Joule heating of logs for phytosanitary purposes and timber processing pre-treatment

University of Canterbury Electric Power Engineering Centre, Christchurch, 8001, New Zealand

Adv. Mater. Lett., 2018, 9 (11), pp 767-775

DOI: 10.5185/amlett.2018.2133

Publication Date (Web): Jul 24, 2018

Copyright © IAAM-VBRI Press

E-mail: bill.heffernan@epecentre.ac.nz

Abstract

Joule heating has recently been investigated as a potential alternative to chemical fumigation for phytosanitary treatment of Pinus radiata logs exported from New Zealand. The research was driven by concern regarding the effects of methyl bromide release to atmosphere, following fumigation, as highlighted by the Montreal Protocol. The work has involved creating 1 dimensional and 3 dimensional computer models of the Joule heating process in P. radiata, building a laboratory-scale log test rig with suitable instrumentation and control systems, heating approximately 60 P. radiata logs and using the measured data to refine and validate the models. While engaged in this work it became clear that the process could also potentially be applied to heat veneer peeler logs. This paper describes the application of the 1 dimensional model and laboratory-scale test rig to a typical P. radiata export log and to a Eucalyptus nitens log prepared for veneer peeling. The results demonstrate that, despite the heterogeneities of the timber, the technique is capable of achieving the required temperature profiles for both applications and that the model is a sufficiently good representation of the process to provide a viable control method. 

Keywords

Ohmic heating, joule heating, phytosanitary treatment, peeler log heating, CFD modelling.