Novel isochoric measurement of the onset of vapor–liquid phase transition using differential scanning calorimetry
A novel method for measuring the onset of vapor–liquid phase transition applying an isochoric procedure in a high-pressure micro differential scanning calorimeter is introduced for the first time. Isochoric dew-point measurement is used to measure vapor pressures of CO2 at different boiling temperatures and dew points of a methane/ethane gas mixture at different pressures or temperatures. The isochoric two-phase bubble-point measurement, similar to the isobaric method, is also demonstrated to measure vapor pressures of methanol at different boiling temperatures. All results are in agreement with the literature data. The isochoric method is found to be superior to the widely used isobaric method. It can be used to measure the onset of vapor–liquid phase transition for a wide range of substances and mixtures, including the ones for which the isobaric method is inapplicable, and it eliminates difficulties usually encountered in the isobaric method. The proposed method along with the findings of this study can pave the way for experimental measurements of phase equilibria in more complex systems.
- This article is part of the themed collection: 2018 PCCP HOT Articles