Improvement of heat treatment energy efficiency and control of drying check occurrence using superheated steam

This study was executed to develop a new heat treatment method which uses superheated steam as a medium of heat treatment for reducing the risk of fire while also ensuring a high level of energy efficiency. After a heat treatment under the pressure conditions of 0.1 MPa and 0.5 MPa and the temperature conditions of 180°C and 220°C, a test to measure the surface/inner checks was performed, during which checks were not found in the conditions of 0.5 MPa and 220°C. Also, the required energy and energy efficiency for the superheated steam heat treatment under the same conditions were compared with those of the conventional heat treatment at 220°C. The energy efficiency after the superheated steam heat treatment was much higher than that after the conventional heat treatment. Finally, through an analysis of the temperature and pressure change during the superheated steam treatment, the time when the wood specimen became an oven-dry state and the basic theoretical basis of the water movement in the wood at a high temperature and high pressure were determined. Through the results of this study, it was uncovered that a wood heat treatment using superheated steam can be used as a highly energy efficient and eco-friendly heat treatment method.