the heat transfer performance of air-cooled condensers under natural ventilation condition is directly related to the safety and economy of air cooling unit's operation.Thus

the heat transfer performance of direct air cooling condensers under natural ventilation condition was investigated.Moreover

the FLUENT software was employed to conduct numerical simulation on heat transfer performance of single-row tube of direct air cooling condenser in a subcritical 330MW unit

with low wind speed.The results show that

under natural ventilation condition

the air flow inside the air cooling island is mainly driven by the heat pressure difference and suction force;the face velocity of air cooling unit has a certain relationship with the ambient temperature and wall temperature of fin tubes(the face velocity decreases with an increase in the ambient temperature when the fin tubes' wall temperature is kept at a certain value

while it increases with the fin tubes' wall temperature when the ambient temperature is a constant).