Research of a Combustion Process in a Spark Ignition Engine, Fuelled With Gaseous Fuel Mixtures

Research work relevance is concerned with global energy saving, alternative fuel use and environmental pollution reduction issues in wide world, which is especially important for the transport sector. Dissertation work presents study of efficient and ecological indicators, combustion process behaviour and its parameters of different gaseous fuels and their mixtures in the spark ignition internal combustion engine, which has such adaptations of duel fuel supply, gas direct injection or dual coil ignition systems. Different theoretical evaluations and analysis, experimental investigation and numerical simulation methods are applied in order to have a complex research, to suggest efficiency improving implements and to get a better understanding of gaseous fuels, like biogas, natural gas, hydrogen influence on the engine work cycle. Introduction chapter presents the importance of the thesis, goal and the tasks of this work. In addition, scientific novelty, theoretical and practical significance of achieved results, defendable statements and authors pub-lished scientific papers presented in the chapter. An overview of scientific literature according to thesis theme represent-ed in the first chapter. Different features, like fuel composition, lower heating value, chemical combustion reactions of different gas fuels were re-viewed according other scientist’s works and the influence of these indica-tors on engine efficient and ecological parameters and combustion behaviour were discussed. Second chapter represents different research work methodologies, which were applied for the theoretical analysis and calculations, numerical simulation and experimental tests with different research type spark ignition engines. Experimental test results of biogas, natural gas, natural gas and hydro-gen fuel mixtures, numerical analysis and simulation of mentioned gas fuels presented in the third chapter. Furthermore, test results of methane direct injection system with combustion process imaging and combustion light emission spectroscopy given in the result part. Research of different gas fuels and different types of fuel injection systems revealed that it is possible to achieve promising results, which are concerned with improved gaseous fuel combustion process, higher engine efficiency and lower exhaust gas emissions in spark ignition engine. 12 scientific papers according to the thesis subject have been published: one – in scientific journal, included in Thomson ISI Web of Science data base; two – in editions of international conferences, referred in Thomson Reuters data base Proceedings; four – in other international data base publications; one – in periodical reviewable scientific publication; four – in conferences materials

Spark ignition engine performance, standard emissions and particulates using GDI, PFI-CNG and DI-CNG systems

Gaseous fuels, e.g., natural gas, biogas, have several advantages over liquid fuels owing to their favorable physical and chemical properties, e.g., lower carbon numbers in the fuel composition and no issues regarding fuel evaporation. The present study investigated compressed natural gas (CNG) port fuel injection (PFI) and direct injection (DI) systems compared to gasoline direct injection (GDI) cases in a spark ignition (SI) naturally aspirated single cylinder engine at stoichiometric conditions. The tests included usual engine working points – from 4.5 bar IMEP to 9 bar IMEP engine load at different engine speeds – from 1500 rpm to 2500 rpm. The main aim was to investigate how gaseous fuels can improve the SI engine efficiency, reduce standard emissions and particulates, and explain the benefits of a natural gas DI system versus standard gas PFI and GDI systems. Analysis of the results showed that the rate of heat release of natural gas was lower than that of gasoline fuel. However, the stable combustion process of DI-CNG gave additional benefits, e.g., increased turbulence in the cylinder, which increased the combustion rate and affected the exhaust gas formation. The highest engine efficiency was achieved with the same natural gas DI system. The highest iSHC, iSCO, iSCO2 and iSNOx emissions reduction achieved at low and part load conditions with DI-CNG compared to GDI combustion. Particulates formation was lower with the gaseous fuel compared to gasoline. Additional benefits of lower particulate numbers among three injection systems were observed with DI-CNG combustion

DI-CNG injector nozzle design influence on SI engine standard emissions and particulates at different injection timings

Compressed natural gas direct injection (DI-CNG) systems in spark ignition (SI) internal combustion engines have shown that it can give several benefits compared to CNG port fuel injection systems. However, the DI-CNG injector nozzle head design and gas jet formation may greatly influence engine exhaust gas emissions and performance. Present experimental study investigated the influence of 7 different nozzle head designs of sprayguided DI-CNG injectors on the combustion process, engine performance, standard emissions, and particulate number (PN) when methane fuel was injected at different injection timings (SOI) and injection pressures (18 bar and 50 bar). The nozzle heads had two main design patterns – heads with small multi holes/orifices and heads with larger crevices (swirl or umbrella spray pattern). Naturally aspirated SI engine tests were conducted at part load (6 bar IMEP) and wide-open throttle (WOT) at 2000 rpm engine speed. The results revealed that the difference between the nozzle heads was small when the fuel was injected at an early stage of the intake stroke (310–350 CAD bTDC) either at part load or high load. However, for late injection timing (130–190 CAD bTDC), the design of the DI-CNG injector nozzle head had a large impact on the combustion stability, standard emissions formation and particulates. Multi-hole nozzle heads showed improved CO2, CO, THC, total PN, and slightly higher NOx emissions compared to nozzle heads with larger crevices. For some of the nozzles, the SOI could be retarded more than for other injector head designs at higher injection pressure whilst still ensuring an acceptable engine performance in terms of combustion stability, power output and emissions formation. Overall, 50-bar injection pressure and a late injection timing under WOT conditions achieved higher engine load levels with all injector nozzle types. Images acquired using an optical endoscope technique with a high-speed video camera showed that a yellow flame was present for all nozzle types at a low injection pressure and late SOI. Increasing the injection pressure reduced the injection duration, improved air/fuel mixing which resulted in the reduced byellow flame formation and lower PN for most of the nozzle heads

