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Mixing power, external convection, and effectiveness in bioreactors
Author(s) -
Díaz Mario,
García Ana I.,
García Luis A.
Publication year - 1996
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(19960720)51:2<131::aid-bit1>3.0.co;2-k
Subject(s) - bioreactor , dimensionless quantity , mass transfer , mixing (physics) , reaction rate , dissipation , convection , thermodynamics , chemistry , mass transfer coefficient , fermentation , mechanics , biological system , process engineering , chromatography , physics , biology , catalysis , biochemistry , organic chemistry , quantum mechanics , engineering
The phenomena of mixing and mass transfer of substrates to microorganisms greatly affect the biochemical reactions which take place in fermentation processes. The effect that agitation power has on the observable reaction kinetics involved in beer fermentation has been studied in different types of bioreactors, from laboratory to industrial scale. With this aim in mind, an effectiveness factor, η, is introduced which is defined as the relation between the existing rate of reaction, whichever bioreactor is considered, and the reaction rate in the well‐mixed, and therefore presumably homogeneous, bioreactor with no diffusional limits. The limitation to homogeneously supplying nutrient material to the cells produces a decrease in this effectiveness factor, which has been correlated to the energy dissipation rate with a similar slope to that which appears in an existing correlation in the literature between this energy and the mass transfer coefficient. Additionally, a dimensionless reaction‐convection number, N RC , which is a function of the power input per unit volume, is proposed, which has been appropriately employed in correlating the effectiveness factor for the types of processes in which convection may be the key resistance factor. © 1996 John Wiley & Sons, Inc.