(499f) Microfluidics Approaches to Access Thermodynamics Properties of Fluid Systems

Accessing fluid systems thermodynamics properties at high pressure and temperature is crucial in chemical engineering for they are required in most of process parameter calculations. Nevertheless, these are not always available in the literature or rather time-consuming to obtain. Thanks to the recent development of high pressure microreactors, we have developed and use novel fast microfluidic-based approaches for investigating thermodynamics of multicomponents 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 points 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 / alkanes mixtures. The obtained results were then be compare to PREOS-calculated and literature data.

Another microfluidics approach will also be presented for simultaneously accessing density and viscosity of homogeneous fluids mixtures. In comparison with classical set-ups, microfluidic devices exhibit higher heat transfer capability and small volumes, resulting in an easy control of temperature, fast conditions screening and improved operation safety. The proposed method can be used in a wide range of pressures (10 < P(bar) < 200) and temperatures (303 < T(K) < 500). Some results obtained with pure fluids (CO₂ and N₂), and with mixtures (CO₂ / alkanes and CO₂+H₂) will be presented.

These two microfluidics approaches display equal accuracy compared to conventional high pressure optical cell methods, but allows for a much faster data acquisition, taking advantage of improved heat and mass transfers at microscale.