Emissions of Organic Carbon from ‘In-use’ Diesel Vehicles

Abstract

We studied the characteristics of the organic carbon (OC) exhaust produced by 13 heavy-duty diesel vehicles (gross weight 4,275-25,000 kg) that met the Japanese short-term or long-term standards for emissions. The vehicles were tested under city drive cycles.
Eleven vehicles met the short-term standard. Their average total carbon (TC) emissions were 780 mg/km at an average vehicle speed of 8.4 km/h, 460 mg/km at 17.9 km/h, and 440 mg/km at 28.5 km/h. The average OC emission was about 35 % of the average TC emission, and the OC emission tended to decrease as the average vehicle speed increased.
Four vehicles met the long-term standard. Their average TC emissions were about 80 % less than those of the vehicles that met the short-term standard, and their average OC emission was about 60 % less.
The gross vehicle weight and the weight-to-power ratio (equivalent inertia weight / maximum power) are discussed as factors that might affect OC emissions. OC emissions and the OC emission ratio (OC/TC) increased when the excess power of the engine was large.