Molecular Dynamics Simulations and a Quintic Equation of State for Nitrogen in a Wide P–T Range, with Validation of a Reference Model up to Ultrahigh P–T Conditions,Journal of Chemical & Engineering Data

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Molecular Dynamics Simulations and a Quintic Equation of State for Nitrogen in a Wide P–T Range, with Validation of a Reference Model up to Ultrahigh P–T Conditions
Journal of Chemical & Engineering Data ( IF 2.0 ) Pub Date : 2022-07-27 , DOI: 10.1021/acs.jced.2c00248
Tao Guo _{1,

2} , Siyu Jiang _{1,

3} , Yang-Xin Yu ₄ , Jiawen Hu _{1,

3,

5}

Affiliation

Pressure–density–temperature data of nitrogen (N₂) at 589 state points are obtained by molecular dynamics simulations at 1573.15–3273.15 K and 500–3500 MPa (using NPT ensemble) or 0.2–0.5 g·cm^–3 (using NVT ensemble). The results agree well with those of experiments at high temperatures and pressures, and the Helmholtz free energy model of Span et al. [ J. Phys. Chem. Ref. Data 2000, 29, 1361−1433]. The model of Span et al. is confirmed to be valid to at least 6000 K and 30000 MPa (or 2.0 g·cm^–3) using the new and previous data, as well as thermodynamic analysis. Using this model as a reference, a quintic equation of state (EOS) is developed for supercritical N₂. Compared to the reference model, the volume deviations of the EOS are within 0.21% at 273–4273 K, 0–4300 MPa, and 0–1.035 g·cm^–3. The EOS compares well with the new simulation results and previous experimental and simulated data at high pressures and temperatures. It is capable of accurate prediction of fugacity coefficient, residual enthalpy and entropy, and other properties. It can also be extrapolated to lower temperatures or higher temperatures and densities, but with lowering of accuracy.

中文翻译：

宽 P-T 范围内氮的分子动力学模拟和五次状态方程，以及在超高 P-T 条件下验证参考模型

通过分子动力学模拟在 1573.15 – 3273.15 _K和 500–3500 MPa（使用NPT系综）或 0.2–0.5 g·cm ^–3（使用NVT系综）。结果与高温高压下的实验结果以及 Span 等人的亥姆霍兹自由能模型非常吻合。[ J.物理学。化学。参考。数据2000、29、1361-1433 ]。_ Span 等人的模型。确认在至少 6000 K 和 30000 MPa（或 2.0 g·cm ^–3 ) 使用新的和以前的数据，以及热力学分析。以此模型为参考，建立了超临界 N ₂的五次状态方程 (EOS) 。与参考模型相比，在 273-4273 K、0-4300 MPa 和 0-1.035 g·cm ^-3时，EOS 的体积偏差在 0.21% 以内。EOS 与新的模拟结果以及以前在高压和高温下的实验和模拟数据进行了很好的比较。能够准确预测逸度系数、剩余焓和熵等性质。它也可以外推到较低的温度或较高的温度和密度，但精度会降低。

更新日期：2022-07-27

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