ISSN:
0006-3592
Keywords:
Chemistry
;
Biochemistry and Biotechnology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
For the purpose of a rational design for an automatic feedback control system incorporating a porous Teflon tubing sensor in semibatch culture, steady-state mass-transfer characteristics of tubing sensors have been investigated theoretically and experimentally, and also dynamic responses have been studied experimentally. A distributed mathematical model for steady-state diffusion has been solved numerically and its solution has been shown as useful for the sensor design. The overall mass-transfer resistance of radial diffusion has been shown to be the sum of external liquid-film mass-transfer resistance and membrane diffusion resistance. The steady-state experiments using ethanol dissolved in water revealed that its transfer into the tubing was controlled by the molecular diffusion within the tubing-wall membrane. Oxygen transfer from external water into the tubing was shown experimentally to be controlled by the liquid-film resistance outside the tubing. In general, the radial mass transfer of a substance having a small Henry's constant is controlled by the liquid-film resistance.The response of the tubing sensor-detector-recorder system for the stepwise addition of ethanol into the external water could not be represented by a simple combined system of the first-order delay with lag time. The responses depend on the characteristics of the tubing as well as flow rate of the carrier gas, etc., but they were quite excellent in all cases (e.g., 90% in 20 s).
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bit.260231109
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