Abstract: Thermal storage system and its charging and discharging process using a heat-transfer fluid. The system includes a phase change storage material contained in a casing that is penetrated by heat exchanger tubes (3), preferably vertical ones, connected at their lower end with at least one lower chamber (62) via lower sub-chambers (62?) which include a series of injectors (9) for enabling the heat-transfer fluid to be inserted in gas form; at the upper end, these tubes (3) connect via upper sub-chambers (61?) with at least one upper chamber (61) which in turn is connected to a boiler (1) from which downpipes (8) extend via which heat-transfer fluid in liquid form circulates, located outside of the casing, connecting the aforementioned boiler (1) to the lower chamber (62), which enables the natural circulation of the heat-transfer fluid within the system.

Abstract: Composite material for storing heat energy at high temperatures (225° C. to 488° C.) formed by a porous carbon structure at least partially filled with LiOH/KOH, wherein a large amount of heat energy may be stored or released very quickly. The carbon structure is characterised by a high volumetric thermal conductivity, a low density, a highly interconnected porosity and a relatively high modulus of elasticity. The significant properties of LiOH/KOH mixtures are: a large amount of energy involved in full melting/crystallisation, a fairly low relative volume expansion upon melting and fairly low subcooling. The main advantages of the resulting composites are a very high energy density, a relatively low volume expansion, highly enhanced heat transfer, thermoadaptability, stability and insignificant hysteresis.