A numerical investigation of NH3/O2/He ignition limits in a non-thermal plasma

Galia Faingold, Joseph K. Lefkowitz

Research output: Contribution to journalConference articlepeer-review

Abstract

To investigate the ignition characteristics of ammonia in a pulsed plasma discharge, a kinetic model for the oxidation of ammonia/oxygen/helium mixtures under a plasma discharge was developed. The model was used to perform a series of simulations under varying pulsed discharge frequencies and pulse numbers, at atmospheric pressure and moderate to high temperatures (600-1500 K). A zero-dimensional solver which combines the ZDPlasKin and CHEMKIN software was employed to explore the effect of pulse number and frequency on ignition delay time. For a moderate amount of pulses, a reduction of 40-60% in ignition delay time was achieved, with higher pulse repetition frequencies (PRF) yielding shorter ignition delay times. Analysis of OH radical time evolution showed that high PRF support an increasing radical pool at low temperatures, whereas at lower PRF radicals recombine in between pulses. In the thermal runaway phase, the radicals formed in conventional chain branching events are prevalent, so that OH formed in later pulses has little effect. At low temperatures and high PRF, higher pulse frequencies allow for lower initial temperatures which will result in ignition. At a high enough frequency, the hysteresis of ignition and extinction is altered due to a high amount of radicals supplied and sustained by the plasma, so that there is a smooth transition and reactions at all temperatures.

Original languageEnglish
Pages (from-to)5849-5857
Number of pages9
JournalProceedings of the Combustion Institute
Volume38
Issue number4
DOIs
StatePublished - 2021
Event38th International Symposium on Combustion, 2021 - Adelaide, Australia
Duration: 24 Jan 202129 Jan 2021

Keywords

  • Ammonia oxidation
  • Ignition
  • Non-equilibrium plasma
  • Plasma-assisted combustion

All Science Journal Classification (ASJC) codes

  • General Chemical Engineering
  • Mechanical Engineering
  • Physical and Theoretical Chemistry

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