A study of a eutectic salt of lithium nitrate and sodium chloride (87-13%) for latent heat storage

- A eutectic salt comprised of LiNO3-NaCl were prepared for latent heat storage.
- The salt exhibited excellent thermal cycling repeatability and stability.
- Thermal decomposition temperature was between 400 °C and 450 °C.
- Thermal conductivity was predicted to be within the range of 0.57 and 0.60 W/m/K.
- The salt has a good compatibility with stainless steel 316.

Latent heat storage in salt mixtures has attracted much attention as it can store a large amount of heat within a small temperature range in a small volume compared to sensible heat storage. In this paper, the eutectic salt of LiNO3-NaCl (87-13%) was investigated to evaluate its potential for latent heat storage for medium temperature range applications (<300 °C). The eutectic salt was prepared using the indirect mixing method. Its thermal properties including melting temperature and latent heat were measured over multiple cycles using Differential Scanning Calorimetry (DSC). The measurements show that the eutectic salt of LiNO3-NaCl (87-13%) has a suitable melting temperature (around 220 °C) and a relatively high latent heat (>290 kJ/kg). Its thermal decomposition temperature was tested using a Thermogravimetric Analyser (TGA). The salt mixture exhibits an excellent chemical stability below 400 °C with no changes after tests of multiple cycles with DSC and TGA. The main factors affecting the economic feasibility for this eutectic salt were also discussed.