Thermophysical Properties of Lithium Nitrate Trihydrate from (253 to 353) K

Abstract

Lithium nitrate trihydrate is of interest as a thermal energy storage material, due to its large specific and volumetric enthalpy of fusion and its low melting temperature. Here, we report the thermophysical properties of solid and liquid lithium nitrate trihydrate at temperatures from (253 to 353) K and compare this compound to water and octadecane, two other potential thermal energy storage materials. Furthermore, we examine the lithium nitrate–water phase diagram and accurately determine the enthalpies of fusion and melting temperatures for lithium nitrate trihydrate, ΔH fus = (287 ± 7) J·g–1 and T fus = 303.3 K, and the lithium nitrate trihydrate–lithium nitrate eutectic, ΔH fus = (264 ± 2) J·g–1 and T fus = 301.4 K.

Corrosive effect of lithium nitrate trihydrate on common heat exchanger materials

“…Thermal properties were measured by differential scanning calorimetry (DSC) to confirm the composition of LNH, as the behavior of the melting peak is very sensitive to water content. The melting temperature, T m , is within 1%, and the enthalpy of fusion, Δ fus H , is within 5% of previously reported values (30.1 ± 0.3 °C, 287 ± 14 J/g, respectively) . The pH of the liquid LNH was found to be approximately 3.5.…”

“…Phase change materials (PCMs) absorb heat associated with a physical phase transformation (melting, evaporation), and reversibly release thermal energy as they return to the stable low‐temperature phase. Salt hydrates, one particular class of PCMs, are of particular interest for mobile use in thermal energy storage applications, due to the high specific and volumetric energy density, as well as their relatively large thermal conductivity . Two of the key factors limiting widespread implementation of these materials are the limited reversibility of the phase change due to super‐cooling, and the corrosive effects of the salt hydrate on certain container materials.…”

“…Lithium nitrate trihydrate (LiNO 3 · 3H 2 O; LNH) is a promising PCM with a melting temperature of 30.1 ±0.2 °C and an enthalpy of fusion of 287 ±7 J g −1 . Multiple nucleating agents have been identified which mitigate super‐cooling, making LNH more practical for implementation in a TES system.…”

“…Salt hydrates, one particular class of PCMs, are of particular interest for mobile use in thermal energy storage applications, due to the high specific and volumetric energy density, as well as their relatively large thermal conductivity. [8][9][10] Two of the key factors limiting widespread implementation of these materials are the limited reversibility of the phase change due to super-cooling, and the corrosive effects of the salt hydrate on certain container materials. These limitations can be mitigated by including a nucleating agent to reduce super-cooling, and selecting compatible container materials to avoid chemical degradation of materials.…”

“…Lithium nitrate trihydrate (LiNO 3 · 3H 2 O; LNH) is a promising PCM with a melting temperature of 30.1 ±0.2°C and an enthalpy of fusion of 287 ±7 J g −1 . [9] Multiple nucleating agents have been identified which mitigate super-cooling, making LNH more practical for implementation in a TES system. The copper-based compound likasite, Cu 3 (NO 3 )(OH) 5 · 2(H 2 O), provides LNH with a surface with similar crystal lattice parameters to initiate nucleation and reduces super-cooling in LNH to approximately 6.3°C whereas neat LNH can suffer from a super-cooling of up to ∼70°C.…”