Stenby Andresen, Mette

Det grundlæggende formål med ph.d.-projektet har været at undersøge proces-til-produkt interaktioner i kontinuerte tunnelovne. Arbejdet i projektet har været centreret omkring fem primære målsætninger. Disse omfatter udvikling af en ny eksperimentel pilot plant ovn, matematisk modellering af energi- og massetransport i et småkageprodukt samt evaluering af metoder til kvalitetsbestemmelse af småkager.Pilot plant ovnen er en batchovn specielt bygget til at efterligne kontinuert konvektionsbagning i tunnelovne. Design, konstruktion og validering af ovnen var en del af projektet og er beskrevet i denne afhandling. Ovnen blev succesfuldt valideret mod en 10 m tunnelovn. Udover ovnens evne til at efterligne bagebetingelserne i en tunnelovn er den designet og bygget til brug i forskningsforsøg. Der er derfor lagt stor vægt på at produktet kan følges kontinuert (især vægt og temperatur), samt at processen kan kontrolleres og varieres (luftflow, temperatur og fugtighed). Ovnen er desuden bygget til at fungere uden for det normale procesvindue for den undersøgte type af tunnelovne.En matematisk model der beskriver energi- og massetransport i en småkage er blevet udviklet. Modellen er løst numerisk med en finite element metode. Optimering og validering af modellen blev udført ved brug af eksperimentelle måleresultater fra den nye pilot plant ovn. Bagepladens effekt på fordampning i småkager blev undersøgt gennem forskellige modelleringsopsætninger og sammenligninger med data fra pilot plant ovnen. Undersøgelserne viste at selvom bagepladen ser ud til at mindske fordampningen fra undersiden af småkagen, er det ikke korrekt at antage at den forhindrer al fordampning fra denne overflade.Foruden udviklingen af den nye pilot plant ovn blev en avanceret multi-spektral billedeanalysemetode undersøgt med henblik på kvalitetsbestemmelse af småkager. Metodens evne til at bestemme flere kvalitetsparametre fra et billede var det primære fokus i denne undersøgelse. Metoden viste sig at kunne forudsige både overfladebruning og vandindholdet i de undersøgte småkager.The scope of the PhD project was to increase knowledge on the process-to-product interactions in continuous tunnel ovens. The work has focused on five main objectives. These objectives cover development of new experimental equipment for pilot plant baking experiments, mathematical modeling of heat and mass transfer in a butter cookie product, and evaluation of quality assessment methods.The pilot plant oven is a special batch oven designed to emulate continuous convection tunnel oven baking. The design, construction, and validation of the oven has been part of the project and is described in this thesis. The oven was successfully validated against a 10 m tunnel oven. Besides the ability to emulate the baking conditions in a tunnel oven, the new batch oven is designed and constructed for experimental research work. In the design options to follow the product continuously (especially weight and temperature) and control the process (air flow, temperature, and humidity) are therefore emphasized. The oven is furthermore designed to work outside the range of standard tunnel ovens, making it interesting for manufacturers of both baking products and baking equipment.A mathematical model describing the heat and mass transfer in butter cookies during baking was formulated. The model was solved numerically by the use of a finite element method. Model optimization and validation was successfully carried out against experimental data obtained in the new pilot plant oven. The effect of the baking tray on mass transfer was examined through comparison of different modeling set-ups and experimental data. It was found that while the baking tray is likely to reduce the evaporation from the bottom surface, it is not correct to assume that no evaporation takes place at the covered surface.Parallel to the construction of the pilot oven an advanced multi-spectral imaging method was investigated as a method for quality assessment of butter cookies. The ability of the method to assess multiple quality aspects from one image was the main focus of the study. The system was able to predict both the surface browning and the water content in butter cookies

Online Research Database In Technology

Experimentally supported mathematical modeling of continuous baking processes

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Experimentally supported mathematical modeling of continuous baking processes

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Online Research Database In Technology