Multiphysics synergy analysis of light, CO₂ mass transfer and fluid dynamics in microalgae photobioreactors

Photobioreactors (PBR) are critical systems for cultivating microalgae, offering promising applications in carbon sequestration and sustainable bioresource production. Achieving optimal reactor performance requires an integrated understanding of light distribution, CO₂ mass transfer, and fluid flow dynamics. This study develops a comprehensive multiphysics evaluation method to assess photobioreactor performance by examining the synergistic interactions among these three physical fields. First, a novel synergy angle evaluation diagram considering the synergy angle between light and fluid flow (θ) and the synergy angle between CO₂ mass transfer and fluid flow (φ) is introduced to quantify these interactions, enabling a systematic approach to reactor performance assessment and optimization. Then, by adopting the multiphysics synergy analysis method of illumination, CO₂ mass transfer and fluid dynamics, the performance of various photobioreactor configurations, including flat-plate PBRs and column PBRs are evaluated with computational fluid dynamics. Finally, the evaluation results guide the structural optimization of PBRs, leading to significant improvements in microalgal growth and carbon sequestration efficiency. Several optimized structures of microalgae photobioreactors are proposed. This work provides a framework for analyzing and optimizing photobioreactor systems, contributing to the advancement of microalgae-based technologies for environmental and industrial applications.