Fuel pyrolysis in a microflow tube reactor–Measurement and modeling uncertainties of ethane, n-butane, and n-dodecane pyrolysis

Abstract

A scaled down flow reactor consisting of 4 mm ID quartz tubing and rapid mixing of fuel with a preheated thermal carrier bath was developed to investigate the pyrolysis of both gaseous and pre-vaporized liquid fuels. Starting from a small mixing volume (less than 0.2 cm3), the temperature of the hot section (37 cm long) was controlled within ± 5 K. All species concentrations were measured at the exit plane of the reactor using a GC system while residence time variations were explored by varying the bulk flow velocity. For the atmospheric pressure cases reported here, the temperature and flow residence times explored were in the kinetically controlled regime and ranged from 1000 to 1100 K and 10–90 ms, respectively. The thermal pyrolysis of fuels investigated included ethane, n-butane, and n-dodecane, all diluted in a nitrogen carrier bath of 98% or higher (to minimize temperature departure from the target value). Because the ratio of the mixing volume compared to the kinetically controlled reactor volume is about 2.5%, the associated finite mixing time is shown to have a negligible effect on the temporal evolution of key C0–C4 species. As a consequence, no species profiles shifting (zero-time shifting) was required in comparisons with model predictions. Experimental and modeling uncertainty analysis are presented to determine whether the experimental data can be used in future efforts aimed at minimization of chemical kinetic model parameter uncertainties.