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Viewing 1 to 30 of 2213
2017-10-08
Technical Paper
2017-01-2420
Bertrand Kerres, Andreas Cronhjort, Mihai Mihaescu, Ola Stenlaas
Abstract On-engine surge detection could help in reducing the safety margin towards surge, thus allowing higher boost pressures and ultimately low-end torque. In this paper, experimental data from a truck turbocharger compressor mounted on the engine is investigated. A short period of compressor surge is provoked through a sudden, large drop in engine load. The compressor housing is equipped with knock accelerometers. Different signal treatments are evaluated for their suitability with respect to on-engine surge detection: the signal root mean square, the power spectral density in the surge frequency band, the recently proposed Hurst exponent, and a closely related concept optimized to detect changes in the underlying scaling behavior of the signal. For validation purposes, a judgement by the test cell operator by visual observation of the air filter vibrations and audible noises, as well as inlet temperature increase, are also used to diagnose surge.
2017-10-08
Technical Paper
2017-01-2405
Christophe Chaillou, Alexandre Bouet, Arnaud Frobert, Florence Duffour
Abstract Fuels from crude oil are the main energy vector used in the worldwide transport sector. But conventional fuel and engine technologies are often criticized, especially Diesel engines with the recent “Diesel gate”. Engine and fuel co-research is one of the main leverage to reduce both CO2 footprint and criteria pollutants in the transport sector. Compression ignition engines with gasoline-like fuels are a promising way for both NOx and particulate emissions abatement while keeping lower tailpipe CO2 emissions from both combustion process, physical and chemical properties of the low RON gasoline. To introduce a new fuel/engine technology, investigation of pollutants and After-Treatment Systems (ATS) is mandatory. Previous work [1] already studied soot behavior to define the rules for the design of the Diesel Particulate Filter (DPF) when used with a low RON gasoline in a compression ignition engine.
2017-10-08
Technical Paper
2017-01-2407
Michael Bardon, Greg Pucher, David Gardiner, Javier Ariztegui, Roger Cracknell, Heather Hamje, Leonardo Pellegrini, David Rickeard
Abstract Low Temperature Combustion using compression ignition may provide high efficiency combined with low emissions of oxides of nitrogen and soot. This process is facilitated by fuels with lower cetane number than standard diesel fuel. Mixtures of gasoline and diesel (“dieseline”) may be one way of achieving this, but a practical concern is the flammability of the headspace vapours in the vehicle fuel tank. Gasoline is much more volatile than diesel so, at most ambient temperatures, the headspace vapours in the tank are too rich to burn. A gasoline/diesel mixture in a fuel tank therefore can result in a flammable headspace, particularly at cold ambient temperatures. A mathematical model is presented that predicts the flammability of the headspace vapours in a tank containing mixtures of gasoline and diesel fuel. Fourteen hydrocarbons and ethanol represent the volatile components. Heavier components are treated as non-volatile diluents in the liquid phase.
2017-10-08
Technical Paper
2017-01-2247
Wenbin Zhang, Haichun ding, Shijin Shuai, Bin Zheng, Alex Cantlay, Vinod Natarajan, Zhang Song ZHAN, Yunping Pu
Gasoline direct injection (GDI) engines have been developed rapidly in recent years, driven by stringent legislative requirements on vehicle fuel efficiency and emissions. However, one challenge facing GDI is the formation of particulate emissions, particularly with the presence of injector tip deposits. The Chinese market features some gasoline fuels that contain no detergent additives and are prone to deposit formation, which can affect engine performance and emissions. The use of detergent additives to mitigate the formation of injector deposits in a GDI engine was investigated in this study by testing a 1.5L turbocharged GDI engine available in the Chinese market. The engine was operated both on base gasoline and on gasoline dosed with detergent additives to evaluate the effect on injector deposit formation and engine performance and emissions.
