Twisted tubular photobioreactor fluid dynamics evaluation for energy consumption minimization

Abstract

This paper discusses a new tubular PhotoBioReactor (PBR) called twisted tubular PBR. The geometry of a twisted tubular PBR induces swirl mixing to guarantee good exposure of microalgae to Light-Dark (LD) cycles and to the nutrients and dissolved CO2. The paper analyses the energy uptake for fluid transport through the twisted tubular PBR. The analysis is based on a comparison between the twisted tubular PBR and other tubular PBRs that have swirl mixing generation. Four types of tubular PBRs are simulated using Computational Fluid Dynamics (CFD); these results are used to evaluate energy consumption and mixing conditions. Swirl number is used to evaluate mixing conditions and swirl flow. On the other hand, microalgae particles performing undulatory motion are evaluated with Discrete Fourier Transform (DFT). Characteristics of the microalgae frequency in the swirl mixing depend on average flow velocity. Results show that the new twisted tubular PBR demands less energy for pumping than the other tubular PBRs that have swirl motion; providing an important step towards the construction of a highly efficient tubular PBR.