A novel method using CFD to optimize the inner structure parameters of flat photobioreactors

Abstract

The relationship between growth rates of algae and structure parameters of closed flat-panel photobioreactors was investigated. Ad/Ar (cross-section area of the downcomer/cross-section area of the riser), h 0 (clearance from the upper edge of the baffles to the water level), and h 1 (clearance from the lower edge of the baffles to the bottom of the reactor) were selected as the inner structure parameters. CFD (Computational Fluid Dynamics) was used to simulate the hydrodynamic parameter (TKE) d (turbulence kinetic energy of the downcomers) and the secondary parameters ε (ratio between td and tc), tc (cycle time), and DZ (dead zones), which were deduced from the hydrodynamic parameters mentioned above. The effects of (TKE) d, ε, tc, DZ, and the inner structure parameters on cell growth of Isochrysis galbana 3011 were analyzed using data collected in 15-L airlift flat-panel photobioreactors. A model was developed to predict algae cell growth based on these inner structure parameters, thereby providing a new method for photobioreactor optimization. Validity of the model was confirmed by experimental data of I. galbana 3011 cultured in 15-L and 300-L photobioreactors, respectively. Finally, the prospect of applying CFD to photobioreactor optimization was discussed.

Improving performance of flat-plate photobioreactors by installation of novel internal mixers optimized with computational fluid dynamics

“…The cell concentration in type-2 reactor reached 0.84 g L À1 at 58 h of cultivation, which was 5.0% more than that obtained in type-1 reactor, which indicted a higher top clearance did enhance the performance of the novel PBR. Yu et al (2009) also attained the similar conclusion by culturing the Isochrysis galbana in 15-L flat-plate PBRs with different top clearances. The maximum cell concentration in type-3 reactor recognized theoretically as the optimal reactor was 0.89 g L À1 , which was 11.3% higher than that in type-1 reactor without optimization.…”

“…This is could be beneficial for cells to obtain more illumination. Yu et al (2009) also observed that a higher A d /A r of flat-plate PBRs led to greater mixing intensity. Besides, the faster U r in the downcomers can increase the L/D cycle frequency, which was considers as a significantly important factor to increase growth of microalgae.…”

Microalgal bioreactors: Challenges and opportunities

“…By using principles of fluid dynamics the cost, workload, and design period can all probably be reduced. Yu et al recently applied CFD methods to the inner structure parameter optimization of an airlift flat‐panel photobioreactor through a volume increase from 15 L to 300 L 102. A model was developed to predict algal cell growth and then experimentally confirmed.…”

Aeration and mass transfer optimization in a rectangular airlift loop photobioreactor for the production of microalgae

“…The RALPBR can be classified into three categories according to the geometric structures, i.e., a riser and a downcomer type (Reyna-Velarde et al, 2010), two risers and a downcomer type (Kilonzo et al, 2006), and a riser and two downcomers type (Yu et al, 2009). Before selecting a specific type, one should take many factors into consideration, for instance, characteristics of PBRs, operating costs, maintenance and cleaning, and so on.…”