Investigation of lubricant oil consumption and its contribution to particulate matter emissions

Abstract

The global objective of this study was to determine lubricant oil consumption as a function of engine operating conditions, and determine its contribution to particulate matter (PM) emissions in a hydrogen-fueled engine. Hydrogen offers a promising alternative for internal combustion engines owing to its clean burning properties. The success of gaseousfueled engines lies in the development and use of specially formulated and well researched lubricating oils as these oils are the only source of carbon emissions in hydrogen-fueled engines. The lubricant oil consumption can be determined in a hydrogen-fueled engine by measuring the carbonaceous emissions. This study determined lubricant oil consumption as a function of engine speed, equivalence ratio, and boost for hydrogen-fueled engine operation. The oil consumption data was fitted using multiple linear regression analysis. Elemental Carbon/Organic Carbon analysis, trace metals analysis, ions analysis, and particle size distributions at various steady state operating conditions were also performed to have an understanding of lubricant contribution to particulate emissions. The lubricant oil consumption was also measured using trace metal markers such as Ca and Zn. Oil consumption models would help in calculating ash accumulation in exhaust after-treatment devices like diesel particulate filters (DPF). The oil consumption was found to be well correlated to engine operating conditions. The particulate matter was found to be almost completely organic carbon, and the synthetic oil derived organic fraction was found to be lower in spite of its higher volatility for the conditions tested. It was found that the trace metal marker method for oil consumption determination was not a suitable method as a result of the different rates of consumption of base stocks versus additives. The particle size distributions in the case of hydrogen-fueled operation were found to be in the same order of magnitude as a diesel engine. The particle size distributions and number concentrations were found to be more influenced by the engine operating conditions and amount of oil consumed, and was not influenced by the difference in the oil volatility or the nature of the base stock (synthetic versus mineral) for the conditions tested in this study.

Characterization of the composition and toxicity of particulate matter emissions from advanced heavy-duty natural gas engines

“…However, under certain operating conditions lubricating oil proves to be a significant contributor to nanoparticle formation (Kittelson et al, 2008). A study conducted at WVU on a single cylinder research engine fueled by hydrogen showed oil consumption to be well correlated with engine operating parameters such as intake air boost, engine speed and in-cylinder pressures (George, 2008). The lube oil derived PM is more noticeable in heavy-duty natural gas engines, due to the fact that natural gas combustion is relatively soot free, and vehicles primarily operate without a DPF.…”

Heavy-duty diesel engine oil aging effects on emissions

“…In the case of turbocharged engines, oil leakage past the turbocharger seal also contributes to the total oil consumption. However, the piston-ring-liner system makes the largest contribution to the total oil consumption in the engines [7].…”

“…The analytical test methods used for determination of these properties are listed in Table 3.3 and described in this section. Similar analytical test methods were also used in other studies, [7], [20] and [21]. These tests were conducted by an external laboratory, Analysts, Inc. at their Chicago, IL facility.…”