Wang Huaiyou, Li Jinli, Zhong Yuan, Liu Xu, Wang Min
Key Laboratory of Green and High-End Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences Xining, Xining 810008, China.
Qinghai Provincial Key Laboratory of Resources and Chemistry of Salt Lakes, Xining 810008, China.
Molecules. 2024 May 15;29(10):2328. doi: 10.3390/molecules29102328.
A novel ternary eutectic salt, NaNO-KNO-NaSO (TMS), was designed and prepared for thermal energy storage (TES) to address the issues of the narrow temperature range and low specific heat of solar salt molten salt. The thermo-physical properties of TMS-2, such as melting point, decomposition temperature, fusion enthalpy, density, viscosity, specific heat capacity and volumetric thermal energy storage capacity (E), were determined. Furthermore, a comparison of the thermo-physical properties between commercial solar salt and TMS-2 was carried out. TMS-2 had a melting point 6.5 °C lower and a decomposition temperature 38.93 °C higher than those of solar salt. The use temperature range of TMS molten salt was 45.43 °C larger than that of solar salt, which had been widened about 13.17%. Within the testing temperature range, the average specific heat capacity of TMS-2 (1.69 J·K·g) was 9.03% higher than that of solar salt (1.55 J·K·g). TMS-2 also showed higher density, slightly higher viscosity and higher E. XRD, FTIR and Raman spectra SEM showed that the composition and structure of the synthesized new molten salt were different, which explained the specific heat capacity increasing. Molecular dynamic (MD) simulation was performed to explore the different macroscopic properties of solar salt and TMS at the molecular level. The MD simulation results suggested that cation-cation and cation-anion interactions became weaker as the temperature increased and the randomness of molecular motion increased, which revealed that the interaction between the cation cluster and anion cluster became loose. The stronger interaction between Na-SO cation-anion clusters indicated that TMS-2 molten salt had a higher specific heat capacity than solar salt. The result of the thermal stability analysis indicated that the weight losses of solar salt and TMS-2 at 550 °C were only 27% and 53%, respectively. Both the simulation and experimental study indicated that TMS-2 is a promising candidate fluid for solar power generation systems.
为解决太阳能盐熔盐温度范围窄和比热容低的问题，设计并制备了一种新型三元共晶盐NaNO₃-KNO₃-Na₂SO₄（TMS）用于热能储存（TES）。测定了TMS-2的热物理性质，如熔点、分解温度、熔化焓、密度、粘度、比热容和体积热能储存容量（E）。此外，还对商业太阳能盐和TMS-2的热物理性质进行了比较。TMS-2的熔点比太阳能盐低6.5℃，分解温度比太阳能盐高38.93℃。TMS熔盐的使用温度范围比太阳能盐大45.43℃，拓宽了约13.17%。在测试温度范围内，TMS-2的平均比热容（1.69 J·K⁻¹·g⁻¹）比太阳能盐（1.55 J·K⁻¹·g⁻¹）高9.03%。TMS-2还表现出更高的密度、略高的粘度和更高的E。XRD、FTIR和拉曼光谱SEM表明合成的新型熔盐的组成和结构不同，这解释了比热容的增加。进行了分子动力学（MD）模拟以在分子水平上探索太阳能盐和TMS的不同宏观性质。MD模拟结果表明，随着温度升高和分子运动随机性增加，阳离子-阳离子和阳离子-阴离子相互作用变弱，这表明阳离子簇和阴离子簇之间的相互作用变得松散。Na⁺-SO₄²⁻阳离子-阴离子簇之间更强的相互作用表明TMS-2熔盐比太阳能盐具有更高的比热容。热稳定性分析结果表明，太阳能盐和TMS-2在550℃时的重量损失分别仅为27%和53%。模拟和实验研究均表明，TMS-2是太阳能发电系统中一种有前景的候选流体。
