Abstract:

As natural refrigeration, propane will be alternative refrigerant in the future due to its good performance and its lack of impact on the environment. Currently, the study for flow boiling heat transfer of propane in helically coiled tube is few. This paper presents the experimental results of flow boiling heat transfer of propane in helically coiled tube. The internal diameter, helical diameter and helical pitch of helically coiled tube are 8 mm, 42 mm, 21.5 mm respectively and the outer tube is straight smooth tube. As warm fluid, water flows between outer tube and helically coiled tube. The heat flux can be adjusted by changing inlet temperature and flow meter of water. The heat transfer coefficients in experiment are compared to predictions from several boiling correlations both in straight tubes and helically coiled tubes in the literature. Comparison results show that helically coiled tubes have better heat transfer effect than straight tubes. The results also shows that when the heat flux is less than 6 kW·m^-2, Guo's correlation shows higher accuracy than Ji's correlation. So Guo's correlation is recommended at low heat flux condition.

摘要：

丙烷作为自然工质具有良好的换热性能并且对环境影响较小，是替代传统制冷剂的选择。目前对于丙烷在螺旋管中沸腾传热的研究较少。实验测量了丙烷在管内径8 mm、螺旋半径42 mm、螺距21.5 mm的螺旋管中的流动沸腾传热系数。实验采用套管的形式，在螺旋管外用恒温水对丙烷进行加热，调整水入口温度与水流量得到不同的热通量。实验表明，螺旋管对流动沸腾换热具有一定的强化作用。实验数据与已有的螺旋管流动沸腾换热关联式进行了比较，在6 kW·m⁻²以下的低热通量时，Guo（1998）换热关联式比Ji（2015）预测准确度更高，推荐使用Guo（1998）关联式。