垂直管内R113降膜蒸发传热试验研究

摘要

In order to research the heat transfer characteristics of falling film evaporator,experimental research was carried out on heat transfer characteristics of R113 falling film evaporation in a vertical tube in the range of test parameters,i.e.,at the inlet mass flowrate of 0.121～0.0225 kg/s and heat flux of 1.02～3.35 kW/m2.The results show that the mass flow rate of the outlet steam is closely related to the heat flux.With the increase of heat flux,the mass flow rate of the outlet steam increases gradually;Heat transfer coefficient increases first and then decreases with the increase of inlet mass flow rate;By increasing the inlet mass flow,the heat transfer can be enhanced within a certain range;Under relatively small inlet mass flow rate,increasing heat flux is unfavorable to heat exchange. For relatively large inlet mass flow rate,the heat transfer coefficient increases first and then decreases with the increase of heat flux. There is a critical value at which falling film evaporation has the best heat transfer effect.%为研究降膜蒸发换热特性,在进口质量流量为 0.0121～0.0225 kg/s,热通量为 1.02～3.35kW/m2的试验参数范围,对R113在垂直管内的降膜流动蒸发传热特性进行了试验研究.结果表明:出口蒸汽质量流量与热通量密切相关,随着热通量的增加,出口蒸汽质量流量逐渐增加;换热系数随着进口质量流量的增加呈现先增加而后减小的变化规律,增加进口质量流量在一定范围内能增强换热;在较小进口质量流量下,增大热通量不利于换热,在较大进口质量流量下,传热系数随着热通量增加先增后减,存在某个临界值使得降膜蒸发换热效果最好.