Numerical simulation on optimizing flow field and flashing-light effect in jet-aerated tangential swirling-flow plate photobioreactor to improve microalgal growth

To reduce the dead zone in photobioreactors, strengthen the flashing-light effect and promote microalgal growth, computational fluid dynamics (CFD) simulation was employed to optimize the turbulent kinetic energy (TKE) and light/dark circle frequency in jet-aerated tangential swirling-flow plate (JTSP) photobioreactor. The tangential jets created a large clockwise vertical vortex and several secondary vortices in the JTSP photobioreactor, which significantly reduced the proportion of the dead zone and increased the light/dark circle frequency. Compared with the traditional airlift plate photobioreactor, the dead zone of the JTSP photobioreactor was reduced by 56.9%, whereas TKE increased by 35.5% to 18.2 cm(2)/s(2). Meanwhile, the light/dark circle frequency increased by 11.4-fold to 0.13 Hz, and the light time ratio increased by 17.1-fold to 33.4%. This led to a 46.5% increase in the biomass dry weight and 54.8% increase in the CO2 fixation rate in the JTSP photobioreactor. (C) 2019 Elsevier Ltd. All rights reserved.