Combustion Visualization And Particulate Matter Emission Of A Gdi Engine By Using Gasoline And E85

In order to increase engine efficiency as well as to reduce emission, optimizing combustion is always the challenge in research and product development. Gasoline direct injection (GDI) engines have been popularized due to its higher power density, fuel efficiency, and the possibility for advanced engine technologies over conventional port-fuel-injection (PFI) gasoline engines. However, many issues are heavily investigated, such as air-fuel mixing preparation, fuel wall-wetting, higher HC and PM emissions, catalytic convertor efficiency, knocking, and pre-ignition. Besides, advanced technologies represent higher production cost. Because of the limited resource of petroleum-based fuels, ethanol is deemed as the alternative fuel for gasoline due to its availability, renewability, and fuel properties. It is also known for its lower energy content (LHV ~ 27 MJ/kg) that the fuel economy would decrease if such a fuel is used. Besides that, lower HC, CO, NOX, and PM emissions may be achieved with the presence of ethanol in fuel. The present study is focused on visualizing GDI combustion with different fuels (E0 and E85) along with engine-out emission measurement specially focusing on PM emission. Different engine operation conditions are taken into consideration to study the effects on engine performance in terms of engine start-up, combustion quality and variation, and engine-out emission. High speed imaging techniques are used for visualizing the combustion process, and high speed emission measurement devices are used for engine-out emission study. PM emission is the primary focus in the current study on emissions with the assistance of in-cylinder visualization to identify the location of diffusion flame where the soot is formed. CFD modeling is also implemented to analyze the air-fuel mixture preparation as well as the combustion process. The results indicate that the combustion process may not be ideal under certain operating conditions. By various image processing techniques, it is found that the flame kernel development could be either too slow or too heterogeneous. Fuel wall impingement is also found that pool fire is in inevitable in some cases that HC, CO, and PM emissions are high. Injection timing, ignition timing, and air-fuel ratio are the three primary factors that need to be carefully controlled for engine calibration in order to achieve higher efficiency and lower emissions. Some advanced technologies, e.g. one-valve deactivation, may not be ideal at certain speed and load. The use of alternative fuel could reduce PM emission in mass, but the particle number could sometimes be higher than using E0. The CFD simulation also validates the similar results found from the experiments

Optimization of solenoid driver and controller for gaseous fuel high-pressure direct injector using model-based approach

This study focuses on the Direct Injection (DI) system utilizing Compressed Natural Gas (CNG) as the fuel. A conventional Gasoline Direct Injector (GDI) was converted into a gaseous fuel application. One of the issues that arises is the fluctuation in injector mass flow rate. The crucial factor leading to the occurring problem is a non-optimal injector driver and controller. Thus, the purpose of this study is to identify the most influential parameters of the injector, construct an analytical and data-driven model of the injector, conduct the model-based optimization of the injector and verify the optimal injector setup via simulation and experiment. A standalone injector test rig was used as the experimental setup. A parametric study was conducted using a one-dimensional (1D), first principle injector model builds in MATLAB Simulink. Data-driven modelling using a one-stage plan and an Interpolating Radial Basis Function (RBF) model was generated based on data collected from the injector simulation. An optimization study was conducted using Normal Boundary Intersection (NBI) algorithm in MATLAB Model-Based Calibration (MBC) Toolbox to produce an optimal injector setup. Finally, a verification study was performed using the attained optimal injector setup in both experiment and simulation of the injector. Based on the results, the experimental result shows a similar injector mass flow rate trend compared to the theoretical calculation except for the mass flow rate fluctuation point. The most influential injector parameter is the nozzle diameter with a sensitivity value of 1489.71 g/s/m, while the least significant injector parameter is the spring constant with a sensitivity value of 0.000083 g/s/N/m. Data-driven modelling produced an RMSE of 0 and a validation RMSE of 0.0249. The simulation result of the mass flow rate for baseline versus optimization shows an increment of 15.64% compared to the experimental result for baseline versus optimization, which shows an increase of 35.79%. The results obtained from the study are important to increase the effectiveness of control strategies embedded in the development of a dedicated driver and controller for the gaseous fuel direct injector

Single Hole Direct Injector Simulation Validation and Parametric Sensitivity Study

