Modeling and Simulation of Photobioreactors with Computational Fluid Dynamics—A Comprehensive Review

Abstract

Computational Fluid Dynamics (CFD) have been frequently applied to model the growth conditions in photobioreactors, which are affected in a complex way by multiple, interacting physical processes. We review common photobioreactor types and discuss the processes occurring therein as well as how these processes have been considered in previous CFD models. The analysis reveals that CFD models of photobioreactors do often not consider state-of-the-art modeling approaches. As a comprehensive photobioreactor model consists of several sub-models, we review the most relevant models for the simulation of fluid flows, light propagation, heat and mass transfer and growth kinetics as well as state-of-the-art models for turbulence and interphase forces, revealing their strength and deficiencies. In addition, we review the population balance equation, breakage and coalescence models and discretization methods since the predicted bubble size distribution critically depends on them. This comprehensive overview of the available models provides a unique toolbox for generating CFD models of photobioreactors. Directions future research should take are also discussed, mainly consisting of an extensive experimental validation of the single models for specific photobioreactor geometries, as well as more complete and sophisticated integrated models by virtue of the constant increase of the computational capacity.

Comprehensive Computational Model for Coupled Fluid Flow, Mass Transfer, and Light Supply in Tubular Photobioreactors Equipped with Glass Sponges

“…As existing models of complete PBR are highly differing in the assembly of the multiphysics simulation modules [4], a direct comparison of results is hardly possible. However, the present model recovers isolated key results from reference experiments.…”

“…When designing such PBR with the help of computer simulations, the increased complexity in the light pattern cannot be met by the popular Lambert-Beer-based simulation models. Instead, new powerful simulation tools are needed [4] that are able to consider absorption and scattering in the prediction of general light transport in volume and thus help to speed up the design of novel, more efficient, and low-cost PBR. In addition to the improved light pattern in the reactor, higher mixing rates cause the algae to experience more uniform conditions throughout the reactor geometry.…”

Efficient Production of Microalgal Biomass—Step by Step to Industrial Scale

“…The typical linear flow rate in tubular bioreactors is 0.3-0.5 m•s −1 [22]. Increased cell density in culture can affect the culture medium's properties, including gas retention, but the nature of these changes is not clear [23]. In vertical tubular photobioreactors, large gas bubbles rising rapidly can direct smaller bubbles towards the walls.…”

Structured population balances to support microalgae-based processes: Review of the state-of-art and perspectives analysis

“…They provide a more accurate tool to evaluate break-up and coalescence of bubbles in the photobioreactor, which can be important when the specific-area of the gas-liquid interface needs to be accurately evaluated as related to mass transfer phenomena. On the other hand, the bubbles size and distribution could play also a role in light transfer, hydrodynamics, and potentially heat transfer [15] .…”