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

This paper presents an energy analysis of main and auxiliary steam turbines from conventional coal fired power plant. Main turbine is composed of three cylinders connected to the same shaft which drives an electric generator, while auxiliary steam turbine is used for the boiler feedwater pump drive. The whole analyzed main steam turbine produces mechanical power equal to 312.34 MW, while in an ideal situation, it can produce mechanical power equal to 347.28 MW. The highest part of the mechanical power in the main turbine is produced in the low pressure cylinder. Auxiliary steam turbine in exploitation develops mechanical power equal to 6768.94 kW, while in an ideal situation it can develop 8029.03 kW. Whole main turbine energy efficiency is equal to almost 90% what is in the expected range for such high power turbines. The auxiliary steam turbine has an energy efficiency equal to 84.31%, which is almost 6% lower in comparison to the main turbine. Energy flows delivered to the last two feedwater heaters (HPH2 and HPH3) in the condensate/feedwater heating system are notably higher in comparison to energy flows delivered to any other condensate/feedwater heater.

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.

Damage to the turbocharger of the 8400kW diesel engine, which had operated about 66 640 running hours, has caused off hire of the vessel for 10 days and the turbocharger repair had cost more than half a million euros. The study performed on this work consi sts of evaluating the consequences of the low turbocharger performance on the fuel oil consumption and the reasons for this. Specific data were collected and analysed in order to create an appropriate mathematical model between the studied parameters. Measurements and data collected were performed a month before turbocharger damage and after the TC overhaul (with new cartridge). As results can be concluded that losses in turbocharger performance is very important for the efficient operation of the main engine, they must be monitored and analysed.

In this paper, two-cylinder steam turbine, which operates in nuclear power plant is analyzed from the energy viewpoint. Along with the whole turbine, energy analysis is performed for each turbine cylinder (High Pressure Cylinder – HPC and Low Pressure Cylinder – LPC). A comparison of both cylinders shows that the dominant mechanical power producer is LPC, which also has much higher energy loss and much lower energy efficiency. Therefore, any potential improvement of this steam turbine should be based dominantly on th e LPC, which also has a dominant influence on energy analysis parameters of the whole observed turbine. The whole turbine produces real (polytropic) mechanical power equal to 1247.69 MW, has energy loss equal to 352.70 MW and energy efficiency equal to 77.96%. According to obtained energy efficiency value it can be concluded that the whole analyzed steam turbine is comparable to main marine propulsion steam turbines, while its energy efficiency is much lower in comparison to steam turbines from conventional steam power plant s which operates by using superheated steam.

In the present publication it is considered the technology and the features of the operation of the newly introduced in the marine industry wide spreading dual fuel four stroke engines. There are analysed the significant differences between the conventional Diesel engines and the dual fuel Otto engines in their operation process. The influence of the gas fuel quality in the case of the dual fuel engines is in the main concern underlined. Simulation based experiment is carried out for data attaining, related to the performance of the dual fuel engines influenced by the fuel quality on high load range. The acquired data is analysed, and evaluation of the engine derating outcome is performed. On the base of the results are stated conclusions and recommendations to be followed by the engineering crew members dealing with such kind of engines on board LNG fuelled ships.

The main subject of this paper is the development of a multicylinder engine model for the prediction and optimization of engine performance based on one-dimensional (1D) simulation. 1D simulation is widely used to preoptimize engine geometry and operating parameters to achieve performance targets and comply with operational and emission constraints. Due to the short calculation times, 1D simulation allows the evaluation of a larger number of variants. 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. In this paper the design of experiments (DoE) method is used in connection with 1D simulation to determine the optimal engine configuration as well as parameters related to the combustion process, i.e., valve timing, compression ratio, ignition timing, excess air ratio. This approach enables the determination of the maximum engine efficiency while taking the boundary conditions and the constraints of nitrogen oxide emissions (NOx) and knock into account. The method also enables the reduction of the cylinder-to-cylinder deviations by improving the gas dynamics and the fuel metering in the main combustion chamber and in the prechamber, which is especially important for the multicylinder engine. The simulation results are validated with experimental investigations on a single cylinder research engine.

Normally, maritime, air and surface transport assets powered by internal combustion engines are the major sources of chemical, biological and physical pollution of the environment. In the meantime, oil shortage and world oil prices are rising every year, which raises questions on the use of alternative energy sources that are not fossil fuels.
At the present time, natural gas as one of the types of fuel is widely and successfully used in surface transport owing to the availability of their sufficient reserves and good thermophysical characteristics. The article deals with the prospects for natural gas production in the sea and the possibilities of utilizing its energy source in small-capacity marine and river transport equipment in both diesel-cycle and directly converted to natural gas-powered diesel engines.

Since the fuel-saving idea was introduced in the 20th century, energy efficiency has gained attention in the transport industry. Ground vehicles (military, agricultural, and construction) usually operate on unprepared ground and need to overcome very complex and difficult ground obstacles, such as steep grade and very soft ground. The electrification of conventional vehicles, ranging from passenger vehicles and trucks to ground vehicles such as agricultural tractors, construction equipment and military vehicles, can poten tially offer improvements in fuel economy and emissions. Applied new systems reduce the amount of mechanical energy needed by the thermal engine by recovering the vehicle kinetic energy during braking and then assisting torque requirements. Energy management strategies for off-road vehicles are studied in this paper. With heavily fluctuating fuel prices, the total cost of ownership of loaders, excavators, and other classes of ground vehicles is nowadays strongly influenced by the fuel costs and there is growing concern about CO2 emissions as well as about the long-term availability of fossil fuels.

The article is devoted to the analysis of the most used additives for lubricants. The principle of their operation and the result of their work are considered. The effect of additives on the structure of surface layers on the surface of friction pairs is est imated. The analysis showed the use of only a limited number of principles of the action of antifriction additives. Theoretically promising antifriction additives for base oils, relevant for use in railway transport, have been proposed.

The article discusses the benefits of converting diesel to gaseous fuels, such as reducing the toxicity of engine exhaust gases, fuel costs and noise. It is also noted that the conversion of a gas diesel engine is technically simple and, if necessary, it is possible to operate on diesel fuel. The main focus is on improving the efficiency of the diesel engine by adjusting the fuel mixture so that the power of the gas-diesel engine and the diesel engine is the same under all load conditions. The influence of the explosive properties of fuel and its dosage on the characteristics of gasoline is estimated.

This paper present energy and exergy evaluation of CO2 closed-cycle gas turbine process. The most important operating parameters of the whole observed cycle, as well as of each of its constituent components are presented and discussed. In the observed process, produced useful mechanical power for the power consumer drive is equal to 5189.78 kW, while the energy efficiency of the whole cycle is equal to 36.6%. Heat Regenerator is a crucial component of the observed process – without its operation energy efficiency of the whole cycle will be equal to only 16.91%. From the exergy aspect, Turbocompressor (TC) and Turbine (TU) shows good performances because its exergy efficiencies are higher than 90%. Regenerator exergy efficiency could be increased by lowering the temperature of the ambient in which analyzed CO2 closed-cycle gas turbine operates.

The present paper is focusing on a basic research for an initial design of an internal combustion engine for use in a range extender unit for an electric vehicle. The paper introduces a short description of the power train concept as well some interesting points, problems and challenges during the design process of the internal combustion engine. Some of them are connected with a proper selection of the engine configuration (number of the cylinders, their configuration, etc.), a determination of the engine main parameters (bore and stroke) and how they affect the engine operation and performance. Different parametric models are used and some output results are presented.