Impact of swirl position on supersonic CO2 condensation and energy distribution in hydrogen-rich streams: A throat-swirl optimization strategy

Supersonic condensation separation technology holds promise for hydrogen purification and carbon capture. This study investigates the condensation and energy distribution mechanisms of H 2 -CO 2 mixtures and proposes a nozzle throat-swirl optimization strategy. Using an Euler-Euler multiphase flow model, we developed a numerical framework integrating the real gas equation, swirl effects, and CO 2 non-equilibrium condensation dynamics. A novel throat-swirl configuration was designed and compared with pre-swirl and rear-swirl schemes, while analyzing the energy distribution of the hydrogen-rich stream in axial and radial dimensions. Results demonstrate that the throat-swirl scheme achieves superior nucleation rates (J = 2.6 × 10 23 m −3 ·s −1 ) and turbulent kinetic energy (k = 1312.5 m 2 ·s −2 ), promoting fine droplet formation at the blade tip and addressing expansion limitations of the rear-swirl approach. Condensed droplet density significantly influences energy distribution, with turbulent kinetic energy peaking at the tube wall and increasing along the airflow direction. The throat-swirl scheme effectively balances condensation and separation efficiency. This work reveals how swirl position regulates energy distribution to impact condensation and separation, offering insights for supersonic separator design and clean hydrogen technology advancement. • Potential hydrogen purification and carbon capture approach. • Develop a 3D swirl condensation numerical model of H 2 -CO 2 binary gas. • Clarify that swirl position significantly affects nucleation rate and droplet growth. • Clarify the impact of the swirl position on the energy distribution characteristics. • Throat-swirl can better balance the nozzle liquefaction and separation efficiency.