Development of an Improved Computer Simulation of Vehicle Emissions During Cold Start and Warm-Up Operation

Based on an analysis of model emissions data from vehicles tested by the Environmental Protection Agency (EPA), an algorithm has been developed to simulate cold start and warm-up operation using a vehicle emissions simulation model called VEHSIME. During the first 450 seconds of operation following a cold start, the algorithm applies correction factors to the emission rates contained in "map" of emission rates over the full speed and load range of warmed-up engines. The correction factor increases "engine-out" HC and CO emissions in proportion to the number of seconds left in the warm-up period. The algorithm also applies a catalyst efficiency factor to the map of engine-out emissions as soon as the fuel consumption since start up reaches the cumulative fuel consumption associated with the catalyst reaching "light-off" temperature on the LA4 cycle (120 second into the cycle). The catalyst efficiency factor is computed from the difference between the engine-out and tailpipe emission maps for the engine being used for the simulation.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Appendices; Figures; Tables;
  • Pagination: 24p

Subject/Index Terms

Filing Info

  • Accession Number: 01531909
  • Record Type: Publication
  • Report/Paper Numbers: SR91-09-02
  • Contract Numbers: 68-C9-0053; work assignment 1-02
  • Files: TRIS
  • Created Date: Jul 14 2014 2:14PM