INVESTIGATION OF THERMAL INSULATION CAPACITY OF TREE BARK

Abstract

The problem of industrial use of tree bark is relevant and has practical importance for complex processing of wood raw material. Barks are available in Hungary and Russia in large quantities, but they are not widely used for different purposes than producing energy. One of the perspective areas of utilization of tree bark is its use as raw material for the production of thermal insulation panels. The present study focuses on the thermal insulation capacity of tree bark. Thermal conductivity properties of two broadleaved (black locust (Robinia pseudoacacia), pannónia poplar (Populus euramericana cv. Pannónia)) and three coniferous (larch (Larix decidua), spruce (Picea abies) and scots pine (Pinus silvestris)) tree species were examined. Based on these results, the scopes of the tested species were further narrowed, while the best results showing black locust was used for pressed insulation panel. Three different fractions were produced made of grained black locust bark. Furthermore, the heat insulation capacities of bark were investigated by compressing the chipped bark particles until the lowest heat conductivity was reached. Results show a competitive thermal insulation property to the traditionally used insulation materials, the value was 0.0613 W/mK reached by black locust bark chips. The broadleaved tree bark chips have a lower thermal conductivity than coniferous species. By using fine, mid, and coarse fraction of black locust bark were produced and the difference of thermal conductivity between them was negligible. Although the fine fractionated black locust bark chip thermal conductivity was 0.042 W/mK.