scholarly journals Investigation of the Lean Stable Limit of a Barrier Discharge Igniter and of a Streamer-Type Corona Igniter at Different Engine Loads in a Single-Cylinder Research Engine

Proceedings ◽  
2020 ◽  
Vol 58 (1) ◽  
pp. 11
Author(s):  
Federico Ricci ◽  
Luca Petrucci ◽  
Valentino Cruccolini ◽  
Gabriele Discepoli ◽  
Carlo N. Grimaldi ◽  
...  
Keyword(s):  
High Performance ◽  
Internal Combustion Engines ◽  
Barrier Discharge ◽  
Combustion Process ◽  
Maximum Energy ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Growth Speed ◽  
Stable Limit ◽  
Single Cylinder

Currently, the Radio-Frequency Corona Ignition systems represent an important solution for reducing pollutant emissions and fuel consumption related to Internal Combustion Engines, while at the same time ensuring high performance. These igniters are able to extend the lean stable limit by increasing the early flame growth speed. Kinetic, thermal, and ionic effects, together with the peculiar configuration of the devices, allow the combustion process to start in a wider region than the one involved with the traditional spark. In this work two corona igniters, namely a Barrier Discharge Igniter and a Corona Streamer Igniter, were tested in a single-cylinder research engine fueled with gasoline at different engine loads in order to investigate the igniters’ performance through indicated analysis and pollutant emissions analysis. For each operating point, the devices’ control parameters were set to ensure maximum energy releasement into the medium with the aim of investigating, at the extreme operating conditions, the capability of the devices to extend the lean stable limit of the engine. The corona igniters were tested on a constant volume calorimeter as well, reproducing the engine pressure conditions at the corresponding ignition timing. The target was to give an estimation of the thermal energy released during the discharge and then to compare their capability to provide high-stability energy.

scholarly journals Effect of Fuel and Air Dilution on Syngas Combustion in an Optical SI Engine

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1566 ◽  
Author(s):  
S.D. Martinez-Boggio ◽  
S.S. Merola ◽  
P. Teixeira Lacava ◽  
A. Irimescu ◽  
P.L. Curto-Risso
Keyword(s):  
Internal Combustion Engines ◽  
Combustion Process ◽  
Visible Spectrum ◽  
Propagation Speed ◽  
Fuel Mixture ◽  
Operating Conditions ◽  
Inert Gases ◽  
Pollutant Emissions ◽  
Si Engine ◽  
Lean Burn

To mitigate the increasing concentration of carbon dioxide in the atmosphere, energy production processes must change from fossil to renewable resources. Bioenergy utilization from agricultural residues can be a step towards achieving this goal. Syngas (fuel obtained from biomass gasification) has been proved to have the potential of replacing fossil fuels in stationary internal combustion engines (ICEs). The processes associated with switching from traditional fuels to alternatives have always led to intense research efforts in order to have a broad understanding of the behavior of the engine in all operating conditions. In particular, attention needs to be focused on fuels containing relatively high concentrations of hydrogen, due to its faster propagation speed with respect to traditional fossil energy sources. Therefore, a combustion study was performed in a research optical SI engine, for a comparison between a well-established fuel such as methane (the main component of natural gas) and syngas. The main goal of this work is to study the effect of inert gases in the fuel mixture and that of air dilution during lean fuelling. Thus, two pure syngas blends (mixtures of CO and H2) and their respective diluted mixtures (CO and H2 with 50vol% of inert gases, CO2 and N2) were tested in several air-fuel ratios (stoichiometric to lean burn conditions). Initially, the combustion process was studied in detail by traditional thermodynamic analysis and then optical diagnostics were applied thanks to the optical access through the piston crown. Specifically, images were taken in the UV-visible spectrum of the entire cycle to follow the propagation of the flame front. The results show that hydrogen promotes flame propagation and reduces its distortion, as well as resulting in flames evolving closer to the spark plug. All syngas blends show a stable combustion process, even in conditions of high air and fuel dilution. In the leanest case, real syngas mixtures present a decrease in terms of performance due to significant reduction in volumetric efficiency. However, this condition strongly decreases pollutant emissions, with nitrogen oxide (NOx) concentrations almost negligible.

