Enhanced solution velocity between dark and light areas with horizontal tubes and triangular prism baffles to improve microalgal growth in a flat-panel photo-bioreactor.

•An horizontal tube baffle was used to enhance flashing light in a flat plate PBR.•Liquid mixing time decreased and mass transfer coefficient increased with baffles.•Increased vertical liquid velocity resulted in a decreased dark–light cycle period.•Enhanced flashing light effect with baffles increased biomass yield by 70%.