Research On Heat Transfer Characteristic Of330MW Unit Air-cooled Condenser For Low Wind Velocity In Winter

At low ambient temperature in winter, when the heat load of the unit is low, even if the fans below direct air-cooled condenser stop working, Because of the great fin tube heat exchange area, direct air-cooled unit still has certain cooling capacity,even freeze occurs under the natural ventilation condition. Analyses the heat transfer performance of air-cooled condenser under the condition of natural ventilation, which has close relationship with the safety and economy of air cooling power plant.Using FLUENT software to simulate the heat transfer coefficient of single row tube of air-cooled condenser under the low wind speed. Compared the influence on velocity field and temperature field which caused by inlet air velocity, wall temperature and environmental temperature. exported important parameters such as pressure differential, heat flux by numerical simulation, calculated resistance characteristics and heat transfer characteristic of single row tube under the low wind speed. The research results shows that air outlet temperature close to tube wall temperature, windward side wind speed is the main reason for the influence on heat transfer characteristic and resistance characteristic, ambient temperature has little influence on neither of those.Mathematical model of air flow was set up, Using the matching law between the air operation force and the pressure loss which was caused by the air-cooled condenser when the air passing through, to calculate windward side wind speed caused by natural ventilation. got the relationship among windward side wind speed, wall temperature and environmental temperature. put forward a method of using similarity law to calculate the fan power consumption reduction.Taking a330MW direct air-cooled unit as an example, Which operates at Choking Bask Pressure condition. calculated windward side wind speed caused by natural ventilation. calculated the fan power consumption reduction,total quantity of heat of air cooling island and minimum antifreeze flow due to natural ventilation under different ambient temperature.This paper analyzed the heat transfer performance of air cooled condenser under the condition of natural ventilation, which provides help and guidance for the optimal design and operation of direct air-cooled cooling system at lower ambient temperature in winter.