A microfluidic approach for investigating multicomponent system thermodynamics at high pressures and temperatures

In this work, we present a novel microfluidic-based approach for investigating the thermodynamics of multicomponent systems at high pressures and temperatures, such as determining miscibility diagrams and critical coordinates of complex mixtures. The developed method is primarily based on (i) bubble and dew point detection through optical characterization and (ii) the use of a so-called dynamic stop-flow measurement mode for fast screening of the diagram parameters, mainly P, T and composition. Our strategy was validated through the studies of model binary CO2-alkane mixtures. The obtained results were then compared to PREOS-calculated and literature data. We later applied this strategy for determining ternary and quaternary mixtures critical coordinates. This approach has equal accuracy compared to conventional high-pressure optical cell methods but allows for a much faster phase diagram determination, taking advantage of improved heat and mass transfers on the microscale and of the dynamic stop-flow approach.