Intensification of Round Log Drying

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UDС

674.047.37

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Abstract

The article considers the problems of using round logs in constructing wooden cottage houses, their advantages and disadvantages. The main disadvantages are cracks appearing on the surface of a log and shrinkage due to moisture content reduction in a log. The wood used for production of blockhouses made of round logs has natural moisture. Logs in the assembled house undergo the process of drying for one or two years. During this time, the blockhouse shrinks by 5­7 % of its height. Among other negative consequence of using wet wood we can name an increased risk of fungal decay in the future. Drying of logs to make them fit for further service is quite a long process. Even when drying in natural conditions there can appear deep cracks on the surface, which affects the appearance and performance properties of the constructed house and would require special fillings. Such surface cracks can be avoided by ensuring a uniform exit of moisture from the wood across the log section. Therefore, the research aimed to develop methods of round logs treatment reducing the time of log drying to the service moisture content. The authors propose a new method of convection drying of round logs, according to which diametral through-holes are drilled evenly along the entire length of the log in crosswise direction before drying. This will speed-up the cross-sectional heating of the logs and facilitate the exit of the evaporated moisture. And the greater the number of holes, the faster the drying process, which is determined by the final moisture content in the wood. This was confirmed by a numerical experiment which determined the influence of the number of holes and drying time on the moisture content in round logs. Drying of round logs having 10 holes per 1 running meter from 23 % to 12 % moisture content took  100 hours. While in logs without holes, the moisture content decreased only to 18 % for the same period. Crosswise through-holes facilitate cross-sectional heating of the logs and speed up the drying process. Uniform heating of wood by holes provides simultaneous shrinkage of fibers in the central and peripheral parts of the log, which reduces the internal stresses arising in the log at drying and eliminates the formation of cracks on its surface.

Authors

А.А. Lukash, Candidate of Engineering, Associate Professor; Е.S. Grishina, Postgraduate Student

Affiliation

Bryansk State Engineering and Technological Academy

Keywords

construction, building, wood, log reducing, shrinkage, contraction, drying, process, intensification.

References

1 Lukash A.A., Grishina E.S. Perspektivy i problemy proizvodstva domov iz otsilindrovannogo brevna [Prospects and Problems of Construction of Houses Made of Round Timber]. Biosfernosovmestimye goroda i poseleniya: materialy mezhdunar. nauch.- prak. konf. [Biosphere-Compatible Cities and Settlements: Int. Sci. and Pract. Conf.]. Bryansk, 11–13 December 2012. Bryansk, 2012, pp. 133–137. 2. Lukichev A.V. Perspektivy derevyannogo karkasnogo domostroeniya v Rossii [The Prospects of the Wooden Framework Housing Construction in Russia]. Stroitel'nye materialy oborudovanie, tekhnologii XXI veka, 2008, no. 11, pp. 44–45. 3. Mal'tsev V.V. Maloetazhnoe derevyannoe domostroenie: Kontseptsiya novogo veka [Low-Rise Wooden Buildings: The Concept of the New Century]. Derevo.RU, 2006. 215 p.