2020/10/19 by Olivier Bernard, Bernard, Olivier, Liu‐Di Lu +3 · 1 citation
Energy · Physics and Astronomy · Environmental Science · #Algal biology and biofuel production #Advanced Thermodynamics and Statistical Mechanics #Aquatic Ecosystems and Phytoplankton Dynamics
paper · pdf · doi:10.48550/arxiv.2010.09247
This paper focuses on mixing strategies to enhance the growth of microalgae\nin a raceway pond. The flow is assumed to be laminar and the Han model\ndescribing the dynamics of the photosystems is used as a basis to determine\ngrowth rate as a function of light history. A device controlling the mixing is\nassumed, which means that the order of the cells along the different layers can\nbe rearranged at each new lap according to a permutation matrix P. The order of\ncell depth hence the light perceived is consequently modified on a cyclical\nbasis. The dynamics of the photosystems are computed over K laps of the raceway\nwith permutation P. It is proven that if a periodic regime is reached, it will\nbe periodic immediately after the first lap, which enables to reduce\nsignificantly the computational cost when testing all the permutations. In view\nof optimizing the production, a functional corresponding to the average growth\nrate along depth and for one lap is introduced. A suboptimal but explicit\nsolution is proposed and compared numerically to the optimal permutation and\nother strategies for different cases. Finally, the expected gains in growth\nrate are discussed.\n