An experimental study on MILD combustion of prevaporised liquid fuels

作者：Ye Jingjing^*; Medwell Paul R; Varea Emilien; Kruse Stephan; Dally Bassam B; Pitsch Heinz G

来源：Applied Energy, 2015, 151: 93-101.

DOI：10.1016/j.apenergy.2015.04.019

• MILD combustion
• Prevaporised liquid fuel
• Pressurised combustion

This paper presents an experimental study on moderate or intense low oxygen dilution (MILD) combustion of prevaporised liquid fuels burning in a reverse-flow MILD combustor under elevated pressures. The influence of fuel type, equivalence ratio, carrier gas, operating pressure and air jet velocity on the combustion stability and emissions are investigated. Ethanol, acetone and n-heptane are vaporised and carried to the combustor using either nitrogen or air. It is found that the combustion stability is highly dependent on fuel type, with n-heptane being the most unstable due to its fast ignition under all high-pressure conditions studied. Measured CO emissions emitted from all fuels are very low except when the equivalence ratio approaches the lean extinction limit, and this effect is not dependent on the pressure. The joint regime of low CO and NO, emission becomes narrower under elevated pressure as NO emissions emitted from all fuels increased with pressure. The enhanced NO, formation rate via the nitrous oxide mechanism, the slower mixing, the increased flame temperature and residence time are believed to cause higher NO, emissions as pressure increases. The NO emissions are reduced by increasing the air jet velocity, which is attributed to a lower peak temperature. The NO, emissions are also reduced when the fuel is carried by nitrogen instead of air. Further research is required to understand this trend which will help in reducing NO emissions under these conditions, especially at elevated pressures.

• 出版日期2015-8-1