LiCl-KCl熔盐纳米流体结构和热物性的分子动力学模拟

Molecular dynamics simulation of structure and thermal properties of LiCl-KCl molten salt nanofluids

采用分子动力学方法研究了Al_(2)O_(3)纳米颗粒对二元氯化物熔盐LiCl-KCl结构和热物理性能的影响,分析了熔盐纳米流体(Nanofluids,NF)的径向分布函数、配位数N(r)、自扩散系数D、密度、黏度和热导率随纳米颗粒掺杂量和温度的变化规律。结果表明,在700~1400 K温度范围内,随着纳米颗粒掺杂量的增加,径向分布函数g_(Li-Cl)(r)的第一峰位置逐渐向左移动,且峰高增加,配位数逐渐增大,自扩散系数逐渐减小。熔盐纳米流体的密度、黏度和热导率随温度的升高而降低,随纳米颗粒掺杂量的增加而增加,黏度和热导率最大分别提高了16.83%和4.95%。热物性的变化归因于Al_(2)O_(3)纳米颗粒的加入减小了纳米流体中阴阳离子间的距离,增强了缔合作用,使得熔体结构更加致密。

Herein,the molecular dynamics method investigates the effects of Al_(2)O_(3)nanoparticles on the structure and thermophysical properties of binary chloride salt LiCl-KCl.Furthermore,the effect of doping amount and temperature on radial distribution function,coordination number[N(r)],self-diffusion coefficient(D),density,viscosity,and thermal conductivity of nanofluids were analyzed.The results show that in the temperature range of 700~1400 K,with increasing nanoparticles,the first peak position of the radial distribution function g_(Li-Cl)(r)moves to the left gradually,the peak height and the coordination number increase,and the self-diffusion coefficient decreases gradually.The density,viscosity,and thermal conductivity of nanofluids decreased with increasing temperature but increased with increasing nanoparticles,and the maximum viscosity and thermal conductivity increased by 16.83%and 4.95%,respectively.The change in thermophysical properties was attributed to adding Al_(2)O_(3)nanoparticles that reduced the distance between anions in the nanofluids,enhancing the association effect,and making the melt structure more compact.