Single-Mode Cavity Resonator in Dielectric Heating for Rice Weevil (Sitophilus oryzae) Control
Date Issued
2010
Date
2010
Author(s)
Yang, Wen-Tse
Abstract
An application of electromagnetic energy to rice disinfestation was implemented in this study by using a microwave single-mode cavity resonator. Rice weevil (Sitophilus oryzae), the target insect to be controlled, was suggested to show higher characteristic in dielectric loss factor so that differential heating was possible to be achieved in its host medium. To evaluate the intra-kernel temperature raise in the time-varying electric field, the 3D simulations of microwave model were constructed and computed by using commercial finite element method software COMSOL Multiphysics 3.5a with electromagnetic wave module and conduction heat transfer module to simulate the dielectric heating process. Using a single mode resonator to excite high electric field intensity in the center line of the resonator, high efficiency heating without attenuation is achievable. Results of the analysis showed that rice grain infested with a single weevil reached the literature lethal temperature of 60℃ for 5 seconds, having slight selective heating effect in the simulation models. While 56.8℃ was measured for the average experimental value during the same heating time, our thermal-mortality kinetics model found only 3 ~ 4 seconds at 51℃ was necessary for the adult rice weevil to reach 100 % mortality. Other results suggest that rice grain orientation parallel to the resonator axis has better heating efficiency than perpendicular condition; therefore, the heating uniformity might be improved by rotation under continuous feed-in situation. The finding from this study provides information in dielectric heating application to rice weevil control in rice which might help to deign a more energy-saving and time-saving electromagnetic energy treatment.
Subjects
Microwave heating
Sitophilus oryzae
FEM method
Dielectric property
Type
thesis
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