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Binary and ternary alkali polyphosphates (MPO3, M = Li, Na, K) for thermal energy storage

Abstract : Up-to-date, solar salt (a mixture of 60 mass% NaNO3 and 40 mass% KNO3) is practically the only media for thermal energy storage (TES) in concentrated solar power (CSP). This commercial product’s utilization is limited below 550 °C to avoid an irreversible thermal decomposition. The development of new performing TES materials is decisive for the deployment of CSP technology. Our recent work reported promising results obtained with mono-alkali polyphosphate (M-PO3) as TES materials. These materials can work up to around 900 °C, but their melting point is still high, which is at least 628 °C. In order to lower their melting point, binary and ternary mixtures of alkali polyphosphates are investigated in this work. Dif- ferent mixtures made of two or three alkali polyphosphates were prepared and studied using thermal analysis methods. The most promising mixture found in this work was the ternary Li-Na-K-PO3, which contained 33.3% (mol%) of each alkali metal. This mixture can be used as a liquid TES material in the temperature range of 398 to 900 °C. The results open new prospects for the development of the thermal energy storage field.
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Contributor : Imt Mines Albi Ecole Nationale Supérieure Des Mines d'Albi-Carmaux <>
Submitted on : Wednesday, November 18, 2020 - 4:54:27 PM
Last modification on : Saturday, November 21, 2020 - 3:17:49 AM



Hieu Pham Sy, Doan Pham Minh, Abdoul Razac Sane, Hoan Nguyen Xuan, Nawal Semlal, et al.. Binary and ternary alkali polyphosphates (MPO3, M = Li, Na, K) for thermal energy storage. Journal of Thermal Analysis and Calorimetry, Springer Verlag, In press, ⟨10.1007/s10973-020-10346-1⟩. ⟨hal-03012742⟩