Investigating the hydrodynamic performance of carbonation sumps in High Rate Algal Pond (HRAP)raceways using computational fluid dynamics (CFD)

Abstract

The production of microalgae requires carbonation and deoxygenation which is commonly supplied through a sump. This needs to be designed to minimise the energy loss to ensure a high net energy gain from the biofuel. Computational fluid dynamics was used to evaluate different sump designs and flow velocities in terms of energy loss and flow distribution to find the optimum configuration. It was established that increasing the radius of curvature of the corners to 0.1 m and the implantation of one flow deflector resulted in a reduction in hydraulic power of 73% compared to the basic setup. It was apparent that the central baffle resulted in considerable energy loss and when this was removed then a power saving of 95% was possible. There was, however, a much reduced flow around the sump leading to shortened contact time between the gas and fluid which could in turn decrease the carbonation of the fluid. It was also apparent that the use of standard formulas for the calculation of head loss was not applicable.

Acronyms:

• CFD Computational Fluid Dynamics
• HRAP High Rate Algal Ponds

Acknowledgements

Thanks are due to Jose-Luis Mendoza Martin for advice and validating data for experimental raceways and Costantino Manes for help with the numerical modelling.

Financial & competing interests disclosure

This work was supported by the EU FP7 All-Gas Project under grant number 268208 and by a scholarship from the UK”s Engineering and Physical Sciences Research Council, EP/K503150/1.ORCIDEdward Musgrove http://orcid.org/0000-0001-6825-8006