CFD Simulation of Light Intensity Distribution and Light Energy Absorption in Tank-Photobioreactor

The light intensity distribution and light energy absorption are affected by the microalgae and the bubbles in the photobioreactor (PBR). The discrete ordinate model (DOM) was used to simulate the light distribution affected by gas holdups and bubble sizes in 3 dimensions PBR. The average local volumetric rates of energy absorption (ALVREA) for different bands of light were proposed. The results showed that the light intensity near light tube was higher and the light attenuation was also faster than those without bubbles in reactor. ALVREA was the best in PBR at 3 mm of the bubble diameter and 7. 5% of the gas holdup. Researches on different light bands showed that Chlorella sp. had a greater absorption rate for light at 400-500 nm than any other light band. The results can be used in the design of PBRs and the choice of light system.