The condensation process of supercritical water gasification products in a bicubic supersonic nozzle

The development of energy-efficient and clean supercritical water gasification product (SCWGP) separation technology has become one of the bottlenecks in advancing supercritical water gasification technology. This study suggests utilizing a supersonic nozzle to condense and separate H2 and CO2 from SCWGP. The flow and condensation model are established for a bicubic parametric supersonic nozzle, and the effects of various operating conditions on the condensation separation of SCWGP are analyzed. The liquid phase mass fraction at the nozzle outlet is significantly influenced by the inlet pressure and temperature. The approximate relationship between inlet pressure variations and liquid phase mass fraction is 0.065 per MPa, while the relationship between inlet temperature variations and liquid phase mass fraction is approximately –0.013 per K. The latent heat released during the condensation process has a significant impact on the temperature distribution within the nozzle. Inlet parameters have a notable effect on the peak values and positions of nucleation and droplet growth rates. The condensed liquid CO2 is primarily concentrated near the center of the nozzle outlet. The efficiency of the condensation separation is strongly influenced by the molar fraction of CO2 in the gas mixture, while the small amount of N2 mixed in has little effect on the condensation separation performance.