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1
Content available remote A three-way catalyst system for a five-stroke engine
EN
This paper presents the results of research on the development of an exhaust gas aftertreatment system for a turbocharged five-stroke engine. This engine was designed and constructed at Cracow University of Technology. A characteristic feature of the five-stroke engine is the use of an additional expansion process to increase overall efficiency. A challenge for a catalytic converter is the fact that it has a low exhaust gas temperature. Two three-way catalytic converters were tested – one with a ceramic support and the second with a metal support. The results of the tests showed that the reactor with a ceramic support obtains an acceptable conversion efficiency starting with an exhaust gas temperature of 280°C. For the metal-support reactor, a few percent increase in torque and a decrease in the brake-specific fuel consumption of the engine was obtained; however, the converter itself did not show signs of operation even with an exhaust gas temperature of over 380°C. The performed analyses highlighted directions of further development works in this area.
PL
W artykule przedstawiono efekty badań nad opracowaniem układu oczyszczania spalin dla turbodoładowanego silnika pięciosuwowego, który został zaprojektowany i wykonany na Politechnice Krakowskiej. Cechą charakterystyczną silnika pięciosuwowego jest zastosowanie dodatkowego rozprężania spalin w celu zwiększenia sprawności ogólnej. Wyzwanie dla reaktora katalitycznego stanowi niska temperatura spalin. Badaniom poddano dwa reaktory trójfunkcyjne, z rdzeniem ceramicznym i z rdzeniem metalowym. Wyniki przeprowadzonych prób wskazały, że reaktor ceramiczny uzyskuje akceptowalną sprawność konwersji od temperatury spalin 280°C. Dla reaktora metalowego uzyskano kilkuprocentowy wzrost momentu obrotowego i obniżenie jednostkowego zużycia paliwa silnika, jednak sam reaktor nie wykazywał oznak działania nawet przy temperaturze spalin powyżej 380°C. Przeprowadzone analizy wskazały kierunki dalszych prac rozwojowych w przedmiotowym obszarze.
EN
Today’s passenger car CNG engines are based on petrol engines which typically have restrictions preventing the exploitation of the full potential of methane based fuels, especially if they have to be operated also on petrol as a second fuel. Additionally, the use of threeway-catalysis limits the engine operation to λ = 1. Here, we present the efficiency potential and the raw emission characteristics for a dedicated four cylinder passenger car CNG engine without sticking to the usual combustion peak pressure and λ limitations. Lean combustion reduces the knocking tendency but, because of the higher pressure levels, increases the ignition energy demand. Therefore, different ignition systems (spark plug, prechamber, Diesel pilot) have been used.
3
Content available remote The ignition phenomenon of gases - part I: the experimental analysis - a review
EN
Ignition has a significant impact on the efficiency of the combustion process. Spark ignition is the most commonly used method and is characterized by two important parameters: minimum ignition energy and quenching distance. This paper presents a review of various ways ahead in experimental investigation in the area. We focus on the conditions influencing the experiments and estimation of the minimum ignition energy. The main issues in previous experimental studies are: construction of the ignition apparatus, spark energy estimation and the statistical nature of the phenomenon. A summary of the research conditions data is presented.
EN
The current legislation pushes for the increasing level of vehicle powertrain electrification. A series hybrid electric vehicle powertrain with a small Range Extender (REx) unit – comprised of an internal combustion engine and an electric generator – has the technical potential to overcome the main limitations of a pure battery electric vehicle: driving range, heating, and air-conditioning demands. A typical REx ICE operates only in one or few steady-states operating points, leading to different initial priorities for its design. These design priorities, compared to the conventional ICE, are mainly NVH, package, weight, and overall concept functional simplicity – hence the costeffectiveness. The design approach of the OEMs is usually rather conservative: parting from an already-existing ICE or components and adapting it for the REx application. The fuel efficiency potential of a one-point operation of the REx ICE is therefore not fully exploited. This article presents a multi-parametric and multi-objective optimization study of a REx ICE. The studied ICE concept uses a well-known and proven technology with a favourable production and development costs: it is a two-cylinder, natural aspirated, port injected, four-stroke SI engine. The goal of our study is to find its thermodynamic optimum and fuel efficiency potential for different feasible brake power outputs. Our optimization tool-chain combines a parametric GT-Suite ICE simulation model and modeFRONTIER optimization software with various optimization strategies, such as genetic algorithms, gradient based methods or various hybrid methods. The optimization results show a great fuel efficiency improvement potential by applying this multi-parametric and multi-objective method, converging to interesting short-stroke designs with Miller valve timings.
