Experimental study on the liquid slug of cryogenic slug flow in inclined tubes

An experimental study was carried out to understand the phenomena of the boiling flow of liquid nitrogen in inclined tubes with closed bottom by using a high speed motion analyzer. The experimental tubes are 0.018 and 0.014 m inner diameter (ID) and 1.0 m in length. The range of the inclination angle is 45°–90° from the horizontal. The experimental observation on the liquid slug was carried out along the tubes. Statistical method was employed to analyze the experimental data. The experiment analyzed the influences of the inclination angle and the tube diameter on the liquid slug length and velocity. The results show the liquid slug propagation velocity increases with the decrease of inclination angle θ. For all cases, the maximum values of the mean liquid slug lengths were obtained at θ = 60°. The mean liquid slug lengths were greater for large tube at higher tube position. These conclusions provide a basis for further study liquid slug of cryogenic two-phase undeveloped slug flow.