The presence of water vapor in gaseous flows such as air an‎d natural gas represents a critical challenge across energy, petrochemical, aerospace, an‎d HVAC industries. This impurity not only reduces energy quality an‎d induces pressure losses but also promotes corrosion, hydrate formation, an‎d ultimately decreases the efficiency of transmission systems. Conventional dehumidification methods—such as chemical absorption, refrigeration, an‎d membrane separation—although widely employed at the industrial scale, suffer from high energy consumption, bulky equipment, an‎d significant maintenance costs. Consequently, emerging technologies based on supersonic flows, particularly convergent–divergent (Laval) nozzles, have attracted increasing attention as a promising alternative for gas dehumidification. In this study, the dehumidification of moist air through sudden condensation in a supersonic nozzle was numerically investigated. The modeling was carried out using the two-phase mixture approach, while user-defined functions were incorporated to enhance the accuracy of wet vapor property predictions. The k–ω SST turbulence model was employed to capture flow characteristics more precisely, an‎d the vapor-to-liquid phase transition was modeled via the Lee approach. Simulations were performed under steady, two-dimensional, an‎d adiabatic conditions, covering a range of inlet pressures (1.2–2 bar), inlet temperatures (283–323 K), an‎d initial vapor volume fractions (0.0014–0.031). The results revealed that higher inlet pressures significantly enhance condensation rates, leading to an increase in the maximum liquid water volume fraction up to approximately 13.9%. In contrast, higher inlet temperatures markedly reduced the condensate yield (by nearly 49%). Moreover, elevated inlet humidity was found to play a decisive role in intensifying the condensation process. Beyond the parametric analysis, a multivariable regression model was developed based on simulation results. Utilizing two dimensionless parameters, the model successfully predicted the maximum liquid volume fraction with high accuracy (R² = 0.9879). Importantly, the model was validated not only for the baseline nozzle geometry but also for an alternative configuration, demonstrating consistent reliability. The findings highlight that supersonic nozzles can serve as an innovative, cost-effective, an‎d efficient approach for gas dehumidification in diverse industrial applications. These results provide a scientific foundation for the design an‎d optimization of industrial nozzles in natural gas transmission systems, advanced air-conditioning units, an‎d aerospace equipment. Furthermore, the proposed numerical framework an‎d correlation models offer potential for extension to other gas mixtures.

رامين كوهي كمالي

محسن دوازده امامي

مهدي نيلي احمدآبادي , محمدرضا توكلي نژاد