Exhaust Aftertreatment System; Filtration And Regeneration Unit; Passive Regeneration; Active Regeneration - PREVOST H3-45 VIP Owner's Manual

EXHAUST AFTERTREATMENT
SYSTEM
The exhaust aftertreatment system consists of
two units, the filtration and regeneration unit and
the selective catalytic reduction SCR unit.

FILTRATION AND REGENERATION UNIT

The main purpose of the filtration and regeneration
unit is to capture and oxidize (regenerate) the
particulate matter (soot) in the engine exhaust gas.
The exhaust gas first enters the Diesel Oxidation
Catalyst (DOC) and then flow through the Diesel
Particulate Filter (DPF); together they capture and
regenerate the soot on a regular or passive basis.
Through constant monitoring of the exhaust gas
temperature and the system back pressure, the
engine control module is able to manage
regeneration.

PASSIVE REGENERATION

Passive regeneration is the process by which the
particulate matter is oxidized due to the heat
generated by the engine internal combustion
process. During normal
exhaust temperatures alone are usually high
enough to oxidize accumulating soot. In low
ambient temperatures, however, or in some stop-
and-go applications, the system needs a little help
to regenerate, or clean itself. This process is
called "active" regeneration.

ACTIVE REGENERATION

Active regeneration is necessary when the engine
internal combustion process alone does not
generate enough heat. A dosing system injects a
mist of diesel fuel into the exhaust system to
increase and maintain the aftertreatment system
temperature. Exhaust temperature must be above
572°F (300°C) to initiate the oxidation catalyst,
which in turn oxidizes the injected diesel fuel
molecules to achieve up to 1200°F (650°C)
exhaust temperature at the particulate filter. This
process of active regeneration takes place during
the normal operation cycle of the vehicle without
charges in performance or control for the operator.
EPA2010 compliant and later Volvo engines
produce less soot, so less active or stationary
regeneration will be required.
highway operation,
PA-1619 Owner's Manual H3-45 VIP

STATIONARY (PARKED) REGENERATION

In a small number of specific engine duty cycles,
engine control module may not be capable of
completing an active regeneration. In these
situations, the operator will be notified that a
stationary or parked regeneration may be required.
A DPF telltale light will illuminate indicating the
need for user interaction. The lamp gives the
operator a grace period to allow this process to
take place at a time when most convenient for the
operator. This process requires the vehicle to be
parked while a driver or maintenance technician
initiates the regeneration process using the DID
menus. Once initiated, the stationary regeneration
process will be complete in about 45 minutes.
The driver will be notified of the need for a
stationary regeneration (parked) by illumination of
the DPF Regeneration telltale light.
Other Features 5-3