Romualdas Juknelevičius, Stanislaw Szwaja, Michal Pyrc, Michal Gruca and Saugirdas Pukalskas
The article presents the test results of the single cylinder compression ignition engine with common rail injection system operating on biofuels and conventional diesel blends with hydrogen. Two types of liquid fuels were tested: blend of the 7% Rapeseed Methyl Ester (RME) with conventional diesel fuel and Neste Pro Diesel – blend of the 15% Hydrotreated Vegetable Oil (HVO), produced by Neste Oil Corporation with conventional diesel fuel. The purpose of this investigation was to examine the influence of the hydrogen addition to biofuels and diesel blends on combustion phases, autoignition delay, engine performance efficiency and exhaust emissions. Hydrogen fraction was changed within the range from 0 to 43% by energy. Hydrogen was injected into the intake manifold, where it created homogeneous mixture with air. Tests were performed at both fixed and optimal injection timings at low, medium, and nominal engine load. After analysis of the engine bench tests and simulation with AVL BOOST software, it was observed that increasing hydrogen fraction shortened the fuel ignition delay phase and it affected the main combustion phase. Moreover, decrease of carbon monoxide (CO), carbon dioxide (CO2) and smoke opacity was observed with increase of hydrogen amounts to the engine. However, increase of the nitrogen oxide (NOx) concentration in the engine exhaust gases was observed.
Maciej Gis, Mateusz Bednarski and Piotr Wiśniowski
In 2015, the number of vehicles in the world exceeded 1.1 billion units. In the coming years, it is expected that the largest increase in the number of vehicles will take place in developing countries. This is a problem in particular in terms of emissions of harmful substances from vehicles. Considering that all manufactured vehicle models have to undergo a detailed homologation and meet the exhaust emission requirements before placing on the market, it is necessary to refine test procedures, including test cycles, in which vehicle emissions are determined. At present, the NEDC approval test is valid in Europe. It is a cycle reproduced on a chassis dynamometer in steady conditions. It consists of an urban section repeated four times and an extra urban part. From 2019, a new test procedure will take effect, which uses the WLTC cycle, also reproduced on a chassis dynamometer in fixed conditions. It is much more complex and better reflects the real traffic conditions. For a better illustration of the differences that occur between the current NEDC cycle and the new WLTC, the article presents a comparative analysis of both driving cycles. This is to present the justifiability of using a new driving cycle and to present its complexity. The article presents own research of a vehicle with a spark-ignition engine, which has been tested both in the NEDC and WLTC cycle. On the basis of the obtained data, it was possible to determine the differences in the emission of harmful exhaust gas components and indicate how the new homologation procedure affects the emissions from the vehicle.
The article presents the methodology of calculation of principal parameters of ship’s hull dimensions, called „significant ships list”, at preliminary stage of design process. Knowledge collected in the database is related to new buildings classified according to type, displacement, or DWT, shipping class, maximum speed etc. Are analysed dimensional constraints due of Froude Number, ships dimensional coefficients block and weigh coefficient, relations of main dimensions such as L/B, B/T, L/H, B/H etc. . Those parameters coming out from ship-owners requirements like type of ship, load capacity, type of cargo, shipping zone, speed and some more. Very helpful tool for such analysis is list of significant ships created for specified types of ships. Mentioned lists are very effective under conditions that cover broad-spectrum new buildings and data included are credible. Uncritical taking values included in significant ships list can lead to critical errors in selection of main dimensions of a ship or its propulsion powering. For that reasons, basing on analysis, as main criteria of similarity of ship’s hull were assumed mass coefficient, block coefficient and Froude Number . That procedure has significant impact at proper estimation of propulsion power. Another reliable parameter of evaluation of power seems to be relation between power and load capacity Ne/D.
The aim of analysis presented in the article is results of measurements of torsional deflections of a crankshaft of three-cylinder internal combustion diesel engine. The wavelets of the run of torsional twists were processed by decomposition to harmonics using FFT. In order to exactly recognize all dynamic aspects of gas forces acting during working stroke, decomposition was done in two ways: first one relaying on records encompassing one working cycle (two revolutions), the second one based at separated periods encompassing angular an interval from TDC (Top Dead Centre) of one cylinder to TDC of subsequent in firing order. For three-cylinder engine, width of the interval is 240 degrees of crank angle. In order to obtain reliable results, torsional deflection signals acquisitions were recorded numerous times including changes of outer conditions (temperature, atmospheric pressure) and different values of the engine loads. The main goal of conducted experiments was looking for an answer of a question if exist any differences between frequency spectrums of harmonics of run of full cycle ( two revolutions) and the same cycle divided by three separate intervals. Analysis was conducted in order to state any possibility of diagnostic signals acquisition caused by abnormalities of combustion process. Results were presented in form of comparison of frequency spectra taken from full cycle and divided intervals.
Jarosław Mamala, Mariusz Graba, Andrzej Bieniek and Krystian Hennek
This article describes the method of controlling an electric magnetic linear actuator that moves an inlet valve of an internal combustion engine. Thanks to the use of the electric control of the inlet valve of the internal combustion engine, it was possible to implement a variable effective compression ratio of the operating power unit, adapting it to the current needs and engine load. In this design, valvetrain was modified by introducing an autonomous intake valve operation with the use of a specially designed electromagnetic actuator. The introduction of this system necessitated an additional modification of the intake camshaft. The control was carried out with the use of a real-time controller with a built-in FPGA unit. The proposed design of a system with an electromagnetic actuator will allow obtaining an additional degree of freedom in the control unit. Particular attention should be paid to registered values or air pressure in the intake stroke for a closed or partially opened throttle, which generates significant pumping losses. The use of an electromagnetic actuator in the intake can help reduce said losses.
