Development and investigation of biobased binary eutectic phase change materials for low-temperature building applications: 1-Hexadecanol/1-Dodecanol and 1-Octadecanol/1-Dodecanol

Phase change materials (PCMs) play a crucial role in optimizing thermal management in low-temperature buildings, contributing to reduced energy consumption and greenhouse gas emissions. This study aims to address the limitations of conventional paraffin-based PCM by developing binary mixtures of fatty alcohols. Through theoretical calculations, binary phase diagram fitting, and experimental validation, the thermal performance, phase transition behavior, and integration methods of these mixtures were thoroughly investigated using techniques such as differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The results showed that 1-dodecanol/1-tetradecanol (TD) mixtures were unsuitable for building applications due to their inability to form eutectic phases. However, two eutectic PCMs, namely HD82.44 (82.44 % 1-dodecanol/17.56 % 1-hexadecanol) and OD82.66 (82.66 % 1-dodecanol/17.34 % 1-octadecanol), were successfully synthesized. HD82.44 began melting at 16.4 °C, reached peak heat absorption at 19.6 °C and a melting latent heat of 193.7 J/g. Solidification started at 17.3 °C, with two exothermic peaks at 14.2 °C and 6.8 °C, and a freezing latent heat of 192.4 J/g. The solid and liquid specific heats were 2.02 J/(g·°C) and 2.56 J/(g·°C), respectively. OD82.66 began melting at 18.1 °C, with peak thermal effect at 21.4 °C. Solidification started at 23.1 °C, followed by a freezing peak at 15.1 °C. Both melting and freezing enthalpies were 206.4 J/g. Its solid and liquid specific heats were 2.02 J/(g·°C) and 2.67 J/(g·°C), respectively. Both PCM displayed no supercooling, suitable phase change temperatures, and high thermal storage properties, making them promising alternatives to traditional paraffin-based PCM for thermal energy storage in buildings. Additionally, FTIR analysis confirmed the physical integration of the binary fatty alcohol eutectic PCMs, while thermal cycling tests demonstrated their long-term stability.