Thermodynamic characterization and dynamic simulation of a micro algae air lift photobioreactor

Micro algae production as a source of fatty biomass that can be used to produce biofuels is a promising alternative that needs to be thoroughly evaluated. The tendency to increase production and energy content and to reduce water usage has had an impact in the development of photobioreactors, due to the versatility of this equipment to control and optimize the production parameters. This system requires an adequate scheme for monitoring and controlling the variables such as temperature, light intensity, carbon dioxide and oxygen supply, in order to guarantee the micro algae growth. This paper presents a control strategy for algae growth in an airlift photobioreactor. A thermodynamic characterization was performed and the dynamic behavior of the system is modeled for system analysis and control. A mathematical model is developed using the equations describing the process. A PID controller is set to evaluate the parameters that control algae growth. The results show that the photobioreactor presents a substantial sensitivity to room temperature changes, and this is considered as the main disturbance of the process. For the dynamic characterization a non-linear differential equations-based model was developed, and after tuning a PID controller it was found that the system was robust to changes in ambient conditions.