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Technical Paper

Optimization of CI Engine Performance and Emissions Fueled by Blends of Alternative Fuels Methyl Ester Using Taguchi and Multi Regression Analysis

2019-09-16
2019-01-1893
Today’s frenetic engine manufacturing and transportation sector and its related traces viz; noise and vibration of our modern societies has adverse effect on environment as well as all of us. Modern research affords us the opportunity to understand the subject better and to develop advance technologies. Widely immediate slogan and goal of all industries might be to improve the performance and reduce emission using alternative fuel while, make the quietest and smoothest running Engines. To, reduce the dependency on diesel fuel (Due to rapid worldwide depletion) Biodiesel is one of the immediate, alternative and complimentary solution. In the Present study, to optimize the operating parameters of the Direct Injection Single Cylinder (5.2 kw) CI engine with respect to Brake Thermal Efficiency (BTE), Carbon monoxide (CO), Oxides of Nitrogen, Hydrocarbons (HC) etc..
Technical Paper

CFD Investigation of the Effects of Gas’ Methane Number on the Performance of a Heavy-Duty Natural-Gas Spark-Ignition Engine

2019-08-15
2019-24-0008
Natural gas (NG) is an alternative fuel for spark-ignition engines. In addition to its cleaner combustion, recent breakthroughs in drilling technologies increased its availability and lowered its cost. NG consists of mostly methane, but it also contains heavier hydrocarbons and inert diluents, the levels of which vary substantially with geographical source, time of year, and treatments applied during production or transportation. To investigate the effects of NG composition on engine performance and emissions, a 3D CFD model of a heavy-duty diesel engine retrofitted to spark ignition operations simulated engine operation under lean-combustion, low-speed, and medium load conditions. To eliminate the effect of different gas energy density, three NG blends of similar lower heating value but different H/C ratio have been investigated at fixed spark timing.
Technical Paper

A Computationally Efficient Progress Variable Approach for In-Cylinder Combustion and Emissions Simulations

2019-08-15
2019-24-0011
The use of complex reaction schemes is accompanied by high computational cost in 3D CFD simulations but is particularly important to predict pollutant emissions in in-cylinder simulations. One solution to tackle this problem is to use tabulated chemistry. The approach presented herein combines pre-tabulated progress variable-based source terms for auto-ignition as well as soot and NOx source terms for advanced emission predictions. The method is coupled to CONVERGE v2.4 via user-coding and tested over various speed and load passenger-car Diesel engine conditions. This work includes the comparison between the combustion progress variable (CPV) model and the on-line chemistry solver in CONVERGE 2.4. Both models are also compared against experimental data by means of combustion and emission parameters. A detailed mechanism comprising 190 species, having n-decane/α-methyl-naphthalene as main fuels, is used for both on-line and tabulated chemistry simulations.
Technical Paper

Heavy-Duty Compression-Ignition Engines Retrofitted to Spark-Ignition Operation Fueled with Natural Gas

2019-08-15
2019-24-0030
Natural gas is a promising alternative gaseous fuel due to its availability, economic, and environmental benefits. A solution to increase its use in the heavy-duty transportation sector is to convert existing heavy-duty compression ignition engines to spark-ignition operation by replacing the fuel injector with a spark plug and injecting the natural gas inside the intake manifold. The use of numerical simulations to design and optimize the natural gas combustion in such retrofitted engines can benefit both engine efficiency and emission. However, experimental data of natural gas combustion inside a bowl-in-piston chamber is limited. Consequently, the goal of this study was to provide high-quality experimental data from such a converted engine fueled with methane and operated at steady-state conditions, exploring variations in spark timing, engine speed and equivalence ratio.
Technical Paper

Optimization of Multi Stage Direct Injection-PSCCI Engines

2019-08-15
2019-24-0029
The more stringent regulations on emissions induce the automotive companies to develop new solutions for engine design, including the use of advanced combustion strategies and the employment of mixture of fuels with different thermochemical properties. The HCCI combustion coupled with the partial direct injection of the charge, in order to control the performance and emissions and to extend the operating range, is a promising technique. In this work an in-house developed multi-dimensional CFD software package was used to analyse the behaviour of a multi stage direct injection (DI)-partially stratified charge compression ignition engine fueled with PRF. A skeletal kinetic mechanism for PRF oxidation was employed, with a dynamic adaptive chemistry technique to reduce the computational cost and a model based on the partially stirred reactor model to couple turbulence and chemistry.
Technical Paper

Computational Chemistry Consortium: surrogate fuel mechanism development, pollutants submechanisms and components library.

