Affiliation:
1. Tongji University School of Automotive Studies
Abstract
<div class="section abstract"><div class="htmlview paragraph">Hybrid vehicles, compared to pure fossil fuel vehicles, have added power battery
pack, high-power electric motors. The space of the aftertreatment is limited, so
the layout position of the aftertreatment system must be optimized. Meanwhile,
the European 7 emission standard reduces the particulate number (PN) limit
particles size from 23nm to 10nm, presenting new challenges for the
aftertreatment system. The focus of this study is to investigate the variations
in particles size distribution and nanostructure of soot particles during the
exhaust along a dedicated hybrid engine aftertreatment system (catalyst carrier
free). Four operating conditions were selected for the test, namely 2000
r/min-0.2 MPa, 2000 r/min-0.8 MPa, 4500 r/min-0.2 MPa, and 4500 r/min-0.8 MPa.
The particles sampling points are before Three-way catalyst (TWC), after TWC,
and after gasoline particulate filter (GPF). Engine Exhaust Particle Sizer
(EEPS) was used to analyze the changes in particle modal distribution,
transmission electron microscope (TEM) was used to analyze the nanostructure of
particles, and Raman spectroscopy was used to analyze the degree of
nanostructure order. The results show that with the exhaust transport, the total
PN decreased by an average of about 64.4% under each operating condition. Taking
the 4500 r/min-0.8 MPa as an example, the proportion of nucleation mode
particles decreased from sampling points 1 to 3, the proportion of accumulation
mode increased, the average diameter of primary particle increased by 20.3%, the
fringe separation distance increased by 2.3%, the fringe tortuosity increased by
2.6%, the fringe length decreased by 2.6%, the fractal dimension increased by
11.2%, the degree of disorder of particles increased.</div></div>