Experimental and theoretical investigations of two-phase flow in low pressure steam-water injector

Unlike the typical steam-water injector, the device investigated here operates with relatively low pressure motive steam which is expanded in convergent nozzle to critical (sonic) velocity only. Experimental test were conducted with motive steam pressure in the range of 62-130 kPa (abs), superheated up to 30 K. Distributions of pressure and temperature along the injector's mixing chamber and diffuser were recorded for selected inlet steam and water flow rates and outlet backpressures. The pressure was measured not only along the flow channel walls but also at the centerline near the steam nozzle outlet plane. Maximum backpressure for which the injector works stably was also determined for various inlet flow parameters. In theoretical part of the paper, control volume model was applied to predict the flow parameters in key cross-sections of the injector working with maximum discharge pressure. The proposed model results were compared with the measurements and good prediction of the outlet pressure and temperature was achieved. (C) 2019 Elsevier Ltd. All rights reserved.