2019-08-15
2019-24-0020
The Computational Chemistry Consortium (C3) is dedicated to leading the advancement of combustion and emissions modeling in internal combustion engines. The C3 cluster combines the expertise of different groups involved in combustion research aiming to refine existing chemistry models and to develop more efficient tools for the generation of surrogate and multi-fuel mechanisms, and suitable mechanisms for CFD applications. In addition to the development of more accurate kinetic models for different components of interest in real fuels’ surrogates and for pollutants formation (NOx, PAHs, soot), the core activity of C3 is to develop a tool capable of merging high fidelity kinetics from different sources (i.e. different partners), resulting in a high-fidelity model for a specific application.
Technical Paper

Selection of Three Way Catalyst Converter for CNG engine to meet BSVI Emission Norms

2019-08-15
2019-24-0044
Compressed natural gas (CNG) is a substitution of alternative fuel for automotive application with significant environmental advantages as it is the only fuel cheaper than gasoline or diesel, comparatively lower air pollution emissions, lesser CO2 emissions. Stringent regulations have been adopted to curb the menace of vehicular pollution. In order to meet the stringent regulations catalytic convertor using noble metals proved to a boon in vehicular industry. Noble metals are highly active for removal of methane as a pollutant. However, their expensiveness, deterioration with time can generate even more toxic volatile pollutants. The paper related to developing of a new gas engines with high energy efficiency and meeting future emission standards. It is necessary to develop complex exhaust gas after treatment systems to treat the toxic components efficiently when the engine runs on stoichiometric and lean mixtures.
Technical Paper

Biogenous Ethanol: CO2 Savings and Operation in a Dual-Fuel Designed Diesel Engine

2019-08-15
2019-24-0040
The usage of ethanol and two different mixtures of ethanol and gasoline (E85 and E65) was investigated on a modified diesel engine designed to work in a dual-fuel combustion mode with intake manifold alcohol injection. The maximum ratio of alcohol to diesel fuel was limited by irregular combustion phenomena like degrading combustion quality and poor process controllability at low load and knock as well as auto-ignition at high load. With rising alcohol amount, a significant reduction of soot mass and particle number was observed. At some testing points, substituting diesel with ethanol, E65 or E85 led to a reduction of NOx emissions; however, the real benefit concerning the nitrogen oxides was introduced by the mitigation of the soot-NOx trade-off. With regard to the engine efficiency aspect, the results show bidirectional behaviour: at low load points engine efficiency degrades, whereas the process becomes by up to 6 % (rel.) more effective at higher engine loads.
Technical Paper

Ignition Delay Model of Multiple Injections in CI engines

2019-08-15
2019-24-0071
In compression ignition engines, the combustion starts after the ignition delay period from the start of injection. The degree of mixing between air and fuel during the period have an impact on the combustion characteristic such as pressure rise rate which can worsen the combustion noise. The formation of particulate matter and nitrogen oxides also can be affected. In addition, ignition delay is required when estimating the in-cylinder pressure since it can provide information about the start of combustion. Therefore, a semi-empirical and 0-dimensional ignition delay model has been developed in this study for real-time control applications. As the ignition delay consists of physical and chemical delays in CI engines, the integrated ignition delay model established in this paper considered both of them.
Technical Paper

Performance and emissions of an advanced multi-cylinder SI engine operating in ultra-lean conditions

2019-08-15
2019-24-0075
Along the design process of a new engine, the calibration phase at the test bench usually involves a relevant percentage of the overall time-to-market. Each control variable, in fact, needs to be properly selected to optimize the performance and emissions, complying with thermal and mechanical stresses limits of the engine. This issue is still more critical for advanced engine architectures, which include additional control variables, such as valve phasing, turbocharger control, EGR level, etc. The aim of this work is the development of a numerically performed calibration procedure, applied to a prototype multi-cylinder Spark Ignition (SI) engine, designed to operate at very lean mixtures. To this aim, an active Pre-Chamber ignition system is considered. The required air flow rate is indeed provided by a Low-Pressure (LP) variable geometry turbocharger group, coupled to a high-pressure e-compressor.
Technical Paper

