Vapor–Liquid Equilibria of Mixtures Containing Ethanol, Oxygen, and Nitrogen at Elevated Pressure and Temperature, Measured with In Situ Raman Spectroscopy in Microcapillaries

Abstract

Ethanol and oxygen containing gases are mixed in a T-junction at elevated pressure and then passed into a fused silica microcapillary, located in a heating block. Inside the microcapillary a Taylor flow of alternating liquid and vapor segments is formed. The thermodynamic equilibrium composition of the liquid and vapor segment depends on pressure and temperature. Their compositions are measured inside the microcapillary using in situ Raman spectroscopy. The main results obtained therefrom are temperature–composition ( Tx ) diagrams at conditions relevant for combustion engines [ p = (3 to 8) MPa; T = (303 to 473) K]. Isothermal vapor–liquid equilibria (VLE) data are derived and given in pressure–composition ( px ) diagrams. The investigation of different gas mixtures containing oxygen and nitrogen allows furthermore the illustration of VLE data at constant pressure and temperature in ternary diagrams. The obtained results are compared to scarce literature data. An equation of state (Peng–Robinson EOS) is furthermore adjusted to the measured results.

Geological storage of CO2–N2–O2 mixtures produced by membrane‐based direct air capture (DAC)

“…In this study, we used molecular dynamics simulations (see Appendix) to conduct preliminary evaluations of the storage efficiency of CO 2 -N 2 -O 2 mixtures. Although the behavior of this mixture has been studied at lower temperatures [17][18][19] or other compositions, 20 low-purity CO 2 (N CO2 /N total < 0.9) into a shallow formation (∼1000 m depth) is not efficient (Fig 2a); The density of CO 2 largely decreases with decreasing purity of CO 2 because this condition is close to the phase transition between gas and supercritical phase. On the other hand, in a deeper reservoir (Figs 2c and 2e), the CO 2 has a higher density and is more efficiently stored in limited pore space.…”

Raman Fiber Bundle Probe of Individually Filter-Coated Fibers

“…The Raman spectrum of a sample originates from an inelastic light/matter-interaction, which is referred to as Raman scattering. The Raman spectrum contains valuable information about the sample, such as its chemical composition [1][2][3], its temperature [4][5][6], its polymorphism [7][8][9], its heterogeneity and -with respect to medicine or biology -also the histopathological state of human, animalistic or herbal tissue [10][11][12]. Optical fibers play a pivotal role for making Raman measurements possible deep inside the body, remotely or in hardly accessible or hazardous environments [13,14].…”

“…It is true that the information-rich finger print region (0-1800 cm -1 ) of the Raman spectrum is still detectable with this configuration! But there are many examples, let it be in medicine [15][16][17] or in process engineering [3,18,19], where most interesting information was extracted not from the finger-print region, but from the spectral range exceeding 1800 cm -1 . Remember that this spectral range is not detectable with silicon-based detectors in the case of NIR excitation wavelengths.…”

Lignin valorization using supercritical water technology

“…Andreas Bräuer, two optical fibers and an Ocean View Qepro spectrometer. The Raman gun units optical parts for excitation and detection are described in detail in several publications (Braeuer, 2018;Fechter and Braeuer, 2020).…”

“…The mixing of water and model compound streams is placed in the T-junction located prior to the heating block. A detailed explanation of the system can be found elsewhere (Fechter and Braeuer, 2020).…”