Impregnation of solid wood with 1-octadecanol/1-dodecanol eutectic PCM for potential building thermal energy storage applications

Abstract

In this study, 1-octadecanol/1-dodecanol eutectic phase change material was impregnated into beech wood and pine sapwood using vacuum and pressure impregnation methods to enhance thermal energy storage capacity. The weight percent gain was found to be 55.2 % for beech and 96 % for pine sapwood. Digital microscopy and density distribution analyses revealed that the phase change material was primarily concentrated in the vessels of beech and the earlywood tracheids of pine sapwood, with a uniform distribution. The porosity of the wood was critical to the impregnation efficiency of the phase change material. Fourier transform infrared spectroscopy confirmed the physical bonding mechanism between the phase change material and wood. Differential scanning calorimetry demonstrated that the pore structure of the wood enabled the phase change behavior of the phase change material, leading to higher efficiency in the storage of thermal energy. The melting and freezing latent heats of impregnated beech were 84.8 J g⁻¹ and 84.7 J g⁻¹, respectively, while those of pine sapwood reached as high as 111.9 J g⁻¹ and 111.8 J g⁻¹, indicating a significant heat storage capacity. Thermogravimetric analysis revealed that the thermal stability of impregnated wood decreased due to the phase change material evaporation at high temperatures. Additionally, the thermal conductivity of beech and pine sapwood increased by 58 % and 50 %, respectively, after the phase change material impregnation, while their specific heat capacities increased by 167 % and 217 %, respectively, compared to untreated wood. Finally, leakage experiments confirmed that applying a coating substantially reduced the phase change material leakage, although some residual leakage remained, requiring further treatment. These findings provide valuable insights that may contribute to the application of the phase change material-impregnated wood for thermal energy storage in construction.