Abstract Highlighted experimental studies on nanofluids reveal an anomalous increment in the specific heat capacity (Cp) of these ionic systems when nanoparticles are added. This fact is really important due the applicability of nanofluids in concentrating solar power plants as heat transfer fluid and storage media. These are promising results for the development of high-temperature heat storage applications by enhanced storage capacity materials. The present work focuses on the study of this effect in NaNO3 molten salt doped with SiO2 nanoparticles by molecular dynamics (MD) simulations and Differential Scanning Calorimetry (DSC) experiments. The study shows that for nanoparticles’ concentrations around 1% wt. the Cp increases by 26% compared to pure NaNO3, whereas at higher concentrations the effect disappears. The results approach high agreement between experimental and simulation results and MD simulations reveal that the increase of Cp at low concentrations is explained by the formation of a semi ordered layer of ionic fluid. This layer is rich in Na+ cations, around the nanoparticles whereas the reduction of Cp at concentrations higher than 2% wt. is related to the aggregation of nanoparticles as revealed by Scanning Electron Microscopy (SEM). However, deep experimental results with other materials will be required in order to validate the layering effect.

中文翻译：

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纳米粒子在熔盐中的作用——MD 模拟和实验研究

摘要 纳米流体的重点实验研究表明，当添加纳米粒子时，这些离子系统的比热容 (Cp) 出现异常增加。由于纳米流体在聚光太阳能发电厂中作为传热流体和存储介质的适用性，这一事实非常重要。这些是通过增强存储容量材料开发高温蓄热应用的有希望的结果。目前的工作重点是通过分子动力学 (MD) 模拟和差示扫描量热法 (DSC) 实验研究掺杂有 SiO2 纳米颗粒的 NaNO3 熔盐中的这种效应。该研究表明，对于纳米颗粒的浓度约为 1% wt。与纯 NaNO3 相比，Cp 增加了 26%，而在较高浓度下，效果消失。结果接近实验和模拟结果之间的高度一致性，MD 模拟表明低浓度下 Cp 的增加是通过形成半有序的离子流体层来解释的。该层在纳米颗粒周围富含 Na+ 阳离子，而浓度高于 2% wt 时 Cp 的减少。与扫描电子显微镜 (SEM) 所揭示的纳米颗粒的聚集有关。然而，为了验证分层效果，需要使用其他材料进行深入的实验结果。在纳米粒子周围，而浓度高于 2% wt 时 Cp 的减少。与扫描电子显微镜 (SEM) 所揭示的纳米颗粒的聚集有关。然而，为了验证分层效果，需要使用其他材料进行深入的实验结果。在纳米粒子周围，而浓度高于 2% wt 时 Cp 的减少。与扫描电子显微镜 (SEM) 所揭示的纳米颗粒的聚集有关。然而，为了验证分层效果，需要使用其他材料进行深入的实验结果。