Sustainable Energy and Artificial Intelligence

Molten Salt Nanofluids for High-Temperature Thermal Energy Storage: Advances, Mechanisms, and Challenges

Document Type : Review Articles

Authors

Reza Rabani
Kamyar Hosseinian Naeini

Department of Mechanical Engineering, Ka.C., Islamic Azad University, Karaj, Iran.

https://doi.org/10.61186/seai.2506-1027
Abstract
The transition to clean energy demands advanced thermal energy storage (TES) solutions, especially for high-temperature applications like concentrated solar power (CSP) and industrial processes. Molten salt nanofluids—formed by dispersing nanoparticles in molten salts—offer a promising pathway to enhance thermal properties while maintaining high thermal stability and cost-effectiveness. This review summarizes the recent progress in the development, properties, preparation, and potential applications of these materials. Key focus areas include enhancements in specific heat capacity and thermal conductivity, which are critical for efficient heat storage and transfer. Notably, experimental studies report up to 100% increases in specific heat—defying classical predictions—possibly due to interfacial nanolayers, ionic rearrangement, or secondary nanostructures. Thermal conductivity improvements vary depending on nanoparticle type, morphology, and dispersion quality. The review also covers common base salts (nitrates, carbonates, chlorides) and a wide range of nanoparticle additives. Preparation methods such as ultrasonication and in-situ synthesis are discussed, along with challenges related to nanoparticle agglomeration, sedimentation, and long-term stability. Viscosity, corrosion behavior, and thermal cycling stability are also examined, as they critically affect system efficiency, pumping power, and material compatibility. Molten salt nanofluids hold strong potential for CSP, geothermal energy, enhanced oil recovery, and next-generation nuclear systems. However, commercialization is hindered by uncertainties in scalability, lifecycle impacts, and regulatory readiness. The review highlights the need for standardized methodologies, cross-disciplinary collaboration, and integrated performance-sustainability assessments to advance these materials toward practical deployment.

Keywords

Advanced thermal fluids
Nanostructured energy materials
Solar thermal systems
Heat Capacity
Energy storage
Subjects
1. An, X. H., Cheng, J. H., Su, T., & Zhang, P. (2017, June). Determination of thermal physical properties of alkali fluoride/carbonate eutectic molten salt. In AIP Conference Proceedings (Vol. 1850, No. 1). AIP Publishing.
2. Sang, L., Ai, W., Liu, T., Wu, Y., & Ma, C. (2019). Insights into the specific heat capacity enhancement of ternary carbonate nanofluids with SiO 2 nanoparticles: the effect of change in the composition ratio. RSC advances, 9(10), 5288-5294.
3. Wu, Y., Li, J., Wang, M., Wang, H., Zhong, Y., Zhao, Y., ... & Li, Y. (2018). Solar salt doped by MWCNTs as a promising high thermal conductivity material for CSP. RSC advances, 8(34), 19251-19260.
4. Choi, S. U., & Eastman, J. A. (1995). Enhancing thermal conductivity of fluids with nanoparticles (No. ANL/MSD/CP-84938; CONF-951135-29). Argonne National Lab.(ANL), Argonne, IL (United States).
5. Bhatnagar, P., Siddiqui, S., Sreedhar, I., & Parameshwaran, R. (2022). Molten salts: Potential candidates for thermal energy storage applications. International Journal of Energy Research, 46(13), 17755-17785.
6. Shin, D., & Banerjee, D. (2014). Specific heat of nanofluids synthesized by dispersing alumina nanoparticles in alkali salt eutectic. International Journal of Heat and Mass Transfer, 74, 210-214.
7. Du, L., Tian, H., Wang, W., Ding, J., Wei, X., & Song, M. (2017). Thermal stability of the eutectic composition in NaCl-CaCl2-MgCl2 ternary system used for thermal energy storage applications. Energy Procedia, 105, 4185-4191.
