Experiment and analysis on performance of steam-driven jet injector for district-heating system

The objective of this work is to analyze the performance of steam-driven jet injector for its design and application in the district-heating system. The paper experimentally studied the performance of a steam-driven jet injector with central steam nozzle configuration. Three injectors with throat diameters of 16 and 20 mm were tested. The main inlet parameters tested-steam pressure, water pressure and water temperature-were in the range of 0.20-0.60 MPa, 0.14-0.49 MPa and 18-68 °C, respectively. Experimental results show that the pressures were almost constant for the steam-water two-phase flow in the variable section channel of the mixing chamber tested, whose values were mainly affected by inlet steam pressure, inlet water pressure and temperature, and a shockwave appeared at the outlet of the mixing chamber. The lifting-pressure coefficient and jet coefficient measured were 1.27-2.1 and 7.63-43.65, respectively. A simplified mathematical model has been developed to predict the performance of the injector based on conservation of mass, momentum and energy as well as the present experimental data. The predictions agreed with the experimental data within ±15%.