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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
Author(s) -
Büchs Jochen,
Maier Ulrike,
Milbradt Claudia,
Zoels Bernd
Publication year - 2000
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/(sici)1097-0290(20000620)68:6<594::aid-bit2>3.0.co;2-u
Subject(s) - laboratory flask , volume (thermodynamics) , power consumption , viscosity , power (physics) , mechanics , phase (matter) , earthquake shaking table , materials science , chemistry , thermodynamics , engineering , composite material , physics , structural engineering , organic chemistry
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.