8. Hu, Y., He, Y., Zhang, Z., & Wen, D. (2019). Enhanced heat capacity of binary nitrate eutectic salt-silica nanofluid for solar energy storage. Solar Energy Materials and Solar Cells, 192, 94-102.
9. Grosu, Y., Anagnostopoulos, A., Navarro, M. E., Ding, Y., & Faik, A. (2020). Inhibiting hot corrosion of molten Li2CO3-Na2CO3-K2CO3 salt through graphitization of construction materials for concentrated solar power. Solar Energy Materials and Solar Cells, 215, 110650.
10. Akanda, M. A. M., & Shin, D. (2023). A synthesis parameter of molten salt nanofluids for solar thermal energy storage applications. Journal of Energy Storage, 60, 106608.
11. Frangini, S., Della Seta, L., Paoletti, C., Felici, C., Turchetti, L., & Bellucci, A. (2018). Corrosion behavior of aluminide diffusion coatings in low temperature molten carbonate electrolysis environments. Materials and Corrosion, 69(12), 1837-1846.
12. Chen, M., Shen, Y., Zhu, S., & Li, P. (2017). Digital phase diagram and thermophysical properties of KNO3-NaNO3-Ca (NO3) 2 ternary system for solar energy storage. Vacuum, 145, 225-233.
13. Bauer, T., Pfleger, N., Breidenbach, N., Eck, M., Laing, D., & Kaesche, S. (2013). Material aspects of Solar Salt for sensible heat storage. Applied energy, 111, 1114-1119.
14. Gomes, A., Navas, M., Uranga, N., Paiva, T., Figueira, I., & Diamantino, T. C. (2019). High-temperature corrosion performance of austenitic stainless steels type AISI 316L and AISI 321H, in molten Solar Salt. Solar Energy, 177, 408-419.
15. Forsberg, C. W., Peterson, P. F., & Zhao, H. (2007). High-temperature liquid-fluoride-salt closed-Brayton-cycle solar power towers.
16. Chieruzzi, M., Miliozzi, A., Crescenzi, T., Torre, L., & Kenny, J. M. (2015). A new phase change material based on potassium nitrate with silica and alumina nanoparticles for thermal energy storage. Nanoscale research letters, 10, 1-10.
17. Andreu-Cabedo, P., Mondragon, R., Hernandez, L., Martinez-Cuenca, R., Cabedo, L., & Julia, J. E. (2014). Increment of specific heat capacity of solar salt with SiO 2 nanoparticles. Nanoscale research letters, 9, 1-11.
18. Lu, M. C., & Huang, C. H. (2013). Specific heat capacity of molten salt-based alumina nanofluid. Nanoscale research letters, 8, 1-7.
19. Curtis, C., Toghani, D., Wong, B., & Nance, E. (2018). Colloidal stability as a determinant of nanoparticle behavior in the brain. Colloids and Surfaces B: Biointerfaces, 170, 673-682.
20. Lasfargues, M. (2014). Nitrate based high temperature nano-heat-transfer-fluids: formulation & characterisation (Doctoral dissertation, University of Leeds).
21. Sang, L., Ai, W., Wu, Y., & Ma, C. (2019). SiO2-ternary carbonate nanofluids prepared by mechanical mixing at high temperature: Enhanced specific heat capacity and thermal conductivity. Solar Energy Materials and Solar Cells, 203, 110193.
22. Huang, Y., Cheng, X., Li, Y., Yu, G., Xu, K., & Li, G. (2018). Effect of in-situ synthesized nano-MgO on thermal properties of NaNO3-KNO3. Solar Energy, 160, 208-215.
23. Luo, Y., Du, X., Awad, A., & Wen, D. (2017). Thermal energy storage enhancement of a binary molten salt via in-situ produced nanoparticles. International Journal of Heat and Mass Transfer, 104, 658-664.
24. Heidarinejad, G., Rabani, R., & Shirani, E. (2017). The effect of wall force field on temperature distribution in nanochannel contains Lennard-Jones fluid by molecular dynamic simulation. Modares Mechanical Engineering, 17(6), 23-31.
