CO_(2) Diffusivity in H_(2)O for Supercritical Conditions:A Molecular Dynamics Study

作     者：CHEN Longfei LIU Dong LI Qiang CHEN Longfei;LIU Dong;LI Qiang

作者机构：School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing210094China 

出 版 物：《Journal of Thermal Science》 (热科学学报（英文版）)

年 卷 期：2022年第31卷第5期

页      面：1407-1415页

核心收录：

学科分类：08[工学] 0807[工学-动力工程及工程热物理] 

基　　金：supported by the National Key R&D Program of China(No.2016YFB0600100) the Basic Science Center Program for Ordered Energy Conversion of the National Natural Science Foundation of China(No.51888103) the Fundamental Research Funds of the Central Universities(No.30919011403) 

主　　题：supercritical fluid H_(2)O/CO_(2)mixture diffusion molecular dynamics 

摘      要：Supercritical H_(2)O/CO_(2) mixtures(650 K–973 K and 25 MPa,not far away from the critical temperature and pressure of water)have recently been used as the working fluid for a novel power generation system with higher efficiency and zero pollutant emission compared to conventional coal-fired power *** knowledge of the diffusion of these mixtures is important for efficient design of the system ***,both experimental and theoretical data are scarce for typical working conditions in the ***,we investigated both the self-diffusion and the mutual diffusion of the supercritical H_(2)O/CO_(2) mixtures using molecular dynamics(MD)*** show that the mixture diffusion coefficients for supercritical conditions are more than one order of magnitude larger than those in the sub-critical *** results reveal that H_(2)O molecules prefer to gather with themselves rather than with CO_(2) molecules in the near-critical region,while there is no featured molecular structure for higher temperatures in the supercritical ***,the self-diffusion of CO_(2) in H_(2)O in the infinite-dilution regime features Arrhenius temperature dependent behavior in the supercritical region excluding the near-critical-temperature *** molecular interaction mechanisms also provide insights into the mutual diffusion behavior of CO_(2) in H_(2)O,which is well described by the Darken equation in the supercritical ***,engineering equations,namely the Speedy-Angell power-law equation and the Vignes equation,can reproduce MD simulated infinite-dilution self-diffusion coefficients and Maxwell-Stefan mutual diffusion coefficients,respectively,of the supercritical H_(2)O/CO_(2) mixtures.