Microencapsulated capric–stearic acid with silica shell as a novel phase change material for thermal energy storage

• Microencapsulated C–S with silica shell as phase change material for thermal energy storage.
• Agitation rate plays a crucial role in determining the PSD of C–S/SiO2 MEPCM.
• The phase change temperature and latent heat are measured to be 21.4 °C and 91.48 J/g.
• MEPCM shows good thermal reliability with respect to 1100 times thermal cycling.
• MEPCM has great potential in the application of thermal energy storage.

Microencapsulated phase change materials (MEPCM) with polymeric shells have shortcomings including noxious gas releasing, flammability, poor thermal stability, low mechanical strength and heat conductivity. To overcome these disadvantages, capric–stearic eutectic (C–S) was microencapsulated in silica shell as a novel phase change material for thermal energy storage. The fabrication process was carried out without use of any emulsifiers, which would significantly deteriorate the latent heat storage capacity within conventional method. Such C–S/silica MEPCM possesses typical core–shell structured spherical morphology and the agitation rate plays a crucial role in determining the particle size distribution. DSC analysis shows that the melting and freezing temperatures of MEPCM are 21.4 °C and 22.2 °C, and the latent heats of melting and freezing are 91.48 J/g and 90.52 J/g, respectively. Besides, the thermal stability of PCM is greatly enhanced after embedded in silica shell. Above all, MEPCM reveals good thermal reliability after subjected to 1100 repeated melting/freezing cycling. Based on all results, the C–S/silica MEPCM has great potential in the application of thermo-regulated textiles, air-condition buildings, heat-transfer fluids and so on.