含油R134a水平强化管外池沸腾换热实验研究

EXPERIMENTAL STUDY ON POOL BOILING HEAT TRANSFER OF R134A-OIL MIXTURE OUTSIDE SINGLE HORIZONTAL ENHANCED TUBES

本文对含Solest-120冷冻油的R134a,在饱和温度为5℃和10℃工况下,在水平高效强化管(管E21.为C3型管,管E22为A1型管)管外池沸腾换热进行了实验研究。实验结果表明:与相同管径的光管的换热性能相比,强化管E21、E22的管内传热系数强化倍率分别为3.703和3.035。随着含油浓度的增加,管外池沸腾换热效果得到优化,含油率为1.0×10^(-4)时的管外传热系数比含油5.0×10^(-5)时更高,在实验研究的水流速范围内,在蒸发温度为5℃时增加了3.7%～7.2%,而在蒸发温度为10℃时增加了0.8%～10.9%。从含油R134a的黏度、表面张力等的角度,对含油率高时换热系数大的结论进行了必要的物理解释。研究对开发设计蒸发器有一定实际的指导意义。

Pool boiling heat transfer of R134a with Sloest-120 oil outside single horizontal enhanced tubes （E21 tube is C3 type, E22 tube is A1 type.） is experimentally measured at the saturation temperature of 5℃ and 10℃. The results show that heat transfer coefficients of E21 tube and E22 tube are 3.703 and 3.305 times of that of regular tubes respectively. The heat transfer increases with the oil density, the coefficient of 1.0 × 10^-4 oil is higher than that of 5.0× 10^-5 oil. Within the flow velocity range of water in experiment, the coefficient increases 3.7%-7.2% at 5℃, and 0.8%-10.9% at 10℃. The paper gives a theoretical analysis on the results based on the viscosity and surface tension of R134a-Oil mixtures. This research can provide instruction on designing and developing evaporators.