Experimental and Numerical Study on Autoignition Characteristics of the Gasoline/Diesel/Ethanol and Gasoline/Diesel/PODE/Ethanol Fuels

Polyoxymethylene dimethyl ethers (PODE) with high oxygen content and ethanol with high octane number are ideal additives for diesel and gasoline, respectively. Previous studies have shown that diesel/gasoline fuels and diesel/gasoline/PODE fuels can significantly reduce soot emissions. To further reduce soot emissions, ethanol was blended with these two fuels in this study and the effect of ethanol on fuel ignitability was investigated by experimental study and numerical simulation. Experiments were conducted in a cooperative fuel research engine and a cetane ignition delay instrument under various temperature and exhaust gas recirculation ratio. Results show that the effect of ethanol on chemical ignition delay is higher than that on physical ignition delay. With the addition of ethanol, the combustion phasing is retarded and the maximum apparent heat release rate of both low-temperature heat release and high-temperature heat release become lower. At the same time, an increase in the critical compression ratio (CCR) is observed with the addition of ethanol, while improving ignitability can be observed with the addition of PODE. It is worth noting that ethanol addition affects the CCR more for CCR of diesel/gasoline/ PODE/fuels than that for diesel/gasoline fuels. Furthermore, kinetic simulation shows that there is an antagonism between ethanol and PODE during the decomposition process because OH is the key reactant in both ethanol and PODE decomposition.