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Dielectric Drying

Dielectric heating is the use of either microwave or radio frequency (RF) technologies to heat materials, ie dry them. Microwave and RF interact with individual molecules to quickly generate heat within a product. This is in contrast to conventional heating where heat is applied externally.

Advantages

  • Shorter processing times for heating or drying
  • More uniform, volumetric heating
  • Less energy required
  • Greater controllability
  • Shorter production line lengths

Microwave

Microwave power is generally obtained from a device called a magnetron. The microwaves are ducted into a microwave 'leak-proof' cavity. (see figure below). Trials have been down using a combination of microwave and vacuum drying by staff of CSIRO to season high quality eucalypt timber. The indications from this study are that with purpose designed equipment and good control of conditions the drying of at least short length timber would be successful from an economic and quality point of view (Rozsa 1994)

Microwave

Schematic of microwave oven.

Radio Frequency

Radio frequency power is usually generated with the use of two (or more) electrodes to produce an oscillating electric field. The timber to be heated is placed into the field between the electrodes (see figure below).

Radio Frequency

A schematic of a radio frequency oven

  • For more info on the web


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