This paper presents a parametric study conducted on electronically controlled solenoid direct fuel injector running on compressed natural gas. The purpose of the study is to identify the influential injector parameters on the output mass flowrate. These injector parameters are to be optimized in the next stage of the study. The parametric study is conducted using zero-dimensional, first principle injector model, which consist of electromagnetic, mechanical and flow sub-models. In the current study, seven (six input and one output) parameters have been analysed which are the injection pressure, injection duration, nozzle diameter, armature mass, the input voltage, spring constant and the output mass flow rate. Each input parameters are varied in the prescribed range based on the literature. Based on the study, the most influential parameters (in rank) are the nozzle diameter, the armature mass and the injection duration. The input voltage, the injection pressure and the spring constant were found to have no impact on the injector mass flow rate based on the values of the parameter’s sensitivities. Based on the results, the potential parameters to be optimized are identified

Natural Gas Fueling: A LES Based Injection and Combustion Modeling for Partially Stratified Engines☆

Abstract The Partially Stratified Charge Spark Ignition (PSC-SI) combustion strategy is envisaged as a way of reducing fuel consumption and therefore polluting emissions; the improved fuel economy is mainly due to lean, stratified combustion, and to the reduction of pumping losses at partial load conditions. The aim of this work is to explore the potential capabilities of the PSC-SI combustion strategy over a wide flammability air-to-fuel ratio range with a CFD-based computational approach. A validated LES solver has been used to represent the main occurring phenomena into an experimentally implemented Constant Volume Combustion Chamber (CVCC). For different air fuel ratios, both homogeneous and non-homogeneous combustion processes have been simulated in order to compare and emphasize the benefits of the PSC-SI and the impact of the choice of operating conditions

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

SPRAY CHARACTERISTICS AND SPRAY-WALL IMPINGEMENT OF A DIESEL-CNG DUAL FUEL JET USING THE SCHLIEREN IMAGING TECHNIQUE

Natural gas for direct-injection (DI) compression ignition (CI) engines is considered to be the final optimized method due to its high volumetric efficiency, high thermal efficiency and low emissions. However, CNG has the penalty of high auto-ignition temperature and lower cetane number. An effective way to use CNG in CI engines is to inject the CNG with a pilot of diesel fuel for ignition purposes. In order to understand and control the injection and the jet characteristics, it is essential to understand how the gas jets assist the atomization of the pilot diesel spray and influence its characteristics as well as wall impingement

Investigation Into Advanced Architecture and Strategies For Turbocharged Compressed Natural Gas Heavy Duty SI-engine

CNG is at present retaining a growing interest as a factual alternative to traditional fuel for SI engine thanks to its high potentials in reducing the engine-out emissions. Increasing thrust into the exploitation of NG in the transport field is in fact produced by the even more stringent emission regulations which are being introduced into the worldwide scenario. Specific attention is also to be devoted to heavy duty engines given the high impact they retain due to the diesel oil exploitation and to the PM emissions, the latter issue assessing for the need to shift towards alternative fuels such as natural gas. A thorough control of the air-to-fuel ratio appears to be mandatory in spark ignition CNG engines in order to meet the even more stringent thresholds set by the current regulations. The accuracy of the air/fuel mixture highly depends on the injection system dynamic behavior and to its coupling to the engine fluid-dynamic. The amount of injected fuel should in fact be properly targeted by the ECU basing on the estimation of the induced air and accounting for the embedded closed-loop strategies. Still, these latter are normally derived from engine-base routines and totally ignore the injection system dynamics. Thus, a sound investigation into the mixing process can only be achieved provided that a proper analysis of the injection rail and of the injectors is carried out. The first part of the present work carries out a numerical investigation into the fluid dynamic behavior of a commercial CNG injection system by means of a 0D-1D code. The research has been focused on defining the set of parameters to be precisely reproduced in the 0D-1D simulation so as to match the injection system experimental behavior. Specific attention has been paid to the one component which significantly contributes to fully defining its dynamic response, i.e. the pressure reducing valve. The pressure reducer is made up of various elements that retain diverse weights on the valve behavior and should consequently be differently addressed to. A refined model of the pressure reducer has hence been proposed and the model has been calibrated, tested and run under various operating conditions so as to assess for the set-up validity. Comparisons have been carried out on steady state points as well as through out a vehicle driving cycle and the model capability to properly reproduce the real system characteristic has been investigated into. The proposed valve model has proved to consistently replicate the injection system response for different speed and load conditions. A few methodological indications concerning modeling aspects of a pressure regulator can be drawn from the present study. The model has been run in a predictive mode so as to inquiry into the response of the system to fast transient operations, both in terms of speed and load. The model outputs have highlighted mismatches between the ECU target mass and the actually injected one and have hinted at the need for dedicated and refined control strategies capable of preventing anomalies in the mixture formation and hence in the engine functioning. The second part of the present work aims at deeply investigating into the potentials of a heavy duty engine running on CNG and equipped with two different injection systems, an advanced SP one and a prototype MP one. The considered 7.8 liter engine was designed and produced to implement a Sigle-Point (SP) strategy and has hence been modified to run with a dedicated Multi-Point (MP) system so as to take advantage of its flexibility in terms of control strategies. More specifically, a thorough comparison between the experimental performances of the engine equipped with the two injection systems has been carried out at steady state as well as at transient operations. Better performances in terms of cycle-to-cycle variability were proved for the MP system despite poorer mixture homogeneity. Attention has also been paid to the different engine control strategies to be eventually adopted in compliance with the constraints set by the two different layouts. A 0D-1D model has also been built and validated on the experimental data set to be hence exploited for investigating into different strategies both for the SP and for the MP layout. An extensive simulation has been carried out on the effects of the injection phasing on the SP system performance referring to the engine power output and to the air-to-fuel ratio homogeneity amongst the cylinders. Finally, as far as the MP injection system is concerned, the innovative fire-skipping (DSF) or cylinder deactivation has been considered and deployed by means of the numerical model, assessing for an overall decrease in the fuel consumption of 12% at part load operations

