Study On The Interaction Between Ethanol And Hydrocarbon Fuels In The Premixed Combustion Of Their Blends

In order to comprehensively understand the interaction between enthanol and hydrocarbon fuels in the combustion of their blends,the mechanism of reactions of vinyl radical?C₂H₃?with ethanol,methanol and acetaldehyde were studied because C₂H₃ is a key intermediate in the decomposition of hydrocarbon fuels,and the effect of ethanol on the combustion rate of hydrocarbon fuels in laminar premixed flames were theoretically investigated in this dissertation.The reactions between vinyl radical and methanol,ethanol as well as acetaldehyde were explored using B3 LYP method along with high-level energy modification,and the possibility of these reactions were confirmed,suggesting the existence of interaction through vinyl radical in the combustion of ethanol/hydrocarbon blends.In the analysis of potential energy surfaces,H-abstraction channels were found to have low potential barriers,making them kinetically favorable for all three reactions.The rate constants of all these H-abstraction channels were calculated using transition state theory with tunneling effect correction at the temperature range 300-2500 K.The results indicate that the rate constants of all these channels have positive temperature dependency,and the tunneling effect is only important at low temperatures.The premixed combustion of the blends of ethylene with ethanol indicates that the burning rate of ethylene decreases with the increase in the fraction of ethanol in the blends,which was theoretically studied in this dissertation and different causes were found to be responsible for this phenomenon at different temperature regions.At low temperatures,it is mainly due to the fact that the competition of ethanol on OH and O radicals slows down the consumption of ethylene by these radicals,while the main cause at high temperatures is the formation of ethylene introduced by the decomposition of ethanol.The premixed combustion of the blends of n-heptane with ethanol indicates that the burning rate of n-heptane increases with the addition of ethanol,which was also theoretically studied in this dissertation.The results suggest that this is mainly due to the improvement in temperature caused by the addition of ethanol and when the temperature profile was kept the same,the addition of ethanol was found to have little influence on the consumption of n-heptane.