水和水蒸气热力性质IAPWS-IF97计算模型分析及算法设计

An Analysis of IAPWS-IF97 Formulae-based Model for Calculating Water and Steam Thermodynamic Properties and Its Algorithm Design

用面向对象的方法实现了最新水和水蒸气热力性质工业公式IAPWS-IF97(2007.8修订版),对其各区的计算模型进行了详细地分析并设计了相应的实现算法。实现了其所有区的基本方程、导出方程、各种属性的计算公式、反推方程。实现了2区的亚稳态蒸汽区的补充方程、B23方程和B2bc方程。给出了区域区分算法、2区子区域区分算法和3区通过压力p和温度T求密度ρ的牛顿迭代算法。详细地介绍了最新IAPWS-IF97的实现方法、注意事项、相关推导过程并且补充了等容比热容cv的计算机程序验证值。提高了B23与Ts(p)边界和B2bc与ps(T)边界的一致性。通过在造纸工业中的应用,表明该实现算法具有全面、精确、快速和自动测试等优点。

By adopting an object-oriented method, implemented was the latest industrial formulae-based IAPWS-IF97 (2007.8 Revision) for calculating water and steam thermodynamic properties. The calculation models for various zones were analyzed in detail with their corresponding implementation algorithms being designed. The basic equations, derivative equations, calculation formulae in various attributes and reversely derived equations for all the zones were implemented. The supplementary equation, B23 equation and B2bc equation for the metastable steam regions in two zones were also executed. The authors have presented the regional differentiated algorithm, sub-regional differentiated algorithm in two zones and Newton iterative algorithm in three zones to determine the density ρ from pressure P and temperature T. They have also described in detail the latest IAPWS-IF97 implementation method, matters meriting attention and relevant derivative processes, and supplemented the verification values of the computer program for specific heat capacity of equicapacitance cv, thus enhancing the consistency of B23 with boundary Ts(P) as well as that of B2bc with boundary Ps(T). The application of the above in the paper-making industry indicates that the implemented method enjoys such a variety of merits as comprehensiveness, accuracy, speedy and automatic testing etc.