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

Abstract

Summary 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°C and 59.9°C) and a small particle size (between 565 and 227 nm). Degradation of the n‐octacosane core starts between 150°C and 180°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.

Study on the microstructures and thermal properties of SiO 2 @ NaNO 3 microcapsule thermal storage materials

“…It was worth mentioning that the T peak of SiO 2 @NaNO 3 microcapsules in the decomposition decreased slightly with the increase of the silica addition, which was due to the increase of thermal conductivity. Furthermore, the residual amount of sodium nitrate was 28%, and the residual amount of the M‐1 sample was up to 45% after the second decomposition, which was due to the protection of silica shell in preventing decomposition of NaNO 3 42,43 . During the preparation process of pure SiO 2 , the incomplete condensation reaction results in a large amount of precursor remaining in the reaction system.…”

Thermal properties and applications of form‐stable phase change materials for thermal energy storage and thermal management: A review

“…The shell of the microencapsulated PCM can be organic materials such as polymethylmethacrylate, 80 melamine‐formaldehyde resin, 77 polyurethane, 75 inorganic materials such asGO, 73 SiO 2, 71 AgBr, 74 and mixtures. Thermal conductivity for inorganic shell microencapsulated PCM is usually greater in comparison to that of organic shell microencapsulated PCM 72 . The hybrid shell can be a mixture of two different organic substances such as poly (methyl methacrylate) and polyuria, 83 or it can be an organic‐inorganic mixture.…”

Noticeable improvement in morphological characteristics and thermal reliability of n‐octadecane@ SiO 2 nanocapsules for thermal energy storage

“…Therefore, inorganic materials with a high thermal stability and conductivity compared to organic materials have been employed to encapsulate PCMs, which improves the unfavorable characteristics of organic polymer shells. According to the related studies on PCM encapsulation, inorganic materials, such as SiO 2, [16][17][18] TiO 2, [19][20][21] and CaCO 3, 22,23 are used as shell materials. Among these materials, SiO 2 exhibits improved chemical stability even in corrosive environments, is nontoxic, and has high mechanical strength; therefore, it has been mainly used for encapsulation.…”