Study On The Modeling And Optimizing Simulation Of Light-Algae Bioreactor In Controlled Ecological Life Support System

The material security for astronaut life activities is provided in Controlled Ecological Life Support System(CELSS) by achieving the recycling of material and energy in limited closed space. Microalgae has rich nutrients and the advantages of efficient absorbing carbon dioxide to produce oxygen, rapid growing and easy controlling, therefore, microalgae can be cultivated in Light Algae Bioreactor(LABR)to provide oxygen and ideal food for astronauts in CELSS. Duing to the particularity of the space environment, it is difficult to study the experimental culturation of microalgae in space environment on the ground. So it is of great importance in studying on the modeling and optimizing simulation of Light Algae Bioreactor in Controlled Ecological Life Support System.Firstly, it is in this paper that a volume of 10 L flatbed LABR was study, and the bioreactor mathematical simulation models were established by analyzing the relationship between the light intensity, temperature, nutrient concentration, liquid oxygen, p H and the microalgae growth processes based on the MATLAB/simulink software. By comparing with the existing experimental data, the feasibility of the model was verified.Secondly, on the basis of the established model, the spirulina biomass reference values was set up as the step and square wave signal, the LABR system was optimized and controlled by using PID controller and fuzzy controller, the advantages and disadvantages of the two controllers were compared by analyzing the simulation result of spirulina biomass and the main effect factor in LABR.Finally, from the view of nutrient composition for astronaut, two kinds of microalgae were screened to mixed culture in LABR, and its mathematical simulation model was established. According to the function of LABR in CELSS, the People Microalgae Controlled Ecological Life Support System was established in this paper.The study results showed that: the mathematic simulation model of LABR thatestablished in MALAB was verified; fuzzy controller that used for nonlinear control can better optimized the system under the control process of LABR by comparing with PID controller; from the mathematical simulation model of LABR in which two kinds of microalgae were mixed culture, it is concluded that when the temperature is30℃and light intensity is 150μmol/m2·s, chlorella and spirulina can be better growth in LABR; through the fuzzy controller continuously controlled the growing of spirulina inoculated with 7.5g of spirulina in the LABR everyday, achieved remove 150 g dry biomass of spirulina from the LABR as the main sources for astronaut nutrients(protein-based).