Any three-way catalyst (TWC) vehicle with state-of-the-art technology produces quite low emissions when emission output is evaluated using the standardized certification and type approval procedures that limit their applicability to a temperature range above +20 Grad C in most parts of the world. Also, as previous reports and results presented here show, substantially higher emissions, especially of CO and HC, are produced if the ambient temperature falls below that range. Marked differences in performance and response of the emission control systems have been observed. However, this is in accordance with what we expected, as none of the vehicles tested here had to comply with the newly implemented low-temperature requirements recently introduced by the USA and Sweden. Where no restraints for the emissions in cold conditions exist, the designer is free to make the engineering targets startability and driveability, as these are the issues that most drivers will be sensitive to in their assessment of vehicle performance. However, our test data show that notable differences exist in the fuelling strategies and features of the emission control systems. In 'real world' conditions, i.e. subnormal ambient temperatures, this variance produces sometimes striking differences in emissions output. Yet, all these vehicles remained quite driveable even in cold conditions, and no apparent hesitation was encountered during testing. This calls for some reassessment of the fuelling strategies in many of the tested cars that had exceptionally high emission outputs. The main emphasis in this paper has been on CO emissions, but HC emissions also increase when the ambient temperature falls, usually at the same rate as CO, but not necessarily, as these emissions are derived from two different processes.


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    Title :

    Exhaust emissions from motor vehicles in low ambient temperature conditions


    Contributors:

    Published in:

    Publication date :

    1997


    Size :

    13 Seiten, 8 Bilder, 1 Tabelle, 10 Quellen



    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English





    Exhaust emissions from motor vehicles in low ambient temperature conditions

    Laurikko,J.K. / Tech.Res.Centre of Finland,FI | Automotive engineering | 1997


    Exhaust emissions from motor vehicles in low ambient temperature conditions

    Laurikko,J. / VTT Energy,FI | Automotive engineering | 1996