Cross second virial coefficients and dilute gas transport properties of the (CH 4 + CO 2 ), (CH 4 + H 2 S), and (H 2 S + CO 2 ) systems from accurate intermolecular potential energy surfaces

Abstract

The cross second virial coefficient and the dilute gas shear viscosity, thermal conductivity, and binary diffusion coefficient have been calculated for (CH 4 + CO 2 ), (CH 4 + H 2 S), and (H 2 S + CO 2 ) mixtures in the temperature range from (150 to 1200) K. The cross second virial coefficient was obtained using the Mayer-sampling Monte Carlo approach, while the transport properties were evaluated by means of the classical trajectory method. State-of-the-art intermolecular potential energy surfaces for the like and unlike species interactions were employed in the calculations. All potential energy surfaces are based on highly accurate quantum-chemical ab initio calculations, with the potentials for the unlike interactions reported in this work and those for the like interactions taken from our previous studies of the pure gases. The computed transport property values are in good agreement with the few available experimental data, which are limited to (CH 4 + CO 2 ) mixtures close to room temperature. The lack of reliable data makes the values of the thermophysical properties calculated in this work currently the most accurate estimates for lowdensity (CH 4 + CO 2 ), (CH 4 + H 2 S), and (H 2 S + CO 2 ) mixtures. Tables of recommended values for all investigated thermophysical properties as a function of temperature and composition are provided.

Ab initio intermolecular potential energy surface for the CO2—N2 system and related thermophysical properties

“…The high-temperature data (T > 298 K) of Kestin and Ro are known to suffer from a design flaw 71 in their viscometer that resulted in viscosity values that are always systematically too high above room temperature by up to about 1%. 5,10,13,14,16,17,65 This is consistent with the observed deviations. We conservatively estimate the combined standard uncertainty of the scaled values to vary from 0.2% for pure CO 2 to 0.15% for pure N 2 between 300 K and 700 K, increasing to 1% for pure CO 2 and 0.5% for pure N 2 , respectively, outside of this temperature range.…”

“…Recently, Hellmann and co-workers have extended their work on pure gases 1,[4][5][6][7][8][9][10][11][12][13] to binary mixtures, namely CH 4 -N 2 , 14,15 CH 4 -CO 2 , 16 CH 4 -H 2 S, 16 H 2 S-CO 2 , 16 CH 4 -C 3 H 8 , 17 and CO 2 -C 3 H 8 , 17 and successfully validated the respective kinetic theory expressions for the transport properties. [14][15][16] The extension of the calculations to binary mixtures provides not only accurate thermophysical property data for such systems, but also all the input data for the calculation of thermophysical properties of any multicomponent mixture consisting of species for which the binary properties are available. The addition of the CO 2 -N 2 system will allow for a better characterization of thermophysical properties of a number of industrially important gas mixtures, in particular, for: (i) flue gas and process streams used in capture and cleaning of CO 2 before injection into reservoirs as part of a) Electronic mail: robert.hellmann@uni-rostock.de the carbon capture and storage (CCS) process; (ii) natural gas, where the recent discoveries of CO 2 -rich reservoirs with non-negligible amounts of N 2 require updating and extending the existing thermophysical data; and (iii) combustion modelling.…”

“…However, the few available experimental data below ambient temperature often lie significantly outside our uncertainty interval, in particular, the data of Brewer, 43 of Ng, 44 and, at very low temperatures, of Yakimenko et al 45 At ambient and higher temperatures, the data of Cottrell et al 41 and the datum of Edwards The transport properties of a dilute gas mixture can be determined using the kinetic theory of molecular gases. [14][15][16][53][54][55][56][57][58][59][60] Each transport property is obtained by solving a system of linear equations, the coe cients of which are related to so-called generalized cross sections. The generalized cross sections are determined by the binary collisions of two molecules, which thus connects them directly to the intermolecular PES.…”

“…The approach employed to determine values for transport properties from the generalized cross sections in the present work is the same as in previous works. [14][15][16] Therefore, we do not repeat it here. In this work, we present results for the shear viscosity η in the third-order approximation, for the thermal conductivity λ (under steady-state conditions, see Ref.…”

Intermolecular potential energy surface and thermophysical properties of propane

“…[37][38][39][40] However, by adjusting a single dispersion-related parameter for each PES, we were able to bring the calculated values of the second virial coefficients into excellent agreement with the best experimental data at all temperatures. 1,35,36 In the present work, we have adjusted the fitted C 6 and C 8 parameters for the interactions FIG. 3.…”