修改的BWRS状态方程

Modified Benedict-Webb-Rubin-Starling Equation of State

准确计算流体的属性和热力学模型需要合适的状态方程。BWRS方程包含了计算轻烃组分的系数,决定烃类混合物气体系数的混合规则,可用于热力学性质计算和气液平衡计算,还可用于高密度状态或者有凝液出现的情况。通过对BWRS方程中各个参数的分析研究,提出了改进的MBWRS状态方程。修改模型包括:其一修改了BWRS方程中的11个参数,将BWRS状态方程转化为无因次的状态方程,减小了由于单位制转换带来的累积误差;其二添加了包括C7+在内的烃类和非烃类组分(共25个)的二元交互作用系数。由于BWRS状态方程是关于密度的隐式方程,介绍了求解该超越方程的精确且快捷的计算方法。BWRS状态方程的修改,为精确地求得热力学参数提供了有力的保障。

Applicable equation of state to accurately calculate the property of fluid and thermodynamic model is essentially needed.BWRS(Benedict–Webb–Rubin–Starling) equation contains the coefficients for calculating light hydrocarbon composition and the mixing rules for determining gas coefficients of hydrocarbon mixture,it can be used to calculate the thermodynamic property and vapor/liquid equilibrium,and to simulate states of high density hydrocarbons or condensation.Based on the analysis and research of various parameters which are contained in BWRS equation of state,a modified equation of state,i.e.MBWRS equation of state,is proposed.The modified model includes the following aspects: firstly,modifying 11 parameters of BWRS equation,transferring BWRS equation into dimensionless equation to reduce the cumulated error which caused by unit conversion;secondly,adding binary interaction coefficients of 25 components of hydrocarbon and non-hydrocarbon,including C 7 +.BWRS equation of state is implicit in density,so the accurate and quick calculation method for solving that transcendental equation is offered.MBWRS equation ensures the accuracy of determining thermodynamic parameters.