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Articles containing the keyword 'drying'

Category : Article

article id 5161, category Article

Juhani Päivänen. (1982). Physical properties of peat samples in relation to shrinkage upon drying. Silva Fennica vol. 16 no. 3 article id 5161. https://doi.org/10.14214/sf.a15076

Keywords: peat; density; bulk density; shrinkage; chemicophysical properties; drying; peat type

Abstract | View details | Full text in PDF | Author Info

The study discusses the amount of shrinkage of volumetric undisturbed peat samples when drying to an oven-dry (105°C) condition. The amount of shrinkage is related to various physical properties of peat. In addition, some observations were performed on the shrinkage phenomenon during the drying process. The study results may be used when predicting the shrinkage of peat samples with various peat properties. Knowledge of this kind is particularly important in connection with peat harvesting.

The PDF includes a summary in Finnish.

Päivänen, E-mail: jp@mm.unknown

Category : Article

article id 7311, category Article

S. E. Multamäki. (1934). Metsäojien mittojen ja muodon muuttumisesta. Acta Forestalia Fennica vol. 40 no. 34 article id 7311. https://doi.org/10.14214/aff.7311

English title: Changing of dimensions and form of forest ditches after the drainage in Finland.

Original keywords: ojitus; metsäoja; turpeen painuminen; ojien eroosio

English keywords: erosion; drainage of peatlands; forest ditch; drying of peatland

Abstract | View details | Full text in PDF | Author Info

The aim of the study was to investigate how the drain network and dimensions of ditches change after the drainage. The studied drained peatlands were situated in the municipalities of Parkano and Virrat in Central Finland. The ditches were in average 15 and 17 years old. The depth and width in the surface of the peatland were in average one quarter smaller than after the drainage. The width at the bottom of the ditch has, however, almost doubled. Peat had sunken more in peatlands with thick peat layer and higher humidity. Sinking of peat influenced the depth of the ditches. The volume of the ditches decreased about 30%. The decrease of the ditches by the drying and sinking of the peat was greater than the increase caused by erosion.

The PDF includes a summary in German.

Multamäki, E-mail: sm@mm.unknown

Category : Research article

article id 910, category Research article

Gernot Erber, Christian Kanzian, Karl Stampfer. (2012). Predicting moisture content in a pine logwood pile for energy purposes. Silva Fennica vol. 46 no. 4 article id 910. https://doi.org/10.14214/sf.910

Keywords: moisture content; modelling; natural wind drying of fuel wood; log pile

Abstract | View details | Full text in PDF | Author Info

Determining the moisture content of naturally dried fuel stock without frequent measuring is a problem still unsolved. Modelling moisture content based on automatically captured meteorological data could provide a solution. An accurate model would allow the drying period and the point of chipping to be optimised. For the experimental study, a metal frame supported by load sensors and loaded with 17 tons of logwood was set up next to a meteorological station. A multiple linear regression model was used to link meteorological and load data to provide a formula for determining the moisture content. The pile dried for a period of 14 months (average temperature of 7.3 °C, a humidity of 81%, and 777 mm of rainfall). The overall moisture content dropped from 50.1% to 32.2%. The regression model, which based on daily means and sums of meteorological parameters, provided a mean deviance from the observed curve of –0.51%±0.71% within the period of investigation. Relative humidity was found to be most important parameter in drying. Increased moisture content resulting from rainfall greater than 30 mm per day reverted back to pre-rainfall values within two to three days, if no other rainfall events followed. Covering the pile would have a positive effect on the drying performance. In terms of economic benefit it could be shown that natural drying is beneficial. Overall this study shows that meteorological data used in site specific drying models can adequately predict the moisture content of naturally dried logwood.

Erber, University of Natural Resources and Life Sciences, Peter Jordan-Strasse 82, 1190 Wien, Austria E-mail: gernot.erber@boku.ac.at
Kanzian, University of Natural Resources and Life Sciences, Peter Jordan-Strasse 82, 1190 Wien, Austria E-mail: christian.kanzian@boku.ac.at
Stampfer, University of Natural Resources and Life Sciences, Peter Jordan-Strasse 82, 1190 Wien, Austria E-mail: karl.stampfer@boku.ac.at

article id 190, category Research article

Katri Luostarinen, Veikko Möttönen. (2009). Effect of felling season, storage and drying on colour of silver birch (Betula pendula) wood from four different growing sites. Silva Fennica vol. 43 no. 4 article id 190. https://doi.org/10.14214/sf.190

Keywords: birch; age; colour darkening; conventional drying; environmental factors; plantation; wood

