Development of Na 2 SO 4 ·10H 2 O Salt Hydrate PCMs for Thermal Energy Storage in Building Systems: A Scale‐Up Approach

Abstract The energy consumption in buildings, particularly for space heating and cooling, has increased significantly in recent years. Thermal energy storage has emerged as a promising solution for improving energy efficiency, with inorganic phase change materials (PCMs), such as salt hydrates, offering superior thermal conductivity and energy storage density compared to organic PCMs. However, their practical applications are hindered by challenges related to supercooling, phase segregation, and stability. This study presents the synthesis of a polyurethane‐phase change materials (PU‐PCM) composite incorporating Na 2 SO 4 aqueous solution, polyurethane foam, and LAPONITE ® Gel as a binding material. A 600 mL physical model was developed to investigate the cooling and heating cycles using this composite. The experimental data were then used to construct and validate a computational model in COMSOL 5.0 Multiphysics. Following validation, a scale‐up model (2 L) was developed, and the optimal PU‐PCM composite thickness was determined through computational simulations. DSC result of PU‐PCM composite shows melting temperature is about 34 °C, with melting enthalpy of 233.4 J/g and two freezing peaks were at 10 and −8 °C with freezing enthalpy of 52 J/g and 40 J/g, respectively. The results demonstrated that a 10 mm PU‐PCM layer maintained the desired temperature difference with minimal deviation (0.5 °C error). The study provides a comprehensive discussion on the experimental setup, crystallization process, computational modelling, and scale‐up analysis. Moreover, the model enables practical evaluation of PU‐PCM performance within building wall assemblies, providing insights into energy efficiency, thermal behavior, and environmental impact for sustainable building applications.