Unfortunately, such study is seldom
reported in the literature, although it had been recommended
by some researchers. The reason might be the high cost of
temperature measurement in a microwave environment, the
lack of convenient power and temperature control and
recording techniques, or other engineering difficulties in
microwave drying applications. To address the problem, a
new microwave drying system was developed in this study.
The developed system can automatically and continuously
adjust the power levels, control the product temperature, and
measure the samples’ mass online. Hence it becomes possible
for the first time to monitor and control the power,
temperature and moisture contents in real time. The specific
objectives included: investigating the relationship amongst
microwave power, drying temperature, and moisture
contents; optimizing temperature and power control in a
feedback control loop; and attempting a temperature control
without temperature measurement.