For instance, the gas Mach number is about 1.18, when the expansion ratio is 1.118. Accordingly, the static pressure and temperature are 46 bar and 244 K, respectively. It is a slight expansion, and the water vapor can hardly be removed from natural gas in the supersonic separator. Increasing the expansion ratio to 2.131, the gas Mach number is up to 1.74, leading to a lower static pressure and temperature of around 20 bar and 197 K, respectively.