To reveal the effect of inlet temperature on the supersonic liquefaction characteristics of natural-gas mixtures

a mathematical model for the supersonic condensation flow of two-component natural gas mixtures was established in this study. The spontaneous condensation process of methane-ethane mixed gas in a Laval nozzle at different inlet temperatures was studied. The results indicate that when the inlet pressure and gas composition of the Laval nozzle remained the same

with the decrease in the inlet temperature

the nucleation position of the mixed gas moved forward; the nucleation rate

droplet radius

droplet number

and liquid mass fraction were all increased; and the liquefaction characteristics was improved. By using the Laval nozzle structure designed in this study

inlet gas pressure of 6 MPa

inlet gas temperature of 265 K

methane content of 90% and ethane content of 10% resulted in maximum nucleation rate of 0.9822×1021 (m3?s)?1 in the Laval nozzle

maximum droplet radius of 4.7194×10?7 m

maximum droplet number of the unit mass of 5.0704×1014 kg?1

and maximum liquid mass fraction of 7.8121%. The liquefaction efficiency of the Laval nozzle sharply decreased when the inlet temperature was higher than 275 K. In an actual production

the liquefaction efficiency of the Laval nozzle can be improved by lowering the inlet temperature and reducing the heat exchange between the Laval nozzle and outside environment.