Thermal conductivity coefficient determination of wooden glued structures taking into account macrostructure and wood density

Abstract

The paper considers calculated and experimental methods of determining the thermal conductivity coefficient of wooden glued structures. The author shows that when designing the thermal protection of building enclosure structures in the form of CLT-panels or wooden glued laminated timber, one uses reference data on the thermal conductivity coefficient for pine or spruce. In practice, the value of the thermal conductivity coefficient may be less than the reference value; as a consequence, the thickness of the building enclosing structures is overestimated. This is not reasonable in terms of material intensity of construction. When considering wood as an anisotropic material, the peculiarities of the macrostructure and differences in the density of individual layers, as well as the wood species, should be taken into account when determining the parameters of structures. Based on the physical description of the thermal conductivity process and the fundamental laws of heat and mass transfer, the author proposes that it is necessary to adjust the results of calculations to the actual values of the thermal conductivity coefficient of multilayer wooden glued structures. The paper presents the results of experimental determination of the thermal conductivity coefficient of pine and aspen wood using steady-state and unsteady heat flow methods. It is shown that, depending on the density and wood species, experimental values of the thermal conductivity coefficient from 0.102 to 0.115 W·m-1∙K-1 can be obtained.