Low temperature oxidation of n-hexane in a flow reactor

Abstract

The risk of igniting a flammable mixture in fuel tank vapor space is a major concern in aviation safety. In order to analyze the hazards and develop mitigation strategies, it is necessary to characterize the explosive properties of kerosene vapor-air mixtures over wide ranges of initial conditions. n-Hexane has been extensively used in our laboratory as a single component surrogate of kerosene. In the present study, hexane oxidation by oxygen was studied in a flow reactor at equivalence ratios of 0.7, 1 and 1.5 for mixtures diluted at 90% with nitrogen. Residence time was set at 2 s and the pressure at 100 kPa. The evolution of the gas phase composition at the reactor exit was studied over the range 450-1000 K. Laser-based diagnostics and gas chromatography analysis were used to characterize the exit mixture composition. The chemical species measurements revealed three distinct regimes of oxidation, namely (i) the cool flame region from 600 to 650 K, (ii) the NTC region between 675 and 775 K, and (iii) the high temperature oxidation regime from 800 K. The modeling study demonstrated the capability of reproducing most of the trends observed

An experimental and kinetic modeling study of n -hexane oxidation

“…Other validations of the mechanism were made using ignition delay times, speciation in flow reactors and laminar flame speeds from literature [25][26]60], and are included in the Supplemental Material as Fig. S4-S9.…”

“…In comparison, intermediate length alkanes such as the hexanes have been less studied [23][24][25][26][27].…”

“…Previous work has focused mainly on the high-temperature oxidation of hexane, however few studies have been conducted at low-temperature conditions [25,[27][28]. In 1996, Burcat et al measured ignition delay times for n-hexane-oxygen-argon mixtures in a shock tube over the temperature range of 1020-1725 K at pressures of 1-7 atm [23].…”

“…In 2014, Mével et al studied the oxidation of n-hexane in a flow reactor at low temperatures [25] where n-hexane was used as a single component surrogate for kerosene. The temperature range investigated was 450-1000 K at a pressure of 1 bar.…”

Ignition of fuel–air mixtures from a hot circular cylinder

“…We determined E / R as a function of temperature by computing constant pressure ( p = 101 . 3 kPa ) adiabatic explosions in Cantera [60] using detailed reaction mechanisms (hydrogen-air: [61][62][63] ; ethylene-air: [64][65][66] ; n-hexane-air: [38,65,67] ) and numerically differentiating ignition delay time in Arrhenius coordinates,…”