Ammonia two-phase flow through the horizontal and inclined impacting T-junctions

Abstract

The two-phase ammonia flow through the horizontal and inclined impacting T-junctions has been experimentally studied. The phase separation has been investigated in the ID 4, 6 and 10 mm T-junctions at different saturation temperatures (30 to 65 °C), vapour qualities (0.1 to 0.7) and mass fluxes (50 to 300 kg·m^-2s^-1). Two separation patterns in the horizontal impacting T-junctions were observed. The first one, vapour momentum-independent, shows weak sensitivity of the phase separation behaviour on the pressure, inlet vapour quality and mass velocity. The second one, vapour momentum-dependent, is characterised by the region with the equal phase distribution between the T-junction outlets. The transition between the phase separation patterns does not depend on the inlet two-phase flow pattern. A straightforward phenomenological model was proposed for the separation pattern identification and the evaluation of the vapour quality in the outlet branch of the horizontal impacting T-junctions with a feasible accuracy of ±20 %. Downward orientation (-45°, -90°) of the T-junction inlet leads to a higher phase maldistribution between the outlets than the upward and horizontal configuration. The effect degrades with the mass velocity increase and diameter reduction. The inclination of the T-junction outlets regarding the horizontal plane enhances the phase separation, with the vapour-rich mixture going to the top outlet. The effect intensifies with the increase in the inclination angle and the decrease in the T-junction mass flow rate ratio.