Determination of Vapor–Liquid Equilibrium Data in Microfluidic Segmented Flows at Elevated Pressures Using Raman Spectroscopy

Abstract

A fast, noninvasive, and efficient analytical measurement strategy for the characterization of vapor-liquid equilibria (VLE) is presented, which is based on phase (state of matter) selective Raman spectroscopy in multiphase flows inside microcapillay systems (MCS). Isothermal VLE data were measured in binary and ternary mixtures composed of acetone, water, carbon dioxide or nitrogen at elevated pressures up to 10 MPa and temperatures up to 333 K. For validation, the obtained data were compared with literature data and reference measurements in a high-pressure variable volume cell. Additionally, the mixtures were investigated at temperatures and pressures where no data is available in literature to extend the high-pressure VLE database.

Influence of Liquid Structure on Fickian Diffusion in Binary Mixtures of n-Hexane and Carbon Dioxide Probed by Dynamic Light Scattering, Raman Spectroscopy, and Molecular Dynamics Simulations

“…When coherent light irradiates a transparent fluid in macroscopic thermodynamic equilibrium, scattered light can be observed in all directions. While quasielastic scattering allows the determination of various thermophysical properties in an absolute way, inelastic scattering provides information on the composition of mixtures and about molecular vibrations . Thus, light scattering experiments are a suitable way to establish structure–property relationships.…”

Measurement of Micro Kinetics of Hydrogenation in Liquid Phase Using Raman Spectroscopy

“…Raman spectroscopy is a minimal-invasive technology for gaining in situ information about mixtures. This was already shown, e.g., in the determination of phase equilibria, which had been measured very precisely for large pressure and temperature ranges [17][18][19]. A review about common quantitative analysis of Raman spectra is given by Pelletier [20].…”

Microfluidic approaches for accessing thermophysical properties of fluid systems

“…They operated under pressures ranging from 11 to 100 bar and temperatures from 22 to 100 °C. More recently, Luther et al 66 worked on the determination of vapor-liquid equilibrium data using Raman spectroscopy on a segmented flow inside a capillary. In the studied conditions, they also determined the composition of the different phases at several positions after the mixing point ( Figure 9).…”