Abstract
Water accounts for around half of the total mass in living trees, and therefore large savings can be achieved if logs are dried before transporting or burning. An air-drying model for piled logs of Eucalyptus globulus Labill. and Eucalyptus nitens H.Deane & Maiden was developed. Daily moisture content (MC) loss was modelled based on meteorological variables and pile characteristics. The trial had a factorial design with two species, two debarking treatments (with or without bark) and two log lengths (244 and 350 cm). Independent trials started in July 2007 (winter), October 2007 (spring) and January 2008 (summer). There were five replicate piles per season and treatment. Wood pile masses were weighted weekly or twice weekly using a crane, a 10,000 kg balance and chains to hold the piles. The main and interactive effects of seasons and treatments on daily MC loss were highly significant. However, the effect of season (climate) was far greater than the main effects of treatments or the season × treatment interaction. Overall, E. globulus dried 20 % faster than E. nitens, debarked logs dried 8 % faster than barked logs and 244 cm logs dried 3 % faster than 350 cm logs. Daily MC loss for the current day was better explained by a power function of MC at the start of the day, daily air relative humidity, daily air temperature and the number of logs per square metre of pile cross-section (or an equivalent average log diameter). The air-drying model for piled logs can be used to predict drying times (days) to achieve a given target moisture content, providing a new tool for decision-making in forest transport and industrial planning.
Highlights
Water accounts for around half of the total mass in living trees, and large savings can be achieved if logs are dried before transporting or burning
Log moisture content (MC) decreased for both species at higher rates for logs stacked in summer than spring than winter
Moisture content of logs stacked in winter decreased slowly while weather was cold and damp to decrease at increasing rates as weather conditions improved (Table 1, Fig. 2)
Summary
Water accounts for around half of the total mass in living trees, and large savings can be achieved if logs are dried before transporting or burning. Chile produces around 41 million cubic metres of timber each year from around 2.4 million ha of planted forests. Pinus radiata D.Don (1.470 million ha), Eucalyptus globulus Labill. (541,000 ha) and Eucalyptus nitens H.Deane & Maiden (232,000 ha) are the most widely planted species (Instituto Forestal 2014). Pinus radiata is the main source for sawn timber and long fibre for the pulp industry, while E. globulus and E. nitens are the main providers of short fibre for pulp production, and marginal providers for veneer and other uses (Lignum 2005). Chilean forest companies commonly dry large quantities of pulp logs at the roadside before being transported to pulp and paper plants, and recently to industrial boilers for the generation of steam, heat and. Species exhibit a fivefold range in drying times, and water loss slows down as wood water content decreases
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