Adapting the MgO-CO2 working pair for thermochemical energy storage by doping with salts: effect of the (LIK)NO3 content

Seon Tae Kim (Corresponding author), Haruka Miura, Hiroki Takasu, Yukitaka Kato, Alexandr Shkatulov, Yuri Aristov

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Abstract

The MgO-CO2 working pair has been regarded as prospective for thermochemical energy storage (TCES) due to its relatively high heat storage capacity, low cost, and wide availability. This study is aimed at the optimization of the molar salt content, α, for the MgO modified with the eutectic mixture of LiNO3 and KNO3 (Li0.42K0.58NO3) which was earlier shown to provide high conversion, ∆x, in heat-storage/release processes at 300–400 C. The composites that have different salt content were prepared and carbonation kinetics was investigated under various conditions (carbonation temperature, Tcarb., is 290–360 C and CO2 pressure, P(CO2), is 50–101 kPa). Significant accelerating effect was revealed at α ≥ 0.05, and the ∆x value was maximized at α = 0.10–0.20. The largest conversion of 0.70 was detected at α = 0.10 and Tcarb. = 350 C that corresponds to the specific useful heat (Qcomp.) is 1.63 MJ/kg-composite. However, the salt content of 0.20 ensures the high conversion, ∆x = 0.63–0.67 and Qcomp. = 1.18–1.25 MJ/kg-composite in the whole temperature range between 290 and 350 C. The (LiK)NO3/MgO composite with an optimal salt content of 0.20 exhibits reasonable durability through cyclic experiment at 330 C, namely, the stabilized reacted conversion ∆x = 0.34 (Qcomp. = 0.64 MJ/kg-composite). The studied (Li0.42K0.58)NO3 promoted MgO-CO2 working pair has good potential as thermochemical storage material of middle temperature heat (300–400 C).

Original languageEnglish
Article number2262
Number of pages13
JournalEnergies
Volume12
Issue number12
DOIs
Publication statusPublished - 13 Jun 2019

Keywords

  • Eutectic mixture
  • Magnesium carbonate
  • Magnesium oxide
  • Salt modification
  • Thermochemical energy storage
  • salt modification
  • magnesium oxide
  • thermochemical energy storage
  • eutectic mixture
  • magnesium carbonate

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