Analysis of the operation of marine diesel engines when using engine oils with different structural characteristics

The object of research is the process of lubrication of marine trunk diesel engines. The subject of research is marine diesel engine oils, which provide lubrication, cooling and separation of friction surfaces. The analysis of the operation of marine diesel engines using motor oils with different structural characteristics is carried out. The studies are carried out on Yanmar 6EY18AL diesel engines of a Multipurpose Vessel class ship with deadweight of 27540 tons. The objective of research is to determine the effect of the structural characteristics of the oil layer (contact angle and thickness) on the performance parameters of a marine diesel engine and the performance characteristics of the oil used in its circulating lubrication system. At the same time, the compression pressure, the concentration of nitrogen oxides in the exhaust gases, and the temperature of the exhaust gases after the cylinder are considered as the operating parameters of the diesel engine; as performance characteristics of the oil – its Base Number, as well as its Wear and Contaminant Elements. The studies are carried out on two diesel engines of the same type, in the circulating lubrication system of which oils with different structural characteristics were used. Structural characteristics of the oil layer were determined by ellipsometry. The operational characteristics of the diesel engine – using the Doctor diagnostic system. Oil performance – by spectrographic analysis. It has been established that an increase in the contact angles of wetting and the thickness of the oil layer improves the heat and power and environmental performance of a diesel engine. At the same time (for the period of operation of diesel engines 500–1000 hours), the decrease in compression pressure in the cylinder slows down, the temperature of gases after the cylinder decreases, and the emission of nitrogen oxides with exhaust gases decreases. In addition, the wear of diesel parts and oil oxidation are reduced. The information obtained in the course of the study on the structural characteristics of motor oils will provide the possibility of their selection and further use of those that will contribute to a better maintenance of the operational performance of marine diesel engines.