竖直管道内强迫循环下非凝性气体对蒸汽冷凝的影响  

Effect of non-condensable gases on steam condensation in a vertical pipe with forced convection

作　　者：马喜振 贾海军[1] 刘洋 

机构地区：[1]清华大学核能与新能源技术研究院,先进核能技术协同创新中心,先进反应堆工程与安全教育部重点实验室,北京100084

出　　处：《清华大学学报（自然科学版）》2017年第5期530-536,共7页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金委创新研究群体科学基金资助项目(51321002)

摘　　要：非凝性气体对蒸汽冷凝具有重要影响作用,能够大大增加蒸汽冷凝过程的传热热阻,减小传热系数。为研究非凝性气体对竖直管道内蒸汽冷凝的影响,基于Nusselt理论建立了强迫循环条件下蒸汽冷凝的传热传质类比模型。将模型的计算结果与实验数据进行了对比,结果表明:模型能够准确地预测竖直管道内蒸汽冷凝传热系数。模型中非凝性气体为空气,空气的入口质量分数对蒸汽冷凝传热系数具有较大影响。当入口空气的质量分数从8.73%到22.45%变化时,入口处冷凝传热系数从4.8kW/(m^2·K)到1.2kW/(m^2·K)变化,且沿着管道轴向冷凝传热系数逐渐减小。当入口温度从100℃到140℃变化时,传热系数逐渐减小。该研究表明非凝性气体的种类、质量分数和入口温度为影响蒸汽冷凝传热的重要因素。Non condcnsable gases have an important influence on steam condensation by increasing the thermal resistance during condensation and decreasing the heat transfer coefficient. A heat and mass analogy model based on the Nusselt^s theory is developed for steam condensation in a vertical pipe with forced convection. The predicted effects of the non condensable gases on the condensation are with agreement with experimental data. The heat transfer coefficient in the inlet varies from 4.8 kW/（m2 · K） to 1.2 kW/ （m2 · K） for inlet air mass fractions from 8.73% to 22.45%. The heat transfer coefficient then decreases along the pipe. Increasing the inlet temperature from 100 ℃ to 140 ℃ reduces the inlet heat transfer coefficient. The research shows that the inlet temperatureand the kind and the mass fraction of non condensable gas are the important factors governing steam condensation rate.

关 键 词：非凝性气体 冷凝 传热传质 强迫循环 

分 类 号：TK124[动力工程及工程热物理—工程热物理]