THE SECOND SAUDI INTERNATIONAL CONFERENCE ON NUCLEAR POWER ENGINEERING (SCOPE-2)

Phase Change Materials (PCMs) have garnered considerable attention for thermal energy storage applications due to their capacity to absorb and release latent heat during phase transitions. In nuclear power plant passive containment cooling systems, the effectiveness of PCMs heavily depends on the thermal medium used to initiate and sustain melting. This study presents a comparative numerical investigation of the melting behavior of PCMs when subjected to heating by steam and hot water under identical operational conditions. The simulations were performed using melting and solidification model, with steam and hot water introduced at a flow velocity of 0.5 m/s, inlet temperature of 140 °C, and pressure of 0.4 MPa. The PCM used in the study transitions between 57 °C and 60 °C, characterized in temperature due to latent heat absorption.

Results show that steam significantly enhances the heat transfer rate and accelerates the melting process compared to hot water. This is attributed to the latent heat released during steam condensation, which provides more intense and continuous energy delivery. In contrast, hot water relies solely on sensible heat transfer, resulting in a slower temperature rise and extended melting duration. Post-melting, steam also sustains a higher thermal trajectory, while hot water shows a modest increase. The findings suggest that steam is more effective for rapid thermal storage applications, whereas hot water may suit systems requiring gradual heating. These insights offer valuable guidance for optimizing PCM-based thermal energy storage systems in nuclear containment.