(203f) Multiphysics Simulation of an Internal Loop Airlift Photobioreactor for Microalgae Cultivation

Microalgae can be used for the production of high quality single cell protein. The cultivation of microalgae can be accomplished in a photobioreactor where the requisite culturing conditions such as light intensity, CO₂, O₂, pH, and temperature, are satisfied [1,2]. In order to optimize the reactor geometrical configurations for achieving the maximal biomass yield, a multiphysics model is developed in this study which integrates the hydrodynamics, radiative transfer and algal growth kinetics using computational fluid dynamics (CFD) simulations.

Transient, two-dimensional, Eulerian Euler-Euler approach with the standard k-Ɛ turbulence model is developed for studying the flow dynamics of the gas-liquid or gas-liquid-solid flows in a concentric-tube internal loop airlift reactor (see Fig. 1) using ANSYS Fluent. The radiative transfer model approximates the light intensity as a function of the medium depth and the dry biomass concentration, based on experimentally measured data. The microalgae cell growth kinetic model is developed based on experimentally measured data which considers the effect of light intensity on the algal growth rate. Based on the developed multiphysics model, we evaluate the growth of microalgae as affected by the reactor geometrical parameters, particularly the reactor scale. This work paves the way for developing a low-cost, high-production, pilot-scale modular photobioreactor system suitable for commercial deployment.

References:

[1] J. Pruvost, F. L. Borgne, A. Artu, J. Cornet, J. Legrand, Industrial photobioreactors and scale-up concepts, in: Advances in Chemical Engineering, Vol. 48, 2016, pp. 257–310.

[2] L.-L. Zhuang, D. Yu, J. Zhang, F.-F. Liu, Y.-H. Wu, T.-Y. Zhang, G.-H. Dao, H.-Y. Hu, The characteristics and influencing factors of the attached microalgae cultivation: a review, Renewable and Sustainable Energy Reviews 94 (2018) 1110–1119.