Department of Wood Science
Ciprian LazarescuAngela Dale
Erica SonAdnan Uzunovic
Colette Breuil Stavros Avramidis*
Impact of radio frequency heat treatments over softwoods
infested with fungi or nematodes
*Contact person
Department of Wood Science
Radio frequency heating and drying @ UBC-Wood Science
• first research work into RFV drying of timbers at UBC in 1990
• pilot RFV kiln made in 1992 and basic understanding of the fundamentals or RFV drying research under way
• development of RFV drying schedules and modeling of the process (1993-1999)
• development, design and manufacturing of the first commercial size RFV dryer (in late 1990s)
• manufacturing of more commercial units in the early 2000s
• continuation of basic RF work at UBC, optimization, dielectrics
• project to investigate RF phytosanitation (2008–2011)
Department of Wood Science
Why Radio Frequency heating?
Heat Sterilization
Radio Frequency (RF) Microwave
Conventional Heating
Hot water bath/steam
RF treatment has been used successfully for• Food processing• Textile industries
Department of Wood Science
OBJECTIVE
Test and evaluate several RF heating scenarios in order to determine the time and energy required to bring two wood species infested either with decay fungi (western hemlock, Tsuga heterophylla Raf. Sarg.) or nematodes (lodgepole pine, Pinus contorta) to full pasteurization using dielectric heating at radio frequencies.
Department of Wood Science
MATERIALS - Fungi
Locating, sampling and verifying infected wood
Department of Wood Science
MATERIALS - Fungi
Logs transported and processed at UBC
Department of Wood Science
MATERIALS - Nematodes
Department of Wood Science
METHODS 㧙 Fungal Assessment
2m
Department of Wood Science
METHODS - Nematodes1
2
3
4
6
5
1
2
3
4
1
2
3
Department of Wood Science
METHODS 㧙 Fungal and Nematode Assessment
completely effective (100%)
Treatment Successful
RPT represents the ratio of pests colonizing specimens in controls and RAT is the ratio of pests surviving samples after the treatment;
Department of Wood Science
UBC – Wood Drying Lab RF heater
Department of Wood Science
RESULTS – Fungal pre & post treatment
Department of Wood Science
RESULTS - Fungal diversity
Department of Wood Science
RESULTS - Treatments
Treatment[ºC/min] Infestation Worked Failed Conclusion
RF56/30Fungi
28 2 Treatment failed
RF60/15 30 0 Treatment worked
RF56/30Nematodes
10 0 Treatment worked
RF60/15 55 0 Treatment worked
Department of Wood Science
RESULTS – Time/energy consumption
Treatment[ºC/min]
Wood species
Moisture range[%]
Power density[kW/m3]
Total treatment time[min]
RF56/30hemlock
43…13260…90
49 – 160RF60/15 39…90 35 – 80RF56/30
pine 11…106 17…5152.5 – 64.5
RF60/15 43 – 65
Department of Wood Science
CONCLUSIONS
Upon completion of the pasteurization experiments we concluded that an RF treatment consisting in reaching 60 C and maintaining it for 15 minutes (RF60/15) was the only treatment that killed both types of pests.
Department of Wood Science
CURRENT WORK
Enlarge the available database with more RF-pasteurizationexperiments - benchmark 60ºC for 15 minutes.Perform multiple specimen dimension/number tests (wood pile instead of single specimen).Pasteurize decay fungi infected logs.Pasteurize timbers and logs infected with insects.
Department of Wood Science
AKNOWLEDGEMENTS
This work is financially supported by a Strategic Grant from the Natural Sciences and Engineering Research
Council of Canada. As part of the work was done through support of staff at FPInovations we also wish to
thank Canadian Forest Service that financially supported this work under the Contribution Agreement
existing between the Government of Canada and FPInnovations – Forintek Division.
Questions? Questiones?
