Modeling the Heat Transfer during Log Heating

Abstract

As one of the most commonly planted species in China, Masson pine (Pinus massoniana) logs are potentially used for structural poles and piles. Because phytosanitary regulations require that logs be heat-treated before delivery to customers (log core temperature of 56°C for 30 min), interest has recently arisen in the determination of the time required to reach this criterion. In this study, 12 logs were heat-treated in a laboratory drying kiln with two types of schedules. Using partial differential energy and mass conservation equations with gradient boundary conditions, the temperature increase in a log during heating was simulated. The boundary value problem of heat and mass transfer was solved using a numerical method, namely, a control volume approach. Results from the comparison between the observed and calculated temperatures indicated that the heat transfer performance during log heating can be described with this heating model. This model might therefore serve as a guideline for estimating the log heating times, assisting mill personnel in production planning. In addition, based on the experimental and calculated findings, it was well established that the log diameter, initial moisture content, wood density, and wet bulb temperature depression played significant roles in the heating rate during the heat treatment of logs.