Numerical Modeling of the Effect of Inlet Temperature and Pressure on Steam Condensation and Entropy Generation in High-Pressure Separator

The gas-liquid supersonic separator is a convergent-divergent nozzle in which condensation and phase change at speeds higher than sound are the characteristics of this device. The fluid flow, mass, and heat transfer in supersonic separators are not understood well due to the complicated interaction of the supersonic flow and phase change. In this research, the virial gas equation of state and a mathematical model have been used to accurately predict the phenomenon of spontaneous condensation using theories of nucleation and droplet growth. The droplet average radius and pressure distribution obtained from the numerical model are well consistent with the experimental data. The results showed that with a 3.5% decrease in inlet temperature at a constant pressure, the average radius of the outlet droplets increased by more than 40%. Also, with about a 40% increase in inlet pressure at a constant temperature, the maximum liquid mass fraction increased by more than 90%. Therefore, the use of low temperature and high pressure at the inlet is necessary to improve the separation efficiency.Also, the lowest entropy generation rate due to temperature changes is related to the highest pressure and the lowest temperature, and the lowest entropy generation rate due to pressure changes is related to the lowest temperature and pressure.The Bejan number calculation showed that irreversibility is affected by the effects of fluid friction compared to heat transfer.