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Scaling oxygen mass transfer in agitated fermentors
Author(s) -
Mooyman Johannes G.
Publication year - 1987
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/bit.260290207
Subject(s) - scaling , mass transfer , volume (thermodynamics) , thermodynamics , mass transfer coefficient , oxygen , isothermal process , volume fraction , aeration , chemistry , mixing (physics) , work (physics) , mechanics , physics , mathematics , geometry , organic chemistry , quantum mechanics
There are many scaling formulas that predict the oxygen mass transfer coefficient as k L · a = constant·(Hp/ V ) α Vs β Exponents α and β frequently are scale dependent themselves. A general formula has been derived from the work of Calderbank, 1 Miller, 2 and Tilton, 3 resulting in k L · a = C 1 ϕ + C 2 log ( Pm / V ) ϕ where ϕ equals the gas‐holdup fraction and Pm / V equals the effective mechanical power input per unit of volume. This formula is consistent with the formula of Westerterp 4 modified by Miller. 2 Gas holdup can be predicted in several ways. Gas‐sparged isothermal expansion power input, used for predicting ϕ, demonstrates that scaling can be done by using either superficial air velocity or volume per volume per minute for aeration. The importance of mixing in replenishing oxygen at the boundary layers of microorganisms will be assessed and compared with the k L · a as the oxygen transfer ratelimiting step.