Tomasz Skrzek

Bio: Tomasz Skrzek is an academic researcher from Kazimierz Pułaski University of Technology and Humanities in Radom. The author has contributed to research in topics: Diesel fuel & Ignition system. The author has an hindex of 3, co-authored 17 publications receiving 24 citations.

Assessment of the effect of gaseous fuel delivery mode on thermal efficiency and fuel losses during the valve overlap period in a dual-fuel compression ignition engine

Abstract: The paper describes the effect of dual fuelling of single cylinder AVL test CI engine with the use of two ways of gas delivery to the engine manifold. The engine was fuelled diesel oil and propane. For all the tests, gas consumption was maintained at the same level. In the first mode the gas was delivered by injector located under inlet valve. In the second method, there was used a mixer fitted to the intake manifold. The paper compares the results of thermal efficiency and emissions of propane in the exhaust for both fuelling modes. Research clearly show how important it is to synchronize the injector opening time of the intake stroke. This is especially important for supercharged engines in which there is a valve overlap.

Repeatability of High-Pressure Measurement in a Diesel Engine Test Bed.

Abstract: This paper addresses the issue of metrological accuracy of instantaneous in-cylinder pressure measurement in a diesel engine test bed. In studies, the central unit has been the single-cylinder AVL 5402 engine. The pressure measurement was performed with a sensor designed for thermodynamic analysis, and the results were related to the crank angle, where two rotations corresponding to the four-stroke working cycle were denoted as angles between -360° and +360°. The novelty of this paper is the proposition of how to perform a type A uncertainty estimation of the in-cylinder pressure measurement and to assess its repeatability. It was demonstrated that repeatability of the measurement during the ignition process was difficult to estimate because of the phenomena that cannot ensure the repeatability conditions. To solve the problem, two methods were proposed. In one method, the pressure was measured in the subsequent cycles immediately after the ignition was turned off, and in another method, the engine was driven by a starter. The latter method provided maximal pressure values much lower than during usual tests. The obtained repeatability of measured pressure was %EV = 0.4%, which proved high capability of the evaluated measurement system.

Comparative examination of performance characteristics of an IC engine fuelled with diesel oil and rape methyl esters

Abstract: Results of comparative examination of the performance characteristics of a compression ignition (CI) engine fuelled with diesel oil and rape methyl esters (RME) have been presented. The engine performance characteristics were assessed from the point of view of energy (effective power and torque of the engine), economy (effective efficiency), and environmental impact (pollutant emission). At the tests, the admixture of summer and winter additives to the rape methyl esters was taken into account. The tests were carried out

Effect of the exhaust gas recirculation ratio and the energy share of the gaseous fuel on basic operating parameters and exhaust emissions in a dual-fuel compression ignition engine operating on natural gas

Abstract: For many years in the Department of Automobiles and Internal Combustion Engines at Kazimierz Pulaski University of Technology and Humanities in Radom there are carried out investigations on dual-fuel combustion system in a compression ignition engine. The majority of literature reviews, as well as the authors' studies were limited to the older generation engines, i.e. naturally aspirated engines that are not equipped with the exhaust gas recirculation system. The paper presents results of investigations on a turbocharged engine equipped with an EGR system. The authors tried to assess the effect of the recirculation ratio on engine performances (mainly the mean effective pressure and the engine overall efficiency as well as exhaust emissions). The obtained results indicate that it is possible to apply high energy shares of the gaseous fuel maintaining at the same time high engine overall efficiency and visibly reducing the particulate matter emission. It was also noticed that the NOx emission may be visibly reduced introducing the exhaust gas recirculation system. Unfortunately, an increase of the gaseous fuel energy share results in slightly higher hydrocarbon and carbon monoxide emissions.

Study of the Effect of Physicochemical Degradation and Contamination of Motor Oils on Their Lubricity

Abstract: Internal combustion engine lubrication is essential for unwanted energy and material losses. As part of the experimental work, the lubricity of both new and worn motor oils of Society of Automotive Engineers (SAE) 15W-40 and SAE 10W-40 with different American Petroleum Institute (API) performance classifications, which were taken from various motor trains during maintenance or oil change, was assessed. A total of sixteen lubricant samples were evaluated. Lubricity, i.e., the load capacity of the lubricating film, was evaluated on the basis of the Reichert test. Viscosity, as one of the most important parameters of lubricants, was evaluated by the Stabinger Viscometer. Chemical degradation of motor oils (oxidation, nitration, sulfation), contamination of oils with fuel, soot, water, and loss of antioxidant zinc dialkyldithiophosphate (ZDDP) were monitored by Fourier-transform infrared (FTIR) spectroscopy. Of the fresh motor oils, OMV 10W-40 API SL/CF motor oil had the best lubricity. URANIA LD 15W-40 API CI-4 and M7ADS V 15W-40 API CI-4 CH-4/SL oils showed similar lubricity. M7ADS III 15W-40 API CF-4/SG motor oil showed the highest wear of wear surface, i.e., the lowest lubricity, of the tested new motor oils. Correlation analysis of the experimental data confirmed that the fuel content penetrated the motor oils significantly negatively correlates with the viscosity (R = −0.87). The low water contamination in motor oil does not cause a significant negative effect on lubricity. A significant correlation between the oxidation, nitration, and sulfation products of chemical degradation of the tested oils was confirmed (R ≥ 0.90). These degradation products improve lubricity due to their polarity, i.e., they have caused better lubricity of worn oils compared to new motor oils. Even the depletion of the antioxidant ZDDP did not affect the reduction in lubricity and anti-abrasion properties of chemically degraded motor oils. The experimental results of testing of worn motor oils taken from motor trains showed that current motor oils have excellent lubricity, which they maintain throughout their life.

