Hochfellner, Baptiste

This report represents phase I of a research cluster regarding the scientific deepening of the compre-hension about particulate matter (PM) emission formation traceable to lubricating oil consumption in medium-speed engines. These ICEs are mainly operated on-board ships and in stationary power plants, environments that are fundamentally different from typical land vehicle use. On one hand PM-emission limits do not exist in the maritime sector. On the other hand, service life, reparability, reliabil-ity, efficiency and corrosive wear play decisive roles. Apart from the operating costs, there is there-fore no incentive to reduce the lubricating oil consumption. Consequently, this is about an order of magnitude higher than with their counterparts. However, the increasing interest in new alternative fuels and combustion processes, as well as new and regularly tightened emission limits, point to the need to investigate the undoubted potential for lubricating oil consumption reduction. In the course of this project three research institutes share knowledge and appliances. Two medium speed marine engine test beds at Hamburg University of Technology (ASM) and Flensburg University of Applied Sciences (INMT) have been accompanied by measurements from Institute for Analytical Measurement Technology Hamburg eV (IAM). Phenomena and correlations of the tribological system in the area of the piston group were being investigated. To analyze the oil supply in the combustion chamber, which contributes to emissions, a combination of exhaust gas analysis and optical film thickness measurement was applied. The objective in terms of measuring technology in this project was to validate the measurement capability with these systems on the large bore engines. The development of the measurement systems was accompanied by adjustments to the existing hardware and the development and implementation of new hardware at both engine test beds. At ASM a cylinder liner for the dual-fuel test bed has been designed. It comes with a new form factor, reduced dead volume and is equipped with a modern honing structure. It also is ready for optical oil film thickness measurements. At INMT the whole piston group was updated. The new Mid Stop cylin-der liner design with Anti-Polishing-Rings and modern honing structure is paired with an improved piston ring geometry. In terms of the exhaust gas analysis a mass spectrometer with fast direct inlet system for quantifying oil emission and an aerosol spectrometer for quantifying aerosol particle emission were used. The high particulate load due to soot formation in diesel operation, combined with the much slower set-tling times of large bore engines compared to passenger car engines, required inlet contamination prevention. Measurements were successfully carried out with both systems on the engine at ASM. The measure-ment capability of the aerosol measurement technology was also demonstrated at INMT. The oil emission measurements at INMT show oil emission effects that do not correspond to those of other engines. It is necessary to further modify the measurement method in order to successfully quantify the oil emission. This will be implemented in the follow-up project by tracing the oil with PAHs. The determination of the oil film thickness on the cylinder liner was carried out using the in-house de-veloped, compact and cost-effective LED measuring system based on the fluorescence principle. Initial measurement results obtained at ASM have shown the potential and limitations of the approach. Important steps in this process are interpretation of the measurement results of the oil film thickness-es at different positions on the cylinder liner as well as their correlation with other relevant measurements.

The three main air pollutants produced by marine traffic are sulphur oxides, nitrogen oxides and particulate matter (PM). Due to the fact that marine traffic near shores and even in urban areas is on the rise, while on the other hand air quality is a major political and social concern, special account needs to be taken of the environmental impact of ships operating in these regions. While strict restrictions for the first two mentioned pollutants exist, there are currently none for PM emissions in shipping. Since it is only a matter of time before threshold values will be set, the gaining of knowledge in the field of PM is of exceptional importance. The target of the project is an evaluation of measures that are expected to reduce the lubricating oil-originated PM emissions with respect to their results and impact on engine operation. Additional goals are the classification of PM emissions in medium speed engines and to describe the correlation between these emissions and the lubricating oil film thickness.

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