Emissions from a Light-Duty Diesel: Ambient Temperature and Fuel Effects

Exhaust emissions from a diesel passenger car were characterized and measured to examine the effect of ambient temperature on emissions performance. The vehicle was tested at three temperatures on a chassis dynamometer located within a cold cell. Three driving cycles and three fuels of varying quality were used. The effort included measurements of regulated exhaust gases and particles, particulate organic fractions and their molecular-weight distributions, particulate fractions under 2 microns in diameter, trace metal contents, and fuel economy. Results indicate that reductions in ambient temperature had little effect on emissions or fuel economy in this study. In some cases, statistically significant increases in NO_x emissions were measured with decreases in ambient test temperature. Other differences related to temperature effects occurred more frequently with the lower quality fuels.