International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The usage of alternative fuels that reduce the emission of harmful components, but do not eliminate their presence (especially nitrogen oxides) will be analyzed in the article. researchers prove that operation process of diesel on standard fuel is characterized by the formation of nitrogen oxides during the combustion of a heterogeneous mixture of diesel fuel and air in those local zones, in which the composition of the mixture is close to the stoichiometric mixture. According to this, an actual problem today is to develop the method of perfect combustion process for diesels, when during the diesel operation the local values of air excess coefficient αi and temperature Ti will not be in the range in which nitrogen oxides and soot are formed. So, converting a diesel engine into gaseous fuel ensures a reduction of toxicity and smokiness in exhaust gases and from this point of view, the values of the air excess coefficient will be considered in accordance with the mode of diesel operation and possibility of using various types of impurities to improve fuel properties and, as a result of their consumption, to improve both, ecological and efficient indicators.

The paper will discuss and analyze the values of ecological and efficient indicators of standard fuels used in marine vehicles, and their negative impact on the surrounding environment. Reasons for the deterioration of environmental indicators, considering the processes that occur in the engine and the properties of the fuel. The paper also discusses environmental and economic indicators by using various fuel additives. Marine internal combustion engines’ most important operational characteristics are reliability, fuel efficiency and environment safety indicators, which depend on complex design and operational factors. One of the most important factors is the quality of diesel fuel. The physical and chemical properties of fuel affect the mixture formation and combustion processes in diesel cylinders, the completeness of the combustion of the fuel mixture, fuel efficiency, the content of harmful substances in engine exhaust gases, fuel supply equipment and cylinder parts – (piston group) and others. The most common way to ensure diesel fuel’s required properties is to bring multifunctional additives into practice. An overview of the most modern diesel fuel additives will be presented based on the results of the patent search, which ensures improved formation of the mixture and complete combustion of fuel, The article will also present information about the chemical composition of additives and the effectiveness of their mechanism of action. Dependence on ignitability and structure of air-fuel mixture is described in the paper. Foreign manufacturers of diesel fuel additives are indicated. Tests conducted on four-stroke high-speed diesel engines made it possible to determine that the use of an additive (“Nagro Boost”) provides a reduction in effective fuel consumption by 3-7% and does not increase harmful effects in the exhaust gases of internal combustion engines when the engine operates with load and screw characteristics. A conclusion is made about the perspectives of using these and other additives to increase the fuel efficiency and environmental friendliness of internal combustion engines.

If a fuel mixture consisting of a liquefied gas fuel is prepared in the water transport diesel engines, i.e. the gas-diesel process occurs, where methanol is used as an explosive fuel, resulting in the reduction of the self-ignition delay period and fuel combustion duration, the limits of the working mixture combustion are expanded (hybrid combustion), and the mixture formation process is improved, resulting in an increase in the combustion speed, i.e., the complete combustion of the fuel mixture occurs during the active combustion period, and the cycle in the engine is closer to the Otto cycle, which improves the environmental and efficient indicators of diesel engine compared to the gas-diesel engine, where the diesel fuel is used as an explosive fuel.

In diesel engines, the fuel mixture consisting of liquefied gas and hydrogen is prepared, and a process corresponding to the gasdiesel cycle is implemented, where methanol or diesel fuel are used as an explosive fuel, as a result of which the self-ignition delay period is reduced, and the fuel combustion duration during active combustion is reduced as well. That is, the limits of the working mixture combustion are expanded (hybrid combustion), the mixture formation process is improved, and the cycle carried out in the engine is closer to the Otto cycle, which improves the environmental and efficient indicators of diesel engine compared to the gas-diesel engine, where diesel fuel is used as an explosive fuel, which makes it possible for diesel engine to run: only on liquefied gas; only on hydrogen, only on a diesel fuel or on a combination of different fuel mixtures.