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实验研究了不同水蒸气压力条件下的滴状冷凝传热特性。10 kPa、40 kPa和70 kPa时的传热系数分别是常压下的56%,68%和81%。随着水蒸气压力的下降,液滴脱落直径变大,液滴生长周期延长,冷凝传热系数下降。通过液滴的动力学特性分析和基于界面效应的滴状冷凝传热模型,分析了低压对水蒸气冷凝传热的主要影响因素,压力变化主要影响了分子扩散率和气-液相际传热热阻,导致总冷凝传热系数随压力下降。
Experimental study of droplet-shaped condensation heat transfer characteristics of different water vapor pressure conditions. The heat transfer coefficients at 10 kPa, 40 kPa and 70 kPa were 56%, 68% and 81% at atmospheric pressure, respectively. With the drop of water vapor pressure, droplet diameter becomes larger, droplet growth period prolongs, condensation heat transfer coefficient decreases. Based on the analysis of the droplet dynamics and the droplet condensation heat transfer model based on the interface effect, the main influencing factors of the low-pressure heat transfer to water vapor are analyzed. The pressure changes mainly affect the molecular diffusion rate and heat transfer in the gas-liquid phase Resistance, resulting in the total condensation heat transfer coefficient decreases with pressure.