Modeling of heat and mass transfer in microwave-infrared heating of zucchini

Thesis Type: Doctorate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Food Engineering, Turkey

Approval Date: 2016




The main objective of this study is to develop a finite element model to predict the variation of temperature and moisture content of zucchini during microwave-infrared heating. There is no information in literature about heating of zucchini by using this method. Heat and mass transfer in zucchini heated in microwave and infrared combination oven were modelled by Finite Element method. Microwave power was predicted by using the exact form of Lambert Law and calculating the electric field distribution by Maxwell Equations. Measured temperature at different positions of zucchini and moisture content data were used to verify the models obtained for different microwave and infrared powers. Models based on Lambert Law were determined for the combination of 10, 30 and 50% microwave and 10, 40 and 70% infrared powers for 600 s. These models were in good agreement with the experimental data with an average root mean square error (RMSE) of 5.66 for temperature and 2.52 for moisture content. Microwave power dependency of incident surface power and moisture diffusivity and microwave and infrared power dependency of mass transfer coefficient, which were determined in modeling based on Lambert Law, were empirically modelled. Models based on Maxwell Equations were determined for the combination of 10% microwave and 10, 40 and 70% infrared powers for 100 s. Models fitted well with an average RMSE of 4.15 for temperature and 0.39 for moisture content. Generally, models derived from the Maxwell Equations gave better results of temperature and moisture content than models developed by Lambert Law.