25. Rabani, R., Merabia, S., & Pishevar, A. (2023). Conductive heat transfer through nanoconfined argon gas: From continuum to free-molecular regime. International Journal of Thermal Sciences, 192, 108391.
26. Saranprabhu, M. K., & Rajan, K. S. (2019). Magnesium oxide nanoparticles dispersed solar salt with improved solid phase thermal conductivity and specific heat for latent heat thermal energy storage. Renewable Energy, 141, 451-459.
27. Li, Z., Cui, L., Li, B., & Du, X. (2020). Enhanced heat conduction in molten salt containing nanoparticles: Insights from molecular dynamics. International Journal of Heat and Mass Transfer, 153, 119578.
28. Chen, H., Ding, Y., He, Y., & Tan, C. (2007). Rheological behaviour of ethylene glycol based titania nanofluids. Chemical physics letters, 444(4-6), 333-337.
29. Muñoz-Sánchez, B., Nieto-Maestre, J., Iparraguirre-Torres, I., Sanchez-Garcia, J. A., Julia, J. E., & García-Romero, A. (2016, May). The influence of mixing water on the thermophysical properties of nanofluids based on solar salt and silica nanoparticles. In AIP conference proceedings (Vol. 1734, No. 1). AIP Publishing.
30. Rabani, R., Heidarinejad, G., Harting, J., & Shirani, E. (2020). Heat conduction characteristic of rarefied gas in nanochannel. Journal of Applied Fluid Mechanics, 13(1), 1-13.
31. Zhang, Z., Yuan, Y., Ouyang, L., Sun, Q., Cao, X., & Alelyani, S. (2017). Enhanced thermal properties of Li 2 CO 3–Na 2 CO 3–K 2 CO 3 nanofluids with nanoalumina for heat transfer in high-temperature CSP systems. Journal of Thermal Analysis and Calorimetry, 128, 1783-1792.
32. Wei, X., Yin, Y., Qin, B., Wang, W., Ding, J., & Lu, J. (2020). Preparation and enhanced thermal conductivity of molten salt nanofluids with nearly unaltered viscosity. Renewable Energy, 145, 2435-2444.
33. Li, Z., Li, B., Du, X., & Wu, H. (2020). Experimental investigation on stability of thermal performances of solar salt based nanocomposite. Renewable Energy, 146, 816-827.
34. Rabani, R., Saidi, M. H., Joly, L., Merabia, S., & Rajabpour, A. (2021). Enhanced local viscosity around colloidal nanoparticles probed by equilibrium molecular dynamics simulations. The Journal of Chemical Physics, 155(17).
35. Tiznobaik, H., & Shin, D. (2013). Enhanced specific heat capacity of high-temperature molten salt-based nanofluids. International Journal of Heat and Mass Transfer, 57(2), 542-548.
36. Tiznobaik, H., Banerjee, D., & Shin, D. (2015). Effect of formation of “long range” secondary dendritic nanostructures in molten salt nanofluids on the values of specific heat capacity. International Journal of Heat and Mass Transfer, 91, 342-346.
37. Rabani, R., Saidi, M. H., Rajabpour, A., Joly, L., & Merabia, S. (2023). Enhanced heat flow between charged nanoparticles and an aqueous electrolyte. Langmuir, 39(43), 15222-15230.
38. Mondragón, R., Juliá, J. E., Cabedo, L., & Navarrete, N. (2018). On the relationship between the specific heat enhancement of salt-based nanofluids and the ionic exchange capacity of nanoparticles. Scientific reports, 8(1), 7532.
39. Yaxuan, X., Huixiang, W., Zhenyu, W., Yuting, W., Qian, X., Gang, W., ... & Chongfang, M. (2022). Insights into the Enhancement Mechanisms of Molten Salt Nanofluids. International Journal of Photoenergy, 2022(1), 4912922.
