The use of numerical simulation as a cognitive tool for studying the microwave drying of softwood in an over-sized waveguide

A previously developed mathematical model, which uses a comprehensive two-d imensional heat and mass transport code coupled with a three-dimensional co de for resolving Maxwell's equations in the time domain, will be used to in vestigate numerous aspects of the microwave enhanced convective drying of s oftwood in an over-sized waveguide. At first, in order to highlight the pre dictive capabilities of the developed model, comparisons will be made betwe en theory and experiment for spruce heartwood. It will be shown that the mo del is able to identify most of the important heat and mass transfer phenom ena that arise throughout the drying process. After validation of the numer ical simulation results, the work focuses on using the model as a cognitive tool for investigating important issues for closed microwave systems which include the effect of varying the sample dimensions and changing the locat ion of the material within the applicator. Finally, a study will be present ed that compares the overall drying kinetics generated within two different types of applicator designs. The first design uses a wave-trap located at the end of the waveguide to prevent reflected energy from back-propagating into the over-sized section of the guide, while the second design uses a sh ort-circuit plane to ensure that this reflected energy is back - propagated towards the material. The advantages and disadvantages of these two design s will be deliberated.