Experimental and Theoretical Study of Dimethyl Ether Auto-ignition at Low Temperature and Low Pressure

In view of the lacking data of dimethyl ether (DME) and the inconsistent understanding of the mechanism at low temperature and low pressure, high pressure shock tube was used to measure the ignition delay times of DME. The Negative Temperature Coefficient (NTC) area is completely covered in the measurement. The experimental results were numerically simulated using the Aramco Mech 3.0. It was found that there are two typical regions that differ greatly from the experimental data: the region before the NTC high temperature inflection point and the region after the NTC low temperature inflection point. In this study, Computational Fluid Dynamics (CFD) simulation analysis is used to show that occurrence of hot spots can cause differences in the first region. In addition, the kinetic analysis of DME at low temperature is carried out in this study, and it is believed that the difference in the second region originates from the mechanism itself. Considering the use of third O₂ addition reactions to optimize the DME mechanism, it is found that this path does not contribute much to the improvement of the low-temperature chemical mechanism of DME. However, the experimental data in this study and the kinetic analysis of DME provide ideas and directions for further optimizing the kinetic mechanism of DME at low temperature and low pressure.