Mack CSM 2010, Руководство оператора

Страница: 178 / 232

170 Mack, Emissions Solution
Exhaust Aftertreatment System Components and
Operations
Selective Catalytic Reduction (SCR)
Selective Catalytic Reduction (SCR) is an emissions-reduction technology with the ability
to deliver near-zero emissions of nitrogen oxides (NOx), a smog-causing pollutant and
greenhouse gas. SCR’s performance has been proved in millions of kilometers of real-world
trucks in other countries, as well as in long-term field tests in the U.S.
SCR reduces NOx emissions to very low levels, while at the same time delivering excellent
fuel economy and reliability. The system doesn’t change the design or of the basic engine.
Rather, SCR is an aftertreatment system which converts NOx in the exhaust stream into
harmless gases. Modern diesels already use exhaust aftertreatment systems, called diesel
particulate filters, to control emissions of another pollutant, soot (also known as particulate
matter or PM).
SCR works by injecting Diesel Exhaust Fluid (DEF) into the exhaust. DEF is a solution of
ultra-pure water and urea. DEF works with the heat of the exhaust and a catalyst to convert
NOx into nitrogen and water vapor - two harmless and natural components of the air we
breathe. The end result is cleaner air, excellent fuel efficiency and a reliable emissions
control system for today’s modern diesel engine.
W2061387
1. Diesel Engine
2. Aftertreatment DEF Tank
3. Aftertreatment DEF Pump
4. Aftertreatment DEF Dosing Unit
5. Selective Catalytic Reduction (SCR) Catalyst
6. Aftertreatment DEF Tank Gauge