Authors

Takayuki FUYUTO, Kenji FUKUI, Yoshiyuki MANDOKORO, Reiko UEDA, Kazuaki NISHIKAWA, Teruaki KONDO, Yoshifumi WAKISAKA 
Toyota Central R&D Labs., Inc., JP

Summary

Alcohol fuels, namely, methanol and ethanol, are promising alternatives for diffusive combustion in heavy-duty diesel engines, with methanol already being utilized in the marine sector. In this study, the authors examined the various methods of igniting methanol fuel described in literatures. The use of a diesel pilot is the most robust ignition technique, although this method is not carbon-neutral. The minimum area and location of the pilot flame formed by diesel-fuel pilot injection were evaluated by using in-cylinder visualization. Then, a new injection and ignition strategy for methanol mono-fueled diffusive combustion (which uses spark-ignited methanol pilot sprays) is proposed. This strategy is demonstrated using in-cylinder visualization. After the ignition of the pilot spray, the pilot flame propagates in the swirl direction while flame held behind the electrode ignites the pilot mixture brought by the swirl flow. Then, the main sprays are ignited in a cascade toward the swirl direction. By adding the pilot spray after spark ignition but before the main injection, the pilot flame can be extended toward the nozzle, causing all of the main sprays to form diffusive combustion during injection.

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