Refine Your Search

Search Results

Viewing 1 to 12 of 12
Technical Paper

Combustion and Emission Characteristics of Ammonia Jet Flames, Based on a Controllable Activated Thermal Atmosphere

2023-10-31
2023-01-1645
Ammonia is a new type of carbon-free fuel with low cost, clean and safe. The research and application of zero-carbon fuel internal combustion engines has become the mainstream of future development. However, there still exist problems should be solved in the application of ammonia fuel. Due to the lower flame laminar speed and higher ignition temperature, ammonia may have unstable combustion phenomena. In this work, the characteristics of ammonia combustion have been investigated, based on controllable thermal activated atmosphere burner. The ignition delay has been used to analyze the ammonia combustion characteristics. With the increase in co-flow temperature, the ignition delay of ammonia/air has an obvious decline. In order to investigate the emission characteristics of ammonia, CHEMKIN is used to validate the different chemical reaction mechanisms and analyse the ammonia emissions.
Book

Injection Technologies and Mixture Formation Strategies For Spark-Ignition and Dual-Fuel Engines

2022-06-24
Fuel injection systems and performance is fundamental to combustion engine performance in terms of power, noise, efficiency, and exhaust emissions. There is a move toward electric vehicles (EVs) to reduce carbon emissions, but this is unlikely to be a rapid transition, in part due to EV batteries: their size, cost, longevity, and charging capabilities as well as the scarcity of materials to produce them. Until these issues are resolved, refining the spark-ignited engine is necessary to address both sustainability and demand for affordable and reliable mobility. Even under policies oriented to smart sustainable mobility, spark-ignited engines remain strategic, because they can be applied to hybridized EVs or can be fueled with gasoline blended with bioethanol or bio-butanol to drastically reduce particulate matter emissions of direct injection engines in addition to lower CO2 emissions.
Journal Article

Potentialities of Boot Injection Combined with After Shot for the Optimization of Pollutant Emissions, Fuel Consumption and Combustion Noise in Passenger Car Diesel Engines

2017-03-14
2017-01-9277
The present paper illustrates an investigation about the potentialities of injection rate shaping coupled with an after injection. A pilot shot can either be absent or present before the rate-shaped boot injection. The experimental tests have been performed on a partial PCCI Euro 5 diesel engine endowed with direct-acting piezoelectric injectors. Starting from optimized triple pilot-main-after injection strategies, boot injection was implemented by maintaining the direct-acting piezo injector needle open at part lift. The results of two steady state working conditions have been presented in terms of engine-out emissions, combustion noise and brake specific fuel consumption. In addition, in-cylinder analyses of the pressure, heat-release rate, temperature and emissions have been evaluated. Considering the in-cylinder pressure traces and the heat release rate curves, the injection rate shaping proved to influence combustion in the absence of a pilot injection to a great extent.
Technical Paper

Modal Analysis as a Design Tool for Dynamical Optimization of Common Rail Fuel Injection Systems

2015-09-06
2015-24-2467
A challenging task that is required to modern injection systems is represented by the enhanced control of the injected quantities, especially when small injections are considered, such as, pilot and main shots in the context of multiple injections. The propagation of the pressure waves triggered by the nozzle opening and closure events through the high-pressure hydraulic circuit can influence and alter the performance of the injection apparatus. For this reason, an investigation of the injection system fluid dynamics in the frequency domain has been proposed. A complete lumped parameter model of the high-pressure hydraulic circuit has been applied to perform a modal analysis. The visualization of the main vibration modes of the apparatus allows a detailed and deep comprehension of the system dynamics. Furthermore, the possible resonances, which are induced by the action of the external forcing terms, have been identified.
Technical Paper

Common Feeding Injection System Equipped with Reduced-Leakage Solenoid Injectors

2014-10-13
2014-01-2735
A numerical-experimental analysis of a new generation Common Feeding (CF) fuel injection system, equipped with last generation solenoid injectors that feature pressure-balanced pilot-valves, has been developed. The main feature of the CF system is that it removes the accumulator from the high-pressure layout of the standard Common Rail (CR). In the CF apparatus, the high-pressure pump is connected directly to the injectors, and a small accumulation volume is integrated in the pump high-pressure circuit. The hydraulic performance of the CF system, including the injectors with the pressure-balanced pilot-valve, has been compared with that of the standard CR system in terms of injected masses, fuel leakages, high-pressure and injected flow-rate time histories. A previously developed advanced one-dimensional code for CR type systems has been adapted for the simulation of the CF high-pressure layout.
Journal Article

Impact on Performance, Emissions and Thermal Behavior of a New Integrated Exhaust Manifold Cylinder Head Euro 6 Diesel Engine

2013-09-08
2013-24-0128
The integration of the exhaust manifold in the engine cylinder head has received considerable attention in recent years for automotive gasoline engines, due to the proven benefits in: engine weight diminution, cost saving, reduced power enrichment, quicker engine and aftertreatment warm-up, improved packaging and simplification of the turbocharger installation. This design practice is still largely unknown in diesel engines because of the greater difficulties, caused by the more complex cylinder head layout, and the expected lower benefits, due to the absence of high-load enrichment. However, the need for improved engine thermomanagement and a quicker catalytic converter warm-up in efficient Euro 6 diesel engines is posing new challenges that an integrated exhaust manifold architecture could effectively address. A recently developed General Motors 1.6L Euro 6 diesel engine has been modified so that the intake and exhaust manifolds are integrated in the cylinder head.
Technical Paper

