Frank Manfredi, President of Manfredi & Associates said in a recent interview: “It is hard to imagine that there would be another level of emissions regulations, because if you operated a Tier 4 Final engine in Los Angeles, the air coming out of the exhaust is cleaner than the air going in.” While maybe not literally true, Manfredi’s statement illustrates the magnitude of the challenge the diesel engine industry just met in achieving U.S. EPA Tier 4 Final emissions standards.

Going forward, the industry faces no foreseeable regulations that will require new diesel engine technologies. The suite of solutions now in Perkins' proven portfolio is robust and capable of addressing all foreseeable standards. The EPA previously confirmed it has no intention to regulate non-road greenhouse gases in the short to medium term and is working with industry and end users to determine optimal fuel efficiency improvement/GHG reduction strategies.

Virtually all engines designed to meet Tier 4 Final emissions standards utilize some combination of four basic technologies, and will continue to do so in the coming decades. These key technologies are:

•    Diesel particulate filters (DPFs) that physically trap particulates in the exhaust stream.

•    Cooled exhaust gas recirculation (CEGR) or exhaust gas recirculation (EGR) that lowers combustion temperatures to minimize NOx formation.

•    Diesel oxidation catalysts (DOC) that help remove particulate matter from exhaust gasses, turning hydrocarbons and carbon monoxide into carbon dioxide and water. DOCs also aid the overall performance of aftertreatment systems comprising of DPF/SCR.

•    Selective Catalytic Reduction (SCR) that reduces NOx in the exhaust stream. Diesel exhaust fluid (DEF) is injected into the exhaust gasses after the DOC/DPF and before the SCR to further reduce NOx. DEF consists of high-purity urea dissolved in de-ionized water meeting a specific, required concentration level—the industry standard being DEF which meets ISO 22241. It is stored in a dedicated tank and never comes into contact with the diesel fuel.

The exact technology mix for any given engine and application is arrived at by including everything needed to meet applicable regulatory standards while achieving customer performance requirements. Arriving at such an optimum solution in practice requires a very high level of cooperation between engine builders and their OEM customers.

Perkins, for example, has created the Technology Integration Workshop (TIW) program that gives customers an unprecedented amount of access to, and influence in, the ongoing engineering effort.

Under the TIW program OEMs engineers work side-by-side with Perkins engineers to create optimal solutions for customer applications. To date, the TIW program has generated more than 500 optimized engine/machine installations for 150 OEM customers. Compared to the previous Tier products, these applications deliver better fuel economy, more precise engine response, and more productive duty cycles giving customers clear differentiators in their highly competitive markets.

Having put in place the suite of technologies needed to achieve these near zero levels of emissions, the industry can now provide an even greater focus on enhanced customer value as the technologies mature and experience is gained.

Karl Vandermyde, Americas Sales Director, Perkins, wrote this article for SAE Off-Highway Engineering.