Computational thermodynamics-assisted design of nitrate-based phase change materials for waste heat recovery

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Abstract

Phase change materials (PCMs) are substances that absorb or release latent heat during changes in physical state. PCM is typically introduced in a heat exchanger inside a waste heat recovery system to enhance energy conversion efficiency. Molten salts consisting of multiple components are widely used as a PCM due to their high heat capacity. However, modulating the physical properties of PCMs via experimental trial-and-error is not economically feasible when dealing with complex systems. In this study, we designed six potential nitrates as PCMs via a combinatorial approach with the CALculation of PHAse Diagrams (CALPHAD) method, the Kissinger model, and experimental validations, among the KNO3-NaNO3-LiNO3 ternary system. The measured thermodynamics properties, including the solidus and liquidus temperatures, and enthalpy changes, were in agreement with the predicted values. A promising PCM that exhibited a lower melting activation energy (917.3 kJ/mol) and a higher change in enthalpy (136.4 J/g) than those of the commercial HITEC salt (1135.3 kJ/mol and 86 J/g). The designed PCM also showed a good thermal stability with the 316 stainless steel, which is a typical container material, at temperatures of 150°C and 300°C, respectively, for up to 1 month. The designed PCM is considered promising for waste heat recovery applications in terms of its high heat storage capacity, high heat exchange efficiency, and high thermal stability.

Original languageEnglish
Pages (from-to)14452-14461
Number of pages10
JournalInternational Journal of Energy Research
Volume46
Issue number10
DOIs
Publication statusPublished - 2022 Aug

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Nuclear Energy and Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology

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