2.3.2. FD and MFD procedures
The drying apparatus is shown in Fig. 1. A cylindrical microwave
cavity (diameter 0.6 m, depth 0.5 m) and a 70 mm diameters glass
circular conduit drying chamber as well as two heat supply system
were used for FD and MFD processes. The circular conduit was
wrapped with a jacket through which circulating water can flow.
For FD, the heat required for drying samples was supplied by circulation
of water from a cooling/heating water unit (Model: HAAKE
DC10-K10, Thermo Electron Corporation, Karisruhe, Germany).
But for MFD, the heat required was supplied by microwave and
conduction heat from cooling/heating water unit in the different
drying stages to avoid corona discharge and to improve dried products
quality.