1. 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

2. Outline  Background to this research  Description of this solar kiln  Materials and methods  Actual measurements & assessment of performance  Comments on suitability in NZ  Conclusions

3. Solar kilns for drying timber

4. Solar kiln at Boral Timber’s Herons Creek site, NSW, AUSTRALIA Recent design of solar kiln by Solar Dryers Australia, Bellingen, NSW

5. Air-drying site

6. Typical drying example

7. Materials & methods Boral’s Solar Kiln INPUT OUTPUT SOLAR KILN MODEL Ambient T & RH Timber MC, air T & RH Timber properties Quality prediction

8. Procedure for measuring MC Biscuit samples: 20  250  43 mm, oven-dry test Kiln sample boards: 300  250  43 mm estimated MC based on biscuit samples

9. Results- run 1 (May-June)

10. Results- run 2 (July-August)

11. Results- run 3 (Sep-Oct)

12. Results- run 4 (Nov-March)

13. Results- run 5 (March-May)

14. Results- summary

15. Measured solar radiation

16. Results- HEX status

17. Image goes here Some NZ facts  About 2 million m 3 timber dried each year (mainly radiata pine)  Average 3 GJ/m 3 energy requirements  Total 6 PJ energy consumption  95% thermal, 5% electrical  60% thermal from wood residue  Processing of alternative species is growing

18. Solar radiation at Rotorua, NZ (NIWA, 2002)

19. Image goes here 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

20. Conclusions  Solar energy, ambient T & RH, kiln T & RH and wood MC were measured.  Average increases in kiln air T (compared with ambient) were:  17.3  C (May-June)  13.8  C (July-August)  10  C (September-October)  8.2  C (November-March)  7.5  C (March-May)

21. 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.

22. Acknowledgements  Boral Timber Division &  Faculty of Engineering, The University of Sydney for financial assistance