Influence of Low Ambient Temperatures on the Exhaust Gas and Deposit Composition of Gasoline Engines

2021 ◽  
pp. 1-11
Author(s):  
Dominik Appel ◽  
Fabian P. Hagen ◽  
Uwe Wagner ◽  
Thomas Koch ◽  
Henning Bockhorn ◽  
...  
Keyword(s):  
Internal Combustion Engines ◽  
Gasoline Engine ◽  
Cold Start ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Ex Situ ◽  
Exhaust Gas ◽  
Gasoline Engines ◽  
Ambient Temperatures ◽  
Aftertreatment Systems

Abstract To comply with future emission regulations for internal combustion engines, system-related cold-start conditions in short-distance traffic constitute a particular challenge. Under these conditions, pollutant emissions are seriously increased due to internal engine effects and unfavorable operating conditions of the exhaust aftertreatment systems. As a secondary effect, the composition of the exhaust gases has a considerable influence on the deposition of aerosols via different deposition mechanisms and on fouling processes of exhaust gas-carrying components. Also, the performance of exhaust gas aftertreatment systems may be affected disadvantageously. In this study, the exhaust gas and deposit composition of a turbocharged three-cylinder gasoline engine is examined in-situ upstream of the catalytic converter at ambient and engine starting temperatures of -22 °C to 23 °C using a Fourier-transform infrared spectrometer and a particle spectrometer. For the cold start investigation, a modern gasoline engine with series engine periphery is used. In particular, the investigation of the behavior of deposits in the exhaust system of gasoline engines during cold start under dynamic driving conditions represents an extraordinary challenge due to an average lower soot concentration in the exhaust gas compared to diesel engines and so far, has not been examined in this form. A novel sampling method allows ex-situ analysis of formed deposits during a single driving cycle. Both, particle number concentration and the deposition rate are higher in the testing procedure of Real Driving Emissions (RDE) than in the inner-city part of the Worldwide harmonized Light vehicles Test Cycle (WLTC). In addition, reduced ambient temperatures increase the amount of deposits, which consist predominantly of soot and to a minor fraction of volatile compounds. Although the primary particle size distributions of the deposited soot particles do not change when boundary conditions change, the degree of graphitization within the particles increases with increasing exhaust gas temperature.

scholarly journals Descriptive Statistical Analysis of Vegetable Oil Combustion in a Commercial Burner to Establish Optimal Operating Conditions

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2372 ◽  
Author(s):  
Julio San José ◽  
Yolanda Arroyo ◽  
María Ascensión Sanz-Tejedor
Keyword(s):  
Vegetable Oil ◽  
Combustion Process ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Airflow Rate ◽  
Optimal Operating ◽  
Combustion Performance ◽  
Fuel Flow ◽  
Oil Fuel ◽  
Descriptive Statistical Analysis

This article studies the combustion of refined sunflower, virgin sunflower and virgin rapeseed oils in a low-pressure auxiliary air fluid pulverization burner in order to establish the optimal operating conditions. The influence of varying the type of vegetable oil, fuel flow rate and secondary airflow rate in the combustion process was analyzed. These three factors are independent in the combustion process, which means having to carry out numerous assays, combining the various factors with one another. Given the amount of variables to be optimized and the existence of three factors, a statistical approach is adopted to help interpret the results obtained and to evaluate how each factor influences the combustion results. Optimal combustion is determined based on three criteria, minimum pollutant emissions (CO, NOx and CxHy), maximum combustion performance, and minimum excess air. The result of this study showed that airflow was the principal factor affecting emissions, whereas for combustion performance, both factors (airflow and fuel flow) were determinant. In general, admissible combustion performances were obtained, with CO and NOx emissions below permitted levels. The best combustion performance was achieved under conditions of maximum fuel flow and minimum airflow rates.

