Valorizing Refinery Byproducts: Thermal Enhancement of Paraffin Wax With Algerian Slack Wax for Energy Storage

ABSTRACT The global transition to sustainable energy systems demands high‐performance thermal energy storage, with paraffin wax standing as a prominent phase change material (PCM) due to its high latent heat, chemical stability, and cost‐effectiveness. However, its low thermal conductivity (about 0.2 W/m·K) and phase segregation significantly limit its practical application. While nanofillers and carbon additives can enhance conductivity, they often reduce latent heat, increase costs, and complicate processing. This study introduces a novel, sustainable solution by valorizing Algerian slack wax, a local petroleum refinery byproduct, as a multifunctional enhancer for paraffin. Composites with 6, 10, 15, and 20 mass% slack wax were formulated and characterized using the T‐history method. The results demonstrate a breakthrough in simultaneous property enhancement, overcoming typical trade‐offs. The 20% composite achieved a 35.65% increase in latent heat (from 106.93 to 145.06 kJ/kg), a 30.48% rise in specific heat (from 3.51 to 4.58 kJ/kg·K), and a 33% improvement in thermal conductivity (from 0.18 to 0.24 W/m·K in the solid state). Furthermore, the material's thermal responsiveness was enhanced, with a 25% reduction in solidification time (from 165 to 120 s) and a 20% faster melting rate (from 125 to 100 s). These improvements are attributed to molecular interactions that disrupt paraffin's crystalline order, facilitating more efficient phonon transport and energy distribution. By transforming an industrial waste into a high‐performance PCM, this work provides a cost‐effective, scalable, and circular pathway for advanced thermal storage, directly benefiting solar energy integration, building efficiency, and industrial waste heat recovery.