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

Numerical and Experimental Analysis of Injection and Mixture Formation in High-Performance CNG Engines

L'abstract è presente nell'allegato / the abstract is in the attachmen

Combustion quality and regimes for standard and alternative fuels

Upcoming environmental constraints require the next generation internal combustion engine (ICE) to yield lower pollutant emissions and higher fuel efficiency. Various alternative fuels and combustion strategies and regimes have shown great potential in meeting these goals. The work done in this dissertation aims at exploring different alternative fuels and advanced combustion strategies through a combination of single-cylinder engine performance and emission tests, laser diagnostics in optical engines, and soot analysis using materials research techniques, in order to improve the combustion and emission performance of the modern ICE. Alcohols, especially n-butanol, have been studied as potential fuels and have shown to be a possible alternative to pure gasoline. In this work, the intermediate product in bio-butanol production through acetone-butanol-ethanol (ABE) fermentation, ABE, was studied for the first time as a potential alternative fuel in spark ignition (SI) engines. Various blends of ABE and gasoline, with different ratios of acetone, n-butanol, and ethanol were studied under various engine operating conditions. The results obtained affirm ABE’s potential as an alternative fuel and explain the effects of ABE components on the combustion process. This work also provides information regarding the optimum ABE ratio to be targeted in the ABE fermentation process. Finally, the datasets obtained are valuable for combustion mechanism and model validation. Another promising and attractive alternative fuel is natural gas. Dual-fuel Compressed Natural Gas (CNG)/diesel combustion in compression ignition (CI) engines has shown the ability to substantially reduce the NOx emission and at the same time produce very low particulate matter (PM) emissions. In this study, CNG/diesel dual-fuel combustion has been studied under various CNG substitution ratios and diesel injection strategies at a wide range of engine operating conditions. The results show how an effective pilot diesel injection strategy in dual-fuel combustion could match the efficiency of diesel combustion (CDC). Furthermore, CNG/diesel dual-fuel combustion was also studied in an optical engine in order to understand the mechanism of dual-fuel combustion. Very few studies have performed visualization of this phenomenon. Exhaust particulate matter from CNG/diesel dual-fuel combustion was also studied and characterized for the first time using materials research techniques such as Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA), CHN elemental analysis, Raman spectroscopy, and Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy. The results would be invaluable for the design of exhaust after-treatment systems for vehicles using CNG/diesel combustion. Gasoline direct injection (GDI) engines have shown improved efficiency and reduced fuel consumption, however, GDI combustion faces the serious issue of PM emissions. This study investigated lean-burn GDI combustion of ethanol-gasoline blends in an optical engine and tested a novel injector and combustion chamber design, in order to obtain better atomization and hence better air/fuel mixing, as well as an overall lean air/fuel mixture that would prevent rich zones and hence the formation of soot. Through this work, a) ABE combustion was studied in gasoline engines for the first time and affirmed as an alternative fuel ; b) By developing improved pilot diesel injection strategies, CNG/diesel dual-fuel combustion was shown to obtain diesel-like efficiency; c) Exhaust particulate matter from CNG/diesel combustion was physically and chemically characterized for the first time using materials analysis techniques; d) CNG/diesel dual-fuel combustion was visualized using color high-speed imaging in an optical engine; e) Lean-burn combustion of ethanol-gasoline blends was investigated in an optical engine