AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Using Mini-PEMS to Monitor Motor Vehicle Exhaust PM
Diep Vu, Joseph Szente, Michael Loos, MATTI MARICQ, Ford Motor Co.
Abstract Number: 198 Working Group: Air Quality Sensors: Low-cost != Low Complexity
Abstract As regulations evolve to require cleaner motor vehicle exhaust, attention is turning to ensuring these are not only met in certification tests but also in real world driving. The failure in Europe of diesel vehicles meeting EU6 NOx standards to exhibit comparable emissions in real world driving precipitated development of “read driving emissions” testing, in which emissions are recorded using portable emissions measurement systems (PEMS) during on-road tests. Similar regulations are being adopted in other parts of the world. The US already has in place “not to exceed” regulations for on road testing of in-use heavy duty vehicles. These regulations extend as well to particle emissions.
On-road regulations extend the testing burden during engine and exhaust aftertreatment development in two ways: First, more emissions testing is required to cover the large variability of on-road driving conditions, e.g., speed, load, grade, temperature, altitude, etc. Second, additional testing equipment, namely PEMS, is required. Commercial PEMS that meet regulatory requirements are bulky, costly, and difficult to operate, further exacerbating the testing burden.
The recent development of mini-PEMS offers an alternative. These are smaller, relatively inexpensive, sensor based systems. The tradeoff is that they generally lack the stability and accuracy of the full PEMS. However, they can still perform a useful function as a survey tool to determine engine / driving conditions that lead to undesired emissions levels, after which these situations can be studied more accurately and in more detail in laboratory testing.
The present work examines four commercial mini-PEMS employing four different PM sensing technologies for their ability to detect PM emissions from current gasoline direct injection vehicles. PM is a complex substance that is regulated differently in various parts of the world, for example by total PM mass in the US and by solid particle number in the EU. We find that the mini-PEMS have trouble providing accurate absolute PM mass or solid particle number readings owing to the difficulty in converting their sensor response to number or mass units. But, they provide good qualitative capability for detecting PM emissions events and, thus, can provide useful on-road survey data.