Optimising mini-hydrocyclone designs for enhanced demulsification

Microemulsions find widespread industrial applications due to their high surface area and exceptional stability. However, efficient demulsification and continuous phase separation of microemulsions remain a challenge, where mini-hydrocyclones offer a compact and energy-efficient solution. This study optimised the insert angle and radius of a 10 mm mini-hydrocyclone’s inlet to enhance the demulsification performance for both water-in-oil and oil-in-water emulsions. The mini-hydrocyclone’s performance was assessed in terms of Split Rate ( SR ), Recovery Efficiency ( RE ), Concentration Efficiency ( CE ), and Demulsification Efficiency ( DE ). For water-in-oil emulsions, the optimal inlet geometry achieved an RE of 91.2%, a CE of 1.82, and increased the average droplet size ( d 32 ) from 12.5 µm to 76.8 µm. In oil-in-water emulsions, the optimal design attained an RE of 90.7%, a CE of 1.80, and an average droplet size increase from 8.5 µm to 49.3 µm. These results demonstrate the enhanced separation efficiency and droplet coalescence achieved through the mini-hydrocyclone. To further investigate the influence of inlet geometry on internal flow dynamics, CFD simulations were employed, coupling the Reynolds Stress Model, the Eulerian–Eulerian approach, and the Population Balance Model. This numerical framework provided detailed insights into velocity fields, turbulence distribution, and droplet size evolution. Optimal inlet designs effectively shortened droplet residence time in the forced turbulence region, reduced turbulence in the inner swirling flow, and minimised droplet breakup. To evaluate operational robustness for a numbering-up strategy, a matrix analysis was conducted. Optimal designs consistently outperformed the commercial design, maintaining superior performance despite uneven feed flow distribution. These findings demonstrate the feasibility of mini-hydrocyclone throughput improvement for industrial applications, offering enhanced reliability and adaptability in processes characterised by fluctuating and uneven flow conditions. • Optimal inlet geometry improves separation efficiency of W/O and O/W systems. • Matrix arrays show consistently higher efficiencies with novel designs. • PBM captures the breakup and coalescence of droplets in the mini-hydrocyclones. • The relationship between droplet size and phase separation is discussed.