Abstract The present study evaluates the potential of clean natural gas dehydration using nonequilibrium condensations in high-pressure supersonic flows. A computational fluid dynamics model is developed to study the formation of massive nanodroplets due to the phase change process. The impact of thermodynamic models on nonequilibrium condensations in supersonic flows is analysed based on the ideal gas and real gas equations of state. The sensitivity of high-pressure supersonic separations under different inlet temperatures is discussed in detail, including the influences on gas processing capacities and nonequilibrium condensation processes. The results show that an ideal gas modelling not only predicts the earlier onset of nonequilibrium condensations but also under-predicts the liquid fraction by 61% compared to the real gas model. The decreasing inlet temperatures improve gas processing capacities and predict the earlier condensing onset inside high-pressure supersonic flows. The liquid fraction can be enhanced by 21% with a decrease of 10 K inlet temperature from 593 K and 583 K. It suggests that the decreasing inlet temperature could improve high-pressure supersonic separations from the view of the processing capacity and separation performance.