EN
The combustion process quality is determined by several factors: the composition of the fuel-air mixture in the vicinity of the spark plug and the discharge conditions on the spark plug. This article assesses a high-power ignition system using optical gas flame propagation analyzes. The tests were carried out in a rapid compression machine, using a fast camera for filming. The spark plug discharge quality assessment was determined indirectly by the flame propagation conditions after the ignition of the mixture (during methane combustion). The size of the flame surface and the rate of its change were assumed as a comparative criterion. It has been found that when using an ignition system with high discharge power the rate of flame development is 14% higher with respect to conventional ignition systems. In addition, the shorter development time of the early flame phase after discharge when using the new ignition system was confirmed. Based on the obtained test results and analyzes, modifications of engine operation settings were indicated, resulting from the use of a high discharge power system.
6
Content available remote LES study of turbulence intensity impact on spark ignition in a two-phase flow
EN
The paper presents large eddy simulation (LES) study aiming at investigations of an influence of flow conditions on a spark ignition process in a two-phase shear dominated flow. Implicit LES approach is applied for the combustion modelling and the spark is modelled using the energy deposition model of Lacaze et al. [20]. We examine an impact of turbulence intensities and randomness of initial distributions of velocity fluctuations on a flame development during the spark duration and shortly after it is switched off. It is found that for a strong spark, as used in IC engines, the turbulence intensity has little effect on the ignition and flame kernel growth and no significant differences are seen even if the turbulence intensities differ four times. It is observed that weak turbulent structures cannot affect fast flame propagation mechanism and its development is conditioned by evaporation and rapid thermal expansion. In such regimes, the turbulence seems to be too weak to significantly alter the flame dynamics. It is found that at the initial stage of the flame development it grows toward the fuel-rich region and spread over the fuel-lean side only after the evaporated fuel diffuses and mixes with the oxidizer stream. The flame size and its shape turn out to be equally dependent on the initial distribution of the turbulence fluctuations and turbulence intensity.
PL
W artykule przedstawiono wyniki zależności napięcia mierzonego na zaciskach obciążonego akumulatora w warunkach badań rozruchowych silników o zapłonie iskrowym oraz samoczynnym. Analizie poddano wartość minimalną, maksymalną oraz średnią napięcia w funkcji minimalnej, maksymalnej oraz średniej wartości natężenia prądu oraz temperatury, w której realizowano próby rozruchowe. Przedstawiono jedno oraz dwuczynnikowe zależności opisujące wpływ zmiennych niezależnych na zmienną zależną zarówno dla silnika o zapłonie iskrowym jak i samoczynnym. Przedstawiono zależności pozwalające wyznaczyć wartość napięcia w funkcji parametrów je określających, także przy zmiennych oporach ruchu walu korbowego. Wykazano adekwatność wyznaczonych zależności oraz statystycznie stwierdzono brak istotności wpływu temperatury, jako zmiennej niezależnej na wartość napięcia określanego za pomocą modelu.
EN
The results of the voltage dependence on the terminals of the loaded battery under the starting conditions tests of spark and selfignition engines were presented. The minimum, maximum and average values of the voltage as a function of the minimum, maximum and average values of the current and the temperature at which the starting tests were performed were analyzed. One and two-factorial relationships describing the influence of independent variables on dependent variable in both spark and selfignition engines were presented. The dependencies that determine the value of the voltage in the function of the defining parameters are also presented, also in case of variable crank movement resistance. The adequacy of the determined relationships was found and statistically significant lack of temperature influence on the independent variable of the voltage determined by the model.
