The latent heat storage is one of the most efficient ways to store thermal energy. It provides a higher storage density with a smaller temperature difference between the stored and released heat than the sensible heat storage method.
Being one of the energy saving related applications, phase change materials (PCM) are used to design thermal energy storage systems for recovery of waste heat, discontinuous energy production, and improved insulation materials. To be suitable for energy storage, a PCM should possess large phase change enthalpy, phase change temperature adapted to a given energy storage system, reproducible phase change, and a limited subcooling effect. All these parameters can be determined by calorimetric techniques and several examples will be given.
The thermal behavior of large heterogeneous samples with different shapes (polyolefins encapsulated in polymer beads) was studied by Differential scanning calorimetry, which simulates the actual conditions of use. The latent heat of fusion of a mixture of paraffins and a dicarboxilic acid was measured after several phase changes to evaluate another important parameter – cycling stability.
The experimental results obtained for another type of thermal energy storage materials, hydrated inorganic salts, will be presented in order to assess the quantity of heat, which can be stored for a certain temperature range. The latent heat of fusion and the heat of dehydration were measured and analyzed using highly sensitive DSC technique.