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dc.contributor.authorYe, Zhengcaien_US
dc.date.accessioned2007-05-25T17:46:48Z
dc.date.available2007-05-25T17:46:48Z
dc.date.issued2007-01-10en_US
dc.identifier.urihttp://hdl.handle.net/1853/14641
dc.description.abstractOutbreaks of food-born illness associated with the consumption of unpasteurized juice and apple cider have resulted in a rule published by the U.S. Food and Drug Administration (FDA) in order to improve the safety of juice products. The rule (21 CFR120) requires manufacturers of juice products to develop a Hazard Analysis and Critical Control Point (HACCP) plan and to achieve a 5-log reduction in the number of the most resistant pathogens. Ultraviolet (UV) disinfection is one of the promising methods to reach this 5-log reduction of pathogens. The absorption coefficients of juices typically vary from 10 to 40 1/cm and can be even higher depending on brand and processing conditions. Thin film reactors consisting of two concentric cylinders are suitable for inactivating pathogens in juices. When the two concentric cylinders are fixed, the flow pattern in the gap can be laminar Poiseuille flow or turbulent flow depending on flow rates. If the inner cylinder is rotating, and the rotating speed of the inner cylinder exceeds a certain value, the flow pattern can be either laminar or turbulent Taylor-Couette flow. UV disinfection between concentric cylinders in laminar Poiseuille flow, turbulent flow and both laminar and turbulent Taylor-Couette flow was investigated experimentally and numerically. This is the first systematic study done on UV disinfection between concentric cylinders in all three flow patterns. The present work provides new experimental data for pathogen inactivation in each of the three flow patterns. In addition, the present study constitutes the first systematic numerical CFD predictions of expected inactivation levels. Proper operating parameters and optimum gap widths for different flow patterns are suggested. It is concluded that laminar Poiseuille flow provides inferior (small) inactivation levels while laminar Taylor-Couette flow provides superior (large) inactivation levels. The relative inactivation levels are: laminar Poiseuille flow < turbulent flow < laminar Taylor-Couette flow.
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectUV disinfectionen_US
dc.subjectComputational fluid dynamicsen_US
dc.subjectNumerical modelingen_US
dc.subjectTaylor-Couette flowen_US
dc.subjectTurbulent flowen_US
dc.subjectEscherichia colien_US
dc.subjectYersinia pseudotuberculosisen_US
dc.subject.lcshTaylor vorticesen_US
dc.subject.lcshUltraviolet radiationen_US
dc.subject.lcshDisinfection and disinfectantsen_US
dc.subject.lcshFruit juicesen_US
dc.subject.lcshHazard Analysis and Critical Control Point (Food safety system)en_US
dc.titleUV Disinfection between Concentric Cylindersen_US
dc.typeDissertationen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentChemical Engineeringen_US
dc.description.advisorCommittee Chair: Forney, Larry; Committee Member: Agrawal, Pradeep; Committee Member: Breedveld, Victor; Committee Member: Pavlostathis, Spyros; Committee Member: Pierson, Johnen_US


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