Abstract
This paper presents the experiments on mixing efficiency for aerated media for a laboratory stirred bioreactor with a double turbine impeller. The effects of stirrer rotation speed, air volumetric flow rate and stirrer position on the shaft on mixing time for aerated water and simulated broths (CMCNa solutions) were analyzed. Compared to non-aerated broths, the results indicated that the variation of mixing time with the considered parameters is very different, due to the complex flow mechanism of the gas-liquid dispersion, a mechanism which is changed by changing the broth properties or fermentation conditions. Using the Statistics Toolbox of MATLAB some correlations between the mixing time and rotation speed, air volumetric flow rate and stirrer position on the shaft were established. The proposed equations agree well with the experiments, the average deviation being ?9.02%.
Highlights
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⋅V WKH YDULDWLRQ RI PL[LQJ WLPH ZLWK URWDWLRQ VSHHG.
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
Summary
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⋅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
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
