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PERFORMANCE OF INDUSTRIAL SOLAR KILN FOR DRYING TIMBER. M. N. Haque Forest Research, NZ & T.A.G. Langrish Department of Chemical Engineering, University of Sydney. Outline. Background to this research Description of this solar kiln Materials and methods
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PERFORMANCE OF INDUSTRIAL SOLAR KILN FOR DRYING TIMBER M. N. Haque Forest Research, NZ & T.A.G. Langrish Department of Chemical Engineering, University of Sydney
Outline • Background to this research • Description of this solar kiln • Materials and methods • Actual measurements & assessment of performance • Comments on suitability in NZ • Conclusions
Solar kilns for drying timber Solar kiln at Boral Timber’s Herons Creek site, NSW, AUSTRALIA Recent design of solar kiln by Solar Dryers Australia, Bellingen, NSW
Materials & methods INPUT SOLAR KILN MODEL OUTPUT Timber MC, air T & RH Boral’s Solar Kiln Ambient T & RH Timber properties Quality prediction
Procedure for measuring MC • Biscuit samples: 2025043 mm, oven-dry test • Kiln sample boards: 30025043 mm • estimated MC based on biscuit samples
Some NZ facts • About 2 million m3 timber dried each year (mainly radiata pine) • Average 3 GJ/m3 energy requirements • Total 6 PJ energy consumption • 95% thermal, 5% electrical • 60% thermal from wood residue • Processing of alternative species is growing
Initiatives in NZ • Greenhouse companies • Redpath: www.greenhouse.co.nz • Harford: www.greenhouses.co.nz • Do not have drying tech experience but an engineering company can be brought together
Conclusions • Solar energy, ambient T & RH, kiln T & RH and wood MC were measured. • Average increases in kiln air T (compared with ambient) were: • 17.3C (May-June) • 13.8C (July-August) • 10C (September-October) • 8.2C (November-March) • 7.5C (March-May)
Conclusions (continued) • Drying times were 3 to 4 months from initial (43 to 62%) to final MC (12 to 22%). • Overall solar kiln is considered as an acceptable alternative to air-drying method for pre-drying of hardwoods (e.g. blackbutt, Eucalyptus pilularis). • So Australasian timber industry is showing an increasing interest in use of solar kilns.
Acknowledgements • Boral Timber Division & • Faculty of Engineering, The University of Sydney for financial assistance