Molecular dynamics simulations are carried out to compute the intradiffusion coefficients of H₂ and O₂ in H₂O for temperatures ranging from 275.15 to 975.15 K and pressures ranging from 0.1 to 200 MPa. These conditions span vapor, liquid, and supercritical conditions. For the vast majority of the state points examined, experimental data are not available. The accuracy of six H₂ and six O₂ force fields is tested in reproducing the available experimentally measured densities, self-diffusivities, and shear viscosities of the pure gas and the intradiffusivity of the gas in H₂O. Namely, we screen the H₂ force fields developed by Buch, Vrabec and co-workers, Hirschfelder et al., Cracknell, a modified Silvera–Goldman, and Marx and Nielaba. For O₂, the force fields by Bohn et al., Miyano, Coon et al., Hansen et al., Vrabec et al., and Watanabe are tested. Overall, the force fields by Buch and Bohn for H₂ and O₂, respectively, were found to perform the best, and combined with the TIP4P/2005 H₂O force field are used to compute the intradiffusivities in the entire temperature and pressure range. The new data are used to develop an engineering model that can predict the H₂ and O₂ intradiffusivity in vapor, liquid, and supercritical H₂O. The new model uses 11 parameters and has an accuracy of 4–11%. The model is validated with other available experimental and simulation data for H₂ and O₂ in H₂O and pure H₂O. Aside from the extensive collection of new data for the intradiffusivities of H₂ and O₂ in H₂O, we present new data for the densities, shear viscosities, and self-diffusivities of pure TIP4P/2005 H₂O in the same wide temperature and pressure range. The new data and the engineering model presented here can be used for the design and optimization of chemical processes, for which the knowledge of H₂ and O₂ diffusivities in H₂O is important.

中文翻译：

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基于分子动力学模拟预测蒸汽、液体和超临界水中氢和氧的内扩散系数的工程模型

进行分子动力学模拟以计算 H ₂和 O ₂在 H ₂ O 中的内部扩散系数，温度范围为 275.15 至 975.15 K，压力范围为 0.1 至 200 MPa。这些条件涵盖蒸气、液体和超临界条件。对于所检查的绝大多数状态点，无法获得实验数据。六个 H ₂和六个 O ₂力场的准确性在再现可用的实验测量密度、自扩散率和纯气体的剪切粘度以及气体在 H ₂ O 中的内部扩散率方面进行测试。即，我们筛选了 H ₂Buch、Vrabec 及其同事、Hirschfelder 等人、Cracknell、改良的 Silvera-Goldman、Marx 和 Nielaba 开发的力场。对于 O ₂，测试了 Bohn 等人、Miyano、Coon 等人、Hansen 等人、Vrabec 等人和 Watanabe 的力场。总体而言，Buch 和 Bohn 分别对 H ₂和 O ₂的力场表现最佳，并结合 TIP4P/2005 H ₂ O 力场用于计算整个温度和压力范围内的内部扩散率. 新数据用于开发一个工程模型，该模型可以预测蒸汽、液体和超临界 H _{2 中}的 H ₂和 O ₂内部扩散率O. 新模型使用 11 个参数，准确度为 4-11%。该模型与其他现有的实验和仿真数据验证用于h ₂和O ₂ H中₂ O和纯^ h ₂ O.除了新的数据为H的intradiffusivities广泛收集₂和O ₂ H中₂ O，我们提供纯 TIP4P/2005 H ₂ O 在相同宽温度和压力范围内的密度、剪切粘度和自扩散率的新数据。此处提供的新数据和工程模型可用于化学过程的设计和优化，其中 H ₂和 O ₂的知识H ₂ O 中的扩散率很重要。