40. Xiong, Y., Wang, Z., Sun, M., Wu, Y., Xu, P., Qian, X., ... & Ma, C. (2021). Enhanced thermal energy storage of nitrate salts by silica nanoparticles for concentrating solar power. International Journal of Energy Research, 45(4), 5248-5262.
41. Caraballo, A., Galán-Casado, S., Caballero, Á., & Serena, S. (2021). Molten salts for sensible thermal energy storage: a review and an energy performance analysis. Energies, 14(4), 1197.
42. Jeong, S., & Jo, B. (2021). Understanding mechanism of enhanced specific heat of single molten salt-based nanofluids: Comparison with acid-modified salt. Journal of Molecular Liquids, 336, 116561.
43. Jo, B., & Banerjee, D. (2015). Thermal properties measurement of binary carbonate salt mixtures for concentrating solar power plants. Journal of Renewable and Sustainable Energy, 7(3).
44. Jung, S., & Banerjee, D. (2011, January). A simple analytical model for specific heat of nanofluid with tube shaped and disc shaped nanoparticles. In ASME/JSME Thermal Engineering Joint Conference (Vol. 38921, p. T30023).
45. Thoms, M. W. (2012). Adsorption at the nanoparticle interface for increased thermal capacity in solar thermal systems (Doctoral dissertation, Massachusetts Institute of Technology).
46. Dudda, B., & Shin, D. (2013). Effect of nanoparticle dispersion on specific heat capacity of a binary nitrate salt eutectic for concentrated solar power applications. International journal of thermal sciences, 69, 37-42.
47. Riazi, H., Mesgari, S., Ahmed, N. A., & Taylor, R. A. (2016). The effect of nanoparticle morphology on the specific heat of nanosalts. International Journal of Heat and Mass Transfer, 94, 254-261.
48. Devaradjane, R., & Shin, D. (2016). Nanoparticle dispersions on ternary nitrate salts for heat transfer fluid applications in solar thermal power. Journal of Heat Transfer, 138(5), 051901.
49. Lasfargues, M., Geng, Q., Cao, H., & Ding, Y. (2015). Mechanical dispersion of nanoparticles and its effect on the specific heat capacity of impure binary nitrate salt mixtures. Nanomaterials, 5(3), 1136-1146.
50. Lee, D., & Jo, B. (2021). Thermal energy storage characteristics of binary molten salt nanofluids: Specific heat and latent heat. International Journal of Energy Research, 45(2), 3231-3241.
51. Chieruzzi, M., Cerritelli, G. F., Miliozzi, A., & Kenny, J. M. (2013). Effect of nanoparticles on heat capacity of nanofluids based on molten salts as PCM for thermal energy storage. Nanoscale research letters, 8, 1-9.
52. Grosu, Y., Anagnostopoulos, A., Balakin, B., Krupanek, J., Navarro, M. E., González-Fernández, L., ... & Faik, A. (2021). Nanofluids based on molten carbonate salts for high-temperature thermal energy storage: Thermophysical properties, stability, compatibility and life cycle analysis. Solar Energy Materials and Solar Cells, 220, 110838.
53. Lasfargues, M., Cao, H., Geng, Q., & Ding, Y. (2015). Rheological analysis of binary eutectic mixture of sodium and potassium nitrate and the effect of low concentration CuO nanoparticle addition to its viscosity. Materials, 8(8), 5194-5204.
54. Jo, B., & Banerjee, D. (2014). Viscosity measurements of multi-walled carbon nanotubes-based high temperature nanofluids. Materials Letters, 122, 212-215.
55. Xiao, X., Zhang, G., Ding, Y., & Wen, D. (2019). Rheological characteristics of molten salt seeded with Al2O3 nanopowder and graphene for concentrated solar power. Energies, 12(3), 467.
56. El Far, B., Rizvi, S. M. M., Nayfeh, Y., & Shin, D. (2020). Investigation of heat capacity and viscosity enhancements of binary carbonate salt mixture with SiO2 nanoparticles. International Journal of Heat and Mass Transfer, 156, 119789.