Multidimensional Modeling of SCR Systems via the Lattice Boltzmann Method

2019-08-15
2019-24-0048
In this paper, we deploy a novel, multidimensional approach to simulate SCR reactors across physical scales. For the first time, a full 3D Lattice Boltzmann (LB) solver is developed, able to accurately capture the fluid dynamic phenomena taking place inside SCR reactors, as well as the catalytic conversion of NOx. The influence of engine load on exhaust gas mass flow rate and catalytic converter activity is taken into account. The proposed approach is computationally light and the results prove the reliability and versatility of the LB Method for the simulation of the complex phenomena that take place inside the aftertreatment devices.
Technical Paper

Smart cylinder deactivation strategies to improve fuel economy and pollutant emissions for Diesel-powered applications

2019-08-15
2019-24-0055
Further improvement of the trade-off between CO2- and pollutant emissions is the main motivating factor for the development of new diesel engine concepts, from light-duty car applications via medium-duty commercial vehicles up to large long-haul trucks. The deactivation of one or more cylinders of a light-duty diesel engine during low load operation can be a sophisticated method to improve fuel economy and reduce especially NOx emissions at the same time. Dynamic Skip Fire (DSF) is and advanced cylinder deactivation technology, where the decision to fire or skip singular units of a multi-cylinder engine architecture is taken just prior to each firing opportunity, based on a balanced rankling of multiple input parameters.
Technical Paper

Study and Optimization of Spark Ignition System for Port Injection Turbocharged CNG

2019-08-15
2019-24-0057
Availability of diesel and gasoline is diminishing at a healthy rate and on the other hand, emission norms are getting stringent year by year. So, at such a facet, alternative fuels have become a vital aspect of research for all the commercial and passenger vehicle manufacturers. CNG, being one of the top options for alternative fuels, is getting a lot of attention in commercial vehicles for now a day. Combustion optimization with stringent norms, minimum after treatment cost is becoming much more difficult. Hence, this is forcing everyone to explore different new areas for low cost solutions. Ignition system plays a dynamic role in achieving optimized performance and emissions. Spark gap, spark plug protrusion and desired spark voltage are few key indices from ignition system which majorly affects the combustion process inside the cylinder.
Technical Paper

Piston Bowl Design Selection and Optimization for BS-VI Diesel Engine based on Multi-dimensional Combustion Simulation

2019-08-15
2019-24-0086
Stringent emission norms imposed by the recent changes due to implementation of BS-VI emission regulation requires additional focus on improving in-cylinder combustion and emission behavior. These behaviors are in general influenced by piston bowl shape and design. Properties like local AF ratio inside the cylinder and in-cylinder fuel air mixing are influenced by piston bowl shape and design. These properties in turn affect NOx and soot emission. The load on after treatment system like DPF can thus be decreased by optimizing the piston bowl design such that in-cylinder soot emission is reduced. In this study CFD combustion analysis has been carried out to arrive at a piston bowl geometry design with least soot emission for a 3.76-Liter BS-VI CRDI engine. In this work commercially available CFD code AVL FIRE is used for the combustion simulation.
Technical Paper

Emission factors evaluation in the RDE context by a multivariate statistical approach

2019-08-15
2019-24-0152
The Real Driving Emission (RDE) procedure will measure the pollutants, such as NOx, emitted by cars while driven on the road. RDE will not replace laboratory tests, such as the current WLTP but it will be added to them. RDE is complementary to the laboratory-based procedure to check the pollutant emissions level of a light-duty vehicle in real driving conditions. This means that the car will be driven on a real road according to random acceleration and deceleration patterns conditioned by traffic flow. So, the procedure will ensure that cars deliver real emissions over on-road and so the currently observed differences between emissions measured in the laboratory and those measured on road under real-world conditions, will be reduced. However, the identification of a path on the road to check the test conditions of RDE is not easy and hardly repeatable.
Technical Paper

Emissions Optimization Potential of a Diesel Engine Running on HVO: A Combined Experimental and Simulation Investigation

