In 1990, Roy Douglas developed an analytical method to calculate the global air-to-fuel ratio of a two-stroke engine from exhaust gas emissions. While this method has considerable application to two-stroke engines, it does not permit the calculation of air-to-fuel ratios for oxygenated fuels. This study proposed modifications to the Roy Douglas method such that it can be applied to oxygenated fuels. The ISO #16183 standard, the modified Spindt method, and the Brettschneider method were used to evaluate the modifications to the Roy Douglas method. In addition, a trapped air-to-fuel ratio, appropriate for two-stroke engines, was also modified to incorporate oxygenated fuels.To validate the modified calculation method, tests were performed using a two-stroke carbureted and two-stroke direct injected marine outboard engine over a five-mode marine test cycle running indolene and low level blends of ethanol and iso-butanol fuels. Results indicate that the modified air-fuel ratio method closely relates to the ISO #16183 standard. The modified Spindt method over-estimated the global air-to-fuel ratio. While the Brettschneider is considered an advancement over the Spindt method, it still provided an over-estimate of the air-to-fuel ratio. Applying a trapped air-to-fuel ratio calculation to the modified Roy Douglas method provided a calculation for trapped air-to-fuel ratio for two-stroke engine operation, which correlated with engine-out CO emissions. The trapped air-to-fuel ratio calculation also provided improvements in air-to-fuel ratio predictions, especially during idle conditions.


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    Titel :

    Air-to-Fuel Ratio Calculation Methods for Oxygenated Fuels in Two-Stroke Engines


    Weitere Titelangaben:

    Sae Technical Papers


    Beteiligte:
    Sevik, James M. (Autor:in) / Wasil, Jeff (Autor:in) / Miers, Scott (Autor:in) / Wallner, Thomas (Autor:in)

    Kongress:

    SAE 2015 World Congress & Exhibition ; 2015



    Erscheinungsdatum :

    14.04.2015




    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




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