A Novel Electromechanical Solution for Cam-Switching in High Performance Internal Combustion Engines

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Andrea De Martin ◽  
Giovanni Jacazio ◽  
Massimo Sorli
Keyword(s):  
High Performance ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Operating Conditions ◽  
Valve Lift ◽  
Combustion Engines ◽  
Critical Aspect ◽  
Conceptual Design Phase ◽  
Common Strategy ◽  
Switch System

Abstract The variation of the valve lift is a fairly common strategy currently adopted in several in-service internal combustion engines to optimize their performance depending on the operating conditions of the vehicle. The most critical aspect to consider during the conceptual design phase of a cam switch system is the extremely narrow window of opportunity to perform the cam change, which duration is defined by the time during which the corresponding valve lift is null. To meet this requirement and ensure safe, repeatable movements, a novel architecture based on the combination of a new electromechanical actuator and its dedicated control system is presented. The architecture is at first introduced with reference to the numerous examples available in the literature, and hence mathematically described. The dynamic model of the system derived from the presented equation is then used to study the performance of the presented solution and define its control strategy. Results are finally presented and discussed.

Numerical Optimization of a Waste-to-Energy Plant Under Different Operating Conditions

2011 ◽  
Author(s):  
Niko Samec ◽  
Miran Kapitler ◽  
Filip Kokalj
Keyword(s):  
Numerical Optimization ◽  
Flow Direction ◽  
Input Parameter ◽  
Combustion Process ◽  
Operating Conditions ◽  
Waste To Energy ◽  
Pollutant Emissions ◽  
Plant Design ◽  
Energy Plant ◽  
Input Parameters

The combustion process for using municipal solid waste (MSW) as a fuel within a waste-to-energy plant calls for a detailed understanding of the following phenomena. Firstly, this process depends on many input parameters such as MSW proximate and ultimate analysis, the season of the year, primary and secondary air-inlet velocity and, secondly, on output parameters such as the temperatures or mass-flow rates (MFR) of the combustible products. The variability and mutual dependence of these parameters can be difficult to manage in practice. Moreover, another problem is how these parameters can be tuned to achieving optimal combustion with minimal pollutant emissions during the initial plant-design phase. In order to meet these goals, a waste-to-energy plant with bed-combustion was investigated by using a computational fluid dynamics (CFD) approach with ANSYS CFX 12.0 code within a WORKBENCH 2 environment. In this paper, the adequate variable input boundary conditions based on the real measurement and practical calculations of known MSW composition compared with other authors are used and the whole computational work is updated using real plant geometry and the appropriate turbulence, combustion and heat transfer models. Furthermore, the operating parameters were optimized on output parameters through a trade-off study. The different operating conditions were varied and the fluid flow direction, residence time, temperature field, velocity-field, nitric oxide formation and combustion products through the plant’s combustion chamber and preheat intersection in 3D were predicted and visualized. Optimization in real-time has showed the amounts for each input parameter when meeting the optimal operating conditions. Finally, the response charts between the input and output parameters are presented in order to monitor the dependence among these parameters. Further simulations have to be done to include the geometry dimensions as input parameters when applying the CDF simulation and numerical optimization within the project phase.

Influence of Low Ambient Temperatures on the Exhaust Gas and Deposit Composition of Gasoline Engines

2020 ◽  
Author(s):  
Dominik Appel ◽  
Fabian P. Hagen ◽  
Uwe Wagner ◽  
Thomas Koch ◽  
Henning Bockhorn ◽  
...  
Keyword(s):  
Internal Combustion Engines ◽  
Gasoline Engine ◽  
Cold Start ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Ex Situ ◽  
Exhaust Gas ◽  
Gasoline Engines ◽  
Ambient Temperatures ◽  
Aftertreatment Systems

Abstract To comply with future emission regulations for internal combustion engines, system-related cold-start conditions in short-distance traffic constitute a particular challenge. Under these conditions, pollutant emissions are seriously increased due to internal engine effects and unfavorable operating conditions of the exhaust aftertreatment systems. As a secondary effect, the composition of the exhaust gases has a considerable influence on the deposition of aerosols via different deposition mechanisms and on fouling processes of exhaust gas-carrying components. Also, the performance of exhaust gas aftertreatment systems may be affected disadvantageously. In this study, the exhaust gas and deposit composition of a turbocharged three-cylinder gasoline engine is examined in-situ upstream of the catalytic converter at ambient and engine starting temperatures of −22 °C to 23 °C using a Fourier-transform infrared spectrometer and a particle spectrometer. For the cold start investigation, a modern gasoline engine with series engine periphery is used. In particular, the investigation of the behavior of deposits in the exhaust system of gasoline engines during cold start under dynamic driving conditions represents an extraordinary challenge due to an average lower soot concentration in the exhaust gas compared to diesel engines and so far, has not been examined in this form. A novel sampling method allows ex-situ analysis of formed deposits during a single driving cycle. Both, particle number concentration and the deposition rate are higher in the testing procedure of Real Driving Emissions (RDE) than in the inner-city part of the Worldwide harmonized Light vehicles Test Cycle (WLTC). In addition, reduced ambient temperatures increase the amount of deposits, which consist predominantly of soot and to a minor fraction of volatile compounds. Although the primary particle size distributions of the deposited soot particles do not change when boundary conditions change, the degree of graphitization within the particles increases with increasing exhaust gas temperature.

