Solving the problem of ocean's airspace polluting with harmful emissions of ship-generated diesel engines by exhaust gases is associated with the creation of highly effective technologies for the neutralization of nitrogen oxides NOx from the diesel plant that apply both to vessels in service, designed and built. The air entering the engine is a working fluid that carries out a certain thermodynamic cycle, resulting in a change in its chemical composition, and the exhaust gas mixture contains many components. Emissions of harmful substances during the combustion of marine fuels are limited in accordance with international programs for the protection of the atmosphere and requirements of the International Maritime Organization IMO. Requirements apply all groups of harmful emissions of marine engines. The most stringent of them concern nitrogen oxides NOx and sulfur oxides SOx. To reduce harmful emissions from the exhaust gases into the environment, scientists and world leaders in engine construction, such as MAN Energy Solutions and Wärtsilä, apply and offer a variety of techniques to reduce the number of harmful substances in the exhaust gases. One of the most promising is the exhaust gas recirculation system (EGRS) of the ship diesel engine. Its advantage over other methods is the insignificant impact on the operation of the engine. During the exhaust gas recycling a temperature of the flame in the combustion chamber decreases, which leads to the reduction of NOx number. This is a consequence of the high rates of carbon dioxide and water vapor. Since the combustion rate is reduced, the exhaust temperature and the thermal load on the engine part are increased. The dilution of the inflow air with waste gas reduces the oxygen content in the supercharged air from 21 to 13%. The possibilities of the technology of the system of recirculation of exhaust gases of a marine engine are limited by the value of the ratio of O2/CO2 in the intake air, due to which the amount of combustion products at the inlet is limited to no more than 30%

The efficiency of air cooling at the inlet of the main low speed engine of a transport vessel during operation in tropical climatic conditions on the Shanghai-Karachi-Shanghai route was analyzed. The peculiarity of the tropical climate is the high relative humidity of the air at the same time its high temperatures, and hence the increased thermal load on the cooling system, which requires efficient transformation of the waste heat into the cold in the case of the use of waste heat recovery refrigeration machines. The cooling of the air at the inlet of the low speed engine by absorption lithium bromide chillers, which are characterized by high efficiency of transformation of waste heat into cold – by high coefficients of performance, is investigated. A schematic-construction solution of the air cooling system at the inlet of the ship's main engine using the heat of exhaust gases by an absorption chiller is proposed and analyzed. With this the cooling potential of the inlet air cooling from the current ambient air temperature to 15 ° C and the corresponding heat consumption for the operation of the adsorption chiller, on the one hand, was compared with the available exhaust gas heat potential, on the other hand. The effect of using the exhaust gas heat to cool the air at the inlet of the engine has been analyzed taking into account the changing climatic conditions during the voyage. Enhancement of fuel efficiency of the ship's engine by reducing the inlet air temperature were evaluated by current values of the reduction in specific and total fuel consumption. It is shown that due to the high efficiency of heat conversion in absorption chillers (high coefficients of performance 0.7…0.8), a significant amount of excessive exhaust gas heat over the heat required to cool the ambient air at the inlet of the engine to 15 ° C, which reaches almost half of the available exhaust gas heat during the Shanghai-Karachi-Shanghai route. This reveals the possibility of additional cooling a scavenge air too with almost double fuel economy due to the cooling of all cycle air of the low speed engine, including the air at the inlet.

The efficiency of air cooling at the inlet of the main low-speed engine turbocharger of a transport vessel during operation in tropical climatic conditions on the Shanghai-Singapore-Shanghai route was analyzed. A feature of the tropical climate is the high relative humidity, respectively, moisture content at its simultaneously high temperatures. The cooling of the air at the inlet of a low-speed engine with an ejector chiller by transforming the waste heat of exhaust gases into cold was studied. The ejector chiller is used as the most simple and reliable in operation. However, the efficiency of the transformation of heat into cold by ejector chillers is low - low thermal coefficients.A design solution of the system for cooling air at the inlet of the ship's main engine using the heat of the exhaust gases by an ejector chiller is proposed and analyzed. The effect of using the heat of the exhaust gases to cool the air at the engine inlet is analyzed taking into account the variable climatic conditions during the voyage of the vessel. It is shown that because of the insufficiently high efficiency of transforming the waste heat of the exhaust gases by an ejector chiller (low thermal coefficients), the obtained cooling capacity is not sufficient for cooling the air at the inlet of the turbocompressor during operation of a marine engine in tropical climatic conditions. Therefore, the possibility of use in the ejector chiller of additional heat of charge air, which is removed by cooling water, is also considered. It is shown that the use of the heat of exhaust gases and charge air for cooling the air at the engine inlet in an ejector chiller makes it possible to double decrease the air temperature at the inlet of the main engine by 20-30 °C when the vessel operates in tropical climatic conditions on a voyage lines Shanghai-Singapore-Shanghai. This, in turn, provides an almost twice fuel consumption reduction in compared with its reduction in the case when the ejector chiller uses only the heat of the exhaust gases.

The problem of air basin pollution of the World Ocean with harmful emissions from the exhaust gases of marine diesel engines is primarily associated with the creation of highly efficient technologies for the neutralization of nitrogen oxides NOx on exhaust gases from a diesel engine. Emissions of harmful substances from the combustion of marine fuels are limited by international atmospheric protection programs and the requirements of the International Maritime Organization (IMO). The requirements relate to almost all groups of harmful emissions in marine engines and the more stringent of them are primarily related to nitrogen oxides NOx and sulfur oxides SOx. To reduce harmful emissions from exhaust gases into the environment, scientists and world engine leaders use and suggest various methods for reducing the content of harmful substances in exhaust gases. The implementation of new standards in the areas of further improvement of the working process, the use of alternative fuels, fuel, and air additives, as well as selective catalytic reduction systems do not preclude further development of scientific research in the field of exhaust gas cleaning. One of the promising ways in environmentalizing marine internal combustion engines is the neutralization of harmful substances in exhaust gases through particular gas recirculation (EGR-technology). However, the use of such techniques conflicts with the engine's energy efficiency. In the work presented, the scheme-design solution of the exhaust gas recirculation system with using the heat of recirculation gases by an ejector refrigeration machine for cooling the air at the intake of ship's main engine is proposed. The effect of using the heat of recirculation gases for cooling the air at the intake of the engine is analyzed taking into account the changing climatic conditions for a particular vessel's route line. It is shown that the use of an ejector refrigeration machine reduces the air temperature at the entrance of the main engine by 5…15 ° С, which reduces the specific fuel consumption. This reduces emissions of harmful substances when the engine is running with recirculation of gases.