Thermodynamics Research Center / ThermoML | Thermochimica Acta

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

Schmit, H.[Henri], Pollinger, S.[Simon], Pfeffer, W.[Werner], Hiebler, S.[Stefan]
Thermochim. Acta 2015, 609, 20-30
ABSTRACT
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.
Compounds
# Formula Name
1 Br2CaH12O6 calcium bromide hexahydrate
2 Br2Ca calcium bromide
3 H2O water
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 1
  • Normal melting temperature, K ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DTA
  • 1
  • POMD
  • 1
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal
  • Crystal
  • Liquid
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • Small sample (50 mg) DSC
  • 1
  • POMD
  • 3
  • 2
  • Molar heat capacity at constant pressure, J/K/mol ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Mass fraction - 2; Liquid
  • Liquid
  • Small sample (50 mg) DSC
  • 1