Abstract |
An emission study was conducted on a 1987 Ford Crown Victoria flexible-fuel vehicle, an early prototype which had been driven about 25,000 miles. The vehicle was designed to run on either gasoline or blends of gasoline and methanol. Emission rates of regulated (hydrocarbons, carbon monoxide, nitrogen oxides, formaldehyde, and methanol) and nonregulated pollutants (speciated organic materials) were determined for both exhaust and evaporative emissions. Some tests were run using federal test procedures, but additional tests employed different driving schedules (New York City Cycle and Highway Fuel Economy Test) and an ambient temperature of 90 F. Both gasoline and a blend containing 85% methanol, 15% gasoline were tested. In the first round of tests, formaldehyde emission rates were somewhat higher than normally observed for similarly aged flexible-fueled vehicles; other emissions were not as elevated. In a second round of tests, the catalyst was replaced with a new one, and carbon monoxide and most organic emissions were substantially reduced. In general, hydrocarbon composition of exhaust emissions was significantly affected by cold starts, slightly affected by driving schedule, and unaffected by ambient temperature, test fuel, and catalyst replacement. Hydrocarbon composition of evaporative emissions was only sensitive to the type of evaporative test being performed: diurnal tests typically had larger fractions of lower molecular weight paraffins than hot soak tests. |