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

Prehospital Stroke Care. Paramedic Training Needs, and Hospital-Directed Feedback in Lithuania

Background: Emergency medical services (EMS) are the first health care contact for the majority of stroke patients. However, there is a lack of data on the current paramedics’ hospital-directed feedback and training needs across different health care settings. We aimed to evaluate paramedics’ prehospital stroke care knowledge, training needs, and current status of feedback on suspected stroke patients. Methods: We surveyed paramedics from the Vilnius region from September to November 2019 and compared the answers between the city and the district agencies. The questionnaire content included questions on paramedics’ demographic characteristics, prehospital stroke care self-assessment, knowledge on stroke mimics, stroke training needs, and the importance of hospital-directed feedback on suspected stroke patients. Results: A total number of 161 paramedics (or 49.4% of all paramedics from our stroke care network) were surveyed, with more district paramedics rating their prehospital stroke care knowledge as inadequate (44.8% (95% confidence interval (CI) 32.8–57.6) vs. 28.1% (95% CI 20.1–27.8), p = 0.028). In addition, more district paramedics indicated a need for additional stroke training (83.1% (95% CI 71.5–90.5) vs. 69.8% (60.0–78.1), p = 0.043). However, respondents reported being the most confident while dealing with stroke (71.3%, 95% CI 63.8–77.7) compared to other time-critical conditions (p < 0.001). Vertigo (60.8%, 95% CI 53.0–68.0), brain tumors (56.3%, 95% CI 48.5–63.8), and seizures (54.4%, 95% CI 46.7–62.0) were indicated as the most common stroke mimics. Only 6.2% (95% CI 3.4–11.1) of respondents received formal feedback on the outcome of suspected stroke patients brought to the emergency department. Conclusions: A high proportion of paramedics self-perceive having inadequate stroke knowledge and an urgent need for further stroke training. The EMS staff indicate receiving insufficient feedback on suspected stroke patients, even though its usefulness is perceived as paramount.publishersversionPeer reviewe

Interactive Training of the Emergency Medical Services Improved Prehospital Stroke Recognition and Transport Time

Funding Information: This study received funding from Boehringer Ingelheim GmbH & Co KG Lithuania. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit for publication. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Funding Information: We greatly acknowledge the EMS staff for taking part in the training. LS was supported by the Swiss National Science Foundation postdoctoral scholarship (P2GEP3_191584). This article/publication is based on work from the IRENE COST Action—Implementation Research Network in Stroke Care Quality (CA18118), supported by COST (European Cooperation in Science and Technology; www.cost.eu ). Publisher Copyright: Copyright © 2022 Sveikata, Melaika, Wiśniewski, Vilionskis, Petrikonis, Stankevičius, Jurjans, Ekkert, Jatužis and Masiliūnas.Background and Purpose: Acute stroke treatment outcomes are predicated on reperfusion timeliness which can be improved by better prehospital stroke identification. We aimed to assess the effect of interactive emergency medical services (EMS) training on stroke recognition and prehospital care performance in a very high-risk cardiovascular risk population in Lithuania. Methods: We conducted a single-center interrupted time-series study between March 1, 2019 and March 15, 2020. Two-hour small-group interactive stroke training sessions were organized for 166 paramedics serving our stroke network. We evaluated positive predictive value (PPV) and sensitivity for stroke including transient ischemic attack identification, onset-to-door time, and hospital-based outcomes during 6-months prior and 3.5 months after the training. The study outcomes were compared between EMS providers in urban and suburban areas. Results: In total, 677 suspected stroke cases and 239 stroke chameleons (median age 75 years, 54.8% women) were transported by EMS. After the training, we observed improved PPV for stroke recognition (79.8% vs. 71.8%, p = 0.017) and a trend of decreased in-hospital mortality (7.8% vs. 12.3, p = 0.070). Multivariable logistic regression models adjusted for age, gender, EMS location, and stroke subtype showed an association between EMS stroke training and improved odds of stroke identification (adjusted odds ratio [aOR] 1.6 [1.1–2.3]) and onset-to-door ≤ 90 min (aOR 1.6 [1.1–2.5]). The improvement of PPV was observed in urban EMS (84.9% vs. 71.2%, p = 0.003), but not in the suburban group (75.0% vs. 72.6%, p = 0.621). Conclusions: The interactive EMS training was associated with a robust improvement of stroke recognition, onset to hospital transport time, and a trend of decreased in-hospital mortality. Adapted training strategies may be needed for EMS providers in suburban areas. Future studies should evaluate the long-term effects of the EMS training and identify optimal retraining intervals.publishersversionPeer reviewe

