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Convective Mass Transfer in Large Porous Biocatalysts: Plant Organ Cultures
Author(s) -
Prince C. L.,
Bringi V.,
Shuler M. L.
Publication year - 1991
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp00008a015
Subject(s) - mass transfer , convection , drag , reynolds number , chemistry , mechanics , oxygen , porous medium , diffusion , flow (mathematics) , chemical engineering , thermodynamics , porosity , chromatography , physics , turbulence , organic chemistry , engineering
The importance of convective contributions to the total rate of mass transfer into porous biological catalysts has been insufficiently appreciated. For liquid systems, diffusion within large particles is generally slow relative to reaction, especially for sparingly soluble nutrients such as oxygen. We report experimental evidence demonstrating that oxygen consumption within porous root culture clumps is normally restricted by the rate of convective mass transfer within the clump. Increasing liquid flow rates around spheres of entangled rootlets induces higher rates of internal convective mass transfer and gives rise to increased total rates of oxygen consumption. Minimum external velocities for full nutrient sufficiency on the interior are not predicted well by creeping external flow models and, especially for larger biocatalysts, inertial effects must be taken into account. For higher Reynolds number external flow, form drag may be used to suggest the dependence of internal convection on external flow conditions. The minimum external liquid velocity for nutrient sufficiency is then seen to be a strong and unpredictable function of catalyst size and catalyst density. Implications for organ culture reactor design are discussed.