Melt front tracking is vital in a solid–liquid phase change process to understand the melting process and quantify the system’s liquid faction, sensible and latent energies. This study presents a method to track the solid–liquid interface during the melting of a phase change material using liquid crystal thermography. The melt front movement is captured simultaneously through temperature influenced color variation in Thermochromic Liquid Crystal (TLC) sheet and direct visualization. Experiments have been performed for the cases of (i) heating from the bottom and (ii) heating from the top. Further, three-dimensional numerical simulations have been performed to validate the mushy zone temperatures and understand the effect of the mushy zone constant in the mushy zone temperature and liquid fraction. The results show that the TLC easily captures the dynamic motion of the solid–liquid interface during melting. From numerical simulations, it is found that the mushy zone constant affects the numerical prediction of melting in the bottom heating case with the low and high mushy zone constants, respectively, over predicting and under predicting the mushy zone temperatures during melting. Additionally, in this case, it is seen that the Rayleigh–Benard convection creates a wavy interface and accelerates the melting rate of the PCM. In the case of heating from the top, the numerical prediction of melting is independent of the mushy zone constant. Besides, a flat interface is observed in this case due to the absence of convection in the PCM during melting. Additionally, in the case of heating from the top, the combination of the PCM’s low thermal conductivity and heat diffusion through conduction leads to the self insulation effect of the PCM during melting. The convection-driven melting of PCM maintains the heater temperature lower by up to 35%, reduces the melting thermal resistance up to 78%, and increases the average volumetric melting to 92% over the case of melting without convection in the PCM.

熔体前沿跟踪在固-液相变过程中至关重要，可以了解熔化过程并量化系统的液体成分、显能和潜能。本研究提出了一种使用液晶热成像技术跟踪相变材料熔化过程中固液界面的方法。通过热致变色液晶 (TLC) 片中受温度影响的颜色变化和直接可视化同时捕获熔体前沿运动。已经针对（i）从底部加热和（ii）从顶部加热的情况进行了实验。此外，已经进行了三维数值模拟以验证糊状区温度并了解糊状区常数对糊状区温度和液体分数的影响。结果表明，TLC 很容易捕捉到熔化过程中固-液界面的动态运动。从数值模拟中发现，在低和高的糊状区常数下，糊状区常数分别影响熔化过程中糊状区温度的高预测和低预测。此外，在这种情况下，可以看出 Rayleigh-Benard 对流会产生波浪形界面并加快 PCM 的熔化速度。在从顶部加热的情况下，熔化的数值预测与糊状区常数无关。此外，由于在熔化过程中 PCM 中没有对流，在这种情况下观察到平坦的界面。此外，在从顶部加热的情况下，PCM 的低导热性和通过传导进行的热扩散的结合导致了 PCM 在熔化过程中的自绝缘效果。相较于在 PCM 中没有对流的情况下，PCM 的对流驱动熔化使加热器温度降低了 35%，将熔化热阻降低了 78%，并将平均体积熔化率提高了 92%。