Experimental study on boiling flow of liquid nitrogen in inclined tubes—Velocities and length distributions of Taylor bubbles

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 the high-speed motion analyzer. The tubes in the experiment are 0.014 and 0.018 m in inner diameter separately and both 1.0 m long. The range of the inclination angles is 0–45° from the vertical. The statistical method is employed to analyze the experimental data. The experiment focused on the effect of the inclination angles on the velocities and the length distributions of the nitrogen Taylor bubbles at different positions along the tubes. The trend of velocity along the tubes is related with θ. At the same position of the tubes, the velocity of the Taylor bubbles increases first, and then decreases with the increase of θ. And the mean Taylor bubble length increases with the increasing x/D along the tubes at various θ. At the same position of the tubes, the mean Taylor bubble length increases first, and then decreases with increasing θ, maximum at 30°. In vertical tubes, standard deviations of the nitrogen Taylor bubble lengths increase with the increasing x/D. For inclined tubes, standard deviations of the nitrogen Taylor bubble lengths increase first, and then decrease with the increasing x/D.