Thermal performance and mold discoloration of thermally modified wood containing bio‐based phase change material for heat storage

Abstract

AbstractThe work presents the results of thermal performance and mold discoloration of thermally modified wood‐based composites incorporating multicomponent fatty acids as a bio‐based phase change materials (BPCM). Thermally modified Scots pine (TMP), beech (TMB), and spruce (TMS) sapwood were impregnated with a multicomponent mixture of linoleic acid and coconut oil fatty acids at a ratio of 20:80. Samples with different BPCM uptakes were analyzed in the temperature range typical for building indoor conditions. Leakage tests were conducted and revealed that the maximum leakage for all the samples is 3% to 5%. T‐history and heat flowmeter methods were used to evaluate the thermal characteristic of the composites. The incorporation of BPCM into thermally modified woods (TMWs) resulted in significant thermal mass improvements, expressed by the ability of the composites to store excessive energy in terms of latent heat and keep the temperature constant for long time. The specific heat capacity of the TMWs was around 2 J/g K, which increased to 4 to 8 J/g K after impregnation with BPCM, depending on the impregnation uptake. Results showed also that TMB has higher thermal conductivity than TMP and TMS, while incorporating of BPCM into these materials resulted in even improved thermal conductivity. Results showed that the thermal conductivity of TMP increased after incorporation of BPCM from 0.06 W/m K to 0.1 and 0.14 W/m K for TMP/BPCM with 48% and 95% uptake respectively. Mold tests showed that BPCM encapsulated in TMWs is less susceptible to mold discoloration compared to untreated wood.