Journal of Earth Sciences and Geotechnical Engineering

Active Diesel Particulate Filters and Nitrogen Dioxide Emission Limits

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• Abstract

   

  Diesel engines are major source of nitrogen oxides (NOx). NOx, primarily nitric oxide (NO) and nitrogen dioxide (NO₂), are formed at high temperatures during diesel fuel combustion. While neither NO nor NO₂ are desirable, NO₂ is the more reactive gas associated with health problems. Both US Environmental Protection Agency (US-EPA) and California Air Resources Board (CARB) initiated rulings for diesel emissions retrofit technologies to limit NO₂ emissions increase “slip” to 20% over the engine baseline emissions. In this paper, an active diesel particulate filter that reduces NO2 emissions is presented. The active diesel particulate filter utilizes a porous sintered metal filter medium, which is divided into pleated filter strips. These filter strips are regenerated (cleaned) by applying direct electric heating to burn off accumulated soot. Exhaust emissions measurements show that a degreened active diesel particulate filter reduces NO₂ by 42% from the diesel engine exhaust. The data also show that the efficiency of NO₂ emissions reduction improves with aging. Following a break-in or “aging” period, the active diesel particulate filter achieved 96% NO₂ reductions. This far exceeds latest US-EPA and CARB verification standards on NO₂.