At present, large-scale and high-efficiency microalgal cultivation is the key to realizing the technology for carbon capture and storage (CCS) and bioresource recovery. Meanwhile, tubular photobioreactors (PBRs) have great potential for microalgal cultivation due to their high productivity. To improve the mixing performance and flashing-light effect, a novel tube PBR with the inner tube tangential to the outer tube was developed, whose radial aeration pores are situated along the length of the inner tube. The direction of aeration, aeration rate, light/dark cycle period (L/D), light-time ratio, average turbulent kinetic energy (TKE), and degree of synergy between the velocity and direction of the light field in the PBR were optimized by a computational fluid dynamics (CFD) simulation and field synergy theory. The results show that a downwards aeration direction of 30° and an aeration rate of 0.7 vvm are the most conducive to reducing the dead zone and improving the light/dark cycle frequency. Compared to the concentric double-tube PBR, the light/dark cycle frequency and light time of the tangent double-tube PBR increased by 78.2% and 36.2% to 1.8 Hz and 47.8%, respectively, and the TKE was enhanced by 48.1% from 54 to 80 cm²·s⁻². Meanwhile, field synergy theory can be extended and applied to the design of tubular microalgae PBRs, and the average synergy of the light and velocity gradients across the cross-section increased by 38% to 0.69. The tangential inner tube aeration structure generated symmetrical vertical vortices between the light and dark areas in the PBR, which significantly improved the mixing performance and flashing-light effect. This novel design can provide a more suitable microenvironment for microalgal cultivation and is promising for bioresource recovery applications and improving the yield of microalgae.

中文翻译：

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具有充气切线内管的新型管状微藻光生物反应器的仿真：混合性能和闪光效果的改进。

目前，大规模高效的微藻栽培是实现碳捕集与封存（CCS）和生物资源回收技术的关键。同时，管状光生物反应器（PBRs）由于其高生产率而具有巨大的微藻培养潜力。为了提高混合性能和闪光效果，开发了一种新颖的PBR，其内管与外管相切，其径向通气孔沿内管的长度分布。优化了PBR中的曝气方向，曝气速率，明/暗周期（L / D），光时比，平均湍动能（TKE）以及光场速度和方向之间的协同程度通过计算流体动力学（CFD）模拟和场协同理论。结果表明，向下的30°曝气方向和0.7 vvm的曝气速率最有利于减少死区并改善明/暗循环频率。与同心双管PBR相比，正切双管PBR的明/暗循环频率和亮时间分别增加了78.2％和36.2％至1.8 Hz和47.8％，而TKE相对于同心双管PBR则提高了48.1％。 54至80厘米² ·s ^-2。同时，场协同理论可以扩展到管状微藻PBR的设计中，并且整个截面的光和速度梯度的平均协同作用增加了38％，达到0.69。切向内管曝气结构在PBR的明暗区域之间产生对称的垂直涡流，从而显着提高了混合性能和闪光效果。这种新颖的设计可以为微藻培养提供更合适的微环境，并有望用于生物资源回收应用并提高微藻的产量。