Parameter estimation and model selection for water vapour sorption of welded bond-line of European beech and Scots pine

Abstract The single exponential kinetics (SEK) and parallel exponential kinetics (PEK) models were fitted to kinetic sorption data of welded and unwelded Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.). Furthermore, diffusion coefficients of water vapour in wood were determined using two different Fickian diffusion solutions. The objective was to identify how well these models could represent the moisture contents of the specimens and to characterize differences between the sorption behaviour of welded and unwelded wood. This knowledge can be used to enhance the moisture resistance of welded wood, develop drying schedules, and improve the quality of timbers. The PEK and SEK models provided the most precise and the second most precise fits to the sorption kinetic data, respectively. The two Fickian models are equivalent when both the infinite series are truncated at n = 10 $n=10$ . The Fickian models also exhibited the highest discrepancy with the experimental data. Nevertheless, the Fickian models fit relatively better to the sorption data of the welded wood than to that of the unwelded wood. This behaviour may be due to the rigid and less-swelling structure of the welded bond line.