Experiment Study on Major and Intermediate Species of Ethanol/n-Heptane Premixed Flames

Abstract

An experimental study was reported on premixed ethanol/n-heptane/oxygen/argon flames at low pressure (4.655 kPa) with ethanol blending ratios of 0 (Flame 1), 15% (Flame 2), and 30% (Flame 3). The equivalence ratio was 1.0. Flame species were identified using molecular beam mass spectrometry with tunable synchrotron photoionization. The flame temperature profiles were measured with a Pt-6%Rh/Pt-30%Rh thermocouple. The mole fraction profiles of major and intermediate flame species under different ethanol ratios were analyzed in this article. Experimental results showed that the temperature profiles of measured flames fall almost on a single curve, which means that ethanol had little effect on flame temperature. The peak mole fraction of the main combustion products occurred 2–6 mm above the burner. With the increase of ethanol blending ratios, the mole fractions of H₂, CO, and CO₂ decreased, the mole fraction of H₂O increased, and the mole fractions of intermediate combustion products (C₂H₂, C₂H₄, HCHO, C₃H₃) decreased. During the combustion process, the oxygen atom of ethanol partly replaces the O₂, thus the final mole fraction of O₂ increased with the increase of ethanol ratios.

Keywords:

• Ethanol/n-heptane
• Intermediate species
• Molecular beam mass spectrometry
• Premixed flames

ACKNOWLEDGMENTS

The authors gratefully acknowledge the National Synchrotron Radiation Laboratory of China for the experiment. This study is financially supported by the National Natural Science Foundation of China (NSFC, 50776042 and 51376083), the Natural Science Foundation of Jiangsu Higher Education Institutions Project (10KJA470009), Postgraduate Research and Innovation Projects of Jiangsu Province (CXZZ12_0676), and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) year 2011.