Study Of The Effect Of Methanol On The N-heptane Oxidation

In order to understand the chemical interaction between methanol and n-heptane in the oxidation of their blends comprehensively,the low temperature oxidation characteristic and high temperature oxidation characteristic of methanol/n-heptane blends were studied respectively.A closed homogeneous reactor was used to explore the ignition delay time of n-heptane in differernt temperature regions and equivalence ratios.The results show that the ignition is delayed as the temperature increases in the initial temperature range of 700K-900 K that is a negative temperature coefficient(NTC)zone for n-heptane oxidation.The ignition delay time lags and the system temperature decreases with an increase of equivalence ratio.With the analysis of production rate for major species and reaction velocity of major elementary reaction,the effect of methanol on the ignition delay time of n-heptane was explained.The results show that the ignition delay time of n-heptane lags with the addition of methanol which is attributed to a decrease of the concentration of active radicals with the addition of methanol.The effect of the methanol addition on the burning rate of n-heptane was investigated with the laminar premixed flame model.The results indicate that the burning rate of n-heptane decreases with an increase of the fraction of methanol in the blends.This is mainly attributed to the reaction of methanol with H radicals that slows down the consumption of n-heptane.