Abstract Molten salts are widely applied as heat transfer and thermal storage medium for solar thermal power. In order to research the effect of preparation conditions and the types of nanoparticles on the thermophysical properties of molten salt nanocomposite, different molten salt nanocomposites were developed by mixing the nitrates (Ca (NO3)2·4H2O–KNO3–NaNO3–NaNO2) with 1.0 wt% of SiO2, MgO, TiO2 and CuO nanoparticles using a microwave method, which was a new preparation process of molten salt nanocomposite based on high temperature mixing without water. The effect of different microwave heating temperature (250, 350 and 450 °C) and heating time (30, 60, 90 and 120 min) were experimentally studied. The melting point, latent heat and specific heat of the samples were analyzed by differential scanning calorimeter (DSC). The morphology was observed by scanning electron microscope (SEM). The results showed that the nanoparticles induced a decrease of the melting point of 0.1–2.4% while the latent heat decreased by 3.3–7.9%. Compared with other molten salt nanocomposites, the molten salt with the addition of SiO2 nanoparticles had the biggest increase in specific heat, which increased by 7.7% in solid state and 21.0% in liquid state after heating for 90 min at 250 °C. The total heat storage density could reach to 783.0 J/g between 30 and 500 °C, which was 13.3% higher than the base salt. In addition, according to the morphology of the samples, network nanostructures were observed in the molten salt nanocomposite doped with SiO2.

中文翻译：

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微波法制备熔盐纳米复合材料及其热物理特性研究

摘要 熔盐作为太阳能热发电的传热和蓄热介质被广泛应用。为了研究制备条件和纳米颗粒类型对熔盐纳米复合材料热物理性质的影响，通过将硝酸盐（Ca (NO3)2·4H2O–KNO3–NaNO3–NaNO2）与 1.0使用微波法制备SiO2、MgO、TiO2和CuO纳米颗粒的wt%，这是一种基于无水高温混合制备熔盐纳米复合材料的新工艺。实验研究了不同微波加热温度（250、350和450℃）和加热时间（30、60、90和120分钟）的影响。用差示扫描量热仪（DSC）分析样品的熔点、潜热和比热。通过扫描电子显微镜（SEM）观察形貌。结果表明，纳米颗粒导致熔点降低 0.1-2.4%，而潜热降低 3.3-7.9%。与其他熔盐纳米复合材料相比，添加SiO2纳米颗粒的熔盐比热增加最大，在250℃加热90分钟后，比热增加了7.7%，液态增加了21.0%。总蓄热密度在 30 至 500 °C 之间可达 783.0 J/g，比基盐高 13.3%。此外，根据样品的形貌，在掺杂 SiO2 的熔盐纳米复合材料中观察到网络纳米结构。4%，而潜热减少了 3.3-7.9%。与其他熔盐纳米复合材料相比，添加SiO2纳米颗粒的熔盐比热增加最大，在250℃加热90分钟后，比热增加了7.7%，液态增加了21.0%。总蓄热密度在 30 至 500 °C 之间可达 783.0 J/g，比基盐高 13.3%。此外，根据样品的形貌，在掺杂 SiO2 的熔盐纳米复合材料中观察到网络纳米结构。4%，而潜热减少了 3.3-7.9%。与其他熔盐纳米复合材料相比，添加SiO2纳米颗粒的熔盐比热增加最大，在250℃加热90分钟后，比热增加了7.7%，液态增加了21.0%。总蓄热密度在 30 至 500 °C 之间可达 783.0 J/g，比基盐高 13.3%。此外，根据样品的形貌，在掺杂 SiO2 的熔盐纳米复合材料中观察到网络纳米结构。总蓄热密度在 30 至 500 °C 之间可达 783.0 J/g，比基盐高 13.3%。此外，根据样品的形貌，在掺杂 SiO2 的熔盐纳米复合材料中观察到网络纳米结构。总蓄热密度在 30 至 500 °C 之间可达 783.0 J/g，比基盐高 13.3%。此外，根据样品的形貌，在掺杂有 SiO2 的熔盐纳米复合材料中观察到了网络纳米结构。