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论文类型：会议论文

发表时间：2014-08-10

收录刊物：EI、Scopus

摘要：Droplet departure characteristics in dropwise condensation of saturated steam in a pressure range from atmospheric to 1.5kPa were studied experimentally on a hydrophobic surface. The effect of steam pressure on departure size and departure velocity of condensed droplets was investigated. The results suggested that departure diameter depended strongly on the steam pressure but remained rather insensitive to the increase of surface subcooling. Condensed droplets grew larger and moved slowly in the departure process at low pressure compared to that at atmospheric. The droplet departure velocity at atmosphere pressure was much higher than that at low pressure. Introducing the effect of departure velocity and departure diameter, a modified dropwise condensation model was presented to explain the great reduction of heat transfer performance at low pressure by dividing the condensation cycle into growth period and departure period. The growth period depended strongly on the surface subcooling while the departure period remained rather sensitive to the steam pressure which resulted in two control mechanisms for different surface subcooling range. The modified model very well predicted the experimental data at various steam pressures. In addition, the nonlinearity of heat flux and surface subcooling was explained by the droplet retention effect which was confirmed by the heat transfer performance at various pressures.