Previously reported drying experiments on highly impermeable hardwoods have shown that bell-shaped within-board moisture content profiles develop as drying proceeds, with a change in concavity around the fibre saturation point. However, drying models based on Fick's second law of diffusion with an Arrhenius temperature dependency for the diffusion coefficient predict a parabolic form. The present work showed that the influence of moisture content on the diffusion coefficient must also be considered to improve these drying predictions. A drying model that includes both temperature and moisture content effects on the diffusion coefficient was developed. This model is able to accurately predict the drying rates and within-board moisture content profiles of New Zealand's indigenous red and hard beech timbers for various timber thicknesses over a range of temperatures, relative humidities and air velocities used in practice.

Anisotropic shrinkage (tangential and longitudinal), equilibrium moisture content (EMC) and fibre saturation point (FSP) were measured for separated earlywood (EW) and latewood (LW) of a 0.75-m-long log of 20-year old Pinus radiata that was cut at breast height from a selected tree in the forest of Central North Island, New Zealand. The experimental results have shown that at 12% moisture content (MC), tangential shrinkage was 3.23% for EW and 3.90% for LW, with an overall average of 3.56%. Longitudinal shrinkage was 0.23% for EW and 0.21% for LW with an overall average of 0.22%. Shrinkage for the oven dry (OD) state showed similar trends to those at 12% MC in terms of the differences between EW and LW. The tangential and longitudinal shrinkage varied significantly along the radius from pith to bark. The EW tangential shrinkage increased from pith to the seventh growth ring and then remained relatively constant until the last ring adjacent to the bark. The LW tangential shrinkage also increased from the pith outwards until the seventh growth ring, but beyond that was more variable than the EW shrinkage. Both EW and LW showed similar longitudinal shrinkage, with the highest values in the second growth ring, from which the shrinkage decreased exponentially towards the bark. LW had a slightly higher EMC than EW at a relative humidity (RH) below 80%, but the trend was reversed for RH above 80%. The EMC differences between EW and LW were less than 0.6%. The overall average FSP for Pinus radiata was 29.1%, with actual values varying from 25% to 32.8%. The earlywood FSP (28.9%) was slightly lower than that of the latewood (29.4%).

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Key decisions in developing a model of a steam methane reformer were investigated in this paper. A comprehensive one-dimensional Python model of a reformer tube is proposed, including the effects of sintering and poisoning. Comparison between the Redlich−Kwong and ideal gas equations of state shows little difference upon reformed gas outlet properties. Different reaction kinetic models are tested over a variety of realistic conditions and compared against industrial data. Overall, these changes only impact conditions near the reactor inlet, as the approach to thermodynamic equilibrium near the reactor outlet ensures that all model-predicted process variables at the outlet are similar. Models from both Xu and Froment and Hou and Hughes are recommended for future reformer models where accurate outlet variables are required.

Results from a multiscale one-dimensional model of a steam methane reformer were applied to investigate carbon formation. Using a combined thermodynamic and kinetic approach, regions of likely carbon formation are predicted in line with industrial observations. This prediction is used to show that real gas considerations improve predictions of carbon formation regions. Kinetic reaction models were compared in their predicted carbon forming regions showing Xu and Froment's kinetics as the most applicable and realistic model with Hou and Hughes' kinetics showing carbon formation inconsistent with industrial observations. This deeper understanding of carbon formation mechanisms allows the development of a system to avoid carbon formation using CO 2 in place of/in conjunction with steam.