Future Transportation Systems - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 262

injection pump

EGR valve

Common Rail
piezoelectric injection

heat
exchanger

2.2.1 self ignition
engine with 4 in-line
cylinders

exhaust port injector

EGR cooler

air

filter

pressure diference sensor

NO reduction catalyst
X
DPNR catalyst

variable nozzle turbocharger
Lambda sensor
oxidation catalyst

gas temperature sensor

exhaust gas

Fig. 17.3 Common Rail and exhaust gas after treatment system in a self ignition engine

17.1.1.5 DPNR Technology

Injecting pure fuel into the exhaust gas when congestion in the particle filter is
detected increases the temperature and leads to the combustion of the particles as
well as to the reduction to nitrogen oxides. A system that includes exhaust
recirculation is called Diesel Particulate Nitrogen Reduction (DPNR) which
eliminates the remaining CO, HC, NO, and NO 2 emissions in downstream cata-
lysts. In this technology, no additional urea is necessary in contrast to the con-
ventional SCR technique [ 7 ].
Today, a common exhaust gas after treatment system consists of:

• SCR catalyst;
• NO x storage catalyst;
• DPNR catalyst;
• Oxidation catalyst;
• Particulate filter; and
• Appropriate sensors; see Fig. 17.3 .

17.1.1.6 Heat Recovery and Noise Reduction in the Exhaust Gas System

The primary task of the exhaust gas system is decreasing pollutant concentration in
the exhaust gases.
The exhaust gas after treatment system of the engine discharges the exhaust
gases and also recycles energy, depending on the engine power. Air-borne noise