Date of Graduation

2008

Document Type

Dissertation/Thesis

Abstract

Interest in alternative fuels is rapidly growing due to environmental concerns. One alternative is hydrogen, which has the potential to replace conventional fuels such as gasoline and diesel in internal combustion engines. However, a key enabling factor for hydrogen to be become a viable alternative is the development of lubricating oils specifically formulated for hydrogen-fueled engines. Published data on particulate emissions (PM) from gaseous fueled engines has implicated lubricating oils as major contributors to total mass, though negligible, and the number count of PM emissions. Unlike conventional liquid petroleum-based fuels, which have been shown to be highly mutagenic, there exists sparse data, if any, on the potential mutagenicity of PM emissions from hydrogen fueled engines, and the effects of lubricating oil formulations on the chemical and physical characteristics of PM emissions. It is hypothesized that the potential mutagenicity of lubricating oil in hydrogen-fueled heavy-duty engines is a function of engine speed, equivalence ratio, boost, lubricant oil viscosity, and volatility. The global objective of this study is to develop lubricating oil formulations, which will permit extensive use of hydrogen as a fuel in internal combustion engines. The specific objective of this study is to establish the potential mutagenicity PM emissions from a hydrogen-fueled single cylinder engine using different lubricating oil formulations. To fulfill the objective of this study, a single cylinder Ricardo Proteous engine was modified to operate in the spark ignition mode, and a gaseous fuel port injector was installed. A nine condition test matrix was executed for two lubricating oil formulations, a mineral oil and synthetic oil. PM emissions were collected on 90 mm Teflon filters, and the soluble organic compounds (SOC) were solvent extracted. The oil consumption was calculated using the carbon-balance method, based upon measurement of emissions of total hydrocarbon (THC), carbon dioxide (CO2), and carbon monoxide (CO). The SOC on each filter was extracted using the soxhlet extraction method. The mutagenic activity was evaluated using the Ames Salmonella Typhimurium assay. The TA 98 was used, without metabolic activator (S9). Samples from the PM extracts were analyzed using gas chromatography (GC) to determine concentrations of polycyclic aromatic hydrocarbons (PAH) compounds. Tests performed on the mineral oil reveal that none of the conditions passed the two fold rule, but most of the conditions did pass the mutagenic response statistical test. The two fold rule requires that at least one of the doses doubles the revertants count of the negative control. The synthetic oil mutagenic results show that only two conditions (high speed and high load) passed the two fold rule and the mutagenic response test. Samples of lubricating oils, taken during testing, were analyzed for viscosity, water content, metals content, total base number (TBN), total acid number (TAN), oxidation, and nitration. The statistical analysis revealed that there was no statistical significance between oil properties and oil age, except viscosity at 40°C and water content of the synthetic oil. Further, lubricating oil formulation did not have any effect on the regulated and CO2 emissions. The chemical characterization of the PM extracts showed that PM emissions during the synthetic oil test had a lower PAH concentration in comparison to the mineral oil emissions. PAH concentration.

Download

Share

COinS