Microwave drying kinetics of jack pine wood: determination of phytosanitary efficacy, energy consumption, and mechanical properties

Abstract

The aims of this study were to determine (1) the effects of microwave irradiation on the drying kinetics of jack pine wood, (2) the phytosanitary efficacy, and (3) the processing energy consumption and mechanical strength of the dried product. Microwave drying experiments were performed at 2.45 GHz frequency and at microwave powers ranging from 300 to 1000 W. Results indicate that higher microwave power and initial wood temperature and lower sample thickness increases the internal sample temperature, improves the drying rate, and reduces both drying time and energy consumption. The microwave irradiation efficacy to sanitize jack pine wood boards was determined in terms of temperature/time combinations based on actual drying kinetics according to standards for phytosanitary measures. The energy required to dry 12 mm thick wood board samples at microwave power ranging from 300 to 1000 W was in the range of 36.4–12.3 MJ/kg of water, respectively, for up to 65% energy consumption savings. The impact of microwave power on the mechanical properties was not statistically significant, although mechanical properties tended to decrease with increasing power.