Effect of Fuel/Air Ratio Variations on Catalyst Performance and Hydrocarbon Emissions During Cold-Start and Warm-Up 962075
Effects of fuel/air equivalence ratio variations (Φ = 1.0±0.02) on engine-out and catalyst-out hydrocarbon (HC) mass and speciated emissions were measured under simulated cold-start conditions in order to suggest ways to optimize the engine-controls-catalyst system for minimum HC mass emissions and specific reactivity. A single-cylinder engine (installed in a temperature-controlled room and using commercial-grade gasoline) is run under controlled steady-state conditions (at 24 °C or -7 °C) which simulate cold starting. Speciated and total hydrocarbon emissions are measured from engine-out exhaust samples and from samples taken after an oven-temperature-controlled catalyst (either a fresh platinum/rhodium production catalyst, a 50,000 mile vehicle-aged catalyst, or a ceramic brick with standard washcoat containing no noble metal). Changes in engine fuel/air equivalence ratio (Φ = 1.0±0.02) have a small effect on engine-out HC mass emissions (± 10 %) and specific reactivity (0 - 2%). However, changing Φ from 1.02 (slightly rich) to 0.98 (slightly lean) has a large effect on catalyst performance - decreasing post-catalyst ozone forming potential values by a factor of 36 for a fresh catalyst and a factor of 6 for an aged catalyst.
Citation: Drake, M., Sinkevitch, R., Quader, A., Olson, K. et al., "Effect of Fuel/Air Ratio Variations on Catalyst Performance and Hydrocarbon Emissions During Cold-Start and Warm-Up," SAE Technical Paper 962075, 1996, https://doi.org/10.4271/962075. Download Citation
Michael C. Drake, Robert M. Sinkevitch, Ather A. Quader, Keith L. Olson, Thomas J. Chapaton
General Motors Research and Development Center
1996 SAE International Fall Fuels and Lubricants Meeting and Exhibition
Emissions and Emissions Control-SP-1207, SAE 1996 Transactions - Journal of Fuels and Lubricants-V105-4