Harvey Allan H
National Institute of Standards and Technology, Boulder, CO 80305, USA.
J Res Natl Inst Stand Technol. 2017 Nov 20;122:1-14. doi: 10.6028/jres.122.041. eCollection 2017.
Rigorous calculation of the Poynting correction, which describes the effect of pressure on the fugacity of a condensed phase, requires time-consuming evaluation of a thermodynamic potential such as the International Association for the Properties of Water and Steam (IAPWS-95) formulation for water. Simplifying approximations are used in many applications, but the error introduced by the approximations is seldom evaluated. In this work, first-order and second-order approximations were developed for the Poynting correction for both ice and liquid water (including supercooled liquid water), and their errors were evaluated by comparison to the full thermodynamic potentials. The range of conditions covered is from -100 °C to 200 °C at pressures to 20 MPa. Some implications for the calculation of the enhancement factor used in humidity metrology are discussed.
对描述压力对凝聚相逸度影响的坡印廷校正进行精确计算，需要耗时评估诸如国际水和水蒸气性质协会（IAPWS - 95）水的公式等热力学势。许多应用中使用了简化近似，但很少评估这些近似引入的误差。在这项工作中，针对冰和液态水（包括过冷液态水）的坡印廷校正，开发了一阶和二阶近似，并通过与完整的热力学势进行比较来评估其误差。涵盖的条件范围是温度从 - 100°C 到 200°C，压力至 20 MPa。讨论了对湿度计量中所用增强因子计算的一些影响。
