Lubricant oil consumption effects on diesel exhaust ash emissions using a sulfur dioxide trace technique and thermogravimetry

Abstract

A detailed experimental study was conducted targeting lubricant consumption effects on ,diesel exhaust ash levels using a model year 2002 5.9L diesel engine, high and low Sulfur commercial lubricants, and clean diesel fuels. Regulatory decreases in allowable particulate matter emissions for on road diesel engines are driving industry to develop diesel particulate filters to trap and combust particulate. Remaining ash not combusted in this process clogs filters requiring engine down time and additional cleaning expenses. Recent reductions in fuel Sulfur and ash levels have also made lubricant consumption a significant relative contributor to particulate and ash generation. The goal of this study, a detailed understanding of lubricant contribution to particulate formation and ash transport, is required to enhance future filter design. 'The use of ultra clean fuels enhances accuracy of the Sulfur Dioxide tracer technique for estimating lubricant consumption and increases the relative contribution of lubricant to particulate emission. Results indicate the subject engine lubricant consumption is typical of others reported in literature. Particulate matter emission increases were measured after switching from a relatively low Sulfur, low sulfated ash oil to a high Sulfur, high sulfated ash lubricant.

(cont.) Volatile organic fraction and ash emission rates measured using thermogravimetric analysis indicate exhaust ash increases correlate with increasing sulfated ash content and lubricant consumption. Increased exhaust Sulfur and wear metal debris can also increase relative ash in particulate. Particulate generated using high Sulfur fuels has a higher ash emission rate than that obtained using near zero Sulfur fuel. The consequences of on road emissions improvements will have a significant impact on -the marine industry in coming years. New emissions regulations are reducing allowable particulate emission from marine diesels for the first time, with adaptation of on road ·technologies for these applications expected in the near future.