Technical Paper
Emissions Reduction During Warm-Up Period by Incorporating a Wall-Wetting Fuel Model on the Fuel Injection Strategy During Engine Starting
1995-10-01
952478
The purpose of this paper is to quantify the improvements possible for ULEV emissions by improved air-fuel ratio control during starting by modifying conventional fuel injection strategy with a first order wall-wetting-fuel model. Measurements of emissions during first 30 starting cycles of a ULEV engine, made with a fast response flame ionization detector (FID) and conventional fuel injection strategy, show that these account for 17% of the overall FTP-75 mode HC emissions. The wall-wetting-fuel model is a two coefficient model: α, the ratio of the injected fuel mass to the fuel mass inducted into the cylinder during a given cycle, and β, the ratio of the total fuel mass accumulated on the intake port wall to the mass inducted into the cylinder from the accumulated fuel at a given cycle.
