Abstract
The penetration of diesel particulate filters (DPFs) in the market is growing fast. However, in the current inspection/maintenance (I/M) regulation for these vehicles, particulate emissions were capped with smoke opacity, which is incompetent to identify the excessive particle number (PN) induced by non-major DPF failures such as small cracks in substrate. This research aimed at developing a fast identification method for such malfunctioning vehicles using a low-cost condensation particle counter (CPC). To verify the effectiveness of idle PN test, 33 China-5 and China-6 heavy-duty vehicles fueled with diesel and natural gas (NG) were tested using the regulatory portable emission measurement system (PEMS) as per China-6 protocol and idle PN tests using a low-cost CPC-based system. PN emissions from China-6 vehicles with malfunctioning DPFs were at a similar level to those from China-5 vehicles (without DPF), which were significantly higher than the proper counterparts. Idle PN tests using a CPC-based system managed to identify the vehicles with DPF failures. Volumetric PN concentrations of these vehicles were much higher than those of the proper ones. This study proved that an easy, fast, and low-cost procedure could be used to screen out those high emitters with DPF failure.
Highlights
Academic Editor: Yongming HanParticulate matter (PM) is one of the major urban air pollutants in developing countries, with mobile sources being a dominant contributor
Testing vehicles, while Figure 4c,d depicts the particle number (PN) emissions corresponding to the 90 percentiles of moving average window calculation results and the averaged idle PN concentrations measured by portable emission measurement system (PEMS)
Threshold capable of picking out the dirtiest 10% or 20% of vehicles from the fleet will be largely successful, because a majority of emissions from road vehicles are attributed to this small group of preservation. Both PEMS tests in accordance with heavy-duty China-6 regulations and idle PN emission tests using a low-cost condensation particle counter (CPC) system were performed on 33 China5/6 diesel and natural gas (NG)-fueled vehicles to validate the feasibility of prompting a simple and quick procedure to use idle PN tests to screen out vehicles with diesel particulate filters (DPFs) malfunction from in-use fleets
Summary
Academic Editor: Yongming HanParticulate matter (PM) is one of the major urban air pollutants in developing countries, with mobile sources being a dominant contributor. To curb tailpipe PM emissions and to purify the sky, mass-based PM regulations were promulgated decades before and have been updated periodically until today [1]. Mass-based PM limits confront greater challenges; through the application of high-pressure fuel injection systems and advanced combustion concepts, PM has been reduced by at least an order of magnitude, while the particle number (PN) increased notably as the mean diameter of exhaust particles dropped to a much smaller level. Together with the widely-reported higher health risks of smaller particles associated with easier inhalation, longer deposition, and greater potential of carrying dangerous substances such as the COVID-19 virus [3,5,6,7,8,9,10], number-based harmonizing with mass-based particulate regulation is deemed necessary.
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