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Vaporization Characteristic of High-ethanol Gasoline (E85) and Cold Startability

Article of Honda R&D Technical Review Vol.21 No.1


The research discussed in this paper focused on the vaporization characteristics of high-ethanol gasoline (E85) and cold startability. The cold startability of an E85 (ASTM Class 3) and a gasoline with identical Reid Vapor Pressures (RVP: 71 kPa at 37.8 °C) was tested at -30 °C. When the E85 was injected in the same quantity as that which enabled engine start using gasoline, the engine failed to start. The results of a simulation of the fuel concentration in the air-fuel mixture showed that the mixture concentration formed by the E85 was lower than the mixture concentration formed by the gasoline, and that the E85 mixture did not reach the concentration required for engine start. Meanwhile, the formation of a mixture with a fuel concentration of approximately 2 vol% during cranking was necessary for engine start at low temperatures. Both simulation and test results showed that increasing the fuel injection quantity was an effective method of increasing the mixture concentration. Increasing the RVP of the fuel is another effective method of increasing the mixture concentration. The results of a simulation of the conditions required for low-temperature engine start using E85 at the same injection quantity as gasoline indicated that it would be necessary to increase the RVP of the E85 by approximately 30-35 kPa against that of gasoline.


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Author (organization or company)

Koichiro AIKAWA(Automobile R&D Center)、Takayuki SAKURAI(Automobile R&D Center)、Aruto HAYASHI(Automobile R&D Center)

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