The Influence of Moisture Content on the Evaluation of Latent Heat of Molten Salts used for Thermal Energy Storage Applications

Abstract

Precise measurements of the thermo-physical properties are essential for the process design of thermal energy storage systems. This paper is concerned with the measurement of heat of fusion of molten salts, which plays a key role in determining the storage capacity of latent heat based thermal energy storage units. The focus of the work is on the effect of moisture content of molten salts on latent heat measurements using a differential scanning calorimetry. The results reveal that, the change in the mass of the samples investigated is due to moisture content, and hence, this leads to a reduction in the value of the heat of fusion of the phase change material. For instance, the heat of fusion for one of the wet samples (containing moisture) was determined to be 314.29J/g. However, the calculated heat of fusion for the same sample without moisture is found to be 350.029J/g. This is associated with the methodology of the DSC analysis, which does not consider the mass of the moisture in the sample. It is found that, the deviation in the heat of fusion due to the effect of the moisture content in the investigated samples is proportional to the amount of moisture in the original sample. Therefore, it is imperative to consider the effect of the moisture content on the evaluation of the latent heat of molten salts. In order to obtain reliable findings, either the samples should be dried and then weighed promptly, or weighed after the test and then re-evaluate the latent heat using the new weight.