Characterization of Sodium Nitrate as Phase Change Material

In this article the results of material investigations of sodium nitrate (NaNO3) with a melting temperature of 306 degrees C as a phase change material (PCM) are presented. The thermal stability was examined by kinetic experiments and long-duration oven tests. In these experiments the nitrite formation was monitored. Although some nitrite formation in the melt was detected, results show that the thermal stability of NaNO3 is sufficient for PCM applications. Various measurements of thermophysical properties of NaNO3 are reported. These properties include the thermal diffusivity by the laser-flash, the thermal conductivity by the transient hot wire, and the heat capacity by the differential scanning calorimeter method. The current measurements and literature values are compared. In this article comprehensive temperature-dependent thermophysical values of the density, heat capacity, thermal diffusivity, and thermal conductivity in the liquid and solid phases are reported.