The article is devoted to one of the most important problems of modern power engineering is to improve the efficiency of fuel utilization, characterized by energy efficient motors. Traditional methods of improving energy efficiency are the use of secondary energy resources (heat) of the exhaust gas of engines and heat transfer for their cooling systems. The article presents the results of calculations of power efficiency of utilization of the turbine, working under direct Rankine cycle using different coolants. The basic reserve of increase of power efficiency of thermal engines is the rational use of secondary energy resources.To assess the prospects of using secondary energy resources heat transfer fluids (coolants) cooling systems the calculation of the heat pump, working on the reverse Rankine cycle. Based on the results of the calculations in the article the conclusion about the prospects of using these devices, including the replacement of Autonomous boilers in ship power plants. The article also contains proposals for use of alternative types of secondary energy resources, such as the mechanical energy of a fuel and its gladatorial. The article shows that the use of these energy resources seems to be promising when using gas fuel. This research is relevant in connection with active introduction of gas and gas-diesel engines in various sectors of energy and transport. The data obtained in the result of the research show that the use of secondary energy resources heat engines using the utilization of turbines and heat pumps of modern design is promising and allows to increase the rate of fuel consumption of piston and gas turbine engines. When using gaseous fuels have the additional possibility of using secondary energy resources.

The paper is devoted to the urgent problem of improving the automatic regulation of the thermal state of internal combustion engines and controlling the water-chemical cooling regimes during the transition to high-temperature cooling. Principal and functional diagrams of cooling systems with improved control are presented. The prospects of controlling the pressure in the internal circuit of high-temperature engine cooling systems and the automatic control of the physicochemical characteristics of the coolant have been proved.

The paper is devoted to the study of the regularities of changes in the quality of working fluids circulating through the systems of internal combustion piston engines. During the research, the parameters of fluids that characterize its operational properties, as well as external effects that can lead to changes in the properties of the fluid, were determined. It is shown that the deterioration of the quality of engine oil and coolant of piston engines during operation is caused by the destruction of additives that are part of the fluid and provide their required properties. A laboratory installation has been developed and created that allows simulating thermal and mechanical effects on working fluids similar to those acting during circulation through engine systems. The graphical dependencies obtained as a result of the experiment are presented. Mathematical processing of the experimental data allowed obtaining regression dependencies that correctly describe the processes of changes in time of the most important characteristics of working fluids under the action of cyclic thermal and mechanical effects. The described method can be used to study the influence of operational factors on the properties of various working fluids of internal combustion piston engines.

A prerequisite for the long-term and safe operation of marine diesel engines is the high quality of operational materials, which include engine oils and coolants. The required quality of operational materials is ensured by the introduction of additives into their composition, which are now increasingly used as nanoparticles. During operation, as a result of the destruction of additives, the operational properties of coolants and engine oils deteriorate. The conducted studies allowed us to evaluate the change in the lubricating ability of engine oils of two brands that are used in marine diesels during operation. As a characteristic of the lubricating ability of the oil, its kinematic viscosity was used. The experimental determination of the kinematic viscosity of engine oil samples having different periods of operation, and the subsequent mathematical processing of the experimental results made it possible to determine the dependencies characterizing the change in the kinematic viscosity of engine oil during its operation. The research results confirm the possibility of scientific justification for extending the use of marine diesel engine oils, which reduces operating costs and increases the environmental safety of marine diesel engines.

Forcing of ship internal combustion engines at the average effective pressure is accompanied by an increase in the maximum cycle pressure, an increase in the thermal stress of the cylinder-piston group parts and an intensification of their wear. Wear of parts of the cylinder group leads to an increase in the gap between the piston and the cylinder mirror. The consequence of increasing the gap is a decrease in heat transfer from the piston to the cylinder walls and an increase in the breakthrough of gases having a high temperature from the combustion chamber to the gap. A critical increase in the temperature of the piston can lead to its destruction and engine failure. The most typical types of piston failure are presented in the article. The aim of the research was to assess the influence of these two factors on the temperature condition of the piston. Calculation of heat transfer processes in the annular channel, performed using differential equations of energy and continuity, as well as the criterion equations of fluid flow in flat channels allowed to determine the temperature of the gases and the lateral surface of the piston at different values of the gap between the piston and the cylinder sleeve and different gas flow rates in the gap. The calculation was performed for the engine CHN 18/20, having a piston made of aluminum alloy. It was found that the increase in the number of gases entering the gap from the combustion chamber has a more significant effect on the temperature condition of the piston compared to the gap, increasing due to wear of the engine cylinder group parts. It is concluded that the number of gases with high temperature entering the gap leads to a significant increase in the temperature of the piston. The increase in the temperature of the piston due to wear of the parts of the cylinder group must be taken into account when determining its heat-stressed state. To ensure the permissible temperature level of the piston during operation, it is necessary to develop design and technological measures aimed at reducing the flow of gases through the gap between the piston and the cylinder mirror. Keywords: marine internal combustion engines, parts of cylinder and piston, wear, gas breakthrough, heat transfer in flat channels, the temperature condition of the piston, the reliability of marine diesel engines.