Analysis of the Multiphase Flow With Condensation in the Two-Phase Ejector Condenser Using Computational Fluid Dynamics Modeling

Abstract

The liquid-driven two-phase ejector condenser is the object of the numerical investigation. The spray-ejector condenser is one of the critical components of the developed gas power plant with negative CO2 emission. The task of the ejector is to entrain exhaust gas and condense steam contained in it. Computational fluid dynamics (CFD) modeling allows analyzing complex phenomena and predicting the influence of a wide range of operating parameters on the local structure of the multiphase flow with condensation. The geometrical model of the ejector was designed to provide efficient steam condensation and generate sub-pressure region at the gas inlet. The 2D, axisymmetric CFD model was created using simcenter star ccm+ software. The multiphase mixture model was used to take into account two-phase flow. Turbulent flow was computed using k–ω SST model. Direct contact condensation of steam was calculated using two different approaches: the Spalding/evaporation model and the thermally-driven boiling/condensation model. The influence of various gas inlet velocities and the presence of CO2 on the operation of the ejector condenser were investigated based on scalar fields and charts representing changes in the most important variables along the flow path. The condensation is the most intense in the suction chamber. The boiling/condensation model predicts lower suction pressure and higher condensation effectivity than Spalding/evaporation model. The CO2 considerably affects the pressure and temperature distributions and reduces the condensation rate.