Bioreactors are of interest for value-upgrading of stranded or waste industrial gases. Reactor intensification requires development of low cost bioreactors with fast gas–liquid mass transfer rate. Here we assess published reactor technology in comparison with a novel downward bubble flow created by a micro-jet array. Compared to known technology, the advanced design achieves higher volumetric gas transfer efficiency (k_La per power density) and can operate at higher k_La. We measure the effect of four reactor heights (height-to-diameter ratios of 12, 9, 6, and 3) on the gas transfer coefficient k_L, total interfacial area a, liquid residence time distribution, energy consumption, and turbulent hydrodynamics. Leading models for predicting k_L and a are appraised with experimental data. The results show k_L is governed by “entrance effects” due to Higbie penetration dominate at short distances below the micro-jet array, while turbulence dominates at intermediate distances, and finally terminal rise velocity dominates at large distances. © 2017 American Institute of Chemical Engineers AIChE J, 2017

中文翻译：

---

向下的微气泡流的化学流体力学，用于强化气源生物反应器

对于滞留或废弃工业气体的价值提升，生物反应器是令人感兴趣的。反应器强化需要开发具有快速气液传质速率的低成本生物反应器。在这里，我们与微喷射器阵列产生的新型向下气泡流相比，评估了已发表的反应堆技术。与已知技术相比，先进的设计实现了更高的体积气体传输效率（每功率密度k _L a），并且可以在更高的k _L a下运行。我们测量了四个反应器高度（高径比为12、9、6和3）对气体传输系数k _L，总界面面积a，液体停留时间分布，能量消耗和湍流流体动力学的影响。预测k _L的领先模型和a均经过实验数据评估。结果表明，k _L受“入口效应”的影响，这是由于Higbie穿透在微射流阵列下方的短距离内占主导地位，而湍流在中距离处占主导地位，最后终端上升速度在远距离处占主导地位。©2017美国化学工程师学会AIChE J，2017