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

Features of the 3D lasers measurement systems

Magistrantūros baigiamojo darbo tikslas yra išanalizuoti 3D lazerines matavimo sistemas, jų panaudojimą geodeziniams darbams ir palyginti su elektroniniu tacheometru. Atliekant tyrimą buvo panaudoti teoriniai bei praktiniai duomenys ir sisteminė analizė. Tyrimo objektas- stacionarus lazerinis skeneris Riegl LMS-Z420i. Pasirinktas prietaisas yra kol kas vienintelis toks Lietuvoje. Modernios technologijos su naujausiais techniniais sprendimais dėl savo produktyvumo gauna vis didesnę reikšmę geodezijoje. Todėl būtina žinoti jų veikimo principus ir panaudojimo galimybes. 3D lazerinės matavimų sistemos palyginti su elektroniniais tachometrais yra naujas dalykas. 3D lazerinės matavimų sistemos - tai įrenginiai, 3D skeneriai, kurie analizuoja realaus pasaulio objektą ir jo aplinką, siekiant surinkti duomenis apie jo formą ir jo išvaizdą (t.y. spalvą). Surinkti duomenys gali būti naudojami kurti skaitmeninius trimačius modeliu- tai informacija naudinga įvairioms programoms. Šie prietaisai yra plačiai naudojami topografiniuose darbuose, kalnakasyboje, fasadų matavimams, pastatų inventorizacijai, miestų modeliavimui. Taip pat ši technologija apima pramoninio dizaino, protezavimo, prototipų kūrimo, kokybės kontrolės tikrinimo funkcijas. Darbe išanalizuoti lazerinis skeneris Riegl LMS-Z420i, jo parametrai bei funkcijos, matavimo technologija ir palyginta matavimo sparta, tikslumas ir duomenų apdorojimas su elektroniniu tacheometru Sokkia set 5x. Atlikus palyginimą lazerinis skeneris Riegl LMS-Z420i buvo pranašesnis už elektroninį tacheometrą Sokkia Set 5x.Magister thesis is to analyze the 3D laser measurement systems, the use of geodetic work and compared with an electronic tachometer having. The study was theoretical and practical use of data and systematic analysis. The object of the stationary-laser scanner Riegl LMS-Z420i. The selected device is so far the only one in Lithuania. Modern technology with the latest technical solutions for its performance are receiving an increasing larger role in geodesy. Therefore, it is necessary to know the principles of operation and usability. 3D laser measurement system in relation to electronic tachometer is a new thing. 3D laser measurement system - a device, 3D scanners, which examines real-world object and its environment in order to collect data about its shape and its appearance (ie color). The data collected can be used to create digital three-dimensional model, this information is useful for various applications. These devices are widely used for topographical works, mining, facade measurements, building inventory, urban simulation. Also, this technology include industrial design, prosthetics, prototype development, quality control inspection functions. The paper analyzed a laser scanner Riegl LMS-Z420i, its parameters and functions, measurement techniques and compared the measurement speed, accuracy and data processing with an electronic tacheometer having Sokkia Set 5x. After a comparison of laser scanner Riegl LMS-Z420i has superior electronic tachometers Sokkia Set 5x.Žemės ūkio akademijaVytauto Didžiojo universiteta

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

Design and Verification of Delfi-PQ Satellite Propulsion Sub-system: Experimental Analysis and Design Improvements of the Technology Demonstration Payload for Micro-Thrusters

AE faculty at TU Delft is currently developing a PocketQube satellite under the name of Delfi-PQ. Following the previous study, performed on a high level systems engineering on Delfi-PQ propulsion sub-system, there is a need to verify the propulsion sub-system's design, its final operational envelope values, and propulsion sub-system's requirements by using TEST and ANALYSIS methods. Leak, volume and mass, solenoid valve PWM, and heater efficiency tests have been performed. The verification tests of the propulsion sub-system design provided a lot of valuable information. Not only some of the its requirements have been verified, but also the underlying issues have been observed, registered, and described for future researchers who are going to test such a micro-propulsion system and optimize its design.Aerospace Engineerin