EN
Ecological, economic and exploitation requirements force manufacturers to develop propulsion systems. In the combustion engines with spark ignition for use in non-road mobile machines, it is common to use fuel supplied systems with carburetors. The mechanical adjustment process of the fuel-air mixture makes it difficult to automate the processes using these engines, one of which is the German 390 engine. The paper presents the concepts of automation solutions to control the fuel-air mixture process. The paper also shows advantages and disadvantages of the construction solutions of transferring motion between the throttle damper actuator and the throttle flap injection unit 30 MM4 by Weber. Among the mentioned solutions were characterized: gear transmission, strand transmission with cogbelt, lever mechanism, solid coupling. In addition, the article presents a prototype solution using strand transmission with cogbelt.
PL
Wymagania ekologiczne, ekonomiczne i eksploatacyjne wymuszają na producentach rozwój konstrukcji układów napędowych. W silnikach spalinowych o zapłonie iskrowym w zastosowaniu do pozadrogowych maszyn ruchomych powszechne jest zasilanie paliwem z wykorzystaniem gaźników. Mechaniczny proces regulacji składu mieszanki paliwowo-powietrznej utrudnia automatyzację procesów z wykorzystaniem tych silników, których jednym z reprezentantów jest silnik German 390. W pracy przedstawiono koncepcje rozwiązań automatyzacji procesu sterowania mieszanką paliwowo-powietrzną. Wykazano wady i zalety zastosowanych rozwiązań konstrukcyjnych przekazania ruchu między aktorem napędzającym klapę przepustnicy, a klapą przepustnicy zespołu wtryskowego 30 MM4 firmy Weber. Wśród wymienionych rozwiązań scharakteryzowano: przekładnie zębatą, przekładnie cięgnową z pasem zębatym, mechanizm dźwigniowy, sprzęgło sztywne. Ponadto przedstawiono prototyp rozwiązania z wykorzystaniem przekładni cięgnowej z pasem zębatym.
PL
W artykule przedstawiono diagnostyczną metodę pośredniego określenia luzów zaworowych w silnikach o zapłonie iskrowym za pomocą pomiarów napięcia samoindukcji obwodu pierwotnego cewki zapłonowej lub interpretacji mierzonego bezwzględnego ciśnienia powietrza w kolektorze dolotowym. Ta metoda umożliwia, po spełnieniu warunków koniecznych, określenie czy wymagana jest regulacja luzów zaworowych.
EN
This paper presents a diagnostic procedure for indirect determining valve clearance in spark-ignition engines by measuring the voltage of self-induction of the primary circuit of the ignition coil or interpret the measured absolute air pressure in manifold. This procedure determines, after fulfilling the necessary condi-tions, the need to adjust the valve clearance.
Logistyka
|
2015
|
nr 4
9102--9107, CD3
PL
Ze względu na ograniczone zasoby ropy naftowej, kryzysy paliwowe, a także na ochronę środowiska, w ostatnich czasach obserwuje się coraz większe zainteresowanie biopaliwami, które często nazywane są paliwami alternatywnymi dla paliw kopalnych. Artykuł ma na celu przedstawienie wybranych aspektów zasilania biopaliwami silników spalinowych używanych w transporcie drogowym. Przeanalizowane zostały techniczne możliwości zasilania biopaliwami, silników spalinowych używanych w transporcie kołowym. Przedstawiono parametry poszczególnych rodzajów biopaliw istotne ze względu na prawidłowe funkcjonowanie silników oraz aspekt ochrony środowiska. Oprócz zmian konstrukcyjnych silników oraz rozwiązań stosowanych w układach zasilania, celem uzyskania coraz mniejszego zużycia paliwa poszukuje się paliw pochodzących z innych źródeł niż przeróbka ropy naftowej celem uniezależnienie się od jej dostaw. Paliwa te mogą być stosowane jako domieszki lub jako główne paliwo do zasilania silników używanych w transporcie samochodowym. Najczęściej stosowanymi paliwami alternatywnymi są paliwa ciekłe pochodzenia roślinnego oraz w mniejszym stopniu paliwa gazowe. W najbliższej przyszłości biopaliwa nie będą stanowić zagrożenia dla paliw pochodzących z przeróbki ropy naftowej. Jednakże ich udział jako dodatku do paliw konwencjonalnych wraz z upływem czasu powinien się stopniowo zwiększać.
