Microencapsulated capric-stearic acid with silica shell as a novel phase change material for 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.