TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The latent heat storage medium comprises sodium acetate trihydrate or its solution, preferably sodium acetate trihydrate solution in water.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The separating agents are provided in the chamber, which divide the chamber into separate areas, where the latent heat storage medium is at least partially in the partial chambers. The separating agents are designed as plates (24), preferably flat or curved plates, where at least one edge of the plate is bent or angled relative to the plate plane. The separating agents are designed such that at least sectionally a gap remains between the separating agent and the wall of the receptacle. The separating agents are stacked and/or at least two of the separating agents has a distance from each other of 1-30 mm, preferably 5-10 mm. The receptacle is designed as a heat exchanger, where the latent heat storage medium is present in the heat exchanger such that the heat is supplied to the latent heat storage medium and/or the heat is discharged from the latent heat storage medium. At least one tube extends in the receptacle for the heat exchange. At least one, many or all the tubes extent through the recesses of at least one, many or all the separating agents, or connected with one, many or all separating agents. The receptacle is associated with or connected with at least one energy source, preferably a solar plant or with a burner and/or with at least one consumer, preferably with a heater or a hot water system.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The substance comprises carboxymethyl cellulose or a derivative of carboxymethyl cellulose. The latent heat storage medium is capable of crystallization and/or the phase transition temperature of the latent heat storage medium is 0-100 degrees C. The latent heat storage medium is a salt hydrate, preferably a semi-congruent melting salt hydrate. The proportion of the viscosity increasing substance, preferably carboxymethyl cellulose or its derivative in the latent heat storage medium is 0.1-15%, preferably 1.5-3%.