Synthesis and application of paraffin/silica phase change nanocapsules: Experimental and numerical approach

The present study has been focused on the synthesis of silica encapsulated paraffin phase change materials and its application in cement-based systems. One-pot in-situ hydrolysis of tetraethyl orthosilicate as silica precursor and subsequent polycondensation have successfully encapsulated the paraffin droplets into nano-sized capsules of phase change materials (PCMs). The fabricated nanoencapsulated PCMs (NEPCMs) possess distinct core-shell structures with spherical geometry. Encapsulation ratio and encapsulation efficiency have been accomplished up to 92.9 and 90.24% with the latent heats of melting and solidification of 173.79 and 158.93 J/g, respectively. Calorimetry studies of the fabricated NEPCMs with ordinary Portland cement (OPC) have demonstrated 11% temperature reduction during the evolution of the heats of hydration, with the addition of only 3% NEPCMs. The synthesized PCMs are found to perform as high thermal energy storage materials with the capability of congruent heat storage and release without affecting their structure and geometry, therefore, can be considered as reliable and durable PCMs for concrete and building materials. The use of these NEPCMs can control the maximum temperature rise due to heat of hydration and therefore reducing the defects and cracks formation inside the mass concrete structures.