The evolution and explanation of an approach to achieving a stated set of very low emissions limits was described in a previous paper (1)*. The method outlined was to use stoichiometric mixture preparation with EGR dilution in order to employ a 3-way catalyst for low emissions, whilst giving an engine power output competitive with a turbocharged diesel engine.This approach has been followed in an engine development programme, which has resulted in a responsive and driveable engine being produced. The engine has demonstrated the achievability of very low emissions over the US heavy duty diesel transient test (FTP) cycle as follows: The lean-burn approach to low emission heavy duty operation has also been considered, using steady-state engine test results. The NOx-HC trade-off has been identified as a key indicator of engines' potential, and is also considered to give an indication of the accuracy of air-fuel ratio control required to achieve proposed emissions standards.Results from stoichiometric, naturally aspirated gas engines, indicate that they have potential for low emission operation using 3-way catalysts. Although considered unsuitable for heavy-duty application due to knock and temperature limitations, this type of engine could find use in light-medium duty applications, where greater torque and power then diesel engines and better efficiencies than gasoline engines would be attractive features.


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    Title :

    Low Emission Engines for Heavy-Duty Natural Gas-Powered Urban Vehicles - Development Experience


    Additional title:

    Sae Technical Papers


    Contributors:

    Conference:

    International Fuels & Lubricants Meeting & Exposition ; 1990



    Publication date :

    1990-10-01




    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English





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