Testing and Simulation Approaches for Single-Use Bioreactor Scale-up

Calculation of energy dissipation, shear rate, blend-time, and mass transfer (e.g., of oxygen and carbon dioxide) at small and large scale can be used to assess how critical parameters change with scale (because it is impossible to hold all parameters constant) and how these critical parameters can be managed by changing other design variables (e.g., hardware configuration). Case study: comparing a small-scale single-use bioreactor with a large-scale stainless-steel bioreactor As another example, a multi-pronged approach can also be used to (i) demonstrate equivalent performance between traditional alloy and proposed single-use equipment, (ii) validate CFD simulation, and (iii) extend performance projections to intermediate and full-scale equipment. [...]if experience indicates an improved product yield at lower shear rate or shorter blend time, one can change impeller selection and operating speed with scale to achieve the desired result while maintaining P/V and OTR. Because the mass transfer coefficient is a function of both agitator energy input and gas velocity, this side-by-side comparison shows that air sparge rate must be increased as scale decreases to achieve the equal OTR.