Vapor-Liquid equilibria of the systems 1-octanol/nitrogen and 1-octanol/oxygen at pressures from 3 to 9 MPa and temperatures up to 613 K - Measured in a microcapillary with Raman spectroscopy

Vapor-liquid equilibria (VLE) of the binary systems 1-octanol/nitrogen and 1-octanol/oxygen were investigated at engine-relevant temperatures (T = 303 to 613 K for 1-octanol/nitrogen; T = 303 to 493 K for 1-octanol/oxygen) and pressures (p = 3 to 9 MPa). In order to acquire vapor-liquid equilibrium data, the pressurized fuel (1-octanol) and gas (nitrogen or oxygen) are mixed in a T-junction, where a Taylor flow of alternating liquid-phase and vapor-phase segments is formed. This segmented flow passes into a micmcapillary that is inserted in a steal heating block, in which the equilibrium compositions of both phases are measured by in situ Raman spectroscopy. The measured Raman signal ratios are correlated to mole fractions by a calibration, performed in the unsaturated vapor and liquid phase regimes. The obtained VLE data agree well with the few available literature data points. The VLE compositions calculated by the Peng-Robinson equation of state (PR-EoS) and perturbed-chain statistical associating fluid theory (PC-SAFT) were furthermore compared to the here obtained experimental data. Both models show good agreement as indicated by the absolute average deviations (AAD), that are at maximum 9.5 % for the saturated vapor phase and 4.2 % for the saturated liquid phase.

Automated summary

Vapor-liquid equilibria of the binary systems 1-octanol/nitrogen and 1-octanol/oxygen were investigated at engine-relevant conditions. The experiment utilized T-junction and micmcapillary to measure the equilibrium compositions of the two phases, and compared the results with computational models. The study showed good agreement between the experimental data and the models.