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Honda R&D team uses gasoline-diesel dual fuel method for high thermal efficiency at low loads

A team from Honda R&D in Japan reports using a gasoline-diesel dual-fuel method to control ignition timing and combustion duration. A paper on their work is published in the International Journal of Engine Research.

Premixed charge compression ignition technology for diesel engines has been attracting increasing interest in recent years because of its ability to reduce nitrogen oxide emissions. At the same time, homogeneous charge compression ignition technology for gasoline engines also has been expected for high thermal efficiency and reduction in nitrogen oxide emissions. However, both methods have common challenges, such as limited part-load operation and ignition timing control. Additionally, under very low load conditions, thermal efficiency decreases due to the difficulty of providing steady combustion.

—Kuzuoka et al.

In their study, the Honda team supplied diesel fuel as the high ignitability fuel to the direct injector, and gasoline as an inhibitor to the port injector. They applied negative valve overlap and multiple fuel injection under very low load conditions.

Diesel fuel injected during the negative valve overlap duration oxidized partially in the high-temperature environment with the oxygen-containing exhaust gas of the previous cycle. The oxidation reaction of fuel during the main compression stroke was inhibited by the products from these reactions that occurred during the negative valve overlap.

This allowed the control of the timing of the heat release immediately after top dead center.

As a consequence, high controllability of combustion and high thermal efficiency at low loads were achieved through independent control of the ratio of diesel fuel injected at negative valve overlap and the fractions of the two fuels.

—Kuzuoka et al.

Members of the Honda team have also explored the use of tudy a high-compression-ratio engine combined with an ethanol-gasoline fuel separation system running on a combination of Otto and Miller cycles under different load conditions. That study also yielded higher-load and higher thermal efficiency operation, due to the increased compression ratio.

Resources

  • Kohei Kuzuoka, Takashi Kondo, Hirotsugu Kudo, Hiroyoshi Taniguchi, Hiroshi Chishima and Kohtaro Hashimoto (2015) “Controlling combustion with negative valve overlap in a gasoline–diesel dual-fuel compression ignition engine” International Journal of Engine Research doi: 10.1177/1468087415580216

  • Kuzuoka, K., Kurotani, T., Chishima, H., and Kudo, H. (2014) “Study of High-Compression-Ratio Engine Combined with an Ethanol-Gasoline Fuel Separation System,” SAE Int. J. Engines 7(4):1773-1780 doi: 10.4271/2014-01-2614

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