EN
Because of the limited resources of oil, fuel crises, as well as on environmental protection, in recent times we observed a growing interest in biofuels, which are often called alternative fuels for fossil fuels. The article aims to present selected aspects of biofuels used to admitting internal combustion engines used in road transport. Technical possibilities of biofuel admitting of internal combustion engines used in road transport have been analyzed. Parameters of individual types of biofuels important for the proper functioning of the engine and the environmental aspect were presented. Except engine design changes and solutions used in admitting systems, in order to obtain lesser fuel consumption there is a tendency to look for fuels derived from sources other than processing crude oil. The aim is to become independent from suppliers of conventional fuels. These fuels can be used as admixture or as the major fuel to admitting the engines used in road transport. The most frequently used alternative fuels are liquid fuels from vegetable material, and in a lesser extent – gaseous fuel. For the foreseeable future, biofuels will not constitute a threat to fuels derived from crude oil. However, their participation as an additive to conventional fuels as time passes should gradually increase.
EN
The results of the visualization researches, with the pressure measurement results are presented in the paper. Researches deal with the combustion system with semi-open combustion chamber for spark ignition engines. This system was elaborated in Aircraft Engine Department of Heat Engineering Institute of Warsaw University of Technology. During researches the influence of CR on a flame front propagation and turbulences into combustion chamber, when CR and ignition advance are varied, was determined. The model combustion chamber was made with the constant volumes ratio (the prechamber volume to the prechamber plus main combustion chamber volumes) of 28%. The CR were varied: 6:1, 8:1, 10:1 and 12:1, by changing of combustion chamber length and establish high. The researches were performed using rapid compression machine (RCM). The combustion sequences were recorded using high-speed digital camera with speed of 5000 frames per second. Simultaneously with combustion sequences recording, the high-speed pressure courses were registered. The research results show that the growth of compression ratio causes an improvement of combustion system performances; an increase of maximum cycle pressure and useful work field. The improvement of the performances is caused mainly by shortening of the combustion time and intensification of the turbulences and approaching of supposed combustion course.
EN
In the present work there have been shown the results of initial researches concerning heat release process in the spark ignition engine with inner catalyst. There has been presented the calculative model of heat release process and calculative methodology leading to obtaining temperature course, combustion function and its derivative because of measured course of combustion pressure. The pressure courses, which are necessary for calculations, were obtained on the measure seat with AD 1600 engine that is load with eddy- current brake. The engine was equipped with spark plug with miniature pressure sensor f-my Kistler, and the courses of pressure were recorded by the use of f-my Smetec apparatus. The courses of heat release process were analysed in rotations of n=1500 rotations/min and n=3000 rotations/minute and load of 50 Nm and 70 Nm. The analysis was made comparatively for the system with the catalyst and without catalyst. In the work there have been presented the results of experimental and model researches which aim was the analysis of the issue of influencing the catalytic active surfaces placed in the spark ignition engine combustion space. Those surfaces, catalysing the process of creating combustible mixture and its combustion, influence the combustion process course and, simultaneously, have impact on the engine work parameters and the heat release course.
