CFD-based investigation of sparger position and aeration rate in inclined flat plate photobioreactors

Optimizing photobioreactor (PBR) design is essential for improving the productivity and energy efficiency of microalgal cultivation systems. This study employed Computational Fluid Dynamics (CFD) simulations to assess the hydrodynamic performance of an inclined flat plate PBR for Arthrospira platensis cultivation. The CFD model, validated against experimental data (maximum discrepancy: 8.4 %, R 2 = 0.81), reliably predicted biomass productivity and internal flow dynamics. Five sparger configurations and four aeration rates were investigated for their effects on radial velocity, turbulence kinetic energy (TKE), and dead zone formation. The results highlighted the hydrodynamic advantages of the rear-most sparger position (R). At 0.21 vvm (volume of air per volume of culture per minute), position R achieved a radial velocity of 0.125 m·s −1 , a TKE of 4.32 × 10 −3 m 2 ·s −2 , and a dead zone fraction of 18.23 %, closely matching the middle sparger position at 0.23 vvm. Notably, 0.23 vvm represented the highest tolerable aeration rate experimentally, as exceeding this threshold induced shear-related mechanical stress, negatively impacting microalgal cell integrity and reducing productivity. Thus, sparger position R provided equivalent mixing at reduced aeration, lowering energy demand and operational stress. The inclined geometry enhanced flow uniformity and turbulence, particularly with rearward sparger placement. Integrating dead zone analysis with velocity and TKE metrics, this study offers a validated framework for optimizing sparger design in inclined flat plate PBRs. These findings have significant implications for improving energy efficiency and scalability in laboratory and industrial scale microalgal cultivation systems. • CFD simulations used to evaluate hydrodynamic performance in flat plate PBRs • CFD validation showed strong alignment with experimental results for A. platensis . • CFD validation indicated Rear sparger can achieve superior mixing at 0.21 vvm. • Dead zone analysis highlighted minimized stagnation with rearward sparger placement. • Optimizing sparger placement can reduce energy consumption and operational costs.