57. Wei, X., Yin, Y., Qin, B., Ding, J., & Lu, J. (2017). Thermal conductivity improvement of liquid Nitrate and Carbonate salts doped with MgO particles. Energy Procedia, 142, 407-412.
58. Sang, L., Ai, W., Wu, Y., & Ma, C. (2020). Enhanced specific heat and thermal conductivity of ternary carbonate nanofluids with carbon nanotubes for solar power applications. International Journal of Energy Research, 44(1), 334-343.
59. Jiang, Z., Palacios, A., Lei, X., Navarro, M. E., Qiao, G., Mura, E., ... & Ding, Y. (2019). Novel key parameter for eutectic nitrates based nanofluids selection for concentrating solar power (CSP) systems. Applied energy, 235, 529-542.
60. Salim, N. J., & Rahman, M. A. (2020). Effect of Nanoparticle Concentration on the Specific Heat Capacity and Thermal Stability of Graphite Nanoparticle-based Molten Salt.  International Exchange and Innovation Conference on Engineering and Sciences . Kyushu University.  52-59.
61. Song, W., Lu, Y., Fan, Z., & Wu, Y. (2022). Preparation and thermophysical properties of sodium nitrate/nanoparticle/expanded graphite composite heat storage material. Frontiers in Energy Research, 10, 878747.
62. Myers Jr, P. D., Alam, T. E., Kamal, R., Goswami, D. Y., & Stefanakos, E. (2016). Nitrate salts doped with CuO nanoparticles for thermal energy storage with improved heat transfer. Applied Energy, 165, 225-233.
63. Yang, X., Jiang, W., Ji, C., & Wang, Q. (2022). Experimental study on heat storage and corrosion properties of ternary carbonate salt-based ZnO nanofluids for solar thermal energy storage. Journal of Thermal Analysis and Calorimetry, 147(23), 13935-13947.
64. Nithiyanantham, U., Grosu, Y., González-Fernández, L., Zaki, A., Igartua, J. M., & Faik, A. (2019). Corrosion aspects of molten nitrate salt-based nanofluids for thermal energy storage applications. Solar Energy, 189, 219-227.
65. Lasfargues, M., Stead, G., Amjad, M., Ding, Y., & Wen, D. (2017). In Situ production of copper oxide nanoparticles in a binary molten salt for concentrated solar power plant applications. Materials, 10(5), 537.
66. Muñoz-Sánchez, B., Nieto-Maestre, J., Guerreiro, L., Julia, J. E., Collares-Pereira, M., & García-Romero, A. (2017, June). Molten salt based nanofluids based on solar salt and alumina nanoparticles: An industrial approach. In AIP Conference Proceedings (Vol. 1850, No. 1). AIP Publishing.
67. Navarrete, N., Gimeno-Furió, A., Forner-Escrig, J., Juliá, J. E., & Mondragón, R. (2019). Colloidal stability of molten salt–based nanofluids: Dynamic Light Scattering tests at high temperature conditions. Powder Technology, 352, 1-10.
68. Aljaerani, H. A., Samykano, M., Saidur, R., Pandey, A. K., & Kadirgama, K. (2021). Nanoparticles as molten salts thermophysical properties enhancer for concentrated solar power: A critical review. Journal of Energy Storage, 44, 103280.
69. Gil, A., Medrano, M., Martorell, I., Lázaro, A., Dolado, P., Zalba, B., & Cabeza, L. F. (2010). State of the art on high temperature thermal energy storage for power generation. Part 1—Concepts, materials and modellization. Renewable and sustainable energy reviews, 14(1), 31-55.
70. Bonk, A., Sau, S., Uranga, N., Hernaiz, M., & Bauer, T. (2018). Advanced heat transfer fluids for direct molten salt line-focusing CSP plants. Progress in Energy and Combustion Science, 67, 69-87.
71. Wang, W., Wu, Z., Li, B., & Sundén, B. (2019). A review on molten-salt-based and ionic-liquid-based nanofluids for medium-to-high temperature heat transfer. Journal of Thermal Analysis and Calorimetry, 136, 1037-1051.