2019-08-15
2019-24-0039
The present work investigates some recalibration possibilities of a 1.4l common rail turbo-charged diesel engine for the optimal operation in terms of emissions and fuel consumption (FC) with pure Hydrotreated Vegetable Oil (HVO). Initially, steady-state experimental data with nominal engine settings revealed HVO benefits as a drop-in fuel. Under these conditions, pure HVO is associated with lower engine out PM (up to 75%) and CO2 (up to 10%) emissions, and lower mass-based FC (up to 9%), while NOx are similar or slightly higher to diesel fuel. At the next step, a combustion model was developed for the particular engine targeting to identify the optimal IT (Injection Timing) and EGR settings for further emissions (PM, NOx and CO2) and FC reduction with pure HVO. For this purpose, four re-adjusted IT and EGR maps were developed with both conventional diesel and HVO.
Technical Paper

Reduction of NOx in a Single Cylinder Diesel Engine Emissions Using Selective Non Catalytic Reduction (SNCR) with In-Cylinder Injection of Aqueous Urea

2019-08-15
2019-24-0144
The subject of this study was the effect of in-cylinder selective non-catalytic reduction (SNCR) of NOx emissions in diesel exhaust gas by means of direct injection of aqueous urea (NH2-CO-NH2) into the combustion chamber. A naturally aspirated single cylinder test engine was modified to accept an electronically controlled secondary common rail injection system to deliver the aqueous urea directly into the cylinder during engine operation. Direct in-cylinder injection was chosen to ensure precise delivery of the reducing agent without the risk of premature reactions. Aqueous urea also works as the primary reducing agent by breaking down into ammonia (NH3) and Cyanuric Acid ((HOCN)3). These compounds serve as the primary reducing agents in the NOx reduction mechanism explored here. The main reduction agent, aqueous urea, was mixed with glycerol (C3H8O3) in an 80-20 ratio by weight with the desire to function as a lubricant for the secondary injector.
Technical Paper

Virtual Investigation of Real Fuels by Means of 3D-CFD Engine Simulations

2019-08-15
2019-24-0090
The worldwide environmental issues are affecting the development processes in all industrial sectors. Among these, the automotive is probably the one facing the toughest challenges. The reduction of both harmful emissions (CO, HC, NOx, etc.) and gases responsible for greenhouse effects (especially CO2) are mandatory aspects to be considered in the development process of any kind of propulsion concept. A comprehensive well-to-wheel analysis – in comparison with the less inclusive yet very common tank-to-wheel approach – is for sure the most appropriate way in order to effectively measure future progresses. All mobility scenarios until 2050 confirm that internal combustion engines (ICEs) will still play an important role (especially as hybrid-solutions) for passenger cars and even more for trucks and marine applications.
Technical Paper

PIV and DBI Experimental Characterization of Air flow-Spray Interaction and Soot Formation in a Single Cylinder Optical Diesel Engine using a Real Bowl Geometry Piston

2019-08-15
2019-24-0100
With demanding emissions legislations and the need for higher efficiency, new technologies for compression ignition engines are in development. One of them relies on reducing the heat losses of the engine during the combustion process as well as to devise injection strategies that reduce soot formation. Therefore, it is necessary a better comprehension about the turbulent kinetic energy (TKE) distribution inside the cylinder and how it is affected by the interaction between air flow motion and fuel spray. Furthermore, new diesel engines are characterized by massive decrease of NOx emissions. Therefore, considering the well-known NOx-soot trade-off, it is necessary a better comprehension and overall quantification of soot formation and how the different injection strategies can impact it.
Technical Paper

Experimental Studies of Gasoline Auxiliary Fuelled Turbulent Jet Igniter at Different Speeds in Single Cylinder Engine

2019-08-15
2019-24-0105
Turbulent Jet Ignition (TJI) is a pre-chamber ignition system for an otherwise standard gasoline spark ignition engine. TJI works by injecting chemical active turbulent jets to initiate combustion in a premixed fuel/air mixture. The main advantage of TJI is its ability to ignite and burn completely very lean fuel/air mixtures in the main chamber charge. This occurs with a very fast burn rate due to the widely distributed ignition sites that consume the main charge rapidly. Rapid combustion of lean mixtures leads to lower exhaust emissions due to more complete combustion at lower combustion temperature. This research investigates the effectiveness of the TJI system on combustion stability, lean limit and emissions in a single cylinder spark engine fuelled with gasoline at different speeds. The combustion and heat release process was analysed and exhaust emissions measured. Results show that the effect of TJI system on the lean-burn limit and exhaust emissions varied with engine speeds.
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