Master's Dissertation
DOI
10.11606/D.3.2016.tde-12122016-114858
Document
Author
Full name
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2016
Supervisor
Committee
Gut, Jorge Andrey Wilhelms (President)
Ditchfield, Cynthia
Paiva, José Luis de
Title in Portuguese
Modelagem e simulação dinâmica da pasteurização contínua de leite sujeito à incrustação.
Keywords in Portuguese
Dinâmica (Modelagem; Simulação)
Incrustação
Leite
Modelagem matemática
Pasteurização
Tratamento térmico
Abstract in Portuguese
Title in English
Modeling and dynamic simulation of milk continuous pasteurization under fouling.
Keywords in English
Dynamic simulation
Fouling
Lethality
Mathematical modeling
Milk
Pasteurization
Plate heat exchanger
Thermal treatment
Abstract in English
In order to guarantee harmlessness, some processed foods are thermally treated in a continuous process named pasteurization, in which the purpose is to eliminate pathogenic microorganisms, while avoiding sensorial and quality losses. This operation is used in products such as juice, beers, milk and dairy food, pulp, and so on. Mathematical modeling of this process seeks to help its understanding, controlling, and optimization. Thus, the aim of this work was to develop and simulate a model of a continuous process pasteurization, and to conduct the experimental validation of a fouling model in the plates of the heat exchanger plates, without a process controller (PID). The phenomenological modeling was composed by differential energy and material balances, for temperature and lethality, respectively, in the channels, plates, holding tube and its connections of the pasteurizer. It was also developed an empirical fouling model for the product in the heating section. All these models represent a set of first and second order differential equations which were solved by a finite difference method through the gPROMS software. This modeling was used to express the behavior of a laboratory scale plate pasteurizer, with and without fouling, with and without system disturbances and during the equipment startup, in a case study. The simulated data was presented by the unidimensional spatial and temporal distribution of temperature and lethality along the process, and overall heat transfer coefficient profile in the heating section. To validate the fouling model, an experimental test by using a protein solution (similar to cow milk) was conducted. The temperature logging over time was done by various thermocouples inserted in the pasteurizer. All the plates were weighed and photographed before and after the tests to quantify the amount of deposits. From laboratory results, fouling model parameters were adjusted and simulation was performed again. These results were compared to the experiments, being the model validated adequately.