Calorimetric and theoretical determination of the concentration dependent enthalpy change around CaBr2·6H2O

In large latent heat storages based with the phase change material (PCM) being a salt hydrate, it is difficult to assure the stoichiometrically correct hydrate concentration of the salt hydrate. In this study the impact of the concentration of CaBr2 + H2O in a concentration range of about 2.6 wt% around the congruent melting CaBr2·6H2O on the melting enthalpy and the maximum storage capacity is exemplary investigated via differential scanning calorimetry (DSC) and via a model. The melting enthalpy of CaBr2·6H2O is found to be 142.1 J g−1, which is significantly larger than the value indicated in literature (115.5 J g−1). For a CaBr2 concentration around 0.8 wt% lower than the concentration of CaBr2·6H2O, a decrease of over 17% is found for both the melting enthalpy and the maximum storage capacity. A good agreement is found for the maximum storage capacity between the experimentally determined values and the values determined by the model.