Use of New Applicator Design Ideas to Improve Uniformity of Paper Drying via Microwave Energy

Previous studies of microwave drying of paper have employed slotted waveguides having the slots along the centerlines of the waveguide broad walls. It has now been recognized that a slot height that varies with cross-machine position can be designed to achieve better heating uniformity. This configuration can compensate for the reduction in peak electric field strength due to absorption in the paper web as the waves propagate across the width of the paper machine. In this paper, we present a model that facilitates design for uniformity. We then investigate the tradeoff between efficiency and heating/drying intensity, and present preliminary model results indicating the ranges and combinations of basis weight and moisture content which are most compatible with the goals of achieving uniform microwave energy absorption, high efficiency, and high drying rate.