2017-10-08
Journal Article
2017-01-2257
Linjun Yu, Yanfei Li, Bowen Li, Hao-ye Liu, Zhi Wang, Xin He, Shi-jin Shuai
This study compares the combustion and emission performance of gasoline Homogeneous Charge Compression Ignition (HCCI) and Multiple Premixed Compression Ignition (MPCI) in a single-cylinder, intake-boosting and water-cooling diesel engine with a compression ratio of 16.7. The test fuel was commercial gasoline in China with RON of 92, and intake pressure varied from 0.16 to 0.21 MPa, while Indicated Mean Effective Pressure (IMEP) was fixed at 1.0 MPa. Both the knock limit and misfire limit of gasoline HCCI were studied. The results showed that Low Temperature Heat Release (LTHR) was observed before High Temperature Heat Release (HTHR) in gasoline HCCI, and the LTHR accounted for less than 10 percent of total heat release. The knock limit and misfire limit of gasoline HCCI coincided when the intake pressure decreased to 0.16 MPa. Increasing the intake pressure helped to promote the Indicated Thermal Efficiency (ITE) for both gasoline HCCI and MPCI.
2017-10-08
Technical Paper
2017-01-2264
Hyun Woo Won, Alexandre Bouet, Joseph Kermani, Florence Duffour, Simon Dosda
Recent work has demonstrated the potential of gasoline-like fuels to reduce NOx and particulate emissions when used in compression ignition engines. In this context, low RON gasoline, a refinery stream derived from the atmospheric crude oil distillation process, has been identified as a highly valuable fuel. In addition, thanks to its higher H/C ratio and energy content compared to diesel, CO2 benefits are also expected when used in such engines. In previous studies, different Cetane Number (CN) fuels have been evaluated and a CN 35 fuel has been selected. The assessment and the choice of the required engine hardware adapted to this fuel, such as the compression ratio, bowl pattern and nozzle design have been performed on a single cylinder compression-ignition engine. The purpose of this paper is to assess different airpath and after treatment system (ATS) definitions to maximize the potential of a low-RON gasoline fuel running on a multi-cylinder compression ignition engine.
2017-10-08
Technical Paper
2017-01-2263
S. Vedharaj, R Vallinayagam, Yanzhao An, Mohammad Izadi Najafabadi, Bart Somers, Junseok Chang, Bengt Johansson
Naphtha boils in the gasoline range of 40°C to 75°C with a RON of 65, showing increased resistance to auto-ignition. It is not possible to use naphtha as a drop in fuel for CI engine and therefore, it is ideal to investigate premixed combustion of naphtha. Previous studies reports the use of naphtha in CI engine under partially premixed combustion (PPC) mode, wherein the fuel injection timing and intake air temperature controls combustion. In this study, we investigate the combustion visualization and stratification of surrogate fuel in PPC mode. The composition of naphtha surrogate is 2-methyl butane (0.21% mol), 2-methyl hexane (0.07% mol), n-pentane (0.6% mol), n-heptane (0.07% mol) and toluene (0.05% mol). Investigation of surrogate fuel in engine expands on the previous studies on surrogate fuel formation for naphtha. Based on the experimental outcome, start of injection (SOI) was found to be inversely correlated with combustion phasing during early injection timings.
2017-10-08
Technical Paper
2017-01-2266
Bin Yang, Hu Wang, Mingfa Yao, Zunqing Zheng, Jialin Liu, Naifeng Ma, Qiping Wang, Haien Zha, Peng Chen
Gasoline partially premixed combustion shows the potential to achieve clean and high efficiency combustion. Injection strategies show significant influence on in-cylinder air flow and in-cylinder concentration distribution before auto-ignition, which can significantly affect the combustion characteristics and emissions. This study explored the effects of various injection strategies, including port fuel injection (PFI), single direct injection (DI), double direct injection (DIP+DIM) and port fuel injection coupled with a direct injection (PFI+DIM) on the combustion characteristics and emissions on a modified single cylinder heavy duty diesel engine fueled with 92# gasoline. The results showed that CA5 and CA50 of DIP+DIM are more sensitive to injection timing than PFI+DIM and single direct injection strategy, partially due to the effects of DIP on mixture stratification and low temperature reaction of gasoline.
