Deep Potential Molecular Dynamics Systematic Study of Microstructure and Thermophysical Properties of NaCl-CaCl_(2) Molten Salt System across Phase Transition Temperature  

作　　者：Gegentana CUI Liu ZHOU Leping DU Xiaoze 

机构地区：[1]School of Energy,Power and Mechanical Engineering,North China Electric Power University,Beijing 102206,China [2]Key Laboratory of Power Station Energy Transfer Conversion and System(North China Electric Power University),Ministry of Education,Beijing 102206,China

出　　处：《Journal of Thermal Science》2024年第6期2245-2258,共14页热科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.51876058 and No.52376053).

摘　　要：Understanding the microscopic ionic structure and thermal properties of the NaCl-CaCl_(2) mixture is of great importance for improving its photothermal energy conversion efficiency.However,the measured values of thermophysical parameters are affected by the processes near the phase transition temperature,and the measured values often change abruptly.Classical and first-principles molecular dynamics studies have recently been performed to determine the thermal properties of molten salts,but such simulations for binary molten salts including NaCl-CaCl_(2) are still rare and limited to a range above the phase transition temperature(786.0 K),and the deviations from the measurements are still large.In this study,the molecular dynamics method based on the trained deep potential is used to systematically predict the variations of the ionic structure,phonon density of state,density and thermophysical properties including heat capacity,thermal conductivity,and diffusivity,and Prandtl number of the binary chloride system of NaCl-CaCl_(2) in a wide temperature range(600-1000 K)above the phase transition temperature.The variations and correlations of the properties(especially thermal diffusivity and Prandtl number)with temperature are deduced.It is found that an increase in temperature enhances ionic vibration,thus increasing the specific heat capacity.An increase in temperature weakens the interaction and vibrational transfer between ions,and hence the thermal conductivity tends to decrease.As the temperature increases,the heat capacity increases,while the density,thermal conductivity,thermal diffusion coefficient,and Prandtl number of the system all decrease.In general,the properties obtained by applying the deep potential trained in this work reflect the experimental values more accurately than the classical and first-principles molecular dynamics simulations.

关 键 词：chloride molten salt molecular dynamics simulation deep potential transport characteristics 

分 类 号：TM615[电气工程—电力系统及自动化]