No abstract

A new version release (2.0) of the molecular simulation tool ms2 [S. Deublein et al., Comput. Phys. Commun. 182 (2011) 2350] is presented. Version 2.0 of ms2 features a hybrid parallelization based on MPI and OpenMP for molecular dynamics simulation to achieve higher scalability. Furthermore, the formalism by Lustig [R.Lustig, Mol. Phys. 110 (2012) 3041] is implemented, allowing for a systematic sampling of Massieu potential derivatives in a single simulation run. Moreover, the Green-Kubo formalism is extended for the sampling of the electric conductivity and the residence time. To remove the restriction of the preceding version to electro-neutral molecules, Ewald summation is implemented to consider ionic long range interactions. Finally, the sampling of the radial distribution function is added.

Vapor–liquid equilibrium data of the binary mixtures nitrogen + acetone and oxygen + acetone are measured and compared to available experimental data from the literature. The saturated liquid line is determined for both systems at specified temperature and liquid phase composition in a high-pressure view cell with a synthetic method. For nitrogen + acetone, eight isotherms between 223 K and 400 K up to a pressure of 12 MPa are measured. For oxygen + acetone, two isotherms at 253 K and 283 K up to a pressure of 0.75 MPa are measured. Thereby, the maximum content of the gaseous component in the saturated liquid phase is 0.06 mol/mol (nitrogen) and 0.006 mol/mol (oxygen), respectively. On the basis of these data, the Henry’s law constant is calculated. In addition, the saturated vapor line of nitrogen + acetone is studied at specified temperature and pressure with an analytical method. Three isotherms between 303 K and 343 K up to a pressure of 1.8 MPa are measured. All present data are compared to the available experimental data. Finally, the Peng–Robinson equation of state with the quadratic mixing rule and the Huron–Vidal mixing rule is adjusted to the present experimental data for both systems.

For computer calculations, it is helpful to use ancillary equations to generate starting values for density iterations. Therefore ancillary equations for vapor pressure, saturated liquid density, and saturated vapor density were developed. The equations and parameters are given below. These ancillary equations are no reference equations, so that the fundamental equation of state for octamethylcyclotetrasiloxane must be used to calculate accurate saturation properties.

Vapor–liquid equilibria (VLE) of the binary mixtures nitrogen + acetone and oxygen + acetone are studied by molecular simulation and experiment. A force field model for pure acetone (CH3–(CO)–CH3) is developed, validated, and then compared with four molecular models from the literature. The unlike dispersive interaction between nitrogen and acetone as well as oxygen and acetone is adjusted. On the basis of these mixture models, the VLE of nitrogen + acetone and oxygen + acetone is determined by molecular simulation and validated on the basis of experimental data. To extend the experimental database, a gas solubility apparatus is constructed and the saturated liquid line of nitrogen + acetone is measured at the three isotherms 400 K, 450 K, and 480 K up to a maximum pressure of 41 MPa. Finally, the results from simulation and experiment are used to parametrize the Peng–Robinson EOS for nitrogen + acetone with the Huron−Vidal mixing rule.