纳米颗粒对二元硝酸盐表面张力和密度的影响

Effect of nanoparticles on surface tension and density of binary nitrate

为准确计算纳米熔盐的传热储热能力,利用高温熔融法将SiO_(2)纳米颗粒分散至二元硝酸盐(60%NaNO_(3)-40%KNO_(3))中,制备了5种不同含量SiO_(2)纳米颗粒的纳米熔盐复合材料。基于阿基米德法测量液体密度和拉筒法测量液体表面张力的原理改进实验装置,搭建高温熔盐密度、表面张力实验台。实验对制备的5种纳米熔盐的表面张力和密度进行实验测量,并对实验数据进行拟合,得到5种纳米熔盐密度和表面张力随温度的变化关系,拟合得到纳米熔盐密度和表面张力与温度之间的实验关联式。结果表明,基盐及5种纳米熔盐的密度均随温度的升高而下降,且加入SiO2纳米颗粒后,熔融盐的密度变化不明显。基盐及5种纳米熔盐的表面张力也随温度的升高而下降,且加入SiO2纳米颗粒后,熔融盐的表面张力值均有所增加。提出纳米熔盐形成机理,并对纳米熔盐密度和表面张力改变的原因进行解释。

To accurately calculate the heat transfer and heat storage capacity of a molten salt nanofluid,SiO_(2)nanoparticles were dispersed into a binary nitrate mixture(60%NaNO_(3)-40%KNO_(3))by a high-temperature melting method,and then five molten salt nanofluids with different SiO_(2)nanoparticles were prepared.Using the Archimedes method to measure the liquid density and the pulling escape method to measure the liquid surface tension,the experimental stand was improved.The surface tension and density of the five molten salt nanofluids were measured,and the experimental data were fitted to obtain the relationships of density and surface tension of the five molten salt nanofluids with temperature,and the experimental correlations of the density,the surface tension of molten salt nanofluids,and the temperature was obtained.The results demonstrated that the density of the base salt and the molten salt nanofluids decreased with increase in temperature,and the density of the molten salt nanofluids did not significantly change after addition of the SiO_(2) nanoparticles.The surface tension of the base salt and the five molten salt nanofluids decreased with increasing temperature.A formation mechanism of molten salt nanofluids was proposed,and an explanation was given for the changes in density and surface tension.