3D finite element enthalpy method for analysis of phytosanitary treatment of wood by microwave

Circulations of some wood products are identified as one of the causes that have facilitated the introduction of pathogens and insects in several countries of the world. This biological invasion has caused the destruction of plant species, causing significant economic and ecological losses for many regions of the world. To this end, the World Trade Organization (WTO) has established, through the International Plant Protection Convention (IPPC), the “ISPM 15” standard on the use of microwaves for phytosanitary treatment. The goal of this work is to quantify numerically the minimum time required for the phytosanitary treatment of three Eastern Canadian wood species, trembling aspen (Populus tremuloides Michx.), white birch (Betula papyrifera) and sugar maple (Acer saccharum). The nonlinear heat conduction problem is solved using three-dimensional volumetric specific enthalpy based on finite element analysis. The incident microwaves are supposed plane wave. The dielectric and thermophysical properties are a function of temperature, moisture content and structural orientation. It is worth noting that these investigations were performed at the frequency of 2466 MHz, temperatures from − 20 to 60 °C, and moisture content of 131%. This study focused on a sample cube of wood 22 mm thick and a pallet (100 mm × 50 mm × 22 mm).