Ignition And Combustion Characteristics Of Short Chain Methyl Ester

Ignition characteristics of alcohol/n-heptane dual fuel blends were conducted on a rapid compression machine because of the positive influence from alcohol fuels on energy crisis and engine emissions. In view of the fact that the biodiesel can alleviate the energy crisis and resolve internal combustion engine emission problems,and when biodiesel work with alcohol emission of NOx could be reduced with SOOT, this paper studied ignition characters of the mode fuel of biodiesel in a rapid compress machine. And the biodiesel/alcohol mixture was studied the same time. The ignition characteristics of methyl pentanoate were studied, and in order to get a deep study about the reaction process of methyl pentanoate, simulation had been done. The ignition characteristics of methyl heptanoate and methyl octanoate were studied to figure out the impact of the length of carbon chain and alcohols.(1) According to the study of methyl pentanoate, methyl pentanoate shows different ignition delay variation trend. In the condition of 90 dilutions, methyl pentanoate shows low temperature reaction phenomenon, the ignition delay time reduced with temperature increase. In the condition of 79 dilutions, when the temperature is lower than 850 K, the ignition delay time of methyl pentanoate reduced with temperature increase. When the temperature is at 850 K~1250 K, the negative temperature coefficient region of methyl pentanoate appears. According to the reaction path analysis, methyl pentanoate dehydrogenate by the stimulation of OH and HO2. Then MPExj was generated. Isomerization happened between MPExj and then generates MPxd, et al. Based on the sensitivity analysis, the main reaction that influent the ignition progress is the reaction that can generate OH. And the reaction of main path of MPE consumption plays an important role in the process of ignition.(2) According to the study of methyl heptanoate in rapid compress machine, the ignition delay time decrease with the increase of TDC temperature. And the ignition delay decreases with the TDC pressure. Methyl heptanoate ethanol mixture was studied too. Ignition delay time of mixture increases with the addition of ethanol fuel; Ignition delay increases with the decrease of the ratio of equivalent. With the increase of TDC pressure, methyl heptanoate/ethanol mixed fuel ignition delay ignition delay close under the condition of low temperature, because in this temperature range, chemical reaction is mainly affected by temperature.(3) According to the study of methyl octanoate, when the temperature is higher than 750 K, the ignition delay time reduces with the increase of TDC temperature. When the temperature is lower than 750 K, methyl octanoate shows NTC region. Ignition delay decreases with the increase of TDC pressure. Ignition delay time of mixture increases with the addition of ethanol fuel; ignition delay increases with the decrease of equivalence ratio.