Thermophysical Characterization and Experimental Evaluation of a Paraffin Wax-Palm Stearin Composite Phase Change Material for Tropical Thermal Energy Storage

Thermal energy storage (TES) using phase change materials (PCMs) offers an effective strategy for mitigating renewable energy intermittency and reducing cooling demand in tropical climates. This study presents the development and evaluation of a paraffin wax–palm stearin composite PCM designed for low-temperature thermal energy storage applications. A 70:30 mass ratio composite was prepared via controlled melt blending and macro-encapsulation in aluminium foil. Thermophysical properties were estimated using the rule of mixtures, yielding a theoretical latent heat of 184.5 kJ/kg and a total storage capacity of 276.75 kJ for a 1.5 kg slab. Experimental performance was assessed using a comparative dual-chamber model under 200 W heating and natural cooling conditions. Results indicate successful latent heat storage, with a pronounced phase transition plateau at 40–42°C during discharge and a temperature retention of 11.7°C relative to the control after 60 minutes of cooling. The composite demonstrates cost reduction relative to pure paraffin wax and exhibits promising thermal buffering capability for passive cooling and solar heat storage in tropical environments.