Extending lean operating limit and reducing emissions of methane spark-ignited engines using a microwave-assisted spark plug

Journal Article · Sun Jan 01 00:00:00 EST 2012 · Journal of Combustion

DOI:https://doi.org/10.1155/2012/927081· OSTI ID:1198312

Rapp, Vi H.; DeFilippo, Anthony; Saxena, Samveg; Chen, Jyh-Yuan; Dibble, Robert W.; Nishiyama, Atsushi; Moon, Ahsa; Ikeda, Yuji

A microwave-assisted spark plug was used to extend the lean operating limit (lean limit) and reduce emissions of an engine burning methane-air. In-cylinder pressure data were collected at normalized air-fuel ratios of λ = 1.46, λ = 1.51, λ = 1.57, λ = 1.68, and λ = 1.75. For each $\lambda$, microwave energy (power supplied to the magnetron per engine cycle) was varied from 0 mJ (spark discharge alone) to 1600 mJ. At lean conditions, the results showed adding microwave energy to a standard spark plug discharge increased the number of complete combustion cycles, improving engine stability as compared to spark-only operation. Addition of microwave energy also increased the indicated thermal efficiency by 4% at λ = 1.68. At λ = 1.75, the spark discharge alone was unable to consistently ignite the air-fuel mixture, resulting in frequent misfires. Although microwave energy produced more consistent ignition than spark discharge alone at λ = 1.75, 59% of the cycles only partially burned. Overall, the microwave-assisted spark plug increased engine performance under lean operating conditions (λ = 1.68) but did not affect operation at conditions closer to stoichiometric.

• Sponsoring Organization: USDOE
• OSTI ID: 1198312
• Journal Information: Journal of Combustion, Journal Name: Journal of Combustion Vol. 2012; ISSN 2090-1968
• Publisher: Hindawi Publishing Corporation
• Country of Publication: Country unknown/Code not available
• Language: English