Energy efficient design of high depth raceway pond using computational fluid dynamics

Open Raceway Ponds (RWP) are at present the most used large-scale reactors for microalgae culture. RWPs are extensively applied technology for algae mass cultivation although the scientific design of these ponds remains a major hurdle in this field. An erroneous design result in the presence of dead zones where the fluid flow is sluggish and non-uniform velocity throughout the pond actualized negative impact on algae growth, further these designs are energy inefficient. A dominant component of energy loss is the energy required to circulate the fluid around the raceway, particularly at the 180° bends. This paper investigates effects of various ratio of channel length to width (L/W) and position of side entry axial flow impeller (distance from the bottom of the tank) on the hydrodynamics in RWP. To curtail the dead zone, power consumption, shear stress and enhance surface renewal, the different designs of RWPs with flow deflectors and different types of central baffles were investigated by using Computational Fluid Dynamics (CFD). The CFD model was validated through Particle Image Velocimetry (PIV) tests. A feasible move headed for energy optimization and thus reduction in operational cost can be established through a better understanding of the mixing phenomena by CFD simulations.