Power consumption in shaking flasks on rotary shaking machines: II. Nondimensional description of specific power consumption and flow regimes in unbaffled flasks at elevated liquid viscosity

Abstract

This article is the second part of a series presenting and modeling the hydrodynamics and specific power consumption in shaking flasks on rotary (orbital) shaking machines. In part I, a new method was introduced that enables the accurate determination of the specific power consumption in shaking flasks. The method was first applied to investigate unbaffled flasks with a nominal volume of ≤1 L at low viscosity. In part II, the results for the specific power consumption of unbaffled shaking flasks at elevated viscosities are investigated after varying shaking frequency, flask size, filling volume, and shaking diameter. The theory introduced in part I is extended to liquids of elevated viscosities using nondimensional equations. With these results, the specific power consumption in unbaffled shaking flasks can now be fully described. For the first time, the phenomenon of the liquid being “out of phase” is observed and described. This occurs at certain operating conditions and is characterized by an increasing amount of liquid not following the movement of the shaking table, thus reducing the specific power consumption. This, of course, has much relevance for practical work with microbial cultures. The phenomenon of being “out‐of‐phase” is described in the form of a newly defined nondimensional phase number (Ph) in analogy to a partially filled, rotating horizontal drum. The Ph can be used to determine reasonable operating conditions for shaking flask experiments when using viscous media, avoiding unfavorable “out‐of‐phase” operation. © 2000 John Wiley & Sons, Inc. Biotechnol Bioeng 68: 594–601, 2000.

Cross-section perimeter is a suitable parameter to describe the effects of different baffle geometries in shaken microtiter plates

“…One effector is elevated viscosity. In this case, out-of-phase conditions are provoked, if the rotating centrifugal force is not strong enough to overcome the viscous forces [16]. A new Phase-Number Ph was defined and concluded that Ph > 1.26 is the relevant constraint for desired in-phase operation [16].…”

“…In this case, out-of-phase conditions are provoked, if the rotating centrifugal force is not strong enough to overcome the viscous forces [16]. A new Phase-Number Ph was defined and concluded that Ph > 1.26 is the relevant constraint for desired in-phase operation [16]. Another reason for out-of-phase conditions are unsuitable high ratios between the maximum diameter of the shaken bioreactors and the shaking diameter of the applied shaker, as shown for non-baffled large shake flasks by Büchs et al [15] and for microtiter plate with round geometry by Kensy et al [17].…”

The components of shear stress affecting insect cells used with the baculovirus expression vector system

“…To gain a measure of the conditions in the shaker flask, the average energy input can be calculated empirically [52,53]: …”

Characterization of hydromechanical stress in aerated stirred tanks up to 40 m3 scale by measurement of maximum stable drop size

“…In submerged fungal fermentations turbulence intensity may interact with morphological behaviour of the fungus [5]. It was shown that volumetric power input in shake flasks is comparable to volumetric power input in stirred fermenters [6,7] for typical operating conditions. Nevertheless, even at comparable levels of volumetric power input pellets grow much larger in shake flask culture compared to cultures in stirred tank reactors because turbulence intensity is much lower than in stirred reactors [8-10].…”