Computational fluid dynamics simulation of mixing characteristics and light regime in tubular photobioreactors with novel static mixers

BACKGROUNDTubular photobioreactors are considered to be important and potential photobioreactors due to their higher photosynthetic efficiency and biomass productivity. In this work the performance of a new tubular photobioreactor with novel static mixers on mixing characteristics and light regime was studied through computational fluid dynamics. RESULTSThe effects of cross-angle of two blades, horizontal spacing, open porosity and hole radius of the novel static mixers on mixing characteristics were investigated to obtain appropriate configurations. Compared with the tubular photobioreactor without static mixers, the tubular photobioreactor with novel static mixers was proved to have strong fluid mixing and significant swirling flow. Average velocity magnitude along the light direction increased by nearly 1000 times and turbulent kinetic energy increased by 1.3 times after adding novel static mixers into the tubular photobioreactor. Additionally, with novel static mixers most cells were promoted to circulate between the light zone and the dark zone. The light/dark cycle frequency was also improved and increased by 85.21% and 95.77% at fluid inlet velocity of 0.3 and 0.4ms(-1), respectively. CONCLUSIONThe simulation results showed the novel static mixers could effectively enhance mixing degree of fluid and increase the light/dark cycle frequency of microalgal cells in tubular photobioreactors. (c) 2014 Society of Chemical Industry