Effects of cross baffles on the flow of the microalgae in raceway photobioreactors

•Cross baffle enhance fluid mixing in raceway photobioreactor.•Cross baffle reduce mixing time and enhance mass transfer coefficient of runway photobioreactor.•The optimized cross baffle can significantly increase the biomass of chlorella vulgaris. This paper focuses on the increase in the mixing degree of the fluid in the raceway photobioreactors and puts forward a new type of cross baffles. Computational fluid dynamics is adopted to study the fluid mechanics and the trajectory of the microalgae in the raceway photobioreactors. The research result indicates that cross baffles, compared with other baffles, bring better distribution of the vortex flow, higher vorticity, and a more favorable proportion of the dead zone. In addition, it is found that in the raceway photobioreactors with cross baffles, the light-dark cycle is reduced by 18%, 5.9%, and 7.3% respectively than that of the raceway photobioreactors with other three types of baffle plates. Meanwhile, the outdoor cultivation experiment of Chlorella proves that the optimized cross baffle which can enhance the mixing effects is able to increase the biomass concentration of the RWP by 11.1%. [Display omitted]