With the rapid growth of pharmaceutical and biotechnology industry, stirred tank bioreactors have received much attention due to simple design, easy control of operating conditions, and low operating cost. In the development of commercial processes, however, a transition from laboratory to industrial scale faces great challenges because many properties related to size change nonlinearly as a system increases. In this context, along with an understanding of fluid dynamics, application of an efficient method for scale-up is critical for designing successful industrial process. Particularly in cell cultivation processes, it is important to evaluate the oxygen transfer and viscous properties of liquid medium. In the present study, the effect of various key operating variables such as agitation rate and aeration rate, impeller diameter, and bioreactor working volume for different impellers on the volumetric mass transfer coefficient (k_La) have been investigated in a stirred tank bioreactor for cultivating Escherichia coli BL21. It was found that the k_La tends to increase with the operating variables except the bioreactor working volume. Among the tested impellers, the pitched blade was observed to be most promising because of relatively higher k_La but less shear force owing to its low power number. It was also found that the liquid medium with E. coli behaves as a Newtonian liquid. Compared to conventional designs of Rushton turbines, dislocated Rushton turbine was found to deliver higher k_La. Finally, using dimensional analysis, the k_La for different impeller configurations was correlated in the form of dimensionless groups, suggesting that this approach can be used for predicting k_La in different scales of stirred tank bioreactors.

随着制药和生物技术行业的快速发展，搅拌釜式生物反应器因其设计简单，操作条件易于控制以及运行成本低而备受关注。但是，在商业流程的发展中，从实验室到工业规模的转换面临着巨大的挑战，因为随着系统的增加，许多与尺寸相关的特性会非线性变化。在这种情况下，除了对流体动力学的理解之外，应用有效的放大方法对于设计成功的工业过程至关重要。特别是在细胞培养过程中，重要的是评估液体培养基的氧转移和粘性。在本研究中，各种关键操作变量（如搅拌速率和通气速率，叶轮直径，已经在用于培养大肠杆菌BL21的搅拌槽生物反应器中研究了k _L a）。发现除了生物反应器的工作体积以外，k _L a倾向于随操作变量而增加。在经过测试的叶轮中，人们发现变桨叶片最有前途，因为其相对较高的k _L a，但由于其低功率数而剪切力较小。还发现具有大肠杆菌的液体介质表现为牛顿液体。与常规设计的Rushton涡轮机相比，错位的Rushton涡轮机可提供更高的k _L a。最后，使用尺寸分析，将不同叶轮配置的k _L a以无因次组的形式关联起来，这表明该方法可用于预测搅拌釜生物反应器不同规模的k _L a。