# Inorganic Salt Hydrate for Thermal Energy Storage
## 2 Properties of Inorganic Salt Hydrated PCMs
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Salt Hydrates** & **Melling Temperature (\({}^{\circ}\)C)** & **Heat of Fusion (\(\mathrm{\eta g}\))** & **Density (Solid) (\(\mathrm{\eta^{3}}\) kg/m\({}^{3}\))** & **Thermal Conductivity (Solid) (W/mK)** & **Specific Heat (Solid) (\(\mathrm{\eta_{g}}\)\({}^{\circ}\)C)** & **Reference** \\ \hline LEGO, 3H\({}_{0}\)O & 8 & 253 & & & 1.84 & [3,1] \\ K-H\({}_{0}\)O & 19 & 231 & 1.45 & & & 1.84 & [5,11] \\ Mn(NO)\({}_{2}\)H\({}_{0}\)O & 25.8 & 125.9 & 1.60 & & & [13] \\ CGC\({}_{2}\)H\({}_{0}\)O & 28 & 174 & 1.80 & 1.088 & 1.42 & [1,3] \\ LNO\({}_{3}\)H\({}_{0}\)O & 30 & 256 & & & & [13] \\ Na\({}_{3}\)S\({}_{0}\)H\({}_{0}\)O & 32.4 & 248 & 1.49 & & & [14] \\ Na\({}_{3}\)C\({}_{0}\)H\({}_{0}\)O & 33 & 247 & & & 1.88 & [14] \\ Ca\({}_{3}\)H\({}_{0}\)O & 34 & 115.5 & 1.52 & & & [19] \\ Li\({}_{3}\)H\({}_{0}\)O & 34 & 124 & & & & [19] \\ Na\({}_{3}\)H\({}_{0}\)O & 35-44 & 280 & & 0.514 & 1.7 & [5,11] \\ ZnZn(NO)\({}_{0}\)H\({}_{0}\)O & 36 & 149.6 & 1.94 & & 1.34 & [19] \\ K-Zn(NO) & 42 & 162 & & & & [14,9] \\ Mn\({}_{3}\)H\({}_{2}\)O & 42 & 133 & & & & [5,11] \\ Ca(NO)\({}_{0}\)H\({}_{0}\)O & 42.4 & 14 & & & 1.46 & [14] \\ Fe(NO)\({}_{0}\)H\({}_{0}\)O & 47 & 155 & & & & [14] \\ Na\({}_{3}\)S\({}_{0}\)H\({}_{0}\)O & 48 & 168 & & & & [14] \\ K\({}_{0}\)H\({}_{0}\)O & 48 & 99 & & & & [14] \\ Na\({}_{3}\)S\({}_{0}\)H\({}_{0}\)O & 49 & 220 & 1.75 & 1.46 & & [1] \\ Ca(NO)\({}_{3}\)H\({}_{0}\)O & 51 & 104 & & 1.46 & & [14] \\ Fe(NO)\({}_{2}\)H\({}_{0}\)O & 56 & 90 & & & [11] \\ Ni(NO)\({}_{0}\)H\({}_{0}\)O & 57 & 169 & & & [11] \\ Cl\({}_{3}\)CO\({}_{3}\)H\({}_{0}\)O & 88 & 226-254 & 1.45 & 1.97 & & [14,14] \\ Mg\({}_{0}\)Cl\({}_{4}\)H\({}_{0}\)O & 88 & 178 & & & & [14] \\ Na\({}_{3}\)H\({}_{0}\)O & 1214.0 & 65-49 & 190 & & & [14] \\ Li\({}_{3}\)CO\({}_{0}\)H\({}_{0}\)O & 70 & 150 & & & & [14] \\ Na\({}_{3}\)P\({}_{0}\)O & 2114.0 & 70 & 184 & & & [14] \\ Na\({}_{3}\)P\({}_{0}\)O & 88-60 & 78 & 266 & & & [14] \\ Al(NO)\({}_{0}\)H\({}_{0}\)O & 89-3 & 150 & & & 1.17 & & [1] \\ Mg\({}_{0}\)O\({}_{0}\)H\({}_{0}\)O & 89.9 & 163 & 1.636 & 1.81 & 0.69 & [1] \\ Ni(NO)\({}_{0}\)O\({}_{12}\)H\({}_{0}\)O & 95 & 269 & 1.65 & 1.71 & & [11] \\ Al(NO)\({}_{0}\)O\({}_{12}\)H\({}_{0}\)O & 112 & & & & [11] \\ Mg\({}_{0}\)Cl\({}_{2}\)H\({}_{0}\)O & 117 & 167 & 1.56 & 1.59 & & [14] \\ \hline \end{tabular}
\end{table} 
Table 1: Thermo-physical properties of salt hydrates. Generally speaking, it is difficult to determine the thermo-physical properties of PCMs due to the limitation of the conventional devices such as differential scanning calorimetry (DSC), modulated differential scanning calorimetry (MDSC) and differential thermal analysis (DTA). DSC method is common for measuring enthalpy, specific heat and phase change temperature for PCMs. However, only a small amount of samples can be measured once, which lead to possible errors of results. In addition to this, the measuring results are largely influenced by environmental factors. Consequently, the investigations on thermo-physical properties of salt hydrates are inadequate in literature. However, they are vital for heat flow transformation process, which is a decisive factor for effective heat storage system. In recent years, Temperature-history (T-history) method has been mentioned by [PERSON] et al. [20]. As a simple, accurate, and economic way for determining the main thermophysical properties such as enthalpy, specific heat, supercooling degree as well as process of phase transition, T-history method represents an advance to obtain average properties of PCMs especially for sensitive salt hydrate PCMs which suffer supercooling.