Development of an Official Test Method for On-Board PM Measurements From Heavy-Duty Diesel Engines in the European Union

摘要

Portable Emissions Measurement Systems (PEMS) are becoming part of the emissions control regulations, as evidenced by the latest requirements introduced in the United States regulations for on-highway and non-road machinery. The European Union is currently following the same route to check the in-use behavior of heavy-duty diesel vehicles. The current research programs tend to demonstrate that both the instrumentation and the test methods are mature for gaseous emissions. For PM emissions, the development of portable PM instruments and their test protocols remain a complex challenge, as simultaneous progress take place in the engine after-treatment technologies and the official homologation procedures (the PMP program in particular). The present paper discusses the current research strategy proposed in the EU for the development of an on-board PM test protocol. Case studies from the EU-PEMS project are presented. Portable commercial PM instruments are evaluated under controlled laboratory conditions (i.e., on reference test cycles) against reference laboratory instruments using a Euro III heavy-duty engine running on different fuels, including bio-fuel. Other supporting instruments, measuring real-time soot or the total PM composition, are also used. Under these test conditions, the study has demonstrated the equivalency between the tested portable technology and its laboratory counterpart. Another part of the work is to evaluate the applicability of the methodology for on-board testing: results and lessons learned from onboard measurements conducted on diesel city buses on urban test routes are presented and discussed showing very good test-to-test repeatability. Issues, such as filter handling and conditioning on board, need particular attention for the adaptation of the test method to the future generations of vehicles.