Improving Diesel Engine Reliability While Minimizing Emissions

Railcars, trucks, and ships powered by diesel engines account for approximately 85% of the nation’s freight as measured in tons per mile. During operation, these engines produce particulate matter in the form of soot and ash.

To limit the amount of particulate matter released into the environment, diesel particulate filters (DPFs), which capture the soot and ash, are required on all new dieselengine vehicles. However, the accumulation of soot and ash in the filter induces back pressure on the engine, which can cause higher fuel consumption and lower power output, affect engine durability, and under worst-case scenarios, render the engine/vehicle inoperative. For this reason, engine manufacturers recommend temporarily removing the DPF at prescribed maintenance intervals in order to clean out the accumulated ash.

Hunsicker Emissions Services, LLC (HES)—an Earlington, Pennsylvania-based company that services diesel emission devices for small and large fleets—had observed that when some DPFs were removed for maintenance, the filters had failed during industrial-fleet vehicle use. Not only is this costly for both the vehicle owner and the environment, DPFs that fail during vehicle use have been shown to contribute disproportionally to particulatematter emissions.

HES and John Fox, a Lehigh University assistant professor in civil and environmental engineering, are working together to enhance the reliability of diesel emissions control through a fundamental understanding of DPF failure so as to improve maintenance techniques and services. HES provided the Lehigh University team with DPFs that had failed; the HES-observed failures were then analyzed by the Lehigh University team. The physical and chemical characteristics of pinhole failure, melt failure, crack failure, and fouling failure were determined by applying scanning electron microscopy–energy dispersive spectrometry, x-ray photoelectron spectroscopy, and x-ray diffraction. Lehigh’s analytical results indicate that the chemical composition of deposits changed according to the failure characterization—and most importantly, that specific particulate matter components were to blame.

“One of the tremendous benefits of working with HES is the industry-wide understanding and practical technical knowledge that HES offers, which unlocks the potential of this research otherwise not achievable through an academic perspective,” said Fox. “For example, until our partnership, we did not know that DPFs were failing until HES showed us what they were observing in the field. We were then able to work together to use our analytical capabilities to investigate what was occurring in industry,” said Fox.

The Lehigh partnership has also been empowering for HES. Bob Hunsicker, founder of HES, said, “The level of analytical capabilities offered by Lehigh University far exceeds that capacity available in industry, and truly helps to advance our understanding of the challenges facing our customers.” HES is now moving towards tailoring their services to provide a longer service life for emission control devices, particularly DPFs. This research has enabled HES to broaden and enhance the spectrum of services they offer to the transportation industry and to ensure more sustainable vehicle emission control.