(203c) Fluid-Dynamic Simulation of a Flat-Panel Bioreactor with Emphasis on Mixing, Mass Transfer and Inorganic CO2 Chemistry

The potential for microalgae to have an impact on direct air capture increases as we better understand the driving mechanisms behind growth and fluid-dynamics in the different cultivation systems [1]. The design and operation of bioreactors affect the photosynthetic process of the microorganisms and effectively contribute to CO₂ capture [2]. Additionally, the biomass produced via growth can become an attractive raw material for the bio-feed/bio-fuel production [3,4]. Despite all these potential advantages, it is important to characterize the influence in growth and mass transfer of the availability of dissolved inorganic carbon, pH, reactor operation among others. This work is two-fold. First, we use computational fluid dynamics (CFD) to simulate the cultivation system, a flat panel bioreactor. We utilize the Euler-Euler multiphase framework from OpenFOAM to characterize the multiphase system including mass, momentum and energy between the gas and the liquid phases [5]. We analyze the impact of sparging system design on mixing and mass transfer by varying orifice distribution in the sparger manifold. Second, we implement the inorganic reaction rates for the CO₂ chemistry and analyze their impact on mass transfer at different growth pH. These trends would help us optimize the design and operation of the bioreactor for effective utilization of CO₂.

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