Thermal conductivity of selected salt hydrates for thermochemical solar heat storage applications measured by the light flash method

Highlights: • The light flash method was used to measure thermal conductivities of salt hydrates. • We verified the method to determine the thermal conductivity with NaCl. • Thermodynamic data for hydrates of MgSO₄, ZnSO₄, SrCl₂ are presented. • The thermal conductivities of the salt hydrates are between 0.6 and 1.0 W m⁻¹ K⁻¹. - Abstract: Salt hydrates of MgSO₄, ZnSO₄ and SrCl₂ are promising materials for thermochemical heat storage applications. It is necessary to know the thermal conductivity of their hydrates in order to optimize heat storage systems. Therefore, the hydrates which occur as reaction products of a hydration were pressed into pellets and the thermal diffusivity was measured with the light flash method. To calculate the thermal conductivity, the heat capacity, which was determined by calorimetry, is also required. The method used to determine the thermal conductivity was verified with NaCl. MgSO₄·7H₂O, MgSO₄·6H₂O and ZnSO₄·7H₂O showed thermal conductivities of about 0.7 W m⁻¹ K⁻¹, while SrCl₂·6H₂O reached 1.0 W m⁻¹ K⁻¹.