水平管内二氟乙烷两相流动摩擦压降实验研究

对制冷剂二氟乙烷(HFC-152a)在内径为8mm的水平管内进行了两相流动沸腾摩擦压降的实验测量.实验测量的压力范围为0.19—0.41MPa,热流密度范围为14—62kW/m2,流量范围为128—200kg/m2s.实验测量表明:HFC-152a的两相摩擦压降随质量流量、质量含气率的增大而增大;热流密度则对摩擦压降的直接影响很小,但通过影响两相流流型间接影响了摩擦压降;当流型由分层流动转变为半环状流或环状流时,总压降中加速压降所占比例有所减小,而摩擦压降所占比例则有所增大;摩擦压降随饱和压力的增大而减小.使用两个应用广泛的压降计算式进行了计算.实验测试结果与计算结果对比后发现,Friedel模型与实验结果偏差较大,而Müller-Steinhagen-Heck模型则与实验结果符合较好.

Two-phase frictional pressure drop of 1,1-difluoroethane in a horizontal tube

This paper deals with an experimental investigation of two-phase frictional pressure drop behavior of 1,1-difluoroethane in an 8 mm inside-diameter smooth horizontal tube. Pressure drop characteristics are measured in a pressure range of 0.19—0.41 MPa, heat flux range of 14—62 kW/m², and mass flux range of 128—200 kg/m²s. The effects of experimental parameters on pressure drop are analyzed. It is found that with the increases of mass flow and vapor quality, the frictional pressure drop increases. The proportion of momentum pressure drop in the total pressure drop increases slightly as heat flux increases, and accordingly the proportion of the frictional pressure drop decreases. The frictional pressure drop increases with saturation pressure decreasing. Experimental results are compared with the calculations from the two extensively used correlation formulae. Our investigations show that the Friedel model has a relatively large deviation, and the Müller-Steinhagen-Heck model accords well with the experimental results.