Investigation of hydrogen diffusion in supercritical water: A molecular dynamics simulation study

Zhao, Xiaohan; Jin, Hui

doi:10.1016/j.ijheatmasstransfer.2018.12.164

Cited by 103 publications

(40 citation statements)

References 42 publications

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“…As can be observed in Figure g–i for the cases of H 2 in H 2 O, O 2 in H 2 O, and pure H 2 O, respectively, the supercritical zone exhibits a more complex, non-Arrhenius behavior. Away from the critical point, Arrhenius behavior can be observed in the temperature range of 675–975 K. Such a behavior has also been reported by a number of studies. − For example, Zhao et al reported MD simulations following an Arrhenius behavior at 25 MPa and temperatures in the range of 673–973 K. To generalize the methodology developed here, the computed self- and intradiffusivity data for the supercritical region have been collapsed onto a single curve that has the following form where ρ is the density of H 2 O (in kg/m 3 ), while o 0 , o 1 , and o 2 are fitting parameters. Figure shows the resulting fits, while the calculated parameters for the three cases considered in this study are listed in Table .…”

Section: Resultssupporting

confidence: 58%

“…To this end, molecular dynamics (MD) simulations are used as a complementary approach for computing diffusivities when experimental data are not available. , In the past few decades, MD simulations have played a pivotal role in science and engineering since they provide a fundamental understanding of phenomena and processes at the molecular level. , The advent of faster computers and more efficient algorithms has resulted in the extensive use of MD simulations for computing the thermodynamic, transport, and structural properties of pure components and mixtures relevant to industrial applications . A number of MD simulation studies of the intradiffusivity of H 2 − and O 2 ,− in H 2 O have been reported. However, these studies are mostly limited to supercritical H 2 O conditions, with only a few considering lower pressures and temperatures, e.g., the study by Thapa and Adhikari on O 2 diffusivity in H 2 O at 0.1 MPa and temperatures up to 306 K …”

Section: Introductionmentioning

confidence: 99%

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Engineering Model for Predicting the Intradiffusion Coefficients of Hydrogen and Oxygen in Vapor, Liquid, and Supercritical Water based on Molecular Dynamics Simulations

et al. 2021

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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.

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Section: Resultssupporting

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Engineering Model for Predicting the Intradiffusion Coefficients of Hydrogen and Oxygen in Vapor, Liquid, and Supercritical Water based on Molecular Dynamics Simulations

et al. 2021

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“…Consequently, further studies for exploring the diffusion property of methanol are required. It is worth noting that findings pointed out that molecular dynamics simulations could be utilized to study diffusion property and even mechanisms [13]- [15], by which the obtained results will consistent with the actual experiments. Since molecular dynamics simulations can support detailed microscopic modeling at the molecular and atomic scale combining electricity, physics, chemistry, and other disciplines [16], [17], the research of diffusion mechanisms of methanol at atomic and molecular levels thus could be achieved by using molecular dynamics simulations.…”

Section: Introductionsupporting

confidence: 76%

Investigation on Diffusion Mechanisms of Methanol in Paper/Oil Insulation Based on Molecular Dynamics Simulation

et al. 2021

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Methanol is regarded as an available indicator to analyze the aging condition of cellulose insulation. However, the diffusion mechanism of methanol molecules in the paper-oil insulation system is still unclear, since it cannot be explored by using only experiments. Given this issue, the molecular dynamics simulations were performed to investigate the diffusion mechanism of methanol molecules. In the current work, the mean square displacement of methanol during the diffusion process was calculated and analyzed, as well as its trajectory tracking. Then, the research on interaction energies and hydrogen bonds in paper/oil system were conducted. Finally, the effect of temperature on the diffusion of methanol molecules was also studied. Findings revealed that the diffusion of methanol in cellulose insulation is faster than that in insulating oil, besides, the presence of hydrogen bonds affects the diffusion rate of methanol molecules in cellulose insulation and insulating oil. Thus, the present findings could support the investigation of the diffusion mechanisms of methanol molecules, by which the aging condition evaluation of cellulose insulation could be also promoted.

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“…Temperature usually plays a vital role in diffusion. The Arrhenius equation has been used multiple times [19] to explain this relation as shown in eq. (13), where D 0 denotes the pre-exponential factor, E a -the activation energy for diffusion, N A -the Avogadro's constant, k B -the Boltzmann constant, and T [K] -the temperature.…”

Section: Resultsmentioning

confidence: 99%

Determining diffusion coefficients of oxygen in supercritical water with molecular dynamics

et al. 2019

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250 atm with the molecular dynamics software. The mean squared displacement method is used to calculate the diffusion coefficient. At 300 K, 1 atm, our calculation gives 0.20 ⋅ 10-8 m 2 /s, which is very near to three empirical equations. When the condition is beyond the critical point, these empirical equations lost their accuracy, and only Kawasaki-Oppenheim equation can be compared to our calculation results. At supercritical conditions, we illustrate the diffusion coefficients with the Arrhenius equation and the activation energy is 22.54 kJ/mol.

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Investigation of hydrogen diffusion in supercritical water: A molecular dynamics simulation study

Cited by 103 publications

References 42 publications

Engineering Model for Predicting the Intradiffusion Coefficients of Hydrogen and Oxygen in Vapor, Liquid, and Supercritical Water based on Molecular Dynamics Simulations

Engineering Model for Predicting the Intradiffusion Coefficients of Hydrogen and Oxygen in Vapor, Liquid, and Supercritical Water based on Molecular Dynamics Simulations

Investigation on Diffusion Mechanisms of Methanol in Paper/Oil Insulation Based on Molecular Dynamics Simulation

Determining diffusion coefficients of oxygen in supercritical water with molecular dynamics

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