CFD application on photobioreactor design for microalgae cultivation

Biodiesel is urgently needed to alternate transportation fuel against fossil energy depletion and carbon dioxide reduction. The bio-diesel from soybean or corn, etc. can be confronted with food crisis. Microalgae, therefore, has recently been spotlighted as a new source because it has high oil lipid with fast growth rate. Photobioreactor (PBR) can be used for microalgae cultivation against changeable outside weather conditions and insufficient land availability. The internal environmental conditions can be controlled artificially in PBRs. In this study, computational fluid dynamics (CFD) was used to make an optimum design of bubble-column PBR for mass cultivation of the microalgae against field limitations. A three dimensional CFD model based on the multi-phase model was initially validated by bubble movement, and independent tests in mesh and time step. A new evaluation method of mixing efficiency in the PBRs was developed by tracking the movement of particles in the PBRs connected with the growth model according to the light intensity. Various types of PBRs were compared quantitatively with consideration of a microalgae growth model adaptable for the CFD model. The result can be used for scaling up the PBR for mass cultivation of microalgae to make a year-roundly stable biodiesel production.