Abstract | View details | Full text in PDF | Author Info

Darkening of birch wood during artificial drying is a significant problem regarding the use of its timber as raw material by the mechanical wood industry. In the future, an increasing proportion of birch timber will be obtained from plantation forests, which differ from natural forests in many respects. In this investigation sample boards of Betula pendula, both from naturally regenerated stands and plantations, were sawn into the dimensions used as raw material for parquet billets. Growing site, felling season, and storage of logs were taken into account as possible factors affecting wood colour changes during drying. The wood of birches from fertile plantations remained lighter-coloured during conventional drying than the wood of naturally regenerated birches from low- and medium-fertile stands. The reason may be the difference in tree age and growth rate between natural and planted stands. Thus, it could be beneficial to grow birch in fertile stands so that the trees reach log size as young as possible. The results of this study emphasise the good quality of the birch wood from planted stands compared to natural stands with regard to its colour.

Luostarinen, Faculty of Forest Sciences, University of Joensuu, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: katri.luostarinen@joensuu.fi
Möttönen, Department of Mechanical Engineering, Lappeenranta University of Technology, P.O. Box 20, FI-53851 Lappeenranta, Finland E-mail: vm@nn.fi

article id 198, category Research article

Henrik Heräjärvi. (2009). Effect of drying technology on aspen wood properties. Silva Fennica vol. 43 no. 3 article id 198. https://doi.org/10.14214/sf.198

Keywords: stability; heat treatment; modification; press drying; strength

Abstract | View details | Full text in PDF | Author Info

Heräjärvi, Metla, Joensuu Research Unit, Box 68, FI-80101 Joensuu, Finland E-mail: henrik.herajarvi@metla.fi

article id 278, category Research article

Katri Luostarinen. (2007). The effect of annual ring orientation and drying method on deformations, casehardening and colour of silver birch (Betula pendula) boards. Silva Fennica vol. 41 no. 4 article id 278. https://doi.org/10.14214/sf.278

Keywords: wood; timber quality; dimensional stability; distortion; drying schedules; kiln drying; L*a*b* coordinates

Abstract | View details | Full text in PDF | Author Info

Deformations of timber, caused mainly by anisotropic shrinkage, can be partially directed by controlling annual ring orientation through different sawing patterns. Ring orientation also affects the movement of water from within the board to its surface, with rapidity of drying having implications for the wood colour. Here sawn silver birch (Betula pendula Roth) timber was classed into two groups according to ring orientation. Two drying methods were used. The final moisture content was lower and the colour lighter in dried boards with radial than with tangential flats, but deformations were larger in radial than in tangential boards. Both drying and ring orientation affected the final moisture content and moisture gradient of the boards. Very small differences in board sizes or shape had an effect on both colour and deformations. The results support the need for accurate sawing and for classing silver birch timber sawn into parquet billets according to ring orientation in order to optimise the drying quality.

Luostarinen, University of Joensuu, Faculty of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: katri.luostarinen@joensuu.fi

article id 652, category Research article

M. J. Youngman, G. D. Kulasiri, I. M. Woodhead, G. D. Buchan. (1999). Use of combined constant rate and diffusion model to simulate kiln-drying of Pinus radiata timber. Silva Fennica vol. 33 no. 4 article id 652. https://doi.org/10.14214/sf.652

Keywords: simulation; timber drying; diffusion; constant drying-rate

Abstract | View details | Full text in PDF | Author Info

This paper presents the use of a combined constant drying-rate and diffusion model to simulate the drying of Pinus radiata timber under kiln-drying conditions. The constant drying-rate and diffusion coefficients of the model, which control the drying rate of individual pieces of timber, were determined from calibrating the model against the experimental drying curves obtained under the kiln-drying conditions. The experimental drying curves were obtained from the gravimetric measurements of the moisture content of timber during kiln drying. Statistical relationships were developed for the constant drying-rate and the diffusion coefficients of the model as functions of kiln temperature and the dry basis density of timber. To determine the effects of variability of timber, a simulation scheme was developed based on the model, the probability distribution of the density of timber, the equations for the constant drying-rate coefficient and the diffusion coefficient. The model and the associated simulation method provides a simple way to estimate the drying time of a stack of timber using parameters determined from experimental results for the specific timber kiln.

Youngman, Lincoln University, Appl. Management and Computing Division, P.O. Box 84, Canterbury, New Zealand E-mail: mjy@nn.nz
Kulasiri, Lincoln University, Appl. Management and Computing Division, P.O. Box 84, Canterbury, New Zealand E-mail: kulasird@tui.lincoln.ac.nz
Woodhead, Lincoln University, Appl. Management and Computing Division, P.O. Box 84, Canterbury, New Zealand E-mail: imw@nn.nz
Buchan, Lincoln University, Appl. Management and Computing Division, P.O. Box 84, Canterbury, New Zealand E-mail: gdb@nn.nz

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