Alain Valtz

Bubble pressures and saturated liquid molar volumes of difluoromonochloromethane—fluorochloroethane binary mixtures: experimental data and modelling

Abstract A previously described apparatus (variable volume cell method) was used to obtain bubble pressures and saturated liquid molar volumes at four temperatures for systems involving difluoromonochloromethane with tetrafluorodichloroethane, trifluorotrichloroethane and difluoromonochloroethane. The experimental bubble pressures are well represented by the Peng-Robinson equation of state with one adjusted interaction parameter. Adjusting a second interaction parameter does not significantly improve the representation. Soave and Mathias equations give a quite similar representation. Saturated liquid molar volumes calculated from the different equations of state, with binary interaction parameters adjusted on bubble pressure data, do not agree well with experimental results: the standard deviation between calculated and experimental densities is ≈ 8% with the Peng-Robinson equation of state and ≈ 18% with that of Soave and Mathias.

Solubility measurements for carbon dioxide and nitrous oxide in liquid oxygen at temperatures down to 90 K

The solubility of nitrous oxide and carbon dioxide in liquid oxygen at temperatures between 90 and 110 K has been measured using a static-analytic method. The NRTL model has been used to calculate the liquid-phase activity. The overall experimental data-set is compared both with the results of the model and with experimental data available in literature.

Bubble pressure and saturated liquid molar volumes of the propane (1)-dichlorotetrafluoroethane(2)-trichlorotrifluoroethane(3) ternary system and of the three corresponding binaries

Abstract An apparatus described previously has been used for the present measurements. It is based on a synthetic static method with a variable-volume cell. Results are given at different temperatures between 343 and 423 K for three binary mixtures: propane-dichlorotetrafluoroethane (C 3 H 8 -R114), propane-trichlorotrifluoroethane (C 3 H 8 -R113), dichlorotetrafluoroethane-trichlorotrifluoroethane (R114-R113), and the corresponding ternary propane-dichlorotetrafluoroethane-trichlorotrifluoroethane (C 3 H 8 -R114-R113). The two binaries with propane are well represented by a one-parameter δ ij Peng-Robinson equation of state to within less than 1% for pressures and 6%, without volume translation, for saturated liquid molar volumes. By using a volume translation, an improved volume representation, 2%, for the propane-dichlorotetra-fluoroethane system is achieved. For the third binary system, δ ij = 0 is the best choice (representation is within 0.6% for pressure and 2% for molar volumes through a volume translation). Use of values of the binary interaction parameters δ ij established for binary systems enables good prediction of ternary data (representation to within 1% for pressures and 3.8% for saturated molar volumes). Volume translation does not improve the representation of the ternary saturated liquid molar volumes because it does not do it for the propane-trichlorotrifluoroethane system.

A New Thermodynamic Correlation for Apparent Henry's Law Constants, Infinite Dilution Activity Coefficient and Solubility of Mercaptans in Pure Water

Abstract Mercaptans (RSH) or thiols are odorous substances offensive at low concentration and toxic at higher levels. The presence of mercaptans as pollutants in the environment creates a great threat on water and air safety. In this study, the solubility of mercaptans in water was studied through the use of apparent Henry’s Law constant (H) and infinite dilution activity coefficients (γ∞). These thermodynamic properties are useful for environmental impact studies and engineering design particularly in processes where dilute aqueous systems are involved. The aim of this paper is to develop a new thermodynamic correlation for estimation of apparent Henry’s Law constant (H), infinite dilution activity coefficient (γ∞) and solubility of C1-C4 mercaptans including their isomers in pure water. This correlation was developed based on compiled literature data. New measurements of apparent Henry’s Law constant and infinite dilution activity coefficients of methyl mercaptan and ethyl mercaptan in water were carried out to validate the developed correlation. Validation with new measurement data showed a good consistency with low differences (less than 5%) for majority of the data. Additionally, heat of absorption of various mercaptans in pure water was discussed based on temperature influence, Henry Law Constants and solubility.