PL
Skład chemiczny benzyny przeznaczonej do zasilania silników o zapłonie iskrowym sukcesywnie ulega ewolucji ze względu na wymagania dotyczące ochrony środowiska naturalnego oraz rozwój konstrukcji silników. Wymagają one paliwa spełniającego kryteria zawarte w projekcie najnowszej Światowej Karty Paliw. Z praktyki eksploatacyjnej wynika, że użytkowanie benzyn, nawet najwyższej jakości, zawsze prowadzi do powstawania osadów w układzie dolotowym, układzie zasilania i komorach spalania silnika. Mechanizm tworzenia tych osadów nie jest do końca wyjaśniony, gdyż na ich powstawanie wpływa rodzaj i skład paliwa, parametry konstrukcyjne silnika oraz warunki jego pracy. Przeprowadzono badania eksploatacyjne silnika o zapłonie iskrowym zasilanego benzyną węglowodorową i benzyną węglowodorową z dodatkiem 5% obj. etanolu w samochodach osobowych eksploatowanych w okresie eksploatacji 60 tys. km, aby określić tworzenie się osadów. Etanol ze względu na swoje walory użytkowe (wysoka liczba oktanowa, wzrost mocy silnika, efektywność energetyczna, obniżona emisja szkodliwych składników spalin) stanowi cenny składnik paliw do zasilania silników o zapłonie iskrowym.
EN
Com. motor gasoline was improved by addn. of EtOH (5% by vol.) and used for fueling 4 cars with spark ignition engines to det. the masses of deposits formed on intake valves, combustion chambers and surface of the piston top during a 60.000 km long run. The EtOH addn. resulted in increasing the deposit mass.
PL
W pracy przedstawiono różne typy rozwiązań konstrukcyjnych układów zapłonowych i ich wpływ na wartość energii wyładowania iskrowego. Pokazano schematy różnych typów klasycznych oraz bezstykowych układów zapłonowych. Omówiono oraz przeprowadzono analizę porównawczą układów. Pokazano proces sterowania w bezstykowych układach zapłonowych oraz przedstawiono poglądowy układ mikroprocesorowy systemu sterującego pracą silnika.
EN
Various types of ignition systems solutions and their impact on the vale of spark ignition has been presented in the paper. Wiring diagram showing the operational model of spark discharge ignition systems together with discussion and comparative analisys of ignition systems has been presented. Ignition systems control process together with diagram of microprocessor engine control system has been presented in the paper.
PL
W artykule przedstawione zostały rozwiązania układów zasilania tłokowych silników spalinowych o zapłonie iskrowym. Przegląd został dokonany w oparciu o najwcześniejsze stosowane rozwiązania autorstwa Nicolausa Augusta Otto, poprzez rozwiązania typowo mechaniczne gaźnikowe, następnie jedno i wielopunktowe po rozwiązania współczesne umożliwiające bezpośredni wtrysk paliwa do komory spalania. Ponadto autorzy zwracają uwagę na tendencję w rozwoju układów zasilania silników o zapłonie iskrowym głównie w aspekcie poprawy parametrów pracy, osiągów i emisji silnika.
EN
The article presents the solutions of power internal combustion engines with spark ignition. The review was carried out on the basis of the earliest solutions used by Nicolaus August Otto, through solutions typically mechanical carburettor, then single point injection and multipoint injection. until today's solutions allow direct injection of fuel into the combustion chamber. The authors draw attention to the trend in the development of power systems for spark ignition engines primarily in terms of improving the operating parameters, performance and engine emissions.
EN
The combustion system with semi open combustion chamber (SOCC) was originally elaborated in Aircraft Engine Department of Warsaw University of Technology. In this system the original combustion chamber of the standard SI engine, was divided by partition in prechamber and main combustion chamber, but yet this division exists only when the piston is close to TDC, on the contrary by the rest of the cycle the chambers are fully open. The system operation mechanism, the visualization research results, the high speed changed of the pressure measurements, was presented in this paper. The influence on the system performances of the different combustion systems parameters: the prechamber volume, the nozzle hole diameter in the partition, the ignition place, the compression ratio, and the ignition advance angle (IAA), on the basis of the research results, using rapid compression machine was presented in this paper. All research results show, that the best results of the system operation can be obtained if the stream outflow from prechamber to main combustion chamber starts when the piston is at TDC, and if the stream energy will be so big to displace all main combustion chamber before the clearance between partition and piston crown was opened. If the system operated correctly, the combustion time shortening, the growth of the maximum cycle pressure, and the combustion efficiency increase were obtained.
