The thermodynamic properties of vapour mixtures.
Thesis DisciplineChemical Engineering
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
An apparatus to measure the excess second virial coefficient of gas and/or vapour mixtures has been designed, constructed, developed and tested. Six-litre, stainless steel vessels with all-metal diaphragm valves and an all-metal sensitive capacitance differential pressure transducer were used to construct the apparatus. The excess second virial coefficient of benzene and cyclohexane vapour mixtures has been determined. The differential nature of the pressure change experiment allows the excess second virial coefficient, E, and hence the interaction second virial coefficient, B12 , to be determined with an accuracy nearly three times better than can be obtained from measurement of the second virial coefficient of the mixture. E is determined from a loading pressure, the thermostat temperature and the pressure change on mixing of the two components. Measurements of ε, to between ±1 and ±10x10 m3 mol-1, for benzene and cyclohexane, were made at 373, 348, 323, 315 and 298 K. The lower temperature measurements were affected by surface adsorption. A mathematical model has been postulated to calculate a correction for surface adsorption. A detailed error analysis has been carried out, illustrating the method's robustness, defining the best operating pressures and extreme sensitivity to oil contamination.