Numerical simulation of a center-water two-phase ejector with non-condensable gas

Abstract

The application of gas-liquid ejectors can effectively improve system performance while achieving steam condensation and non-condensable gas dissolution and discharge. In the presence of non-condensable gases, the flow field and performance of the ejector are significantly affected. This paper employs the two-phase Eulerian model, with water as primary flow and steam and air as secondary flows. The effects of non-condensable gas on a water-centered two-phase ejector were comprehensively investigated. The results show that as the backpressure increases, the steam wing gradually retreats upstream, and the pressure within the mixing chamber increases. Increasing the primary flow inlet pressure causes the flow inside the ejector to transition from subsonic to supersonic. The impact of the non-condensable gas content is primarily concentrated in the mixing chamber. As the non-condensable gas content increases, the pressure in the mixing chamber increases, the velocity decreases, the axial liquid volume fraction increases, and the ejector's injection capability decreases. When the inlet pressure is 1.60 MPa, increasing the non-condensable gas content from 1 % to 15 % leads to a reduction in the entrainment ratio from 2.13 % to 2.01 %, a decrease of 5.6 %. The influence of non-condensable gas content on the ejector is more pronounced at low inlet pressures.