Search

In this paper we report the results of the detailed monitoring and analysis of combustion emissions from fast moving diesel trains. A new highly efficient monitoring methodology is proposed based on the measurements of the total number concentration (TNC) of combustion aerosols at a fixed point (on a bridge overpassing the railway) inside the violently mixing zone created by a fast moving train. Applicability conditions for the proposed methodology are presented, discussed and linked to the formation of the stable and uniform mixing zone. In particular, it is demonstrated that if such a mixing zone is formed, the monitoring results are highly consistent, repeatable (with typically negligible statistical errors and dispersion), stable with respect to the external atmospheric turbulence and result in an unusual pattern of the aerosol evolution with two or three distinct TNC maximums. It is also shown that the stability and uniformity of the created mixing zone (as well as the repeatability of the monitoring results) increase with increasing length of the train (with an estimated critical train length of ~10 carriages, at the speed of ~150km/h). The analysis of the obtained evolutionary dependencies of aerosol TNC suggests that the major possible mechanisms responsible for the formation of the distinct concentration maximums are condensation (the second maximum) and thermal fragmentation of solid nanoparticle aggregates (third maximum). The obtained results and the new methodology will be important for monitoring and analysis of combustion emissions from fast moving trains, and for the determination of the impact of rail networks on the atmospheric environment and human exposure to combustion emissions., (Copyright © 2010 Elsevier B.V. All rights reserved.)

In this paper, evolution of the size distribution of fine and ultra-fine particles emitted from vehicles on a busy road is investigated experimentally. In particular, several different modes (distinct maxima) of the particle size distribution are investigated as a function of the distance from the road. An unusual and complex evolution of these modes is discovered. In particular, it is demonstrated that some of the modes tend to shift towards smaller particle size, which has never been reported previously. Complex correlation between the modes is determined experimentally. In addition, for the first time, the total number concentration is clearly shown to go through a significant maximum at some distance from the road. This could have significant influence on the assessment of exposure to fine and ultra-fine particles in the vicinity of busy roads. [Copyright &y& Elsevier]