Studies Of Oxygen Additives Influences On Gasoline Performance And Its Mechanism

In recent years, the automobile output increase brings with energy and environment problems that are drawing more and more attentions. As oil price increase and global warming as well as other environmental problems become more and more seriously, the automobile structure should be modified and fuel properties be improved to meet the requirements of energy and environment. Additives and alternative fuels are two realitic approaches to improve gasoline performance. This study presented in the thesis investigated in the combustion characteristics of MTBE (methyl tert-butyl ether) and ethanol and their effect on gasoline from the angle of combustion science combined by means of chemical analysis and optical measurements.Compared the advantages and disadvantages of in situ optical spectroscopic probes and extractive sampling method, it was introduced that the synchrotron radiation combined with molecular beam sampling and time-of-flight mass spectrometry, including its principle, development and characteristic, and compared with other common combustion diagnostics methods.The mass spectrometry of basic gasoline, gasoline with MTBE and gasoline with ethanol burning in oxygen were measured via synchrotron radiation single-photon ionization combined with molecular beam sampling technical. The differences of combustion intermediates and temperature profiles in the three flames were also compared. The effects of MTBE and ethanol on gasoline combustion were analyzed by recognizing the differences of combustion intermediates and their spatial profiles in the three flames. The results show that MTBE and ethanol can restrain the dissociation of alkanes at low temperatures and the oxidation rate of aromatic hydrocarbons.In order to confirm some of the conclusions of synchrotron radiation experiment, a constant volume combustion bomb test system was designed to conduct some researches about premixed flame characteristics of gasoline with additives. A brief introduction of principle, structure and specific characters about the experiment system which contained constant volume combustion bomb, mixture preparation system, heating system, ignition system, combustion pressure measurement system, high speed camera system and data acquisition system, was also presented. By analyzing the flame pictures and pressure profiles, the differences of ignition delay period and flame propagation velocity were studied. The conclusions obtained agreed with those from synchrotron radiation experiment.