Influence of flow characteristics on thermal energy storage during Paraffine wax melting process

This study investigates the thermal performance of paraffin-based phase change material (PCM) in a Passive Containment Cooling System (PCCS), specifically for nuclear safety applications. Using validated numerical simulations, the effects of key parameters, including inlet temperature (100–140 °C), Thermal stratification of PCM domain, velocity of high temperature fluid (0.3–0.9 m/s), flow direction (bottom-to-top vs. top-to-bottom) of HTF, and heating medium (water vs. steam) on PCM melting dynamics were systematically analyzed. The results reveal that higher inlet temperatures and flow velocities significantly reduce melting Time and improve heat transfer coefficients, thereby enhancing energy absorption efficiency. Among the flow configurations, top-to-bottom flow outperforms bottom-to-top flow due to improved convective interaction. At the same Time, steam heating proves more effective than hot water by utilizing latent heat. These findings emphasize the critical role of optimizing thermal and flow parameters in improving the performance of PCM-based thermal energy storage systems for emergency cooling in nuclear reactors. Future research will focus on advanced heat transfer designs and enhancing the long-term reliability of PCM-based systems for nuclear safety applications.