Numerical Study on Two-Phase Flow of Transcritical CO2 in Ejector
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The transcritical CO2 two-phase flow in the ejector was investigated numerically by the computational fluid dynamics (CFD) method. The accuracy of the built three-dimensional CFD model was validated by contrasting the simulating results with the available experimental data in the literature. The distribution of pressure, velocity and two-phase volume fraction inside the ejector was analyzed. The effect of the primary nozzle diverging angle on the performance of the ejector was obtained. The results showed that the pressure of the CO2 is decreased and the velocity is increased after the stream enters the primary nozzle. The velocity at the exit of the primary nozzle reaches a maximum value, which is about 168 m/s. The two streams are then mixed in the mixing chamber; the velocity and the pressure were found to be shocked initially and then tend to be stable. The velocity decreases and the pressure increases gradually in the diffuser section. The vaporization of the transcritical CO2 was found to be occurred near the throat of the primary nozzle. The optimum diffusion angle of the primary nozzle was found to be about 6°, where the mass entrainment ratio is 0.83.
KeywordsEjector CO2 Numerical simulation Primary nozzle
The project is supported by Scientific and Technological Research Projects of Universities in Hebei Province (ZD2017061), Hebei Province Construction Science and Technology Research Project (2017-131), supported by the Graduate Student Innovation Fund of North China University of Science and Technology (2019S21).
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