Aluminum alloy AW-7020 is characterized by high fatigue strength. It is used primarily in welded constructions, which should be characterized by high strength and resistance to cyclically variable operational loads. They have found wide application in light welded ship constructions, bridge-carrying elements, cranes, hoists, vehicles, roof beams in roof constructions, and security barriers. The paper attempts to determine the influence of selected types of applied heat treatment on the structure and hardness of the AW-7020 alloy used in the shipbuilding industry. Heat treatment processes have been described in the aspect of improving the mechanical and strength properties of the tested alloy and its impact on ductility. Several supersaturation and aging sequences were used in the course of the study. The results of hardness tests of aluminum alloy after its earlier supersaturation and aging (natural and artificial) have been presented. Photographs of internal structures in individual sequences were taken. The obtained hardness measurement results and analysis of structures in individual states were compared with the delivery condition. To illustrate selected heat treatment processes, transient tests were also performed to accurately verify the effect of aging after saturation on hardness and changes occurring in the material structures. The results of the material tests showed that the type of heat treatment after saturation is of significant importance for the hardness and structures of the AW-7020 alloy. As a result of the research, it was proved that the tested alloy obtained in the artificial aging process more favourable strength properties, in a shorter period, compared to the use of the natural aging process.
Low speeds of heavy mobile machines combined with large inertia result in the excitation of low frequency vibrations. Dissipation of vibration energy in the case of unsprung machines is performed only through tires, which slightly reduces the intensity of vibrations. Effective reduction of vibrations of mobile machines is possible only with active or semi-active methods. In unsprung mobile machines, on the way of propagation of vibrations between the source of vibrations and the protected object (machine operator), are vibroisolation systems located. These are most often controlled seat suspensions. In the case of the active suspensions, it is necessary to provide external energy, e.g. in the form of compressed air. The compressed air has the advantage that it is generally available in working machines as the working fluid and has its environmentally friendly properties (leaks do not contaminate the environment). This article is the result of the continuation of work on active methods of vibro-activity lowering in mobile machines, which resulted in, among others, elaboration of simulation model of the active operator’s seat suspension with controlled pneumatic actuator and its experimental identification. In particular, it was verifying the effectiveness of the adopted solution made the identification the friction model and thermodynamic phenomena in the controlled pneumatic cylinder. The aim of this work is parametric optimization of the suspension system and searching for the optimal control strategy. Experimental tests were carried out under conditions of harmonic excitations, coming from the electromechanical vibration exciter with controllable pitch and frequency. Data acquisition system and control circuit of the proportional directional control valve, supplying compressed air to the actuator were implemented using MATLAB-Simulink Real-Time software.
Environmental emission of road transport is a key problem. Periodic environmental test are designed to ensure minimum emission. Periodic checks are based on measurements. In this emission measurements fuel type plays an important role. The Brettschneider equation is a method used to compare the idealized and actual air fuel ratio. Brettschneider established a method to calculate ratio of oxygen to fuel by comparing the ratio of oxygen molecules to carbon and hydrogen molecules in the exhaust. In this article, authors have investigated blended ethanol effect on idealized and actual air fuel ratio based on Brettschneider equation. The main result of the article that blended ethanol has insignificant effect on air-fuel ratio. The article presents inter alia difference in stoichiometric air fuel ratios in case of different fuels, changes in λ due to blending ethanol and comparison of influence of emissions of different types of transport. In the article authors focus particularly on periodic checks and gasoline driven cars. The main research question was if ethanol blends have effect on idealized and actual air fuel ratio based on Brettschneider equation.
In recent years, the interest in the use of renewable fuels in transport has increased. This is due to the European Union’s policy to reduce greenhouse gas emissions. These fuels, in addition to the effect of reducing carbon dioxide and the other greenhouse gases, may increase the emissions of other exhaust components. The article describes the problems of pollutants emissions from the engine exhaust system, related to the use of biofuels in combustion engines or their additives in conventional fuels. The influence of the chemical composition of selected biofuels on the emissions properties of vehicles and their engines will be discussed. The tests results of engines fuelled with selected biofuels, carried out by the authors of the article, will be presented. These tests will be carried out on chassis dynamometer and engine test bench, in standard research tests used in measurements of pollutants emissions like NEDC, ESC, ETC, etc. Furthermore, selected operational parameters of vehicles and engines will be compared with biofuels and conventional fuels.
The main idea of the work is to create scientifically grounded technological conditions for treatment of tab grooves in the discs from heat resisting steel, which stipulate formation of roughness of treated surfaces at the level of design requirements, useful compressive residual stresses and a defective surface layer, which increases reliability of operation of interlock in the absence of any defects on the working surfaces of tab grooves of various types, under conditions of maximizing efficiency of their treatment method. Dependences of roughness of the treated surface on the technological factors of the broaching process Ra = f (V, S, γ, HRC) have been proposed. As a result of experimental studies, the nature of distribution of residual stresses, depth and degree of strengthening of the surface layer, depending on the technological conditions of the tab grooves treatment, has been established. The article presents research of surface quality parameters; study all the selected parameters of the surface quality and surface layer and an algorithm to perform experimental work. The algorithm has been built on major principles of control and fixation methods, which stipulate use of non-destructive methods of control. Graphs of strengthening the surface layer of samples, depending on their processing modes and graphs of the distribution of residual stresses in the surface layer are also presented.