The effects of operating conditions on particulate matter exhaust from diesel locomotive engines

Abstract

Numerous reports have shown that fine particulates threaten human health. Since their health impact is associated with both mass and number concentrations, it is necessary to evaluate the emission standards for particulate mass accordingly. This study examined the particulate matter characteristics of diesel locomotive engine exhaust at various engine ratings. Diesel engine exhaust was collected via a dilution tunnel and the concentration and size distribution of fine particles were measured by a scanning mobility particle sizer. Exhaust gasses were measured simultaneously by a stack sampler. The maximum carbon monoxide emission was reached at 59% of the maximum rating, after which emissions decreased. The particle count median diameter increased with the engine rating, until a maximum was reached at 40% of the maximum rating. Most exhaust particles were nanoparticles with the nuclei mode range, a particle diameter (DP)<50nm. The increase in particles with the accumulation mode range, 50<DP<1000nm, led to a mass concentration increase and number concentration reduction. The count median diameter was within the nuclei mode range at lower engine ratings, and within the accumulation mode range at higher engine ratings. Since diesel engines mainly generate fine particles, exhaust particle mass and size distribution should be considered in emission regulations.