Phase-change materials (PCM) are particularly promising for thermal storage in energy systems where the working fluid is either characterized by small specific heat or small temperature difference. In these cases, sensible heat storage would involve small energy densities (i.e. energy per unit volume). Latent heat storage would allow one to reduce the volume of storage tanks, but also reduce problems related with thermal stratification. On the other hand, heat transfer in PCMs needs to be enhanced in order to complete the charging and discharging processes in reasonable time. This paper reports the numerical and experimental activity performed by the authors related with the design of latent heat storage systems for district heating applications. Among the various enhancement methods, fins present some technical advantages related with manufacturing and management, which make them suitable for the application in district heating systems. The following aspects are considered in this paper: 1) melting and solidification; 2) modeling approaches and validation; 3) thermal enhancement with circular, radial or Y-shaped fins.
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