Study on Ignition and Combustion Characteristics of PODE/Diesel Blended Fuel at High Altitude

Based on the chemical reaction mechanism of diesel fuel with PODE, the TRF-PODE chemical kinetics model was constructed and verified, the ignition and combustion characteristics of PODE/diesel fuel were studied by numerical simulation at high altitude. The results show that the addition of PODE increases the instantaneous heat release rate and decreases the corresponding time of the highest point of ignition temperature under the condition of low pressure at high altitude. The maximum ignition promotion rate occurs in the region of negative temperature coefficient (NTC), which is increased with higher PODE blending ratio. PODE increases the formation of OH· and promotes the pre-oxidation of nC7H16 in the low temperature oxidation at high altitude. As a result, the highest mole fraction of hydroxyl group in the reaction increases obviously with the decrease of pressure, which leads to the decrease of reaction rate. Under high temperature, the oxygen of PODE itself increases the formation of OH· in the reaction, leading to a reduction of the proportion of O2 participating in the formation of OH·. Therefore, more O2 could oxidize the small molecules in the reaction, promote the formation of free ions, and enhance the reaction activity, which is beneficial to improve the combustion characteristics of diesel engines at high altitude. © 2024 Science Press. All rights reserved.