Effect of SiO2 nanoparticle addition on the wetting and rheological properties of solar salt
Effect of SiO2 nanoparticle addition on the wetting and rheological properties of solar salt
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DOI：
10.1016/j.solmat.2020.110483
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发表时间：
2020-06
影响因子：
6.9
通讯作者：
A. Anagnostopoulos;A. Palacios;M. H. Navarro;S. Fereres;Yulong Ding
中科院分区：
文献类型：
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作者：
A. Anagnostopoulos;A. Palacios;M. H. Navarro;S. Fereres;Yulong Ding
熔盐基纳米流体作为传热流体和能量存储材料参与热能存储（TES）系统。流变性和润湿性在材料的处理和储存中起着至关重要的作用，并且与泵送和腐蚀问题密切相关。在这项研究中，纳米粒子添加对上述性质的熔盐纳米流体的影响进行了研究。太阳盐（60%NaNO3 - 40%KNO3）及其单独组分NaNO 3和KNO 3与各种浓度的SiO2混合。在整个液相中测量接触角和粘度。添加小百分比的纳米颗粒显著改变纳米流体的接触角和粘度。在不存在二氧化硅的情况下，所有熔融盐显示出相对于温度的线性行为。然而，在纳米颗粒的存在下，太阳能盐在接触角的情况下保持升高的值直到300 °C，在粘度的情况下保持升高的值直到260 °C，之后发生急剧降低。随着纳米颗粒浓度的增加，这种效应会转移到更高的温度。然而，类似的行为，是不存在的情况下，硝酸钠和硝酸钾单独，这两个，添加纳米粒子，保留曲线趋势类似于他们的基线情况。进一步的研究，包括差示扫描量热法，表明纳米粒子延迟的熔融盐混合物的液/固相转变过程，这反过来又影响熔融混合物的流变学和润湿行为。
Molten salt based nanofluids are involved in Thermal Energy Storage (TES) Systems, both as heat transfer fluids and energy storage materials. Rheological and wetting properties play an acute role in the handling and storage of materials and are closely related with pumping and corrosion issues. In this study the effect of nanoparticle addition on the aforementioned properties of molten salt nanofluids is investigated. The solar salt (60% NaNO3– 40% KNO3), as well as its individual components NaNO3and KNO3, are mixed with various concentrations of SiO2. The contact angle and viscosity are measured throughout the liquid phase. Addition of a small percentage of nanoparticles, significantly alters the contact angle and viscosity of the nanofluid. In the absence of silica all the molten salts display a linear behavior with respect to temperature. However, in the presence of nanoparticles the solar salt retains an elevated value until 300 °C in the case of the contact angle and 260 °C in the case of the viscosity, after which a steep reduction occurs. With larger concentrations of nanoparticles, this effect is shifted to higher temperatures. Similar behavior, however, is not present in the case of the NaNO3and KNO3individually, both of which, with the addition of nanoparticles, retain curve trends similar to their baseline cases. Further investigation, involving differential scanning calorimetry, suggests that nanoparticles delay the liquid/solid phase transition process of the molten salt mixture, which in turn affects the rheological and wetting behavior of the molten mixture.