Separation enhancement of conventional and square cyclones through the tailored inlet and vortex finder configurations using different particle characteristics

A gas–particle cyclone separator is an economical device for removing heterogeneous particulate matter from a gas system and is widely used in industrial and environmental applications. This paper presents a numerical analysis of gas–particle flow in square and circular cyclone separators with different inlet and vortex finder configurations to compare their separation performance. Nine cyclones labeled C₁ to C₉ were fabricated in three groups based on the inlet configuration. Each group comprised a conventional cyclone with a circular cross-section, a square cyclone, and a square cyclone with a cylindrical vortex finder. The turbulent flow of the gas phase was simulated using a three-dimensional Reynolds stress model (RSM), while the dispersion of particles was simulated using a Lagrangian equation through the two-way coupling of CFD–DEM. Heterogeneous mixtures of biogenic and solid particles, such as jojoba seeds, jojoba leaves, and sand, were modeled with their actual shape and size, considering particle interactions and impact. The results indicated that inlet configurations and cyclone type influenced turbulent flow dynamics and separation performance. Under the same boundary conditions, the square cyclone exhibited enhanced performance compared to the square cyclone with a cylindrical vortex finder, where the conventional cyclones failed for particle separation. Remarkably, the square cyclone (C₅) demonstrated the highest performance, reporting 23%, 30%, and 94% increases in separation efficiency, cleaning efficiency, and effectiveness, respectively, over the experimental cyclone design (C₁). The comprehensive particle force analysis revealed that the particle–wall collision is intense at the wall opposite the cyclone inlet for all cyclones and in the cone wall bottom where the particles accumulate, which is particularly evident in the C₁, C₃, and C₆ cyclones. Particle–particle interaction forces played a significant role in cyclone performance, with increased separation efficiency observed due to particle collisions. The gas–particle interaction forces, including drag and pressure gradient forces, were mainly affected in the inlet region and extended into the cylindrical part, where the drag force impact continued to the conic part and mainly affected the leaf particles that reversed their direction toward the vortex finder. The pressure gradient force exhibited minimal values; however, it had only a maximum impact on seed particles, proving the dominant drag force on particle behavior. This work provides for the first time the conditions under which particle collisions occur for varying biogenic and solid shapes and orientations and their behavior on approach with associated cyclone designs, where the developed DEM–CFD coupled method makes it feasible to apply the high-performance cyclone to an industrial-scale system.