Research On Heat Transfer Characteristics Of Wavy-finned Flat Tube Under Natural Draft In Winter

North China has terrible climate in winter, the ambient temperature is very low in some areas, which is the biggest problem of directed air-cooled condenser security, how to ensure safety operation in the cold winter is the most important in electricity production the heavier. The direct air-cooled condenser used wavy-finned flat tube has been widely used in the northern region due to its good heat transfer performance, so research on heat transfer characteristics of wavy-finned flat tube under natural draft in winter can provide the basis and guidance for safety and economy of air-cooled power plant.Firstly established the air-side flow and heat transfer model out of the single row finned tube, using FLUENT software to simulate the air flow. Obtained the heat transfer coefficient and flow resistance changed regular pattern by the ambient temperature and wall temperature. The results showed that the flow resistance and heat transfer coefficient is only affected by face velocity, regardless of the wall surface temperature and ambient temperature. The larger wind speed, the lager flow resistance and heat transfer coefficientThen studied the steam condenses characteristics in fin-tube under natural draft, established the mathematical model of steam condensation and freezing. Using the operating parameters of a 330MW power plant for example, obtained the steam condenses characteristics curves under different wall surface temperature and wind speed. The curves showed that with the wind speed increases the decreasing trend of condensation length leveling off. The larger wind speed the smaller affection on condensation length changed by wind speed increasing. The freezing position has the same variation with unit load, the smaller unit load the less steam in the tube, the steam is more easily freeze. The lower the ambient temperature is, the smaller change rate of freeze position under different unit load is.Finally, calculated the minimum antifreeze flow under different ambient temperatures and wind speeds. The research of condensation heat transfer of the finned tube provides reference frame for intensive study in enhancement of heat transfer and winter antifreeze in north China.