Research of Parameters of a Compression Ignition Engine Using Various Fuel Mixtures of Hydrotreated Vegetable Oil (HVO) and Fatty Acid Esters (FAE)

Abstract: The present study is aimed at studying the energy and environmental performance at various engine loads (BMEP) with identical start of injection (SOI) for all fuel types. The combustion parameters for the fuel mixtures were analyzed using the AVL BOOST software (BURN subroutine). Five different blends were tested, consisting completely of renewable raw materials based on hydrotreated vegetable oil (HVO) and fatty acid methyl ester (FE100), and the properties of diesel fuel (D) were compared with respect to these blends. The mixtures were mixed in the following proportions: FE25 (FE25HVO75), FE50 (FE50HVO50), FE75 (FE75HVO25). In this study, diesel exhaust was found to produce higher NOx values compared to FE blends, with HVO being the lowest. Hydrocarbon and smoke emissions were also significantly lower for blends than for diesel. Possible explanations are the physical properties and fatty acid composition of fuel mixtures, affecting injection and further combustion. The results showed that blends containing more unsaturated fatty acids release more nitrogen oxides, thus having a lower thermal efficiency compared to HVO. No essential differences in CO emissions between D and HVO were observed. An increase in this indicator was observed at low loads for mixtures with ester. CO2 was reduced in emissions for HVO compared to the aforementioned blends and diesel. The results of the combustion analysis show that with a high content of unsaturated fatty acids, mixtures have a longer combustion time than diesel fuel.

Repeatability of High-Pressure Measurement in a Diesel Engine Test Bed.

Abstract: This paper addresses the issue of metrological accuracy of instantaneous in-cylinder pressure measurement in a diesel engine test bed. In studies, the central unit has been the single-cylinder AVL 5402 engine. The pressure measurement was performed with a sensor designed for thermodynamic analysis, and the results were related to the crank angle, where two rotations corresponding to the four-stroke working cycle were denoted as angles between -360° and +360°. The novelty of this paper is the proposition of how to perform a type A uncertainty estimation of the in-cylinder pressure measurement and to assess its repeatability. It was demonstrated that repeatability of the measurement during the ignition process was difficult to estimate because of the phenomena that cannot ensure the repeatability conditions. To solve the problem, two methods were proposed. In one method, the pressure was measured in the subsequent cycles immediately after the ignition was turned off, and in another method, the engine was driven by a starter. The latter method provided maximal pressure values much lower than during usual tests. The obtained repeatability of measured pressure was %EV = 0.4%, which proved high capability of the evaluated measurement system.

Review of Energy Challenges and Horizons of Hydrogen City Buses

Abstract: This paper discusses fuel cell electric vehicles and, more specifically, the challenges and development of hydrogen-fueled buses for people accessing this transportation in cities and urban environments. The study reveals the main innovations and challenges in the field of hydrogen bus deployment, and identifies the most common approaches and errors in this area by extracting and critically appraising data from sources important to the energy perspective. Three aspects of the development and horizons of fuel cell electric buses are reviewed, namely energy consumption, energy efficiency, and energy production. The first is associated with the need to ensure a useful and sustainable climate-neutral public transport. Herewith, the properties of the hydrogen supply of electric buses and their benefits over gasoline, gas, and battery vehicles are discussed. The efficiency issue is related to the ratio of consumed and produced fuel in view of energy losses. Four types of engines–gasoline, diesel, gas, and electrical–are evaluated in terms of well-to-wheel, tank-to-wheel, delivery, and storage losses. The third problem arises from the production, operating, and disposal constraints of the society at the present juncture. Several future-oriented initiatives of the European Commission, separate countries, and companies are described. The study shows that the effectiveness of the FCEBs depends strongly on the energy generation used to produce hydrogen. In the countries where the renewables are the main energy sources, the FCEBs are effective. In other regions they are not effective enough yet, although the future horizons are quite broad.