【摘要】 本文简要地叙述了临界热流密度后流动膜态沸腾的现状后,全面地介绍我们在弥散流和逆环状流膜态沸腾方面的实验和理论研究。集中讨论低压小流量下的膜态沸腾研究,实验范围为:弥散流P=2-7bar,G=25—130kg/m²s,x_λ=5-85％,q=20—95kW/m²;逆环状流p=3-7bar,G=45—160kg/m²·s,Δt_subλ=1—20℃q=50—90kW/m²。简要地讨论了弥散流的理论模型及其与实验比较;逆环状流物理模型以及现有经验式与实验比较。弥散流研究虽然比较深入,但尚缺乏液滴信息,因此待定常数尚较多,这是今后研究的重点。逆环状流实验研究,一般仅提供壁温数据,尚未发现关于汽膜特征方面的信息,而且壁温数据也极为稀少,因而目前的经验式极不完善,更无合适的计算模型。只有在突破了汽膜特征研究方面的困难后,才有可能为逆环状流计算模型提供验证基础。尽管目前国际上膜态沸腾研究十分活跃,但是实验数据库仍然十分贫乏,应当进一步有组织地进行一系列实验研究。更多还原

【Abstract】 This paper summarizes authors recent studies on both dispersed flow and inverted annular flow film boilings following a brief review of the works carried out in this field. The research is concerned only with low pressure and low mass flowrate conditions. The experimentation ranges were:P=2-7 bar, G=25-130kg/m.X_in=5-85％, q=20-95kw/m², for dispersed flow; p=3-7 bar, G=45-160kg/m²·s, △t_subλ=1-20℃, q=50-90kg/m², for inverted anndlar flow.Theoretical models and their comparison with data are discussed respectively for both dispersed fespeand inverted annular flow. To date, still reliable information of liquid droplets is laeking, a number of indetermined constants are existed, although our understtanding of the mechanisms governing the liquid deficent regime heat fransfer is a bit better. Improvement in liquid drops behavior is important. Not only little information on vapour film behavior, but wall temperature data are also seldom availabe for inverted annular flow of water. All proposed correlations may not be valid for low quality film boiling for water. No satisfactory predictions are available. It is possible to have a reliable data bank to remove the uncertainty in the prediction of post-DNB heat transfer., only after further work remains to be done to incorporate the rapour film characteristics.更多还原