INVESTIGATION OF COMBUSTION, PERFORMANCE AND EMISSION CHARACTERISTICS OF SPARK IGNITION ENGINE FUELLED WITH BUTHANOL – GASOLINE MIXTURE AND A HYDROGEN ENRICHED AIR

In this study, spark ignition engine fuelled with buthanol-gasoline mixture and a hydrogen-enriched air was investigated. Engine performance, emissions and combustion characteristics were investigated with different buthanol (10% and 20% by volume) gasoline mixtures and additionally supplied oxygen and hydrogen (HHO) gas mixture (3.6 l/min) in the sucked air. Hydrogen, which is in the HHO gas, improves gasoline and gasoline-buthanol mixture combustion, increases indicated pressure during combustion phase and decreases effective specific fuel consumption. Buthanol addition decreases the rate of heat release, the combustion temperature and pressure are lower which have an influence on lower nitrous oxide (NOx) emission in exhaust gases. Buthanol lowers hydrocarbon (HC) formation, but it increases carbon monoxide (CO) concentration and fuel consumption. Combustion process analysis was carried out using AVL BOOST software. Experimental research and combustion process numerical simulation showed that using balanced buthanol and hydrogen addition, optimal efficient and ecological parameters could be achieved when engine is working with optimal spark timing, as it would work on gasoline fuel

Experimental Investigation of Methane Direct Injection with Stratified Charge Combustion in Optical SI Single Cylinder Engine

This paper assesses methane low pressure direct injection with stratified charge in a SI engine to highlight its potential and downsides. Experiments were carried out in a spark ignited single cylinder optical engine with stratified, homogeneous lean and stoichiometric operational mode, with focus on stratified mode. A dual coil ignition system was used in stratified mode in order to achieve sufficient combustion stability. The fuel injection pressure for the methane was 18 bar. Results show that stratified combustion with methane spark ignited direct injection is possible at 18 bar fuel pressure and that the indicated specific fuel consumption in stratified mode was 28% lower compared to the stoichiometric mode. Combustion and emission spectrums during the combustion process were captured with two high-speed video cameras. Combustion images, cylinder pressure data and heat release analysis showed that there are fairly high cycle-to-cycle variations in the combustion. Both blue pre-mixed flame and soot luminescence occurred in the combustion. The occurrence of soot luminescence was also supported by the emission spectrum. Soot formation sources were found to be localized randomly in the bulk flame but not on the piston nor in the vicinity of the spark plug. These findings illustrate the difficulty of achieving proper mixing between air and methane resulting in fairly high cycle-to-cycle variations in the combustion and fuel rich areas which create a source of soot

Suskystintų naftos dujų įtaka slėginio uždegimo variklio rodikliams

Ištirta papildomai tiekiamų suskystintų naftos dujų (SND) įtaka dyzelinu veikiančio slėginio uždegimo (SU) variklio energetiniams ir ekologiniams rodikliams. Atliekant eksperimentinius tyrimus nustatyta, kad papildomai tiekiamos SND daro įtaką degiojo mišinio degimo procesui ir mažina variklio energetinį efektyvumą. Didinant SND koncentraciją išauga nepilno degimo produktų – anglies monoksido (CO) ir angliavandenilių (CH) koncentracija išmetamosiose dujose bei dūmingumas, tačiau sumažėja azoto oksidų (NOx) ir anglies dvideginio (CO2) emisija. Naudojant 50 % SND priedą į dyzeliną bei optimizavus (paankstinus) dyzelino įpurškimo paankstinimo kampą, variklio veikimo energetinis efektyvumas yra artimas dyzelinui nes degalų mišinio degimas pagerėja, nepilno degimo produktų koncentracija sumažėja, tačiau išauga NOx koncentracija deginiuose. Įvertinus mažesnę SND degalų kainą, naudojant didesnę SND koncentraciją, pasiekiamas didesnis ekonominis efektyvumas

Experimental Investigation of Methane Direct Injection with Stratified Charge Combustion in Optical SI Single Cylinder Engine

This paper assesses methane low pressure direct injection with stratified charge in a SI engine to highlight its potential and downsides. Experiments were carried out in a spark ignited single cylinder optical engine with stratified, homogeneous lean and stoichiometric operational mode, with focus on stratified mode. A dual coil ignition system was used in stratified mode in order to achieve sufficient combustion stability. The fuel injection pressure for the methane was 18 bar. Results show that stratified combustion with methane spark ignited direct injection is possible at 18 bar fuel pressure and that the indicated specific fuel consumption in stratified mode was 28% lower compared to the stoichiometric mode. Combustion and emission spectrums during the combustion process were captured with two high-speed video cameras. Combustion images, cylinder pressure data and heat release analysis showed that there are fairly high cycle-to-cycle variations in the combustion. Both blue pre-mixed flame and soot luminescence occurred in the combustion. The occurrence of soot luminescence was also supported by the emission spectrum. Soot formation sources were found to be localized randomly in the bulk flame but not on the piston nor in the vicinity of the spark plug. These findings illustrate the difficulty of achieving proper mixing between air and methane resulting in fairly high cycle-to-cycle variations in the combustion and fuel rich areas which create a source of soot

