Thermal energy storage behavior of composite using hybrid nanomaterials as PCM for solar heating systems

In this study, thermal and heat transfer characteristics of the newly prepared composite as phase change material (PCM) comprising paraffin and hybrid nanomaterials (50 % CuO–50 % TiO₂) have been investigated for solar heating systems. Composite PCMs with 0.25, 0.5, 0.75, and 1.0 mass% of hybrid nanomaterials were prepared individually for assessing their better performances than paraffin alone. Sodium dodecylbenzene sulfonate (SDBS) was preferred as the surfactant to ensure the dispersion stability of the nanomaterials in the paraffin and mass fraction of SDBS was 1.2 times of the mass fraction of hybrid nanomaterials in the paraffin. The thermal properties of the composite PCMs were determined by differential scanning calorimetry in terms of mass fractions of hybrid nanomaterials and number of thermal cycles. The thermal stabilities of the paraffin and composite PCMs were tested by thermogravimetric analyzer. The thermal conductivity and viscosity of the paraffin due to the addition of various mass fractions of CuO, TiO₂, and hybrid nanomaterials were determined by LFA 447 NanoFlash analyzer and Brookfield DV-III Ultra programmable rheometer, respectively. The experimental results proved that the heating and cooling rates of composite PCMs were faster due to the dispersion of hybrid nanomaterials. For composite PCM with 1.0 mass% of hybrid nanomaterials, the melting and freezing times were reduced by 29.8 and 27.7 %, respectively, as compared with the paraffin.