Reducing Energy Costs for Gas Preheating through Gas-Dynamic Stratification in the Leontiev Tube

The main objectives of this study are to reduce the energy consumption for gas preheating and improve the efficiency of compression systems using gas-dynamic temperature stratification in the Leontiev tube. In order to achieve these objectives, the following tasks were carried out: a numerical analysis was performed using the finite volume method (RANS) and the k–ω SST tur-bulence model, and the Navier–Stokes equations were discretized on a multi-block mesh of 3 million cells, with local refinement in the nozzle and separation wall zones. Particular attention was paid to the influence of the inlet nozzle geometry on the temperature distribution, flow ve-locity, and heat transfer through the separation wall, as well as the stability of the flow under different pressure differentials. The most significant results include the superior performance of the bell-shaped nozzle design over the annular one: modelling showed a 60 K temperature dif-ference between supersonic and subsonic flows (110.5% higher than the baseline), a 20–25 K increase in hot flow temperature at the outlet, stable flow without pressure surges, and effective gas heating prior to throttling using pipeline pressure drops, preventing condensation and reduc-ing costs. The significance of these results lies in demonstrating the superiority of machine-free energy separation technologies, such as gas-dynamic stratification in the Leontiev tube with a bell-shaped nozzle, over traditional energy-intensive heating methods, leading to more rational resource utilization and reduced environmental impact under strict energy efficiency and ecolog-ical standards.