System information

1.6.3

1.6.2

1.6.1

1.6

Theory of Operation

The DPF is a system. It consists of a filter element, electrical heater, insulated

exhaust piping, a controller and sensors for measuring exhaust temperature

and back pressure.

Briefly the system operates as follows:

• APU runs normally, produces soot which is captured by filter.

• As soot builds up the filter gradually becomes clogged and causes

increasing exhaust back pressure.

• When back pressure reaches a limit the system regenerates the filter by

directing generator power to an exhaust heater to heat the exhaust and

burn out the soot.

• Regeneration is complete when the back pressure has come down to a

"clean" value.

Filtering the Soot

The filter element works like a standard intake air filter in that all of the exhaust

from the engine must pass through a porous wall. The wall captures the soot

and the cleaned exhaust gases pass through. Due to the temperature of the

exhaust gases the filter element is made from ceramic material, therefore

care should be used to avoid dropping it or subjecting it to severe shock.

Regenerating the Filter

As the filter collects soot it gradually plugs up and causes restriction on the

exhaust system. When the exhaust back pressure gets too high the system

burns the collected soot out of the filter. This process is called "regeneration"

and is accomplished by energizing the electric heater to raise the temperature

of the exhaust gases to about 1100°F (600°C) within the filter. As the soot is

burned it goes out the tailpipe as mostly CO2 gas. When the filter is clean

the heater is turned off and normal operation is restored.

The system includes a controller and sensors to monitor the exhaust back

pressure and temperature. This controller will determine when a regeneration

cycle will take place and how long it should last.

Loss of APU Power During Regeneration

Regeneration usually takes between 10–20 minutes. The heater in the DPF

system is designed for 120VAC and is powered by the generator on the APU.

When the filter requires regeneration all power from the generator is directed

to the heater. For the duration of the regeneration, power will not be available

for the cab comfort or convenience features normally provided by the Carrier

ComfortPRO system.

With a DPF installed, the fuel consumption of the APU is expected to increase

by about 5% if alarms and recommended maintenance guidelines are followed.

The additional fuel consumption comes mainly from performing regeneration.

CLEARSKY COMFORTPRO DPF (PG1050 & PG1060) OPERATION & USERS MANUAL