Advances in performance of nitrate salts-based phase change materials and casing heat accumulator : A comprehensive review

Mao, S. and Hao, K. and Wu, X. and Liu, Y. and Cao, S. and Du, Y. (2026) Advances in performance of nitrate salts-based phase change materials and casing heat accumulator : A comprehensive review. Solar Energy Materials and Solar Cells, 304: 114402. ISSN 0927-0248

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Abstract

The key to improving the energy storage efficiency of solar thermal storage systems lies in developing high-performance thermal storage materials and optimizing the structure of thermal storage devices to address the technical challenges posed by the intermittent and unstable nature of solar radiation. Currently, nitrates salt phase change materials (PCMs) are widely used in solar thermal power generation systems, however, conventional molten salts suffer from limitations such as a narrow operating temperature range and poor thermal conductivity. Thermal storage devices, meanwhile, face challenges including limited optimization options and low thermal storage efficiency. To address these issues, this paper summarized the preparation of modified nitrates and the performance optimization of casing heat accumulators. The performance of single and mixed nitrates was compared and methods for improving performance were analyzed. Subsequently, the optimization of casing heat accumulator structures was examined, focusing on tube geometries, fin configurations, topology optimization and biomimetic design. Moreover, the synergistic optimization between nitrate-based PCMs and casing heat accumulators was proposed. Finally, the critical challenges and promising future research directions were prospected from nitrate-based PCMs development and heat accumulator optimization perspectives.