Abstract:

Low pressure premixed laminar dimethyl ether (DME)/oxygen/argon and ethanol/oxygen/argon flames (equivalence ratio: 1.0) were studied by molecular-beam sampling mass spectrometry (MBMS) combined with the tunable synchrotron radiation photoionization technique. Combustion intermediates were identified by measuring photoionization efficiency (PIE) spectra, and the mole fraction profiles of these species at different flame positions were presented. Similarities and differences of main intermediate formation characteristics between the two flames were analyzed based on derived reaction mechanisms. Experimental results show that both flames contain the same intermediates such as CH3, CH4, C2H2, C2H4, CH2O, CH3OH, CH2=C=O, CH3CHO, and CH2CHOH. In the DME flame, the concentration of the C1 species is much higher than that of the C2 species, i.e., C1 intermediates tend to form rather than C2 intermediates in a DME flame. In addition, formaldehyde is the dominant C1 species in each flame. The concentrations of C2 species like ethylene, acetaldehyde, acetylene, and ketene in the ethanol flame are remarkably higher than that found in the DME flame.

Key words: Synchrotron radiation, Single-photon ionization, Dimethyl ether, Ethanol, Premixed laminar flame