Vortex-tube integration for pressure reduction in near-saturation closed industrial steam systems: A system-level thermodynamic, exergy, exergoeconomic and environmental assessment

Industrial steam pressure reduction is still predominantly achieved by throttling valves, although throttling dissipates steam pressure potential and causes considerable exergy destruction. This study evaluates the theoretical system-level potential of vortex-tube (VT) integration for pressure reduction in near-saturation closed industrial steam systems under an air-data-derived thermal-separation map and the stated modeling assumptions. A VT-integrated configuration is proposed and compared with a conventional throttling-valve reference system under a unified thermodynamic, exergy, exergoeconomic and environmental framework. Unlike most VT studies based on air or other single-phase gases, this work focuses on a steam loop where two-phase separation may occur and where the hot-end, cold-end and drain streams can be utilized within the surrounding system. In the proposed configuration, the hot-end stream supplies the process heat demand, whereas the cold-end separated stream and drain are recovered through the deaeration branch. A performance-map-based system model is developed for steam pressures of 0.2–0.8 MPa and return-water temperatures of 80–100 °C. The adopted thermal-separation basis is used for relative system-level comparison rather than high-fidelity prediction of intrinsic steam-VT performance. Under the prescribed VT scenario and boundary conditions, the model estimates energy- and exergy-efficiency gains of 1.66–1.71 and 1.68–1.97 percentage points, respectively, with annual net savings of approximately 1.05 × 10 5 USD/year and annual CO 2 reductions of 4.29 × 10 5 –4.30 × 10 5 kg/year. These results indicate conditional system-level potential; steam-specific experiments remain necessary to establish intrinsic device performance and industrial applicability.