In light of forthcoming particle number legislation for
light-duty passenger vehicles, time-resolved Particle Mass (PM) and
Particle Number (PN) emissions over the New European Drive Cycle
(NEDC) are reported for four current vehicle technologies; modern
diesel, with and without a Diesel Particulate Filter (DPF), Direct
Injection Spark Ignition (DISI) gasoline and multi-point Port Fuel
Injection (PFI) gasoline. The PN and PM emissions were ordered
(highest to lowest) according to: Non-DPF diesel ≻ DISI ≻ PFI ~ DPF
diesel.
Both the non-DPF diesel and DISI vehicles emitted PN and PM
continuously over the NEDC. This is in contrast with both the DPF
diesel and PFI vehicles which emitted nearly all their PN and PM
during the first 200 seconds. The PFI result is thought to be a
consequence of cold-start mixture preparation whilst several
possible explanations are offered for the DPF diesel trend.
The DPF diesel vehicle emitted less nucleation mode particulate
matter than the other three vehicles and over 4 orders of magnitude
less than the non-DPF diesel vehicle.