Dispersed Flow Film Boiling

Abstract
New data for dispersed flow film boiling of nitrogen are presented for the following conditions: tube diameter 0.228, 0.323, and 0.462 in. ID; length 4 and 8 ft; mass velocity 70,000 to 19,000 lb/hr ft2; heat flux 0 to 2500 Btu/hr ft2; inlet condition near saturation; exit quality 35 to 315 percent. The previously presented analysis [12] is improved by accounting for droplet breakup due to vapor acceleration, modified drag coefficient on accelerating droplets, and a “Leidenfrost” heat transfer from the wall to the droplets at lower qualities. Measurements are also made to verify the existence of the substantial amount of vapor superheat in the presence of liquid droplets, as predicted by the analysis.