Effect of Coolant Exposure on Diesel Exhaust Aftertreatment Performance

Characterizing Diesel Particulate Filter Failure During Commercial Fleet Use due to Pinholes, Melting, Cracking, and Fouling

“…Figure 2d shows a DPF with the inlet plugged by EGR coolant leak-derived ash. Exhaust gas recirculation (EGR) cooler failure can cause coolant to leak into the exhaust after treatment system [21]. The chemical components of ash are determined experimentally via strong acid treatment to dissolve ash components.…”

“…Various pathways are possible for engine fluids to come in contact with the DPF substrate. Coolant leaks from high temperature exhaust gas recirculation (EGR) failure [21], excess lubricant from engine failure, and fuel from incomplete combustion all possess the capability to enter the exhaust stream and to contaminate the DPF. The white ash substance shown layered on the DPF inlet face are clusters of ash as large as 3-7 mm in diameter.…”

“…The EDS results show no detected zinc or magnesium and much higher levels of potassium and sodium. High levels of potassium are indicative of a coolant leak, as fully formulated HDD coolants may contain significant quantities of S (sulfur), P (phosphorus), Na (sodium), and K (potassium) [21].…”

“…The presence of high levels of alkalis (Na, K) in the EGR coolant leak-derived ash can compromise the durability of the DPF twofold. The alkalis have been observed to poison the catalyst coatings in the diesel oxidation catalysts and diesel particulate filters with respect to NO oxidation, or NO 2 make [21]. The reduction of the NO oxidation performance of the DOC and DPF can compromise the soot regeneration process in the DPF during normal vehicle operating conditions, resulting in higher soot loads in the DPF.…”