The transient melting process of the phase change material (PCM) is controlled by heat conduction and natural convection. Several experimental investigations are essential to understand the heat transfer mechanisms and performance for different designs of PCM thermal storage systems. Therefore, the present study experimentally investigated paraffin wax's melting process in a vertical cylindrical enclosure. The PCM, initially at 30 °C, was heated using an electric heater located at the center of the enclosure. The heat flux density varied to 1300, 1000, and 700 W/m². Local temperatures of the PCM were measured, and the solid-liquid interface was tracked. A CFD (computational fluid dynamic) model was developed to numerically investigate the melting process with and without considering the convection effect. The CFD model was validated with the current experiments and with data from the literature. A very good agreement was obtained. The results showed that; the melting was initially dominated by conduction at an early stage, and this period increased with a decrease in heat flux. Natural convection was promoted, at a later time, leading to a curved shape of the solid-liquid interface. Numerical results indicated a robust thermal stratification of the molten liquid in the upper half of the storage unit. It was observed that increasing the input power from 700 W/m² to 1000 W/m² and 1300 W/m² decreased the total melting time by 24.82% and 43.58%, respectively. It is recommended for the future modeling of the PCM melting process to consider the convection effect.

相变材料（PCM）的瞬态熔化过程由导热和自然对流控制。进行几次实验研究对于理解PCM蓄热系统不同设计的传热机理和性能至关重要。因此，本研究通过实验研究了石蜡在垂直圆柱形外壳中的熔化过程。最初使用30°C的PCM使用位于外壳中央的电加热器加热。热通量密度变化为1300、1000和700 W / m ²。测量了PCM的局部温度，并跟踪了固液界面。建立了CFD（计算流体动力学）模型，以在不考虑对流效应的情况下对熔融过程进行数值研究。CFD模型已通过当前的实验和来自文献的数据进行了验证。获得了很好的协议。结果表明：熔化最初在早期以传导为主导，并且随着热通量的减少而增加。后来，自然对流得到了促进，导致了固液界面的弯曲形状。数值结果表明，存储单元上半部分中的熔融液体有强烈的热分层。观察到输入功率从700 W / m ^2增加分别为1000 W / m ²和1300 W / m ²可使总熔化时间分别减少24.82％和43.58％。建议在将来对PCM熔化过程建模时考虑对流效应。