Characteristics and Effects of Lubricant Additive Chemistry on Ash Properties Impacting Diesel Particulate Filter Service Life

Abstract

Ash accumulation in diesel particulate filters, mostly from essential lubricant additives, decreases the filter's soot storage capacity, adversely affects fuel economy, and negatively impacts the filter's service life. While the adverse effects of ash accumulation on DPF performance are well known, the underlying mechanisms controlling these effects are not. To address these issues, results of detailed measurements with specially formulated lubricants, correlating ash properties to individual lubricant additives and their effects on DPF pressure drop, are presented.Investigations using the specially-formulated lubricants showed ash consisting primarily of calcium sulfates to exhibit significantly increased flow resistance as opposed to ash primarily composed of zinc phosphates. Furthermore, ash accumulated along the filer walls was found to be packed approximately 25% denser than ash accumulated in the channel end-plugs. Both lubricant chemistry and the filter's thermal history were correlated to ash packing density and distribution following DPF post-mortem analysis.In this study, a heavy-duty diesel engine was utilized in conjunction with a rapid lubricant degradation and aftertreatment ash loading system, which has been validated in detail previously against engine-out exhaust and ash accumulated in the field. Results with specially-formulated lubricants containing only calcium-based detergents, only ZDDP additives, and conventional CJ-4 oils were compared utilizing an aging cycle simulating 180,000 miles of on-road use. On-engine DPF performance evaluation, coupled with subsequent filter post-mortem analysis, clearly indicate the manner in which lubricant chemistry and exhaust conditions influence ash properties and DPF performance.The results of this work demonstrate the effects of individual lubricant additives on the resulting ash properties controlling DPF pressure drop, including ash packing density and permeability. Results will be useful in optimizing the design of the combined engine-aftertreatment-lubricant system for future diesel engines, balancing the requirements of additives for adequate engine protection with the requirements for robust aftertreatment systems.

Health Risk Assessment of Heavy Metal in Urban Surface Soil (Klang District, Malaysia)

“…In Malaysia, the natural sources of silicate and non-silicate minerals in soil are Al and Fe, which are derived from kaolinite, gibbsite, goethite, and hematite (Tessens and Shamshuddin 1983). Zn is added as an additive in lubricants, and it reduces tire wear and corrosion in automotive exhaust systems (Sappok et al 2010). Pb, which mostly involves aerosol combustion products in vehicle releases close to roadways, is initially deposited within about 50 m of a roadway if no obstructions are present.…”

Effects of an anti-wear oil additive on the size distribution, morphology, and nanostructure of diesel exhaust particles

“…Also a 2008 study by Sappok gives a novel accelerated aging system to study lubricant additive effects on diesel aftertreatment system degradation [31]. Sappok used this system to study the effects of lubricant additive chemistry on ash properties impacting diesel particulate filter service life in 2010, and concluded that additives like ZDDP, Ca affecting the filter performance in different manners [32]. The objective of this study is to determine the influence of an anti-wear oil additive on diesel engine particle emissions, focus on the changes in physical characters like morphology, size distribution.…”

Spatial Assessment of Heavy Metals in Surface Soil from Klang District (Malaysia): An Example from a Tropical Environment

“…Enrichment of heavy metals in the surface soil indicates an association with vehicle traffic and emissions in the surface soil. Zn is added as an lubricant additives to function as corrosion and oxidation inhibitors (Sappok et al 2010). However, according to Najib et al (2012) and Ghazali (2010), there are no soil standards and protocols in Malaysia to evaluate the level of contamination in soil using the bioavailability of heavy metal concentrations.…”

“…The total and bioavailability concentration of Zn is the third highest found in the surface soil of the Klang district. Zn is added as an additive in lubricants and for reducing tire wear and corrosion in automotive exhaust systems (Sappok et al 2010). Anor and Ahmad (2010) showed that the Klang area faces high traffic volume, especially during peak hours (weekdays and after office).…”