Experimental investigation on phase separation comparison between single and double T-junctions

摘要

In this work, experiments were carried out to compare the phase separation performance of double branching T-junction with that of single branching T-junction. The inlet and outlet branches of double T-junction were arranged horizontally with the inner diameter of 8 mm. R134a was used as the working fluid. The inlet mass flow rate (mass flux) was set at 10, 15, 20, 25 g s(-1) (199, 298, 398, 497 kg m(-2) s(-1)) and the inlet quality was set at 0.3, 0.5, 0.7 respectively in the experiment of single T-junction. It is concluded that the inlet mass flux has little influence on phase separation while the phase separation efficiency drops sharply with the increase of inlet quality, which is consistent with the conclusions in literature. The experimental data is also compared with the predicted values generated by theoretical models based on air-water and it is found that there is no model suitable for refrigerants. Furthermore, a comparative study between single T-junction and double T-junction was carried out from two perspectives: separation performance comparison of different branches and comparison between single and double T-junctions. The results show that the double T-junction performance is greatly affected by inlet quality and mass split ratio of the first branch, and not always higher than that of single T-junction for horizontal arrangement. Finally, predicting equations of outlet quality of double T-junction are correlated based on experimental data, which have a high predicting accuracy under the high mass split ratio conditions.