72. Schuller, M., Shao, Q., & Lalk, T. (2015). Experimental investigation of the specific heat of a nitrate–alumina nanofluid for solar thermal energy storage systems. International Journal of Thermal Sciences, 91, 142-145.
73. Pan, G., Wei, X., Yu, C., Lu, Y., Li, J., Ding, J., ... & Yan, J. (2020). Thermal performance of a binary carbonate molten eutectic salt for high-temperature energy storage applications. Applied Energy, 262, 114418.
74. Alnaimat, F., & Rashid, Y. (2019). Thermal energy storage in solar power plants: A review of the materials, associated limitations, and proposed solutions. Energies, 12(21), 4164.
75. Corradini, D., Coudert, F. X., & Vuilleumier, R. (2016). Insight into the Li2CO3–K2CO3 eutectic mixture from classical molecular dynamics: Thermodynamics, structure, and dynamics. The Journal of Chemical Physics, 144(10).
76. Relloso, S., & Delgado, E. (2009, September). Experience with molten salt thermal storage in a commercial parabolic trough plant. Andasol-1 commissioning and operation. In Proceedings of the 15th SolarPACES Conference, Berlin.
77. Ibrahim, A., Peng, H., Riaz, A., Basit, M. A., Rashid, U., & Basit, A. (2021). Molten salts in the light of corrosion mitigation strategies and embedded with nanoparticles to enhance the thermophysical properties for CSP plants. Solar Energy Materials and Solar Cells, 219, 110768.
78. Li, Q., & Wu, J. (2022). Factors affecting the lower limit of the safe mud weight window for drilling operation in hydrate-bearing sediments in the Northern South China Sea. Geomechanics and Geophysics for Geo-Energy and Geo-Resources, 8(2), 82.
79. Li, Q., Wang, F., Forson, K., Zhang, J., Zhang, C., Chen, J., ... & Wang, Y. (2022). Affecting analysis of the rheological characteristic and reservoir damage of CO2 fracturing fluid in low permeability shale reservoir. Environmental Science and Pollution Research, 29(25), 37815-37826.
80. Ye, H., Wu, X., Li, D., Jiang, Y., & Gong, B. (2022). A novel thermal stimulation approach for natural gas hydrate exploitation-the application of the self-entry energy compensation device in the Shenhu sea. Journal of Natural Gas Science and Engineering, 105, 104723.
81. Liu, J., Liang, X., Xue, Y., Yao, K., & Fu, Y. (2020). Numerical evaluation on multiphase flow and heat transfer during thermal stimulation enhanced shale gas recovery. Applied Thermal Engineering, 178, 115554.
82. Sun, X. H., Yan, H., Massoudi, M., Chen, Z. H., & Wu, W. T. (2018). Numerical simulation of nanofluid suspensions in a geothermal heat exchanger. Energies, 11(4), 919.
83. Burgaleta, J. I., Arias, S., & Ramirez, D. (2011). Gemasolar, the first tower thermosolar commercial plant with molten salt storage. SolarPACES, Granada, Spain, 20-23.
84. Barberio, G., Scalbi, S., Buttol, P., Masoni, P., & Righi, S. (2014). Combining life cycle assessment and qualitative risk assessment: The case study of alumina nanofluid production. Science of the Total Environment, 496, 122-131.
85. Li, Q., Wang, F., Forson, K., Zhang, J., Zhang, C., Chen, J., ... & Wang, Y. (2022). Affecting analysis of the rheological characteristic and reservoir damage of CO2 fracturing fluid in low permeability shale reservoir. Environmental Science and Pollution Research, 29(25), 37815-37826.
Sustainable Energy and Artificial Intelligence
Volume 1, Issue 3 - Serial Number 6
Summer 2025
Pages 165-181

  • Receive Date 07 June 2025
  • Revise Date 15 June 2025
  • Accept Date 15 June 2025
  • First Publish Date 15 June 2025

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