Synthesis and characterisation of n-octacosane@silica nanocapsules for thermal storage applications

This work reports the synthesis and characterisation of a core-shell n-octacosane@silica nanoencapsulated phase-change material obtained via interfacial hydrolysis and polycondensation of tetraethyl orthosilicate in miniemulsion. Silica has been used as the encapsulating material because of its thermal advantages relative to synthesised polymers. The material presents excellent heat storage potential, with a measured melting latent heat varying between 57.1 and 89.0 kJ kg(-1) (melting point between 58.2 degrees C and 59.9 degrees C) and a small particle size (between 565 and 227 nm). Degradation of the n-octacosane core starts between 150 degrees C and 180 degrees C. Also, the use of silica as shell material gives way to a heat conductivity of 0.796 W m(-1) K-1 (greater than that of nanoencapsulated materials with polymeric shell). Charge/discharge cycles have been successfully simulated at low pressure to prove the suitability of the nanopowder as phase-change material. Further research will be carried out in the future regarding the use of the synthesised material in thermal applications involving nanofluids.