Engineers at Case IH are adamant about their stand to meet Tier 4A (often called interim Tier 4) emission standards next January with Selective Catalytic Reduction (SCR) methods and say their choice will allow fuel consumption reductions and extended maintenance intervals on Case IH engines of 100 horsepower and larger.
In a discussion with the media recently concerning what's new for 2011 from the "Red Tractor" people, Tom Dean, marketing manager for high-horsepower tractors for Case IH North America, says the downstream treatment of diesel engine exhaust allows for engines to be tuned for maximum power without polluting the air intake with recirculated exhaust gasses (EGR). This approach, he says, allows for smaller engines to do more work with less fuel and maintenance.
Case IH says SCR systems also allow for less bulky cooling systems and negate the need for maintenance-prone diesel particulate filters (DPF). In addition, Dean notes without the extra heat and exhaust gas pollutants being recirculated into the engine, Case IH has found lubricating oil drain intervals can be extended because oil stays cleaner in an SCR-equipped engine.
Case IH will be using its proven engine lineup of 6.7L, 8.7L and 12.9L engines in the 2011 models, but will equip each of them with a Diesel Exhaust Fluid (DEF) system that will automatically reduce NOX in the exhaust stream. "Since the SCR after-treatment is separate from the main engine function, it doesn't interfere with engine performance and allows the engine to perform at its absolute best," Dean explains.
Dean says industry-leading engineers agree all manufacturers will need to use SCR to meet the even more stringent Tier 4B standards coming in 2014. "Case IH believes SCR is the most efficient way to meet EPA standards for agricultural applications, and those who aren't using it, will be playing catch up in 2014."
SCR involves injecting a 33/66% mixture of urea and deionized water - called diesel exhaust fluid or DEF - into the exhaust stream in the presence of catalysts to break down oxides of nitrogen into atmospheric nitrogen and water. Administering the DEF will be the chore of a computer-controlled system that automatically adjusts injection rates for engine load and speed, and alerts the machinery operator when it's time to refill the DEF reservoir. Currently DEF sells for roughly the same price as diesel fuel, Dean notes.
"Filling a DEF tank is easy, and we're designing tanks to be sufficient to supply controls for up to two tankfuls of fuel," Dean explains. "Keeping the tank full will be the only operator requirement, the system takes care of the rest."
Urea injection has been used for a number of years on European over-the-road trucks and buses to control nitrogen oxide emissions, and Case IH is the benefactor of existing system designs developed by its brotherhood with Fiat Power Technologies -- a company that has built and operated millions of DEF-equipped engines globally. FPT-powered vehicles in Europe have logged more than 20 million miles using the SCR technology.
Case IH says tests on its upcoming models show the SCR technology can amount to 10% or more reductions in overall operating costs when compared with other diesel powerplants meeting Tier IVA requirements with EGR and diesel particulate filter (DPF) designs. By using SCR, Case IH engineers explain their engines will be running at a much more efficient level -- therefore, reducing particulate matter to nearly zero -- leaving only NOX to be treated.
In applications below 100 hp., Case IH says it will be using EGR systems because the coming emissions standards are less stringent for those categories of engines and fuel requirements are much lower so fuel-efficiency has less of an overall impact.