Estimation of Drying Time for Air-drying of Logs and Evaluation of Log Properties Affecting Drying Characteristics of Logs Using a Hierarchical Bayesian Model

Air-drying is one of the most frequently used operations to dehydrate logging residues for produc-tion of wood fuel chips. This study developed a drying curve model for the air-drying of logs in order to estimate drying time to reach a given moisture level, and to evaluate the influence of log properties on drying characteristics of logs. Log piles of sugi （(cid:9479)(cid:9526)(cid:9533)(cid:9524)(cid:9528)(cid:9523)(cid:9521)(cid:9513)(cid:9526)(cid:9517)(cid:9509)(cid:9444)(cid:9518)(cid:9509)(cid:9524)(cid:9523)(cid:9522)(cid:9517)(cid:9511)(cid:9509)） were air-dried in Tsukuba city, Japan, from November 2014 to August 2015. A hierarchical Bayesian model was used to estimate the moisture content of individual logs as a function of initial moisture content, diameter, length, heartwood ratio, and drying time. The measured mean moisture content fit well to the estimated drying curve, indicating that the developed model is a potentially useful method to estimate the drying time for any moisture content within the limited range of climate conditions studied here. A comprehensive evaluation of log properties affecting the drying characteristics of logs showed that initial moisture content, diameter, and length have an influence on the drying rate of logs. time, hierarchical Bayesian model.