A novel model for predicting the effective specific heat capacity of molten salt doped with nanomaterial for solar energy application

• Published in: Applied thermal engineering Vol. 195; p. 117129
• Main Authors: Yuan, Fan, Li, Ming-Jia, He, Ya-Ling, Tao, Wen-Quan
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2021; Elsevier BV
• Subjects: Ball milling; Carbon nanotubes; Diameters; Heat conductivity; Heat transfer; Induced crystallization; Molten salts; Nanolayer; Nanomaterial-enhanced molten salt; Nanomaterials; Nanotubes; Potassium carbonate; Prediction models; Solar energy; Specific heat; Specific heat capacity; Thickness; Induced crystallization; Nanomaterial-enhanced molten salt; Nanolayer; Specific heat capacity
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2021.117129

•A prediction model on cV of nanomaterial-enhanced salt for heat storage is given.•Local crystallization in molten salt is induced by nanomaterial and forms nanolayer.•The amount and the specific heat capacity of nanolayer is studied.•Carbon nanotube enhanced molten salt is prepared by ball milling method and tested.•Effective specific heat capacity prediction is validated through experiments. In order to establish instructions for high-performance molten salt preparation, this paper focuses on accurate prediction method on the effective heat capacity of nanomaterial-enhanced molten salt (NMS). With carbon nanotube (CNT) enhanced carbonate eutectic (Li2CO3-K2CO3) taken as the study subject, the microscopic mechanism of nanomaterial on the effective specific heat capacity enhancement of molten salt is revealed. The nanolayer content is calculated, and the specific heat capacity of CNT and nanolayer is quantified. Accordingly, the effective heat capacity prediction model is completed. In addition, the CNT-enhanced carbonate eutectic is experimentally prepared with a high-energy ball milling method. Its effective specific heat capacity is measured and used to validate the prediction model. The results show that, firstly, the thickness of nanolayer is 0.65 nm and 0.98 nm in the single-walled CNT case and multi-walled CNT case, respectively. Secondly, the specific heat capacity of CNT is 1.613 J·g−1·K−1 at 800 K, and the specific heat capacity of nanolayer increases with increasing the surface atom ratio. Finally, the effective specific heat capacity of CNT-enhanced carbonate salt is predicted and validated with experimental results. It is revealed that, in the cases of well-dispersed nanomaterial-enhanced molten salt, the prediction method presented in this research has considerable accuracy (error < 2.90%). Furthermore, the effective specific heat capacity of NMS doped with CNT of various diameter is given.