Precise measurements of properties of aqueous methanol mixtures and discussion on their composition dependence

Recently methanol and its aqueous mixtures have attracted much attention due to their potentiality in use as recovery and fixation for CO I D22齐埃D2being one of greenhouse gases，and as transport and storage of hydrogen fuel.Renewed interest in these materials shows also to other various applications such as natural refrigerants，and working fluids in new power cycles.Thermophysical property data for these materials are fundamental information to industrialize these new and renewed applications.In the present study，bubble point pressures，saturated liquid densities and PVT properties of{xCH I D23i D2OH+(1-x)H I D22ii D2O}with x=(1.0000 and 0.1984)have been measured by a variable volume method with meth metal bellows in the temperature range from320 to 400K suresup to Mpa。The uncertainties in measurements are estimated no greater than3mK in temperature，and 0.1%in pressure，density and composition，respectively。By the aid of these measurements，isothermal compressibility，isobaric expansivity，and non-ideality in bubble point pressures as well as PVT properties have been calculated.The study concluded with followings：(1)Deviations of bubble point pressure from Raoult‘s law show positive.The deviations of mixture with 20mol%methanol decrease with increasing temperature，whereas those with50mol%methanol are constant with variation of temperature.(2)Excess molar volumes show negative，and approach zero being the behavior of ideal mixtures with increasing pressure.As for temperature dependence of the mixtures，behavior of those with50mol%methanol changes at a pressure of about20 Mpa，but no such behavior is observed for the mixture with20mol%methanol。

Recently methanol and its aqueous mixtures have attracted much attention due to their potentiality in use as recovery and fixation for COィイD22ィエD2 being one of greenhouse gases, and as transport and storage of hydrogen fuel. Renewed interest in these materials shows also to other various applications such as natural refrigerants, and working fluids in new power cycles. Thermophysical property data for these materials are fundamental information to industrialize these new and renewed applications.In the present study, bubble point pressures, saturated liquid densities and PVT properties of {xCHィイD23ィエD2OH+(1-x)HィイD22ィエD2O} with x=(1.0000 and 0.1984) have been measured by a variable volume method with metal bellows in the temperature range from 320 K to 400 K at pressures up to 200 Mpa. The uncertainties in measurements are estimated no greater than 3 mK in temperature, and 0.1% in pressure, density and composition, respectively. By the aid of these measurements, isothermal compressibility, isobaric expansivity, and non-ideality in bubble point pressures as well as PVT properties have been calculated.The study concluded with followings:(1) Deviations of bubble point pressure from Raoult's law show positive. The deviations of mixture with 20 mol% methanol decrease with increasing temperature, whereas those with 50 mol% methanol are constant with variation of temperature.(2) Excess molar volumes show negative, and approach zero being the behavior of ideal mixtures with increasing pressure. As for temperature dependence of the mixtures, behavior of those with 50 mol% methanol changes at a pressure of about 20 Mpa, but no such behavior is observed for the mixture with 20 mol% methanol.