Abstract:

In this paper， a 7.8 L heavy-duty diesel engine is selected to run WHSC （world harmonized steady-state cycle）， hot and cold WHTC （world harmonized transient-state cycle）， as well as real driving emission test （PEMS） based on engine-in-the-loop （EIL） methodology on the engine test bench. The fine particle emissions are measured by using a particle counter which can simultaneously measure PN10 （number of particles above 10 nm） and PN23 （number of particles above 23 nm） . The results show that the transient emission of PN10 and PN23 have basically the same trends under different cycles. The specific emission of PN10 is higher than that of PN23. The PN emission of heavy-duty vehicle in the middle and high-speed and high-load range of PEMS test increases rapidly with a larger particle size， resulting in an minor difference between PN10 and PN23.In the mid-speed range， PN10 emissions are significantly higher than PN23. The engine operating points of the two test conditions of WHTC and EIL-based PEMS are quite different. The EIL-based methodology enables the assessment of PN emissions for heavy-duty vehicle PEMS test on the engine test bench.

Key words: heavy duty diesel vehicle, PEMS, engine-in-the-loop, fine particle, particle number, emission