scholarly journals Individual Cylinder Combustion Optimization to Improve Performance and Fuel Consumption of a Small Turbocharged SI Engine

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5548
Author(s):  
Luca Marchitto ◽  
Cinzia Tornatore ◽  
Luigi Teodosio
Keyword(s):  
Fuel Consumption ◽  
Internal Combustion Engines ◽  
Fuel Injection ◽  
Combustion Process ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Exhaust Emission ◽  
Cycle Variation ◽  
Spark Timing ◽  
Experimental Findings

Stringent exhaust emission and fuel consumption regulations impose the need for new solutions for further development of internal combustion engines. With this in mind, a refined control of the combustion process in each cylinder can represent a useful and affordable way to limit cycle-to-cycle and cylinder-to-cylinder variation reducing CO2 emission. In this paper, a twin-cylinder turbocharged Port Fuel Injection–Spark Ignition engine is experimentally and numerically characterized under different operating conditions in order to investigate the influence of cycle-to-cycle variation and cylinder-to-cylinder variability on the combustion and performance. Significant differences in the combustion behavior between cylinders were found, mainly due to a non-uniform effective in-cylinder air/fuel (A/F) ratio. For each cylinder, the coefficients of variation (CoVs) of selected combustion parameters are used to quantify the cyclic dispersion. Experimental-derived CoV correlations representative of the engine behavior are developed, validated against the measurements in various speed/load points and then coupled to an advanced 1D model of the whole engine. The latter is employed to reproduce the experimental findings, taking into account the effects of cycle-to-cycle variation. Once validated, the whole model is applied to optimize single cylinder operation, mainly acting on the spark timing and fuel injection, with the aim to reduce the specific fuel consumption and cyclic dispersion.

Potential of miller timing with synthetic diesel fuels on a single cylinder heavy-duty engine

2021 ◽  
pp. 146808742110436
Author(s):  
Simon Pöllmann ◽  
Martin Härtl ◽  
Georg Wachtmeister
Keyword(s):  
Nitrogen Oxides ◽  
Diesel Fuel ◽  
High Performance ◽  
Internal Combustion Engines ◽  
Soot Formation ◽  
Cetane Number ◽  
Boost Pressure ◽  
Heavy Duty ◽  
Simultaneous Application ◽  
Single Cylinder

Upcoming emission limits such as Euro VII will make it necessary to further reduce the NOx emission level of internal combustion engines while stricter CO2 limits demand lower fuel consumption. Early closing of the intake valves (Miller timing) leads to reduced combustion temperatures due to lower effective compression ratio, and therefore lower formation and emission of nitrogen oxides. Miller timing is frequently used in gasoline engines, while in Diesel engines it competes with exhaust gas recirculation (EGR). When both measures are applied simultaneously, this may lead to increased emission of soot using standard Diesel fuel, as combustion temperature and oxygen content of the charge become too low. This work shows the investigation of different intake valve timings on an externally supercharged single-cylinder heavy-duty Diesel engine, stationary operated with hydrogenated vegetable oil (HVO), oxymethylene ether (OME), and standard Diesel fuel (DF). The synthetic fuels have a higher cetane number than DF, which supports ignition at lower temperatures. Moreover, OME has a soot-free combustion, which allows an extension of the operating limits without increased emissions. The results show that especially with Miller timing a high-performance turbocharging system is crucial, since higher boost pressure is required to compensate for the filling losses due to the earlier intake closing. The application of a high EGR rate is limited in this case, leading to a trade-off between Miller timing and EGR. All fuels show a reduction in nitrogen oxides of up to 40% with an improved efficiency of more than 3% at a typical road-load point. Measures to reduce ignition delay were found to be necessary, especially for DF. For OME, increased soot formation does not occur when combining Miller timing with low rail pressure, reduced boost pressure or EGR, which promotes simultaneous application of the measures resulting in minimized emissions of nitrogen oxides.

