Combustion characteristics of well-dispersed boron submicroparticles and plasma effect

Research output: Contribution to journalArticle

Abstract

Boron is an attractive high-energy fuel additive. But it could not burn efficiently in practical systems due to its high ignition temperature and slow burning velocity. Finding methods to enhance the combustion of boron is desired. This work focused on the combustion characteristics of boron submicroparticles with and without plasma discharges in a hot environment supported by CH4/N2/O2 flat flame based on the optical diagnostics. The boron submicroparticles were dispersed by the nebulization method to control the agglomeration. The well-dispersed boron flame exhibited two different burning modes, depending on the ambient temperature. As the ambient temperature was above 1520 K, the boron flame showed definitely two-stage characteristics where the upstream of particle flow was yellow, corresponding to the first-stage flame, while the downstream was green and diffusive, corresponding to the second-stage flame. The first-stage and second-stage burn times were respectively in the range of 0.46–1.08 ms and 0.92–1.87 ms, as the ambient temperature decreased from 1752 K to 1520 K. The chemical kinetics-controlled mechanism was confirmed by the nearly linear size dependence of the burn time (d1 law). Nevertheless, as the ambient temperature was below 1520 K, the boron submicroparticles were partially burned or oxidized, exhibiting a mildly orange stream. This mild boron flame could be enhanced using a plasma discharge. The ignition delay time was shortened from 3.06 ms to 0.77 ms when the discharge was introduced at the ignition delay stage. The two-stage combustion characteristics occurred when the discharge was introduced at the combustion stage.

Details

Authors
  • Dan Yu
  • Chengdong Kong
  • Jiankun Zhuo
  • Qiang Yao
  • Shuiqing Li
  • Mengze Wang
  • Zhen Yu Tian
Organisations
External organisations
  • Tsinghua University
  • Johns Hopkins University
  • University of the Chinese Academy of Sciences
  • Institute of Engineering Thermophysics, CAS
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Energy Engineering

Keywords

  • Boron particle, Kinetics-controlled, Plasma assistance, Two-stage combustion
Original languageEnglish
Pages (from-to)94-103
Number of pages10
JournalCombustion and Flame
Volume188
StatePublished - 2018
Peer-reviewedYes