体相CO_2约化自扩散系数的标度律关联模型  

On the use of excess entropy scalinglaws to describe the reduced self-diffusivities of bulk CO_2

作　　者：贺鹏[1] 朱吉钦[1] 刘辉[1] 黄世萍[1] 

机构地区：[1]北京化工大学化学工程学院化工资源有效利用国家重点实验室,北京100029

出　　处：《北京化工大学学报（自然科学版）》2012年第3期12-18,共7页Journal of Beijing University of Chemical Technology(Natural Science Edition)

基　　金：国家"973"计划(2010CB732301)

摘　　要：用巨正则转换矩阵蒙特卡罗(GC-TMMC)和分子动力学(MD)模拟方法研究了体相CO2单位分子的过剩熵与其约化自扩散系数(D*s)的标度关系。过剩熵主要考虑3种定义:总体过剩熵sex,以分子重心径向分布函数定义的二体熵s(c 2)和所有原子径向分布函数定义的二体熵s(t 2)。结果表明,总体过剩熵sex与D*s之间存在明显的标度关系,并且独立于状态点所处的相态,可以用热力学量-过剩熵来关联动力学量-自扩散系数(约化方式);二体熵在小于超临界温度范围内的标度结果偏离了-sex-D*s的"共同曲线"。本文拓展了过剩熵标度律在分子流体中的应用范围,得到了其在体相CO2自扩散系数关联中的应用规律。We have used molecular simulations to investigate the connection between self-diffusivity and the excess entropy of CO2.In this work,we consider three versions of the excess entropy.The first is the total thermodynamic excess entropy sex,which accounts for all intermolecular（two-,three-,and higher-body） correlations.The other two are the two-body contributions to the excess entropy obtained from the pair-correlation function of the fluid,which can be defined either from center of mass positional correlations（s（2）c） or from atom-atom pair correlation functions（s（2）t）.We find that all the thermodynamic excess entropies serve as a suitable metric for describing the reduced transport properties over a broad range of state conditions.Interestingly,for the reduced self-diffusivity（D＊s）,a stronger connection between D＊s and sex,and a comparatively weaker connection between D＊s and s（2）c and s（2）t was observed over a broad range of state conditions.

关 键 词：CO2 分子动力学模拟 标度律 自扩散系数 过剩熵 

分 类 号：TQ013.1[化学工程]