| Microalgae and cyanobacteria cultures are attracting great attentions in many industrial applications. However, their mass production in enclosed photobioreactors faces prohibitively high production costs with special difficulty in reactor design and scale-up. The major problem for the PBR design and scale-up is light: its availability and utilization efficiency. It has been found that hydrodynamics and mixing can greatly enhance the biomass productivity by improving the light use efficiency. However, the local flow characteristics remain unclear, and the mechanism of how hydrodynamics interacts with photosynthesis is not fully understood yet.; The overall objective of this study is to advance the understanding of hydrodynamics' role in the photosynthesis and thus the photobioreactor performance, and to develop a fundamentally based modeling approach for photobioreactor performance evaluation. Two experimental techniques (i.e., Computer Automated Radioactive Particle Tracking - CARPT and Computer Tomography - CT) and the Computational Fluid Dynamics (CFD) technique were applied to study the local flow dynamics in a draft tube airlift column photobioreactor.; Based on the findings of the flow dynamic study, how hydrodynamics interact with photosynthesis was carefully analyzed. The time series of irradiance transferred to the microorganisms were computed, and parameters to quantitatively characterize the irradiance patterns were also proposed. Moreover, a fundamentally based dynamic modeling approach is developed for photobioreactor performance evaluation, which integrates the knowledge of photosynthesis, hydrodynamics, and irradiance.; Finally, Porphyridium sp. was grown in three types of airlift column reactors. The biomass concentrations, multiphase flow dynamics, physical properties, and irradiance distribution of the culturing systems were monitored. Nice agreements between the predictions by the developed dynamic model and the experimental data were achieved, indicating the applicability of the dynamic model in industrial interested condition. |
