微藻柱状式光生物反应器流动特性及结构的数值模拟优化

微藻作为最具潜力的可再生生物质能源，在生物固碳和生物燃料生产领域优势显著，有助于碳达峰、碳中和目标的实现。通过改善反应器曝气装置的性能可以大幅度提高微藻的培养效率，本工作采用数值模拟方法对柱式光生物反应器的球型曝气结构进行了优化。模拟采用欧拉模型，湍流模型选取k-ε模型，研究分析了不同曝气装置条件下气含率、平均液相速度、湍流动能几种参数的变化和光生物反应器内的流场情况。结果表明，曝气装置结构的变化对光生物反应器内的流动特性具有很大的影响，通过曝气装置向反应器内通气，气含率、平均液相速度、湍流动能随着曝气量的增大而增大，随着曝气装置孔径的增大而减小。综合各相关参数得到当总曝气量为1400 mL/min、曝气孔数为50、曝气孔径为30μm时，曝气装置性能最好，此时测得气含率为68.6%，平均液相速度为0.905 m/s，湍流动能为0.149 m²/s²。

Numerical simulation optimization of flow characteristics and structure of microalgae column photobioreactor

As the most potential renewable biomass energy, microalgae has significant advantages in the fields of biological carbon sequestration and biofuel production, which contributes to the realization of carbon peak and carbon neutrality goals. The cultivation efficiency of microalgae can be greatly improved by improving the performance of the aeration device of the reactor. In this work, the spherical aeration structure of the columnar photobioreactor was optimized by numerical simulation. The Euler model and k?ε model were used for the simulation and turbulence model, respectively. The changes of gas holdup, liquid velocity, turbulent kinetic energy, and the flow field in the photobioreactor under different aeration conditions were studied and analyzed. The results showed that the change in the structure of the aeration device had a great impact on the flow characteristics in the photobioreactor. When the aeration device was aerated into the reactor, the gas holdup, liquid velocity, and turbulent kinetic energy increased with the increase of the aeration rate and decreased with the increase of the aeration pore size. According to all relevant parameters, when the total aeration rate was 1400 mL/min, the number of aeration pores was 50, and the aeration pore size was 30 μm, the aerator had the best performance. At this time, the measured gas holdup was 68.6%, the liquid velocity was 0.905 m/s, and the turbulent kinetic energy was 0.149 m2/s2. The numerical simulation provided an effective way to optimize the aeration structure parameters, which benefited the photobioreactor design for microalgae cultivation and sewage treatment associated with CO2 fixation.