On-vehicle emission measurement of a light-duty diesel van at various speeds at high altitude

As part of the research on the relationship between the speed of a vehicle operating at high altitude and its contaminant emissions, an on-vehicle emission measurement of a light-duty diesel van at the altitudes of 1000m, 2400m and 3200m was conducted. The test vehicle was a 2.8L turbocharged diesel Ford Transit. Its settings were consistent in all experiments. Regulated gaseous emissions, including CO, HC and NOx, together with particulate matter was measured at nine speeds ranged from 10kmh^-1 to 90kmh^-1 with 10kmh^-1 intervals settings. At each speed, measurement lasted for at least 120s to ensure the sufficiency and reliability of the collected data. The results demonstrated that at all altitudes, CO and HC emissions decreased as the vehicle speed increased. However both NOx and PM increased with vehicle speed. In terms of the effects of altitude, an increase in CO, HC and PM was observed with the rising of altitude at each vehicle speed. NOx behaved different: emission of NOx initially increased as the vehicle was raised from 1000m to 2400m, but it decreased when the vehicle was further elevated to 3200m.