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The application of a two-phase ejector allows for the mixing of liquid and gas and provides effective heat transfer between phases. The aim of the study is a numerical investigation of the performance of a water-driven, condensing two-phase ejector. The research was performed using CFD methods, which can provide an opportunity to analyze this complex phenomenon in 2D or 3D. The 2D axisymmetric model was developed using CFD software Siemens StarCCM+ 2022.1.1. The Reynolds-Averaged Navier–Stokes (RANS) approach with the Realisable k-ε turbulence model was applied. The multiphase flow was calculated using the mixture model. The boiling/condensation model, where the condensation rate is limited by thermal diffusion, was applied to take into account direct contact condensation. Based on the mass balance calculations and developed pressure and steam volume fraction distributions, the ejector performance was analyzed for various boundary conditions. The influence of the suction pressure (range between 0.812 and 0.90) and the steam mass flow rate (range between 10 g/s and 25 g/s) is presented to investigate the steam condensation phenomenon inside the ejector condenser. The provided mixture of inert gas (CO2) with steam (H2O) in the ejector condenser was investigated also. The weakening of the steam condensation process by adding CO2 gas was observed, but it is still possible to achieve effective condensation despite the presence of inert gas. [ABSTRACT FROM AUTHOR]

One promising solution for developing low-emission power technologies is using gaseous fuel combustion in pure oxygen when the exhaust gas mixture is composed of H 2 O and CO 2 , and where CO 2 is separated after steam condensation. The paper presents the results of computational analyses providing to the Spray-Ejector Condenser (SEC) development, which is one of the crucial components of the negative CO 2 gas power plant (nCO 2 PP) cycle development. The proposed design of the ejector-condenser to ensure the high effectivity of vapor condensation and CO 2 compression with preparation to separation, ready for application in gas power cycle, is a novelty of this research. Different computational techniques leading to the development and better understating of ejector operation were applied. The main operating conditions in the characteristic connected with the developed nCO2pp cycle points were investigated to evaluate the impact of the operating conditions on SEC performances. The amount of motive water needed for the cooling purpose is susceptible to the inlet water pressure and temperature and strongly affects the generated pressure of the suction stream. The preliminary results confirm that the SEC's basic design and geometrical dimensions can be applied in the negative CO 2 power plant cycle. Results from CFD modeling give the possibility to investigate the turbulent flow of water/steam/CO 2 mixture together with the condensation process occurring at this same time. It is found that the average droplet diameter and motive water supplying method significantly effects the condensation intensity. The further direction of the presented computational research activities and results is to test various designs of Spray-Ejector Condensers that will enable the evaluation of the direct contact condensation process and develop the final geometrical design. • Spray-Ejector Condenser application in negative CO 2 gas power plant is presented • Performances of Ejector Condenser were calculated using developed model to provide guidelines for a detailed design process • The basic design of the Spray-Ejector Condenser in two variants was developed • CFD model for Direct Contact Condensation was developed, and the impact of water droplet size was studied [ABSTRACT FROM AUTHOR]