Energy Consumption and Efficiency of Autoclaves in Steaming Wooden Beams Aiming for Their Homogeneous Pigmentation

A methodology for computing the heat energy consumption and efficiency of autoclaves during the steaming of wooden beams with the aim of achieving homogeneous pigmentation of the desired wood color throughout their volume is presented. The methodology includes computer simulations with two personal multi-parametric models: one to calculate the 1D non-stationary temperature distribution along the thickness of the beams during their autoclave steaming and the second to compute the heat balance of industrial autoclaves for such treatment. With the help of the first model and a new temperature–time quantitative indicator of the homogeneity of desired wood pigmentation, the parameters of steaming mode providing homogeneous dark brown pigmentation of beech beams with thickness of 80 mm, initial temperature of 0 °С, and moisture content of 0.4, 0.6, and 0.8 kg∙kg−1 were determined at maximum temperature in the autoclave of 123 °C and loading level of the autoclave with beams 30%, 40%, and 50%. Simulations with the second model showed that at 50% filling of the autoclave with beams having a moisture content of 0.6 kg∙kg−1, the energy consumption and efficiency of the autoclave when using the calculated steaming mode are equal to 124.4 kWh∙m−3 and 73.3%, respectively.