Kinetic studies and mechanism development of plasma assisted pentane combustion

Abstract

The present study explores the chemical kinetics of low temperature oxidation and pyrolysis of pentane/O 2 /He mixtures in a nanosecond repetitively-pulsed DBD discharge. Time-dependent TDLAS measurements and steady state GC sampling are conducted to quantify species evolution in a plasma discharge. An improved kinetic model of plasma assisted combustion and pyrolysis of pentane is developed with updated electron impact dissociation reactions and low temperature reactions involving excited species. This kinetic model is then validated against the experimental data. The results show that a nanosecond plasma discharge causes significant low temperature fuel pyrolysis and oxidization as well as fast gas heating. The original kinetic model fails to predict many intermediate species such as CH 4 , C 2 H 2 , and CH 2 O due to missing corresponding reaction pathways and inaccuracies in electron impact cross section areas. The new model shows a dramatic improvement in modeling both pentane pyrolysis and oxidation, with good prediction of the time histories of pentane, CH 2 O, C 2 H 2 and H 2 O, and slight under-prediction of CH 4 . There is still a large discrepancy in OH prediction and measurement in fuel oxidation. The results show that direct electron impact dissociation pathways play a critical role in plasma assisted fuel pyrolysis and oxidation and that plasma generated radicals and excited species such as O and O( 1 D) enhance low temperature fuel oxidation.