Research Projects

Project at a Glance

Project Status: complete

Title: Particulate matter mass measurement and physical characterization - techniques and instrumentation for laboratory source testing.

Principal Investigator / Author(s): Durbin, Norbeck, Cocker

Contractor: UC Riverside

Contract Number: 02-334B


Research Program Area: Emissions Monitoring & Control

Topic Areas: Mobile Sources & Fuels, Monitoring


Abstract:

One of the most important issues in the control of emissions from mobile sources is the reduction in particulate matter (PM) emissions from diesel engines/vehicles. Over the past three decades, diesel PM emissions have been studied extensively, including emissions measurement and characterization studies and health studies. As regulations become increasingly more stringent, more advanced diesel technologies and diesel particulate filters (DPFs) are being implemented on a wider basis. As diesel technology evolves, it is important to understand how the PM component of vehicle exhaust has changed over the years in order to gauge the expected improvement in air quality. One of the most critical aspects of evaluating these changes is the application of the most robust, comprehensive and accurate measurement tools available. This includes instruments for the measurement of PM mass in real-time, PM size distributions, and portable instruments that can be used to measure PM under in-use conditions. The objective of this project is to evaluate and assess the international and domestic literature on PM measurements and measurement technology from vehicles. This work included a comprehensive literature review that identified over 250 references. The fate of vehicle exhaust PM in the ambient atmosphere is an important issue in evaluating the real-world characteristics of PM. These studies have included roadside studies and chase studies. These studies have shown that atmospheric dilution is on the order of 1000:1 after 1 second, considerably higher than that obtained in the dilution tunnel measurements. Ambient measurements also typically show a strong nuclei mode, although this is source dependent. Comparisons of particles in chase studies have also shown considerably higher number of particles measured by a condensation particle counter (CPC) in comparison with a scanning mobility particle sizer (SMPS), which is attributed to a large number of particles < 10 nm that can be detected by the CPC but not the SMPS. In the recent CRC E-43 program, extensive roadside tests were conducted along with experiments in a wind tunnel. The results showed the nuclei mode was quite variable depending on engine operation, thermal history and other parameters, while the accumulation mode was a repeatable function of engine and operating conditions. A model was also developed and it was found that after leaving the tailpipe total particle numbers are reduced by 90% on the order of a few minutes and after traveling 100-1000m.


 

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