Evaluating effective thermal conductivity of PCM-impregnated wood composite at phase change temperature

Abstract

This study examines the effective thermal conductivity of wood composite impregnated with phase change material (PCM) during the PCM phase change process. Incorporating PCMs into wood stabilizes its shape and boosts energy storage capacity, broadening its applications in buildings while reducing energy usage. Most previous studies on PCM focused solely on acquiring the thermal conductivity in their solid state, leaving a gap in research concerning their liquid state. In this study, a PCM-impregnated wood composite was developed with bio-based binders. The effective thermal conductivity was analysed across a temperature spectrum in which the impregnated PCM, ethyl palmitate, exists in three distinct phases: solid, liquid, and mushy (a mix of solid and liquid phases). The results indicate a notable variation in effective thermal conductivity during the phase change process. At 10 °C, the solid PCM has an effective thermal conductivity of 0.13 W/m·K, while at 40 °C, its liquid state maintains the same value. However, a significant 48 % increase in effective thermal conductivity was observed during the phase change temperature measured using a hot disk instrument. These findings are expected to provide valuable insights for both researchers and industrial sectors that use PCMs for TES.

This project was co-funded by the European Union's Horizon Europe Research and Innovation Programme under grant agreement 101135629 (BIOBUILD). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or REA. Neither the European Union nor the granting authority can be held responsible for them. This paper is part of the RYC2023-044196-I, funded by MCIU/AEI/10.13039/501100011033 and FSE+. This work was partially funded by the Ministerio de Ciencia e Innovación - Agencia Estatal de Investigación (AEI) (PID2021- 123511OB-C31 - MCIN/AEI/10.13039/501100011033/FEDER, UE). This work was partially funded by Ministerio de Ciencia e Innovación - Agencia Estatal de Investigación (AEI) (RED2024-153629-T). This work is partially supported by ICREA under the ICREA Academia programme. The authors would like to thank the Departament de Recerca i Universitats of the Catalan Government for the quality accreditation given to their research group (2021 SGR 01615). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia.