硝酸熔盐纳米流体比热容提高的模拟与实验研究  

Simulation and Experiment Investigation into Specific Heat Capacity Enhancement of Nitrate Molten Salt Nanofluid

作　　者：魏小兰[1] 林国庆 丁静[2] 王维龙[2] 陆建峰[2] 刘书乐 WEI Xiaolan;LIN Guoqing;DING Jing;WANG Weilong;LU Jianfeng;LIU Shule(School of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou 510640,Guangdong,China;School of Materials Science and Engineering,Sun Yat-Sen University,Guangzhou 510006,Guangdong,China)

机构地区：[1]华南理工大学化学与化工学院,广东广州510640 [2]中山大学材料与工程学院,广东广州510006

出　　处：《华南理工大学学报（自然科学版）》2021年第9期46-55,共10页Journal of South China University of Technology(Natural Science Edition)

基　　金：国家自然科学基金资助项目(52036011);国家自然科学基金–广东省联合基金资助项目(U1601215)。

摘　　要：熔盐和纳米颗粒复合的纳米流体是使太阳能热发电传储热系统高效储热的重要材料,探究纳米颗粒的加入导致熔盐比热容提高的原因,对于工程实践意义重大。实验中用差式扫描量热仪测试了熔盐中加入不同浓度的纳米颗粒后复合流体的比热容变化,随后以分子动力学模拟计算的方法探究比热容提高的原因。在模拟中固定熔盐不变而改变纳米颗粒的添加量,重点分析纳米颗粒添加量对熔盐比热容及熔盐结构、分布的影响。结果表明:纳米颗粒添加量在1.0%~1.5%(质量分数)时,比热容提高率最大;熔盐阴离子在纳米颗粒表面高密度聚集甚至在更小粒径(约1 nm)纳米颗粒表面规律性排布时产生的额外作用力是纳米流体比热容提高的主要原因。计算结果还证实,熔盐中纳米粒子分散程度高时,比热容提高更大。纳米颗粒的加入在一定程度上会降低熔盐中阴阳离子间的距离,使得库仑能发生变化,这是导致比热容提高的另一原因。Nanofluid composed of molten salt and nanoparticles are important materials for the effective power ge-neration and heat storage system of solar energy.It is of great significance to find out why nanoparticles are able to enhance the specific heat capacity of molten salt.In this paper,nanoparticles were added in molten salt at diffe-rent contents,and the specific heat capacity variation of complex fluids was measured by means of DSC.Then,the molecular dynamic simulation was adopted to explore the reason for the rise of specific heat capacity of complex fluids.In the simulation,the number of molten salt molecules is fixed and the content of nanoparticles is changeable,so as to analyze the effects of the content of nanoparticles on the specific heat capacity,structure and distribution of molten salt.It is indicated that,when the mass fraction of nanoparticles is 1.0%~1.5%,the increase of specific heat capacity is the largest.The additional interaction force produced by the high-density clustering of molten salt anions on the surface of nanoparticles or by the regular restricted distribution on the surface of nanoparticles with smaller particle size(about 1nm)is the main reason for the increase of the specific heat capacity of nano-fluids.In addition,calculation results confirm the positive correlation between the dispersity of the nanoparticles and the increase of specific heat capacity.The addition of nanoparticles can reduce the distance between anion and cation in molten salt to a certain extent,resulting in the change of Coulomb energy,which is another reason for the increase of specific heat capacity.

关 键 词：传储热材料 熔盐 纳米流体 分子模拟 比热容 微观结构 

分 类 号：TQ013[化学工程]