Dynamic Modelling and Simulation of Liquid Food Process Lines

Abstract

In the present work a dynamic model library of components for process lines was developed. The analysis addressed characteristic aspects of liquid food process lines, and new models were developed for fluid transitions, dispersion, mixing zones and first-order chemical reactions in pipes and heat exchangers. The computational efficiency and accuracy of the models were analysed. It was demonstrated that classical models of fluid propagation in process lines could be combined with modern numerical methods to obtain computationally efficient dynamic models for the simulation of dispersed convective flow, with and without chemical reactions.



In particular it was demonstrated that a transport delay model was well suited for the simulation of thermal transients due to fluid transitions in heat exchangers. It was shown that the model could be extended to account for dispersion with a method that, although classical in approach, enables a certain freedom in the choice of degree of discretization depending on the demand for accuracy vs. computational speed. Further extension of the model with first-order chemical reactions to account for microbial deactivation was demonstrated.



The usefulness of the dispersed-convection model to predict the extent of mixing zones and the amount of product rejects in continuous processing was demonstrated. The relevance concerning product traceability is discussed and the concept ?fuzzy traceability? introduced.

Abstract (Swedish)

Popular Abstract in Swedish

I följande arbete har ett dynamiskt modellbibliotek av komponenter utvecklats för processlinjer. Analysen inriktades mot karakteristiska aspekter för processlinjer för flytande livsmedel, och nya modeller utvecklades för byte av fluidum, dispersion, blandfaser och första ordningens kemiska reaktioner i rör och värmeväxlare. Modellernas beräkningseffektivitet och noggrannhet analyserades. Det visades att klassiska modeller av fluiders propagering i processlinjer kunde kombineras med moderna numeriska metoder för att uppnå beräkningseffektiva dynamiska modeller för simulering av dispergerat konvektivt flöde, med och utan kemiska reaktioner.



Speciellt demonstrerades att en transportfördröjningsmodell väl lämpar sig för simulering av termiska transienter orsakad av byte av fluidum i värmeväxlare. Det visades att modellen kunde kompletteras med dispersion genom en metod som, trots klassisk metodik, möjliggör viss frihet i val av diskretisering beroende på behovet av noggrannhet visavi beräkningshastighet. Ytterligare komplettering av modellen med första ordningens kemiska reaktioner för simulering av mikrobiell deaktivering demonstrerades.



Dessutom demonstrerades användbarheten av modellen för dispergerat konvektivt flöde i syfte att prediktera storlek på blandfaser och mängd bortsorterad produkt vid kontinuerlig produktion. Relevansen med avseende på spårbarhet diskuteras och konceptet ?fuzzy spårbarhet? införs.

• author: Skoglund, Tomas
• supervisor: Petr Dejmek
• opponent: Professor de Prada Moraga, César, Dpt. of Systems Engineering and Automatic Control, Universidad de Valladolid, c/ Real de Burgos s/n.
• organization: Department of Food Technology, Engineering and Nutrition
• publishing date: 2007
• type: Thesis
• publication status: published
• subject: Food Engineering
• keywords: Process lines, Dynamic model, Microbial deactivation, Data- och systemvetenskap, computer technology, Systems engineering, Fuzzy traceability, Traceability, Thermal engineering, termodynamik, Termisk teknik, applied thermodynamics, Chemical technology and engineering, Kemiteknik och kemisk teknologi, Food and drink technology, Heat exchanger, Dispersion, Fluid property transition, Liquid food, Dynamic simulation, Livsmedelsteknik
• pages: 124 pages
• defense location: Lecture Hall B, Center of Chemistry and Chemical Engineering, Getingevägen 60, Lund, Sweden
• defense date: 2007-06-12 13:00:00
• ISBN: 978-91-976695-1-1
• language: English
• LU publication?: yes
• additional info: Tomas Skoglund, Karl-Erik Årzén and Petr Dejmek. 2006. Dynamic object-oriented heat exchanger models for simulation of fluid property transitions International Journal of Heat and Mass Transfer, vol 49 pp 2291-2303. ELSEVIER; Tomas Skoglund and Petr Dejmek. 2007. Adynamic object-oriented model for efficient simulation of fluid dispersion in turbulent flow with varying fluid properties Chemical Engineering Science, vol 62 pp 2168-2178. ELSEVIER; Tomas Skoglund and Petr Dejmek. . A dynamic object-oriented model for efficient simulation of microbial reduction in dispersed turbulent flow pp 20. (submitted); Tomas Skoglund and Petr Dejmek. . Fuzzy traceability - A process simulation derived extension of the traceability concept in continuous food processing pp 8. (submitted)
• id: fd97c2cc-3560-499e-bde4-3da9f8fc2611 (old id 548692)
• date added to LUP: 2016-04-04 11:15:44
• date last changed: 2018-11-21 21:03:42