Effect of Spark Assisted Compression Ignition on the End-Gas Autoignition with DME-air Mixtures in a Rapid Compression Machine

2024-01-2822

04/09/2024

Features
Event
WCX SAE World Congress Experience
Authors Abstract
Content
Substantial effort has been devoted to utilizing homogeneous charge compression ignition (HCCI) to improve thermal efficiency and reduce emission pollutants in internal combustion engines. However, the uncertainty of ignition timing and limited operational range restrict further adoption for the industry. Using the spark-assisted compression ignition (SACI) technique has the advantage of using a spark event to control the combustion process. This study employs a rapid compression machine to characterize the ignition and combustion process of Dimethyl ether (DME) under engine-like background temperature and pressures and combustion regimes, including HCCI, SACI, and knocking onsite. The spark ignition timing was swept to ignite the mixture under various thermodynamic conditions. This investigation demonstrates the presence of four distinct combustion regimes, including detonation, strong end-gas autoignition, mild end-gas autoignition, and HCCI. The observation indicates that HCCI exhibits a relatively low-pressure rise rate and a prolonged combustion duration.
On the other hand, the detonation case can achieve a fast flame propagation velocity of up to 2.4 km/s, generating high-frequency pressure oscillation. Pressure traces were processed using the Fast Fourier Transform (FFT) method to characterize the different end gas autoignition regimes under various spark timing. Moreover, hydrogen fuel blends with DME to reduce the auto-ignition tendency of DME fuel but increase the flame propagation speed. The combustion characteristics of the autoignition-initiated flames are compared with that of using neat DME fuel via pressure measurement and high-speed images. The results demonstrated that deploying hydrogen into the fuel exhibits enhanced knock resistance and reductions in pressure oscillations.
Meta TagsDetails
DOI
https://doi.org/10.4271/2024-01-2822
Pages
9
Citation
Jin, L., Yu, X., Wang, M., Reader, G. et al., "Effect of Spark Assisted Compression Ignition on the End-Gas Autoignition with DME-air Mixtures in a Rapid Compression Machine," SAE Technical Paper 2024-01-2822, 2024, https://doi.org/10.4271/2024-01-2822.
Additional Details
Publisher
Published
Apr 09
Product Code
2024-01-2822
Content Type
Technical Paper
Language
English