5mm小管径内R290凝结换热研究

Study on Condensation Heat Transfer of R290 in 5 mm Small-Diameter Tube

对R290在5 mm小管径内的凝结换热特性进行了实验。实验工况:热流密度5~10 kW/m^2、质量流率180~250 kg/(m^2·s)、饱和温度40~55℃、管径5 mm。研究了质量流速、饱和温度、热流密度及管型对管内换热系数的影响。研究表明:换热系数随质量流率的增大而增大,随饱和温度的上升而下降,且在干度较大区域,影响更加明显;换热系数随热流密度的增大而增大,且存在最佳热流密度使其达到最大值;相同工况下,内肋管换热系数大于光管,在质量流速低、干度小的区域内肋管的强化效果更优。

The condensation heat transfer of R290 in a 5 mm small diameter tube was experimentally studied The effects of heat flux(5-10 kW/m^2),mass flow rate(180-250 kg/(m^2·s),saturation temperature(40-55℃)and tube diameter(5 mm)on the heat transfer coefficient of R290 were investigated.The results show that the heat transfer coefficient increases with the increase of mass flow rate,decreases with the increase of saturation temperature,and the influence is more evident in the region with larger dryness.The heat transfer coefficient increases with the increase of heat flow density,and there is an optimal heat flow density.Under the same conditions,the heat transfer coefficient of inner finned tube is larger than that of smooth tube,and the enhancement with the inner finned tube is even better in the region with lower mass flow rate and smaller dryness.