Preheating model of high-temperature setting of Pinus sylvestris var. mongolica Litv. wood

Abstract

Large-section boxed-heart square timber is prone to surface and radial cracks during the drying process. A high-temperature setting pretreatment could prevent cracking in boxed-heart timber. The pretreatment process is primarily determined by the preheating time. To determine the preheating time of the test material, a mathematical model for the internal temperature distribution of Mongolian pine (Pinus sylvestris var. mongolica Litv.) boxed-heart square timber in the preheating stage was established by the finite element method. The model viability was verified by tests that showed that the model simulation results were stable and non-fluctuating. For the prediction error of the temperature change, the early-period error was large, while the later predicted values and measured values tended to be consistent. For the prediction error of the temperature distribution, the core-layer error was smallest, while that of the surface layer was greatest. For the prediction error of the preheating time, greater preheating temperatures exhibited greater error, and the minimum error was 10 min, at 90 °C. Overall, the predicted values were close to the measured values and can be referenced for subsequent pretreatment process research.