For heat storage applications, the solid liquid phase changes of the LiNO3-KNO3 and LiNO3-KNO3-NaNO3 mixtures of eutectic compositions have been investigated by Differential Scanning Calorimetry (DSC) and with a home built calorimeter working on large samples - typically 500 g. The design of the new calorimeter matches at best the geometry and the thermal transfers in the industrial application. The kinetics of crystallization has been particularly studied. Density measurements of the salts in the liquid state allowed to calculate the volumetric storage capacity. (C) 2013 Elsevier Ltd. All rights reserved.