PL
Artykuł kreśli analizę przyczyn mogących prowadzić do porażenia prądem elektrycznym, głownie podczas prowadzonych prac serwisowych silników spalinowych o zapłonie iskrowym. Autor zaproponował i opisał przy tym sposoby postępowania i zasady mające na celu ograniczenie ryzyka porażenia prądem podczas badań i diagnostyki układów zapłonowych.
EN
Ignition circuit is one of the most important electrical circuits of a spark - ignition combustion engine. It is responsible for high – voltage electric discharge between spark plug electrodes to burn air – fuel mixture. Instantaneous value of the high voltage is dangerous because it may reach several dozen kilovolts. The aim of the paper is the electrocution danger evaluation, mainly at combustion engines’ service. Some tips to reduce risk of electrical shock during investigation and diagnostic procedures are proposed and discussed.
18
Content available New design of the five-stroke SI engine
EN
The paper describes design of the five-stroke engine developed in the Chair of Combustion Engines at Cracow University of Technology. The idea of five-stroke engine, in which the expansion ratio is significantly greater than the compression ratio has been presented by the Belgian engineer Gerhard Schmitz. The prototype of such an engine was made by Ilmor Engineering. Engine developers have released results of preliminary research, but there is no detailed information on the toxic exhaust emissions. For this reason, at Cracow University of Technology the research was undertaken to determine the impact of implementing the five-stroke cycle into the engine with spark ignition to reduce toxic emissions and increase total efficiency. To achieve this goal, the test engine was built, which is based on a concept similar to the idea of Gerhard Schmitz, with the difference that it has not been designed from the ground up, and it is based on an existing four-cylinder four-stroke engine. In comparison with the original solution, the engine built in Cracow has a completely different design of timing system, four valves per cylinder and petrol direct injection. This paper presents a detailed description of the engine design and the results of its preliminary research. The results of the tests of the five-stroke engine confirm an increase of specific torque and power (related to unit of engine displacement) and improve of total efficiency within a certain range of the engine map.
EN
Researches of the combustion system with semi-open combustion chamber for spark ignition engines. This system was elaborated in Aircraft Engine Department of Heat Engineering Institute of Warsaw University of Technology. The researches concern the determination of influence CR on a flame front propagation into combustion chamber when CR and ignition advance are varied. The model combustion chamber make up with the constant volumes ratio of the prechamber volume to the prechamber plus main combustion chamber volumes, of 28%, but the CR were varied: 6:1, 8:1, 10:1 and 12:1, by changing of combustion chamber length. The researches were performed using rapid compression machine (RCM). The combustion sequences were recorded using high-speed digital camera with speed of 5000 frames per second. Simultaneously with combustion sequences recording, the high-speed pressure measurements were performed. The results of the visualization researches, with the pressure measurement results are presented in the paper. The research results show that the growth of compression ratio caused an improvement of combustion system performances; an increase of maximum cycle pressure and useful work field. The improvement of the performances is caused mainly by shortening of the combustion chamber length and approaching of supposed combustion course.
20
Content available remote Analiza reologiczna paliw i biopaliw ciekłych
PL
Celem badań było określenie właściwości reologicznych oraz wpływu temperatury na lepkość paliw i biopaliw oraz ich mieszanin wykorzystywanych w silnikach o zapłonie iskrowym i samoczynnym. Zarówno dodatek etanolu do benzyny, jak i bioestrów do oleju napędowego powoduje wzrost lepkości paliwa. Stwierdzono, że w niskich temperaturach zarówno czysty olej napędowy, jak i z dodatkiem bioestru są płynami rozrzedzanymi ścinaniem.
EN
The aim of this study was to determine rheological properties and tempi rature-effect on viscosity of fuels and biofuels and their mixtures used spark-ignition and self-ignition engines. Both, the addition of ethanol 1 gasoline and biodiesel to diesel caused the increase of fuel viscosity. It wj stated that at low temperatures pure diesel and diesel with biodiesel additic were shear thinning fluids.
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