2017-10-08
Technical Paper
2017-01-2325
Midhat Talibi, Paul Hellier, Nicos Ladommatos
The conversion of lignocellulosic biomass to liquid fuels presents an alternative to the current production of renewable fuels for IC engines from food crops. However, realising the potential for reductions in net CO2 emissions through the utilisation of, for example, waste biomass for sustainable fuel production requires that energy and resource inputs into such processes be minimised. This work therefore investigates the combustion and emission characteristics of five intermediate platform molecules potentially derived from lignocellulosic biomass: gamma-valerolactone (GVL), methyl valerate, furfuryl alcohol, furfural and 2-methyltetrahydrofuran (MTHF). The study was conducted on a naturally aspirated, water cooled, single cylinder spark-ignition engine. Each of the platform molecules were blended with reference fossil gasoline at 20 % wt/wt.
2017-10-08
Technical Paper
2017-01-2297
Thomas Dubois, Lidwine Abiad, Pauline Caine
As it is the case for Diesel engines, the Gasoline Direct Injection engines are using higher and higher injection pressures. The state of the art GDI engines are currently using injection pressure as high as 500 bar. A lot of work is also currently ongoing on Gasoline Compression Ignition (GCI) engines which use even higher injection pressure (above 1 000 bar). A high injection pressure means that a high pressure pump has to be used and so, proper lubricity has to be brought by the fuel. In the mean time the use of biofuels is increasing and several studies have shown the positive impact of ethanol on the fuel consumption of gasoline engines mainly thru an octane number effect. For all these reasons, it seems important to evaluate the impact of ethanol on the lubricity of gasoline as well as on the response of lubricity additives that may be required in a medium-term future to provide gasoline enough lubricity to ensure the operability of these new engines.
2017-10-08
Technical Paper
2017-01-2366
Wenzheng Xia, Yi Zheng, Xiaokun He, Dongxia Yang, Huifang Shao, Joesph Remias, Joseph Roos, Yinhui Wang
Abstract Because of the increased use of gasoline direct engine (GDI) in the automobile industry, there is a significant need to control particulates from GDI engines based on emission regulations. One potential technical approach is the utilization of a gasoline particulate filter (GPF). The successful adoption of this emission control technology needs to take many aspects into consideration and requires a system approach for optimization. This study conducted research to investigate the impact of vehicle driving cycles, fuel properties and catalyst coating on the performance of GPF. It was found that driving cycle has significant impact on particulate emission. Fuel quality still plays a role in particulate emissions, and can affect the GPF performance. Catalyzed GPF is preferred for soot regeneration, especially for the case that the vehicle operation is dominated by congested city driving condition, i.e. low operating temperatures.
2017-10-08
Technical Paper
2017-01-2378
Takayuki Ogata, Mikio Makino, Takashi Aoki, Takehide Shimoda, Kyohei Kato, Takahiko Nakatani, Koji Nagata, Claus Dieter Vogt, Yoshitaka Ito, Dominic Thier
Abstract In order to meet the challenging CO2 targets beyond 2020 despite keeping high performance engines, Gasoline Direct Injection (GDI) technology usually combined with charged aspiration is expanding in the automotive industry. While providing more efficient powertrains to reduce fuel consumption one side effect of GDI is the increased particle formation during the combustion process. For the first time for GDI from September 2014 there is a Particle Number (PN) limit in EU of 6x10 sup 12 #/km, which will be further reduced by one order of magnitude to 6x10 sup 11 #/km effective from September 2017 to be the same level as applied to Diesel engines. In addition to the PN limit of the certification cycle NEDC further certification of Real Driving Emissions (RDE) including portable PN measurements are under discussion by the European Commission. RDE test procedure requires stable and low emissions in a wide range of engine operations and durable over a distance of 160 000 km.
