R134a在水平三维内微肋管内的沸腾换热

BOILING IN THE HORIZONTAL TUBES WITH THREE-DIMENSIONAL INNER MICROFIN

本文以 Ｒ１３４ａ为工质，在外径为 １６ ｍｍ的两种不同几何结构的水平三维微肋管内进行了沸腾换热实验，研究了质量流率、热流密度、蒸汽干度等因素对沸腾换热系数的影响。与相同工况下的水平光管比较， １＃微肋管的换热强化因子在１．５～２．１之间，２＃微肋管的换热强化因子在１．９～２．８之间。两种三维微肋管的比较结果显示，单位内表面积上具有更多的微肋数目的 ２＃管的平均沸腾换热系数比 １＃管增加了 ２８～４３％。

Experimental results of R134a boiling in two kinds of three dimensional microfin tubes with 16mm outer diameter are presented. The effects of mass flux, heat flux and vapor quality on the heat transfer coefficients are reported in this paper. Compared to the smooth tube, the heat transfer enhancement ratio of 1# tube is between 1.5 and 2.1, and that of 2# tube is between 1.9 and 2.8. The heat transfer characteristics of the two kinds of tubes are also compared. We find that the average heat transfer coefficients of the 2# tube, which has a greater number of microfins per square centimeter, are 28 - 43% higher than those of the 1# tube.