2010 engines: An overview of technologies for emissions compliance
Oct 1, 2008 12:00 PM, By David A Kolman
Come 2010 Engine manufacturers will have to meet the US Environmental Protection Agency's more stringent diesel emission standards. These regulations dramatically decrease discharges of particulate matter (soot and ash) and nitrogen oxide (NOx), virtually eliminating these emissions from on-road diesel engines.
The standards reduce emissions to 0.2 gram per brake horsepower hour (g/bhp-hr) for NOX and 0.01 g/bhp-hr for particulate.
Basically, particulate matter (PM) is formed by the incomplete combustions of fuel in diesel engines. NOx is formed in small amounts when fuel is burned at high temperatures and pressures during an engine's combustion process.
Engine manufacturers are meeting the 2010 emissions standards through a variety of means. They are making engine modifications for cleaner combustion and adding exhaust aftertreatment (EGA) devices. These remove pollutants from exhaust gases after they leave the engine's combustion chamber.
Meeting the reduced pollutants standards has required a change in diesel fuel to ultra-low sulfur diesel fuel (ULSD) and a reformulation of engine oils.
Fuel
Since 1993, diesel truck engines have been using low-sulfur diesel fuel, which emits 500 parts per million (ppm) of sulfur. Ultra-low sulfur diesel, required by the EPA for 2007-emission compliant engines, began replacing low-sulfur fuel starting in 2006.
ULSD is a cleaner burning fuel that inherently produces less particulate emissions in both older and new engines. It emits only 15 ppm of sulfur, a 97% reduction in the sulfur content compared to low sulfur diesel.
Oil
Lubricating oils had to be developed for compatibility with the new low-emissions solutions. Designated CJ-4, these oils are formulated with lower sulfated ash, phosphorus, and sulfur levels to ensure protection of the aftertreatment devices and to provide better wear protection, higher oxidation protection, and better soot handling characteristics.
Beyond this, engine manufacturers are using a variety of means to comply with the 2010 diesel emissions regulations. Two particular technologies have evolved to control nitrogen oxide emissions: selective catalytic reduction (SCR) and exhaust gas recirculation (EGR). To handle particulate matter emissions, diesel particulate filter technology has been developed.
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