Experimental studies of two phase flow characteristics and void fraction predictions in steady state horizontal two-phase nitrogen flow

• Published in: Cryogenics (Guildford) 2019-06, Vol.100, p.77-84
• Main Authors: Singh, Gaurav Kumar, Pradhan, Subrata, Tanna, Vipul
• Format: Article
• Language: English
• Subjects: Customization; Digital imaging; Equilibrium flow; Flow characteristics; Flow mapping; Initial conditions; Laboratories; Liquid nitrogen; Nitrogen; Steady state; Two phase flow; Void fraction
• ISSN: 0011-2275; 1879-2235
• DOI: 10.1016/j.cryogenics.2019.04.007

•Experiment designed for steady state LN2 two phase flow pattern visualization in horizontal glass tube.•Void fraction is predicted for the range of experimental quality factor using Lockhart-Martinelli, Fauske, Lenvi’s and homogeneous two phase flow models.•Using standard flow regime, Backer’s regime map, The Taitel, the Dukler and Wojtan flow regime map have been analyzed and compared with the flow visualization using Digital camera.•Different flow patterns have been realized using different process parameters in the designed experimental test set up for Liquid Nitrogen study. An experimental characterization of the Two Phase (TP) flow characteristics in a horizontal steady state flow of liquid nitrogen and its subsequent void fraction predictions has been carried out in a novel laboratory set-up. Earlier studies such as that by Jackson et al. (2006) have addressed to such TP characteristics in transient cooling-down scenarios but not in steady state flow regime. Two-phase flow is characterized as per the relative the phase distributions or “flow patterns” or “regimes”. These characteristics have been experimentally investigated in a custom designed laboratory set-up. The flow patterns as a function of externally controlled relative fractions of liquid and gaseous nitrogen have been recorded using a digital imaging device while the temperature and pressure parameters have been recorded with respective sensors. These experiments have revealed the presence of several transitions in the steady state flow of TP nitrogen depending on the initial conditions. The corresponding vapor fractions have been experimentally investigated also. The observed flow regimes have been correlated with standard flow regime maps such as The Backer’s regime map, the regime map given by Taitel and Dukler and The Wojtan flow regime map. The predictions obtained from various flow models are found to be largely converging with the experimental data obtained. These experiments hopefully would lead to future research towards developing prototype void sensor for cryogenic two-phase flows.