Solar Salt above 600 °C: Impact of Experimental Design on Thermodynamic Stability Results

Julian Steinbrecher (), Markus Braun, Thomas Bauer, Sebastian Kunkel and Alexander Bonk
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Julian Steinbrecher: German Aerospace Center (DLR), Institute of Engineering Thermodynamics, D-70569 Stuttgart, Germany
Markus Braun: German Aerospace Center (DLR), Institute of Engineering Thermodynamics, D-70569 Stuttgart, Germany
Thomas Bauer: German Aerospace Center (DLR), Institute of Engineering Thermodynamics, D-51147 Cologne, Germany
Sebastian Kunkel: German Aerospace Center (DLR), Institute of Engineering Thermodynamics, D-70569 Stuttgart, Germany
Alexander Bonk: German Aerospace Center (DLR), Institute of Engineering Thermodynamics, D-70569 Stuttgart, Germany

Energies, 2023, vol. 16, issue 14, 1-16

Abstract: Thermal energy storage (TES) based on molten salts has been identified as a key player in the transition from fossil fuels to renewable energy sources. Solar Salt, a mixture of NaNO 3 (60 wt%) and KNO 3 (40 wt%), is currently the most advanced heat transfer and storage material used in concentrating solar power (CSP) plants. Here, it is utilized to produce electricity via a Rankine cycle, with steam temperatures reaching 550 °C. The goal of this study is to increase the operating temperature of solar salt to over 600 °C, allowing it to be adapted for use in high-temperature Rankine cycles with steam temperatures greater than 600 °C. Yet, this goal is impaired by the lack of available thermodynamic data given the salt’s complex high-temperature decomposition and corrosion chemistry. The study explores the thermodynamics of the decomposition reactions in solar salt, with a focus on suppressing decomposition into corrosive oxide ions up to a temperature of 620 °C. The results provide a new understanding of the stabilization of solar salt at previously unexplored temperatures with effective utilization of gas management techniques.

Keywords: molten salt; nitrite formation; oxide formation; high-temperature chemistry; thermal energy storage; concentrated solar power (CSP) (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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