Ignition characteristics of dual-fuel methane-n-hexane-oxygen-diluent mixtures in a rapid compression machine and a shock tube

FUEL

卷:249

Article

He, Yizhuo^1,2  Wang, Yingdi^1,2  Gregoire, Claire³  Niedzielska, Urszula^3,4  Mevel, Remy^1,2  Shepherd, Joseph E.³ 

[1] Tsinghua Univ, Ctr Combust Energy, Beijing, Peoples R China

[2] Tsinghua Univ, Dept Automot Engn, Beijing, Peoples R China

[3] CALTECH, Grad Aeronaut Labs, Pasadena, CA 91125 USA

[4] Warsaw Univ Technol, Warsaw, Poland

关键词: Dual-fuel ignition;    Methane-n-hexane mixtures;    Rapid compression machine;    Shock tube;    Chemical kinetics modeling;   

DOI  :  10.1016/j.fuel.2019.03.105

来源: Elsevier

【 摘 要 】

Ignition delay times of methane-n-hexane-oxygen-dulent mixtures were studied experimentally and numerically in a wide temperature range (640-2335 K) using both a rapid compression machine (RCM) and a shock tube (ST). The RCM results demonstrated a two-stage ignition and negative temperature coefficient (NTC) behavior. Increasing n-hexane concentration, pressure and equivalence ratio shortened the ignition delay time. For the ST experiments, the addition of 10% n-hexane (relative to methane) can reduce the ignition delay time dramatically. However, no further reduction effect can be achieved with increasing addition of n-hexane from 10% to 20%. In addition, increasing equivalence ratio reduces the effect of n-hexane addition on ignition delay time. Three detailed chemical mechanisms, CaltechMech, GalwayMech and LLNLMech, were evaluated based on a quantitative error analysis. LLNLMech and CaltechMech demonstrated the best performance in the RCM and ST temperature ranges, respectively. Chemical kinetic analyses showed that the addition of n-hexane to methane provides some chemical pathways not available for methane oxidation which result in the production of active radicals and eventually accelerate the ignition of the methane-oxygen mixtures. The crucial intermediate species for the ignition process are H2O2 and H under RCM and ST conditions, respectively.

【 授权许可】

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