“…Still, a major concern for the LHTES system is PCM's minimal thermal Energies 2021, 14, 7179 2 of 23 efficiency, which decreases the phase change rate [14][15][16][17]. Researchers developed several techniques to improve the heat transfer rate of such systems, including the expansion of the heat transfer surface area [18][19][20], adding micro or nano-sized particles [21][22][23][24], using cascade layer PCM [25], encapsulation techniques [26,27], changing the location of the heat transfer fluid (HTF) channel [28][29][30], fins combinations [31][32][33], conductive foams [34][35][36], and using magnetic fields [37,38].…”