**1.1 Phase change material (PCM)**

PCMs are commonly employed to enable efficient TES in compact configurations, leading to the categorization of these TES systems as Latent Heat Storage Units (LHSUs) [1]. TES platforms can be categorized as illustrated in **Figure 1**.

PCMs store energy during melting or solidification through both sensible and latent heat. Initially, a PCM begins in a subcooled solid state, warming up *via* sensible heating until it reaches its phase transition point. At this juncture, energy input causes a phase transformation, maintaining a constant temperature within a portion of the PCM. This phase change absorbs energy, crucial for the transformation process across its volume, eventually transitioning into a liquid phase. Further energy input then increases the temperature, facilitating sensible heat storage based on temperature change (ΔT) and the PCM's specific heat capacity. Although the storage of latent heat, determined by the PCM's enthalpy, is the primary method in PCM TES systems, a minimal amount of sensible heat storage also occurs in both phases, constituting a small portion of the total energy stored. Melting and solidification behaviors, based on the thermal energy stored in the PCM, are depicted in **Figure 2**.
