Why Selective Catalytic Reduction for Diesel Engines is the Choice of the Trucking Industry

Most heavy trucks are powered by diesel engines because it is an extremely cost effective and reliable alternative to gasoline engines. It is not uncommon for a diesel engine to last from 15 to 20 years and it can compete with other advanced technology due to its inherent fuel economy. For the trucking industry, diesel engines are better choice for both off-road and on-road vehicles.  But the concern over diesel engines is the black soot that is considered as a toxic pollutant; hence, companies have made great strides in developing technology that will control these hazardous emissions. One example is selective catalyst reduction for diesel engines.

What is selective catalyst reduction (SCR) for diesel engines?

Interest in emission control systems have gained overwhelming interest in recent years due to the regulations of EPA and Clean Air Act over nitrogen oxide and particulate matter emissions of diesel engines. Selective catalyst reduction for diesel engines uses urea or ammonia as a reducing agent for reducing nitrogen oxide emissions through a process that is extremely efficient and effective. The major components of SCR are hot exhaust, Diesel Exhaust Fluid (DEF) and a catalytic converter. Vaporized DEF and hot exhaust gases enter a catalytic converter that is installed in the exhaust system after the diesel particulate filter. The catalytic converter contains a catalyst which is a substance that causes a chemical reaction wherein nitrogen oxide is converted into nitrogen and water vapor – two clean harmless components of the air we breathe.

What is Diesel Exhaust Fluid?

DEF is one of the key elements of selective catalytic reduction for diesel engines process. It is a non-toxic solution composed on 67.5% purified water and 32.5% urea. When DEF is injected into the hot exhaust as a mist and passed on the catalyst, nitrogen oxide is converted to nitrogen and water vapor. Urea which is component of DEF turns to ammonia when heated. Urea is classified by EPA as non-hazardous and internationally accepted for standards of purity and composition since it is made from natural gas. DEF is available in the same places where diesel fuel is obtained and can be stored in bulk at fleet locations using tanks.

Advantages of selective catalytic reduction for diesel engines

The advantage of using selective catalytic reduction for diesel engines is the lower rate of exhaust gas recirculation. With the lower rates of exhaust gas recirculation, it results into lower heat rejection so no massive coolers made from exotic materials are required for an efficient cooling system. SCR enables great power densities which mean that a smaller displacement engine can deliver the horsepower which would otherwise demand a larger engine. SCR can also be used to comply with the near zero NOX emission requirement while at the same time achieve fuel efficiency of approximately 5% which is favorable to the trucking industry as well as the environment. In fact the trucking industry will likely consider selective catalytic reduction for diesel engines so as to comply with the 2010 EPA standards instead of increased exhaust gas recirculation.