CFD simulation of the influence of swirl intensity on entropy production for wet steam flow in supersonic dehydration

•A steam condensation model and an entropy generation approach are developed.•The non-equilibrium condensation characteristics and irreversible loss under different swirl strengths are investigated.•To maintain optimal performance of the nozzle, it is advisable to limit the swirl intensity to a value below 0.30. The energy loss within a supersonic separator is highly dependent on the cyclonic intensity. In this paper, an entropy production analysis model and a nonequilibrium condensation model are developed to study the liquefaction performance of the supersonic nozzle and the energy loss under different swirl intensities. With an increase in swirl intensity from 0 to 0.94, the nucleation starting point and Wilson point at the centerline move forward by 45.05 mm and 69.17 mm, respectively. The mass-average liquid fraction at the nozzle outlet increases by 28.81 %, but the flow rate decreases by 43.02 %, and the total entropy production experiences a 19.66 % increase. Indirect (or turbulent) dissipation dominates the total entropy production of wet steam flow resulting from the large gradient of velocity at the boundary layer, whereas phase change entropy production ranks second and mainly occurs in the nucleation region. Overall, the swirl intensity should be kept below 0.30 to achieve a balance between gas handling capacity, liquefaction performance, and energy loss for the supersonic nozzle. [Display omitted]