Ignition Process and Flame Lift-Off Characteristics of dimethyl ether (DME) Reacting Spray

Frontiers in Mechanical Engineering

Seong-Young Lee¹  Xiucheng Zhu¹  Khanh Duc Cung²  Ahmed Abdul Moiz² 

[1] Michigan Technological University, Houghton, MI, United States;Southwest Research Institute, San Antonio, TX, United States;

关键词: low temperature combustion (LTC);    DME (dimethly ether);    ignition delay;    compression ignition (CI);    flame stabilization mechanisms;    lift-off length;   

DOI  :  10.3389/fmech.2021.547204

来源: DOAJ

【 摘 要 】

Advanced combustion systems that utilize different combustion modes and alternative fuels have significantly improved combustion performance and emissions compared to conventional diesel or spark-ignited combustions. As an alternative fuel, dimethyl ether (DME) has been receiving much attention as it runs effectively under low-temperature combustion (LTC) modes such as homogeneous charge compression ignition (HCCI) and reactivity control combustion ignition (RCCI). Under compression-ignition (CI), DME can be injected as liquid fuel into a hot chamber, resulting in a diesel-like spray/combustion characteristic. With its high fuel reactivity and unique chemical formula, DME ignites easily but produces almost smokeless combustion. In the current study, DME spray combustion under several different conditions of ambient temperature (Tamb = 750–1100 K), ambient density (ρamb = 14.8–30 kg/m3), oxygen concentration (O2 = 15–21%), and injection pressure (Pinj = 75–150 MPa) were studied. The results from both experiments (constant-volume combustion vessel) and numerical simulations were used to develop empirical correlations for ignition and lift-off length. Compared to diesel, the established correlation of DME shows a similar Arrhenius-type expression. Sensitivity studies show that Tamb and Pinj have a stronger effect on DME's ignition and combustion than other parameters. Finally, this study provides a simplified conceptual mechanism of DME reacting spray under high reactivity ambient (high Tamb, high O2) and LTC conditions. Finally, this paper discusses engine operating strategies using a non-conventional fuel such as DME with different reactivity and chemical properties.

【 授权许可】

Unknown