4. Conclusions
RF heating uniformity of wheat kernels was investigated by using a
computer simulation model, in which thefinite element based software
COMSOL Multiphysics was employed to build the model. The model
was validated and applied to study the influence of sample size and
vertical position on TUI for RF dielectric heating and to determine the
position of cold and hot spots in the samples. The study results showed
that RF heating uniformity closely related to sample size and vertical
position. For samples with small size, samples placed on either bottom
electrode or closed to top electrode would achieve better RF heating
uniformity; while for large size of samples, placed in the middle position
between the two parallel electrodes achieved better temperature
uniformity. Corner heating was also observed where hot spots located
at the corner of samples in cuboid shape. Cold spots located at the center
of the top or bottom layers when the samples were placed at the middle
position between the two parallel electrodes, at the center of top layer
and bottom layer when samples were placed on the bottom electrode
and close to top electrode, respectively. The current study also found
that sample in large size has better temperature uniformity than that
of sample in small size; this indicates that it is better for RF energy to
treat bulk material, which would definitely make RF energy more
suitable for industry application. Results generated from this study are
valuable for exploring the potential of using RF energy to extend the
4. ConclusionsRF heating uniformity of wheat kernels was investigated by using acomputer simulation model, in which thefinite element based softwareCOMSOL Multiphysics was employed to build the model. The modelwas validated and applied to study the influence of sample size andvertical position on TUI for RF dielectric heating and to determine theposition of cold and hot spots in the samples. The study results showedthat RF heating uniformity closely related to sample size and verticalposition. For samples with small size, samples placed on either bottomelectrode or closed to top electrode would achieve better RF heatinguniformity; while for large size of samples, placed in the middle positionbetween the two parallel electrodes achieved better temperatureuniformity. Corner heating was also observed where hot spots locatedat the corner of samples in cuboid shape. Cold spots located at the centerof the top or bottom layers when the samples were placed at the middleposition between the two parallel electrodes, at the center of top layerand bottom layer when samples were placed on the bottom electrodeand close to top electrode, respectively. The current study also foundthat sample in large size has better temperature uniformity than thatof sample in small size; this indicates that it is better for RF energy totreat bulk material, which would definitely make RF energy moresuitable for industry application. Results generated from this study arevaluable for exploring the potential of using RF energy to extend the
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