Prediction of the non-equilibrium condensation characteristic of CO2 based on a Laval nozzle to improve carbon capture efficiency

The supersonic separator is considered as a more efficient and environmentally friendly technology within the field of decarbonization. The flow state of the vapor and the operating environmental conditions are significant factors which affects the separation efficiency. The effect of the inlet pressure (subcritical, near-critical, supercritical), temperature (supercritical), and the outlet back pressure on the CO(2 )non-equilibrium condensation flow characteristics is numerically calculated. The results show that when the pressure is higher or the temperature is lower, the non-equilibrium condensation process is promoted and the formation of droplets is more stable. The nucleation interval increases with the pressure increases. The peak nucleation rate increases with the temperature decreases. The condensation shock wave is weakened and the condensable area is reduced with the back pressure increases, resulting in the liquid mass fraction significantly decreases. The critical condensation back pressure reflects the ability of the vapor to resist back pressure shocks during the condensation process. The effect of inlet pressure, temperature, and expansion angle on the critical condensation back pressure is analysed. The condensation shock wave is enhanced by increasing the pressure, expansion angle, and decreasing the temperature, the vapor has a stronger ability to resist the influence of back pressure.