Numerical and Experimental Investigation on an Effusion-Cooled Lean Burn Aeronautical Combustor: Aerothermal Field and Emissions

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
L. Mazzei ◽  
S. Puggelli ◽  
D. Bertini ◽  
A. Andreini ◽  
B. Facchini ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Combustion Process ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Flame Spray ◽  
Distribution Factor ◽  
Lean Burn ◽  
Radial Temperature ◽  
Flamelet Generated Manifold ◽  
The Impact

Lean burn combustion is increasing its popularity in the aeronautical framework due to its potential in reducing drastically pollutant emissions (NOx and soot in particular). Its implementation, however, involves significant issues related to the increased amount of air dedicated to the combustion process, demanding the redesign of injection and cooling systems. Also, the conditions at the combustor exit are a concern, as high turbulence, residual swirl, and the impossibility to adjust the temperature profile with dilution holes determine a harsher environment for nozzle guide vanes. This work describes the final stages of the design of an aeronautical effusion-cooled lean burn combustor. Full annular tests were carried out to measure temperature profiles and emissions (CO and NOx) at the combustor exit. Different operating conditions of the ICAO cycle were tested, considering Idle, Cruise, Approach, and Take-off. Scale-adaptive simulations with the flamelet generated manifold (FGM) combustion model were performed to extend the validation of the employed computational fluid dynamics (CFD) methodology and to reproduce the experimental data in terms of radial temperature distribution factor (RTDF)/overall temperature distribution factor (OTDF) profiles as well as emission indexes (EIs). The satisfactory agreement paved the way to an exploitation of the methodology to provide a deeper understanding of the flow physics within the combustion chamber, highlighting the impact of the different operating conditions on flame, spray evolution, and pollutant formation.

scholarly journals Effect of Cylinder-by-Cylinder Variation on Performance and Gaseous Emissions of a PFI Spark Ignition Engine: Experimental and 1D Numerical Study

2021 ◽  
Vol 11 (13) ◽  
pp. 6035
Author(s):  
Luigi Teodosio ◽  
Luca Marchitto ◽  
Cinzia Tornatore ◽  
Fabio Bozza ◽  
Gerardo Valentino
Keyword(s):  
Internal Combustion Engines ◽  
Numerical Study ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Combustion Stability ◽  
Pollutant Emissions ◽  
Gaseous Emissions ◽  
Performance And Emissions ◽  
The Impact

Combustion stability, engine efficiency and emissions in a multi-cylinder spark-ignition internal combustion engines can be improved through the advanced control and optimization of individual cylinder operation. In this work, experimental and numerical analyses were carried out on a twin-cylinder turbocharged port fuel injection (PFI) spark-ignition engine to evaluate the influence of cylinder-by-cylinder variation on performance and pollutant emissions. In a first stage, experimental tests are performed on the engine at different speed/load points and exhaust gas recirculation (EGR) rates, covering operating conditions typical of Worldwide harmonized Light-duty vehicles Test Cycle (WLTC). Measurements highlighted relevant differences in combustion evolution between cylinders, mainly due to non-uniform effective in-cylinder air/fuel ratio. Experimental data are utilized to validate a one-dimensional (1D) engine model, enhanced with user-defined sub-models of turbulence, combustion, heat transfer and noxious emissions. The model shows a satisfactory accuracy in reproducing the combustion evolution in each cylinder and the temperature of exhaust gases at turbine inlet. The pollutant species (HC, CO and NOx) predicted by the model show a good agreement with the ones measured at engine exhaust. Furthermore, the impact of cylinder-by-cylinder variation on gaseous emissions is also satisfactorily reproduced. The novel contribution of present work mainly consists in the extended numerical/experimental analysis on the effects of cylinder-by-cylinder variation on performance and emissions of spark-ignition engines. The proposed numerical methodology represents a valuable tool to support the engine design and calibration, with the aim to improve both performance and emissions.

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