PAHs and soot formation in laminar partially premixed co-flow flames fuelled by PRFs at elevated pressures

Research output: Contribution to journalArticle


This study investigated polycyclic aromatic hydrocarbons (PAHs)and soot formation characteristics in laminar jet flames fuelled by primary reference fuels (PRFs)at elevated pressures. Qualitative PAHs and quantitative soot profiles were acquired by using laser-induced fluorescence and laser-induced incandescence, respectively. The backpressure of flames ranged from 1 bar to 5 bar. Proper flames with the volume fraction of iso-octane in PRFs varying between 0% and 100% and flame equivalent ratio varying between 3.0 and 11.4 were stabilised in a pressurised chamber. The effects of backpressure, equivalent ratio and iso-octane ratio on PAHs and soot formation were evaluated. PAHs and soot formation can be promoted by increasing iso-octane ratio, equivalent ratio and backpressure. The data suggest that PAHs with large molecular size are more sensitive to the increase of backpressure compared with those with small molecular size. Backpressure played a positive role in the growth of PAHs size. The averaged soot volume fraction showed an approximate power-law relation with pressure. The measured averaged soot volume fraction was proportional to pn. Pressure exponent n was 1.34–2.17, 1.41–2.12 and 1.56–2.20 at equivalent ratios of 6.2, 8.5 and 11.4, respectively.


  • Shuai Liang
  • Zhongshan Li
  • Jinlong Gao
  • Xiao Ma
  • Hongming Xu
  • Shijin Shuai
External organisations
  • Tsinghua University
  • University of Birmingham
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Energy Engineering


  • Backpressure, LIF, LII, PAH, PRF, Soot
Original languageEnglish
Pages (from-to)363-378
Number of pages16
JournalCombustion and Flame
Publication statusPublished - 2019 Aug 1
Publication categoryResearch