A Trade-off-Aware Eulerian-Lagrangian Study of Gas-Ash Flow in a 'DD Cyclone: A Combined Separation Performance Index and the Coupled Role of Inlet Velocity, Polydisperse Particle Loading and an Angle-Dependent Wall-Restitution Model

Cyclone separators are widely used for the centrifugal separation of solid particles from gas streams owing to their low cost, mechanical simplicity and tolerance of harsh operating conditions. Although the isolated effects of inlet velocity and particle size on cyclone performance are well documented, their coupled interaction with a physically realistic, angle-dependent particle-wall rebound model—and the resulting compromise between separation efficiency and energy penalty—has received far less attention within a single, consistently validated framework. In this study, the gas-ash two-phase flow inside a conventional DVD cyclone (body diameter D = Y..mm, total height H = Amm) is investigated numerically using an Eulerian-Lagrangian approach. The continuous gas phase is resolved with the steady, pressure-based Reynolds-Averaged Navier-Stokes equations closed by the RNG k-ε turbulence model, while the dispersed ash particles are tracked with the Discrete Phase Model (DPM) including stochastic turbulent dispersion. Four inlet velocities (۰, ۱, ۱۰ and Y. m/s) are examined for a Rosin-Rammler-Logarithmic particle-size distribution (۱-μm), together with a uniform μm reference case and an angle-dependent (Grant-Tabakoff) wall-restitution model for fly ash. The continuous-phase solution is validated against the laser-Doppler-anemometry measurements of Hoekstra (...). To rank the operating conditions on a common, physically meaningful basis, a combined Separation Performance Index (SPI), coupling the collection efficiency with the Euler number, is introduced. The results show that increasing the inlet velocity from to m/s raises the collection efficiency from ۹.۷۱% to ۹۰.۹۷% but increases the pressure drop from ۱۱Y Pa to YAOε Pa (a Yo-fold penalty), so that the SPI actually decreases—revealing that the highest velocity is not the optimal operating point. For a uniform μm diameter the efficiency approaches ۹۹.۱%, whereas the angle-dependent restitution model changes both efficiency and pressure drop by less than ۱% for the present fine-particle, dilute system. The study delivers a trade-off-aware performance map and a transferable selection metric for 'DD cyclones.

کلیدواژه ها:

Cyclone separator ، Eulerian-Lagrangian approach ، Discrete Phase Model ، Separation performance index ، Angle-dependent restitution ، Trade-off optimization