Fabrication and characterization of form-stable capric-palmitic-stearic acid ternary eutectic mixture/nano-SiO₂ composite phase change material

Phase change materials (PCMs) have great potential for the regulation of indoor temperature and building energy saving. In this study, capric acid-palmitic acid-stearic acid (CA-PA-SA) ternary eutectic mixture was impregnated into nano-silicon dioxide (nano-SiO₂) to prepare a form-stable composite PCM (CA-PA-SA/nano-SiO₂). The phase change temperature range of the composite PCM is 17.16 °C–26 °C, which is suitable for indoor thermal environment. The high latent heat value and the low thermal conductivity of the composite PCM are 99.43 kJ kg⁻¹ and 0.08239 W (m K)⁻¹, which is helpful to stabilize the indoor temperature for a long time and improve human comfort. Furthermore, after 500 heating/cooling cycles, the composite PCM showed good thermal and chemical stability. The maximum CA-PA-SA mass fraction of the composite PCM was determined as high as 75 wt.%, with no melted CA-PA-SA seeping from the composite PCM. All the results indicated that the composite PCM is suitable for storing excess solar radiation and reducing the amount and rate of heat loss of buildings in the winter, which will help reduce building energy consumption.