Analysis of Energy-Efficient Management of a Light-Duty Parallel-Hybrid Diesel Powertrain with a Belt Alternator Starter

2011-09-11
2011-24-0080
The paper presents the main results of a study on the simulation of energy efficient management of on-board electric and thermal systems for a medium-size passenger vehicle featuring a parallel-hybrid diesel powertrain with a high-voltage belt alternator starter. A set of advanced technologies has been considered on the basis of very aggressive fuel economy targets: base-engine downsizing and friction reduction, combustion optimization, active thermal management, enhanced aftertreatment and downspeeding. Mild-hybridization has also been added with the goal of supporting the downsized/downspeeded engine performance, performing energy recuperation during coasting phases and enabling smooth stop/start and acceleration. The simulation has implemented a dynamic response to the required velocity and manual gear shift profiles in order to reproduce real-driver behavior and has actuated an automatic power split between the Internal Combustion Engine (ICE) and the Electric Machine (EM).
Technical Paper

Development and Application of an Advanced Numerical Model for CR Piezo Indirect Acting Injection Systems

2010-05-05
2010-01-1503
A numerical model for simulating a Common Rail Piezo Indirect Acting fuel injection-system under steady state as well as transient operating conditions was developed using a commercial code. A 1D flow model of the main hydraulic system components, including the rail, the rail to injector connecting pipe and the injector, was applied in order to predict the influence of the injector layout and of each part of the hydraulic circuit on the injection system performance. The numerical code was validated through the comparison of the numerical results with experimental data obtained on a high performance test bench of the Moehwald-Bosch MEP2000/ CA4000 type. The developed injection-system mathematical model was applied to the analysis of transient flows in the hydraulic circuit paying specific attention to the fluid dynamics internal to the injector.
Technical Paper

Experimental Analysis of Combustion Processes and Emissions in a 2.0L Multi-Cylinder Diesel Engine Featuring a New Generation Piezo-Driven Injector

2009-09-13
2009-24-0040
In this paper, the potential of new generation piezo-driven indirect acting injectors on high feature diesel engine performance and emissions was assessed by combining experimental tests (carried out at both hydraulic and engine test beds) with the diagnostics of combustion and emissions. This latter was performed by means of a refined multizone combustion diagnostic tool previously developed at Politecnico di Torino. More in detail, a complete hydraulic characterization of the injection system has been carried out and injector performance, in terms of robustness and repeatability of the injection process, has been also evaluated. Injectors were then installed on 4-cylinder 2.0L Diesel engine and tests were performed in seven key-points, which were specifically selected so as to reproduce the engine operations over NEDC in terms of emissions and fuel consumption.
Journal Article

Advanced Mathematical Modeling of Electronic Unit-Injector Systems for Heavy Duty Diesel Engine Application

2008-04-14
2008-01-1195
A rather complete mathematical model to simulate HD-diesel- engine EUI-system dynamics was developed and applied as a complementary tool of experimentation, for supporting design and performance optimization. The thermo-fluid dynamics of the hydraulic components, including plunger cavity, internal injector pipes and nozzle, was modeled with the solenoid-circuit electromagnetics and the mechanics of rocker arm and follower subsystem. Onedimensional flow equations in conservation form were used to simulate wave propagation phenomena through the injector high-pressure drilled passages. To calculate the temperature variations due to the compressibility of the liquid fuel, the energy equation was used in addition to mass conservation and momentum balance equations. Furthermore, in order to determine the value of the electromagnetic force acting on the spill-valve, the application of a practical procedure was made using easily available experimental current and voltage data.
Technical Paper

Common Rail without Accumulator: Development, Theoretical-Experimental Analysis and Performance Enhancement at DI-HCCI Level of a New Generation FIS

2007-04-16
2007-01-1258
An innovative hydraulic layout for Common Rail (C.R.) fuel injection systems was proposed and realized. The rail was replaced by a high-pressure pipe junction to have faster dynamic system response during engine transients, smaller pressure induced stresses and sensibly reduced production costs. Compared to a commercial rail, whose inside volume ranges from 20 to 40 cm3, such a junction provided a hydraulic capacitance of about 2 cm3 and had the main function of connecting the pump delivery to the electroinjector feeding pipes. In the design of the novel FIS layout, the choice of high-pressure pipe dimensions was critical for system performance optimization. Injector supplying pipes with length and inner diameter out of the actual production range were selected and applied, for stabilizing the system pressure level during an injection event and reduce pressure wave oscillations.
Technical Paper

Thermal Effect Simulation in High-Pressure Injection System Transient Flows

2004-03-08
2004-01-0532
Temperature variations due to compressibility effects of the liquid fuel were evaluated, for the first time in high-pressure injection system simulation, by employing the energy conservation equation, in addition to the mass-continuity and momentum-balance equations, as well as the constitutive state equation of the liquid. To that end, the physical properties (bulk elasticity modulus, thermal expansivity, kinematic viscosity) of the fluid were used as analytic functions of pressure and temperature obtained by interpolating carefully determined experimental data. Consistent with negligible thermal effects of heat transfer and viscous power losses involved in the flow process, the equation of energy was reduced to a state relation among the fluid thermodynamic properties, leading to a barotropic flow model.
X