Developments in vacuum drying and press drying of
Developments in vacuum drying and press drying of
Developments in vacuum drying and press drying of
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Center for<br />
Forest Products<br />
Pr<strong>of</strong>. Dr. Ressel<br />
Introduction<br />
Fundamentals<br />
Plant Facilities<br />
Innovations<br />
Process<br />
Technology<br />
Plant Examples<br />
Brunner<br />
IWT<br />
Mühlböck<br />
Kronseder<br />
Eberl<br />
Opel<br />
HeatWave<br />
Press Dry<strong>in</strong>g<br />
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Press Dry<strong>in</strong>g - Fundamentals<br />
Conductive heat transfer → no ... moderate com<strong>press</strong>ion <strong>of</strong> timber<br />
(or timber surface) to be dried<br />
Limitations<br />
→ Com<strong>press</strong>ion forces < com<strong>press</strong>ion strength <strong>of</strong> wood<br />
perpendicular to gra<strong>in</strong> (s<strong>of</strong>twood species approx. 2...10<br />
MPa; hardwood species approx. 5...20 MPa)<br />
→ Com<strong>press</strong>ion strength depend<strong>in</strong>g on wood species,<br />
moisture content <strong>and</strong> (process) temperature (0...140°C<br />
→ 30...35% strength reduction)<br />
→ Initiated <strong>in</strong>ternal <strong>press</strong>ure (water evaporation) <strong>in</strong>creases<br />
rapidly with temperature (100°C → 0,1 MPa; 120°C → 0,2<br />
MPa; 140°C → 0,38 MPa)
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