三维微肋螺旋管内R134a沸腾环状流区的传热与关联式

首次实验研究了制冷剂R134a在三维微肋螺旋管内流动沸腾环状流区的流动与传热性能。对流型的可视化观察发现：当质量流速大于100kg／(m^2s)时。螺旋管内才开始出现环状流。环状流的起始干度为0．3、0．4。在流型图上给出了环状流区与其它主要流型的分区。回归了实验环状流区的传热实验数据，得到的传热关联武计算值与实验值的平均绝对误差为9．1％。

Annular flow heat transfer correlation of R134a evaporating inside three-dimensional mnicrofin helical coiled tube

Some original experimental results for the boiling annular regime heat transfer of refrigerant R134a in a three\|dimensional microfin helical coiled tube were presented for the first time. The visual observation of the flow through optical glsaa indicatd that with a mass rate of less than 100 kg/(m 2s), the flow was predominantly stratified, with the mass flow rate increase further, however, the flow became annular. The flow pattern was shown for the present test data and the boundaries between the annular flow with other flow patterns were figured out. The initial changing quality for annular flow is approximately 0.3 to 0.4. The annular flow regime heat transfer performance of the helically coiled tube was discussed. Remarkable heat transfer augmentation has been achieved in the present microfin helical coiled tube, with a enhancement factors up to 1.5~2.1. The heat transfer correlation based on the experimental annular flow data was also presented. The mean absolute deviation of this correlation are within 9.1%.