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

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.

During the decades-long development of internal combustion engines, the main criteria for optimality were the increased power, the low fuel consumption and the adjustment of the working process under non-stationary operating conditions. Even when the air quality in some settlements was significantly worsening, due to the high degree of motorization, special attention has been paid to polluting the atmosphere with exhaust gases from the engines. Problems that are created due to the increased environmental pollution significantly influence the choice of providing minimal environmental conditions, they receive priority, especially in urban areas. As toxic components are considered CO, CnNm, NOx, solid particles, etc. So if we know the conditions in which they are created then they can be the criterion for optimality. The requirements also affect their reduction within certain permitted limits.

Future emission legislation will be increasingly stringent. The current German TA Luft limit for nitric oxide (NOx) emissions from large gas engines is 500 mg/mn³ @ 5% O₂ and there is a clear trend toward further reductions. One possible strategy to meet these limits for gas engines is exhaust gas recirculation (EGR). This paper focuses on the application of 1D simulation to a variety of different tasks in gas engine development. First, the basic effects of EGR in gas engines are explained by discussing several 1D simulation results from two 1D simulation models for a large stationary gas engine. A detailed single cylinder engine model is used to study the interaction between the pre-chamber and the main combustion chamber. The boundary conditions are provided by a multicylinder engine model that includes a turbocharger. Based on simulation calculations with both models as well as measurements from a single cylinder research engine, the thermodynamic conditions in the combustion chamber and the gas dynamics are analyzed.

The development of highly efficient combustion concepts for internal combustion engines requires a suitable development methodology. In recent years, the LEC has created LDM (LEC Development Methodology), which is based on the intensive interaction between simulation and experimental investigations on single cylinder research engines. As new engine concepts are developed, many operating parameters are first defined and optimized with a 1D multicylinder engine model. This model illustrates the full complexity of the engine with its geometry, turbocharging and combustion parameters. The design of experiments (DoE) method is used in connection with 1D simulation to find the optimal engine configuration as well as parameters related to the combustion process, i.e. valve timing, compression ratio, ignition timing, excess air ratio. The maximum engine efficiency is found by taking into account the boundary conditions (brake mean effective pressure, turbocharger efficiency), where NOx level and knock limit are constraints.

The escalating fuel price and carbon dioxide legislation have renewed the interest in the methods of increasing engine thermal efficiency beyond in-cylinder techniques. The aim of this study is to review the latest technologies of waste heat recovery of exhaust gases in internal combustion engines. These include turbocompounding systems, thermoelectric generators, thermoacoustic systems and closed-loop thermodynamic cycles based on Stirling, Ericsson and Rankine cycles. A number of studies revealed that Rankine cycle is the most perspective waste heat recovery system due to its higher thermal efficiency. Finally, the components of the Rankine cycle (working fluid, evaporator and expander) were studied in detail.