ABSTRACT
As a key intermediate product, ethylene plays an important role in the combustion of heavy hydrocarbons. Very limited experiments have focused on the high temperature (>1000 K) ethylene ignition at the real fuel–air condition, but no one on the ethylene/air ignition at low temperatures (<1000 K). In the present work, ignition delay times of ethylene/air mixtures were measured at temperatures of 721 to 1307 K, pressures of 0.97 to 20.54 atm, and equivalence ratios of 0.5, 1.0 and 2.0,and ignition characteristics of ethylene/air were discussed. The high-temperature results show that ignition delay times decrease with the increase of temperature monotonously; the ignition delay of fuel-lean mixture exhibits an unusual behavior of almost zero pressure dependence, and stoichiometric and fuel-rich mixtures still have ordinary pressure dependence, with a pressure increase producing a decrease of ignition delay time. The results at wide temperatures indicate that ethylene/air ignition delay shows no negative temperature coefficient (NTC) behavior at low temperatures, and has an inflection point at the temperature of about 1000 K, showing a two-region ignition feature. The ignition delay times at two regions can be described by Arrhenius-type formulas, respectively, and the ethylene/air ignition delay is much less sensitive to the temperature at the low-temperature region. A good agreement is found between current data and another experimental data for high-temperature ignition. The mechanism used predicts the ethylene/air ignition delay well at high temperatures but must overpredict the ignition delay times at low temperatures. This work contributes to understanding the ethylene ignition properties at a wide temperature range and provides experimental data valuable for validating and refining the chemical kinetics mechanism of ethylene.
Funding
The authors acknowledge the support from the National Natural Science Foundation of China (91841301).
Supplementary material
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