Hydrodynamic Behaviors of the Two-Phase Turbulent Flow of Microalgae Suspension and CO2 in a Photobioreactor for Biofuel Production

Microalgae cultivation in horizontal loop tubular photobioreactors (HLTPs) is more efficient for biofuel production than other methods. It is important to inject CO2 into the photobioreactors to ensure microalgal growth. Due to the complex flow path and bubble arising from CO2 penetration in the tube, turbulence may occur in the flow. In this work, a two-phase turbulent flow of CO2 and microalgae suspension is considered for simulating the flow. An HLTP is used here as the computational domain for our simulation. Besides a slow growth in the culture, we have observed that the flow inside the reactor forms a parabolic shape at the straight portion. However, a wavering flow is found around the U-loop portion of the tube. The pressure is gradually dropped along the arc length. The shear rate is somewhat high and fluctuates within the tube. The effect of the nutrient on growth is also found.