Use of mathematical methods of statistics for analyzing engine characteristics

For the development of new models, automobile manufacturers are trying to come up with optimal software for engine control in all movement modes. However, in this case, a vehicle cannot reach outstanding characteristics in none of them. This is the main reason why modifications in engine control software used for adapting the vehicle for driver’s needs are becoming more and more popular. The article presents a short analysis of development trends towards engine control software. Also, models of mathematical statistics for engine power and torque growth are created. The introduced models give an opportunity to predict the probabilities of engine power or torque growth after individual reprogramming of engine control software. Article in Lithuanian. Matematinės statistikos metodų taikymas analizuojant variklių technines charakteristikas Santrauka. Automobilių gamintojai sukurtas degimo variklių valdymo programas pritaiko visiems automobilio judėjimo režimams ir tarp jų siekia optimalaus balanso. Tačiau tuomet automobilis nė vienu režimu nerealizuoja tinkamiausių būtent tam režimui parametrų, todėl labai populiarėja valdymo programos perprogramavimas. Straipsnyje trumpai apžvelgiamos kryptys, kuriomis tobulinami valdymo programų kūrimo metodai. Taip pat pagal eksperimentinių tyrimų metu surinktus duomenis pateikti sudaryti variklio išvystomos galios ir sukimo momento padidėjimo matematinės statistikos modeliai. Sudarant šiuos modelius, nustatytos minimalios ir maksimalios galios ir sukimo momento padidėjimo reikšmės, apskaičiuotos vidutinės reikšmės bei vidutiniai kvadratiniai nuokrypiai, parinkti teoriniai nagrinėjamų duomenų pasiskirstymo dėsniai. Sudaryti matematinės statistikos modeliai leidžia prognozuoti galios ir sukimo momento padidėjimo reikšmės patekimo į tam tikrą intervalą tikimybes. Raktiniai žodžiai: elektroninis valdymo blokas; galia; matematinės statistikos modelis; programavimas; sukimo momentas; valdymo programa; vidaus degimo varikli

Particulates from a CNG DI SI Engine during Warm-Up

To assist efforts reducing harmful emissions from internal combustion engines, particulate formation was investigated in a compressed natural gas (CNG) Direct Injection single-cylinder SI engine in warm-up conditions. This involved tests at low engine speed and load, with selected engine coolant temperatures ranging from 15 to 90 \ub0C, and use of a gasoline direct injection (GDI) system as a standard reference system. Total particulate number (PN), their size distribution, standard emissions, fuel consumption and rate of heat release were analyzed, and an endoscope with high-speed video imaging was used to observe combustion luminescence and soot formation-related phenomena.The results show that PN was strongly influenced by changes in coolant water temperature in both the CNG DI and GDI systems. However, the CNG DI engine generated 1 to 2 orders of magnitude lower PN than the GDI system at all tested temperatures. The PN decreased in both systems when the coolant temperature increased. The results also show that PN was sensitive to a broader engine coolant temperature range in the GDI system. However, PN was around two orders of magnitude higher at the lowest coolant temperature (15 \ub0C) than at the highest temperature (90 \ub0C) in the CNG DI system. In homogeneous CNG combustion (unlike gasoline combustion) high-speed video images revealed no diffusion or yellow flame anywhere in the cylinder, even at the lowest coolant temperature. Thus, no soot formation location could be determined from the images in CNG cases. Overall, engine measurements showed that the CNG DI engine emitted lower standard emissions (CO2, CO, HC, NOx) and PN than the GDI system across the experimental range of engine coolant temperatures

Biometano ir vandenilio mišinių panaudojimo kibirkštinio uždegimo variklyje modeliavimas

Straipsnyje pateikti automobilio Nissan kibirkštinio uždegimo variklio HR 16DE energetinių ir ekologinių rodiklių modeliavimo rezultatai varikliui veikiant biometano ir vandenilio mišiniu. Modeliavimas atliktas su skaitinio modeliavimo programa AVL BOOST. Modeliavimo metu įvertinti įvairios sudėties mišiniai (CH4; CH4+5 % H2; CH4+10 % H2; CH4+15 % H2; CH4+20 % H2; CH4+25 % H2; CH4+30 % H2). Modeliavimo metu analizuota degimo proceso temperatūra ir slėgis, degalų sąnaudos bei deginių emisija. Šio tyrimo tikslas yra nustatyti optimalios sudėties biometano ir vandenilio mišinį, kuris užtikrintų mažiausias degalų sąnaudas ir didžiausią ekologiją