The object of research is marine diesel engine oils, which provide lubrication, cooling and separation of friction surfaces. The subject of the research is the process of ensuring minimum mechanical losses in marine diesel engines. A problematic point in ensuring the lubrication of the cylinder-piston group and motion bearings is the lack of analytical and experimental studies that establish the relationship between the structural characteristics of engine oils and mechanical losses arising in marine internal combustion engines. The degree of orientational ordering of molecules and the thickness of the boundary lubricating layer are considered as the structural characteristics of engine oils. The determination of these values was carried out using the optical method based on the anisotropy of the light absorption coefficient by the boundary lubricant layer and the isotropic volume of the liquid (engine oil). The assessment of the level of mechanical losses arising in marine diesel engines was carried out according to an indirect indicator – the overshoot of the rotational speed and the time to reach the steady state of operation in the event of a change in load. It has been experimentally established that for engine oils used in marine internal combustion engines, the thickness of the boundary layer can be 15–17.5 µm. Motor oils, which are characterized by a higher ordering of molecules and a thickness of the boundary lubricant layer, ensure the flow of transient dynamic processes with less overshoot and a shorter transient time. This ensures the level of minimal mechanical losses occurring in marine diesel engines. The technology for determining the structural characteristics of engine oils can be used for any type and grade of oil (mineral or synthetic; high or low viscosity; used in both circulating and cylinder lubrication systems). The method of indirect assessment of mechanical losses of marine diesel engines can be used for any types of internal combustion engines of ships of sea and river transport (low-, medium- and high-speed; as well as performing the functions of both main and auxiliary engines).

No abstract

In this study, a method for ensuring reliable and safe operation of marine trunk diesel engines is considered. The research was carried out on 5L23/30 MAN-B&W diesel engines of a Bulk Carrier class vessel. The objective of the study was to determine the effect of the structural characteristics of the oil layer (wetting angle and thickness) on the operational parameters of a marine diesel engine (compression pressure, concentration of nitrogen oxides in exhaust gases and temperature of exhaust gases after the cylinder) and performance characteristics of the oil (base number, wear and contaminant elements). It has been established that an increase in the degree of the contact angles of wetting and in the thickness of the oil layer improves the heat and power and environmental performance of a diesel engine. At the same time, 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. Also, it was found that wear of diesel parts and oil oxidation are reduced. The study confirms the possibility of improving the reliable and safe operation of trunk-type diesel engines of maritime vessels by effective control of variables relating to the characteristics of engine oil.

The results of the research work on biofuel’s impact on the environmental and economic performance of marine diesel engines are presented. During the research, a fuel mixture was used that consisted of the diesel fuel RMA10 and FAME biofuel. The objective of the research was to determine the optimal concentration of biofuel mixed with diesel fuel. The research work was carried out on three of the same type of marine medium-speed diesel engine, 6N165LW Yanmar. One of the diesel engines only operated on diesel fuel, and the other two operated on a mixture of diesel fuel and 5–20% biofuel. During the experiment, the diesel engines operated at a load of 50–80% of the rated value. Experimentally, it was found that using biofuel improved the environmental friendliness of diesel engines: the emission of nitrogen oxides in exhaust gases was reduced by 8.7–23.4%, and the emission of carbon oxides in exhaust gases was reduced by 3.1–24%. However, when using biofuel, the economic efficiency of diesel operation decreased as the specific effective fuel consumption increased by 0.5–9.3%. The highest environmental efficiency was achieved when using a fuel mixture that included 10–15% biofuel in an 80% diesel load. In this case, the emission of nitrogen oxides was reduced by 21–23.5%, the emission of carbon oxides was reduced by 16.5–19.2%, and the magnification of the specific useful consumption of the diesel engine was 1–1.55%.

The object of research is the process of operation of marine diesel engines using biodiesel fuel. The subject of research is the process of experimental determination of the optimal concentration of biodiesel fuel in a mixture with fuel of petroleum origin. At the same time, a simultaneous maximum increase in environmental and minimum decrease in the economic parameters of the operation of a marine diesel engine should be ensured. The studies were carried out on Hyundai Heavy Industries 5H17/28 marine diesel engines. Three such diesel engines were part of the power plant of a specialized marine ship with deadweight of 9600 tons. The study was aimed at determining the concentration of biofuel in a mixture with diesel fuel, which provides the best environmental performance of a diesel engine. The fuel supply circuit to the first diesel did not change and the diesel was operated on RMB30 fuel. Two other diesel engines were operated on a fuel mixture – RMB30 fuel and B99.9 FAME biofuel. The content of biofuel in the mixture varied in the range of 5–20 %. The main quantities measured during the experiment were the concentration of nitrogen oxides and the volumetric content of carbon monoxide in the exhaust gases, as well as the specific effective fuel consumption. By switching groups of consumers, the operation of diesel engines was carried out at the same load, the support of which was required during the experiment. The load on diesel engines during the experiments varied in the range of 55–85 % of the nominal value. The operation of diesel engines in each of the studied modes was carried out for at least 1.5–2 hours, during which the main parameters were measured and the obtained values were averaged. It has been established that the use of biofuel increases the environmental friendliness of the marine diesel engine: – by 7.6–26.61 % (depending on the diesel loading and the content of biofuel in the fuel mixture), the emission of nitrogen oxides with exhaust gases is reduced; – by 3.8–23.6 % (depending on diesel loading and biofuel content in the fuel mixture) reduces the emission of carbon oxides with exhaust gases. It has been also determined that when using biofuel, there is an increase in the specific effective fuel consumption by 0.5–8.65 %, which reduces the efficiency of a diesel engine. The optimal composition of the fuel mixture containing biofuel is proposed to be determined experimentally for each diesel load, taking into account its environmental and economic indicators.