Preparation and characterization of fatty acid ternary eutectic mixture/Nano-SiO2 composite phase change material for building applications

In order to prepare a composite phase change material (PCM) with suitable phase transition temperature, strong temperature control performance, good latent heat properties, and low cost for incorporation into concrete, the goal is to control temperature cracks, and endow the building structure with temperature regulation capabilities through phase change. In this study, capric acid (CA), myristic acid (MA) and stearic acid (SA) were used as PCMs. Firstly, based on theoretical calculations, a ternary eutectic mixture of CA-MA-SA with a mass ratio of 67.16:22.98:9.86 was successfully prepared. Subsequently, a new composite PCM was created using a melt blending technique, incorporating nano-SiO2 as a supporting material. The comprehensive characterization results from FT-IR, SEM, XRD, DSC and TG indicate that nano-SiO2 interacts with CA-MA-SA through its porous structure and capillary action, as well as surface tension, rather than through any chemical interaction, when 65% of CA-MA-SA is adsorbed in nano-silica, the melting temperature and latent heat of the composite PCM are 19.23 °C and 97.82 J/g, respectively. Without any leakage of molten CA-MA-SA. This material exhibits a favorable temperature for phase transition and possesses a high amount of latent heat, making it a promising candidate for use in construction projects. Additionally, the composite PCM shows remarkable thermal stability after 200 phase change cycles, which not only lowers building energy usage but also conserves energy, making it ideal for broad use in civil engineering.