Thermo-economic analysis of high-temperature sensible thermal storage with different ternary eutectic alkali and alkaline earth metal chlorides
Date
2018
Authors
Mohan, Gowtham
Brahmadesham Venkataraman, Mahesh
Gomez-Vidal, Judith
Coventry, Joseph
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Elsevier
Abstract
Molten salt mixtures with alkali and alkaline earth metal chlorides were developed for high-temperature sensible thermal energy storage in support of concurrent efforts to develop high-temperature advanced power cycles for concentrating solar power applications. Four ternary chloride mixtures with different cation combinations (Na, K, Li, Mg) were designed using the FactSage® software, and for three of these, the eutectic point was experimentally validated by differential scanning calorimetry. Specific heat capacity measurements were conducted following the ASTM E1269 standard, and were measured between 1.18 J/g/K and 1.31 J/g/K. The mass loss of the molten chloride salts was studied under three different gas blankets of nitrogen, argon and air by thermogravimetric analysis. All the selected salt mixtures were stable up to 700 °C, although weight loss due to vaporisation becomes significant around this temperature due to the high vapour pressure of the chloride salt mixtures. However, it is expected that operation at a temperature up to around 750 °C will be feasible in a closed system with an inert environment. Additionally, removal of chemically-bonded water and salt purification may need to be considered for extending the operating temperature. In terms of economic performance, although the inclusion of LiCl in the ternary eutectic mixtures is advantageous for reducing melting point and increasing specific heat capacity, at current costs, these benefits are unlikely to be justified unless LiCl cost reduces by a factor of three. The NaCl-KCl-MgCl2 mixture has the lowest cost per unit energy stored, at 4.5 USD/kWh.
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Source
Solar Energy
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Journal article
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DOI
10.1016/j.solener.2018.10.008
Restricted until
2037-12-31