2017-10-08
Technical Paper
2017-01-2186
Lukas Urban, Michael Grill, Sebastian Hann, Michael Bargende
Abstract Engine Knock is a stochastic phenomenon that occurs during the regular combustion of spark ignition (SI) engines and limits its efficiency. Knock is triggered by an autoignition of local “hot spots” in the unburned zone, ahead of the flame front. Regarding chemical kinetics, the temperature and pressure history as well as the knock resistance of the fuel are the main driver for the autoignition process. In this paper, a new knock modeling approach for natural gas blends is presented. It is based on a kinetic fit for the ignition delay times that has been derived from chemical kinetics simulations. The knock model is coupled with an enhanced burn rate model that was modified for Methane-based fuels. The two newly developed models are incorporated in a predictive 0D/1D simulation tool that provides a cost-effective method for the development of natural gas powered SI engines.
2017-10-08
Technical Paper
2017-01-2401
Elana Chapman, Pat Geng, Yaowei Zhao, Susan Zhang, JunJun Ma, Jianqiang Gong
Abstract The impact of gasoline composition on vehicle particulate emissions response has been widely investigated and documented. Correlation equations between fuel composition and particulate emissions have also been documented, e.g. Particulate Matter Index (PMI) and Particulate Evaluation Index (PEI). Vehicle PM/PN emissions correlate very well with these indices. In a previous paper, global assessment with PEI on fuel sooting tendency was presented [1]. This paper will continue the previous theme by the authors, and cover China gasoline in more detail. With air pollution an increasing concern, along with more stringent emission requirements in China, both OEMs and oil industries are facing new challenges. Emissions controls require a systematic approach on both fuels and vehicles. Chinese production vehicle particulate emissions for a range of PEI fuels are also presented.
2017-10-08
Technical Paper
2017-01-2231
Yongquan Chen, Liguang Li, Qing Zhang, Jun Deng, Wei Xie, Erbao Zhang, Sunyu Tong
Abstract Pre-ignition may lead to an extreme knock (super-knock or mega-knock) which will impose a severe negative influence on the engine performance and service life, thus limiting the development of downsizing gasoline direct injection (GDI) engine. More and more studies reveal that the auto-ignition of lubricants is the potential source for pre-ignition. However, pre-ignition is complicated to study on the engine test bench. In this paper, a convenient test method is applied to investigate the influence of lubricants metal-additives on pre-ignition. 8 groups of lubricants are injected into a hot co-flow atmosphere which generated by a burner. A single-hole nozzle injector with a diameter of 0.2 mm at 20 MPa injection pressure is utilized for lubricants' injection and spray atomization.
2017-10-08
Technical Paper
2017-01-2233
Gautam Kalghatgi, Kai Morganti, Ibrahim Algunaibet
Knock in spark ignition engines is stochastic in nature. It is caused by autoignition in hot spots in the unburned end-gas ahead of the expanding flame front. Knock onset in an engine cycle can be predicted using the Livengood-Wu integral if the variation of ignition delay with pressure and temperature as well as the pressure and temperature variation with crank angle are known. However, knock intensity (KI) is determined by the evolution of the pressure wave following knock onset. In an earlier paper (SAE 2017-01-0689) we showed that KI can be approximated by KI = Z (∂T/∂x)-2 at a fixed operating condition, where Z is a function of Pko, the pressure, and (∂T/∂x) is the temperature gradient in the hot spot at knock onset. Then, from experimental measurements of KI and Pko, using five different fuels, with the engine operating at boosted conditions, a probability density function for (∂T/∂x) was established.
2017-10-08
Technical Paper
2017-01-2236
Mateos Kassa, Carrie Hall, Fabien Vidal-Naquet, Thomas Leroy
Abstract In this study, the impact of the intake valve timing on knock propensity is investigated on a dual-fuel engine which leverages a low octane fuel and a high octane fuel to adjust the fuel mixture’s research octane rating (RON) based on operating point. Variations in the intake valve timing have a direct impact on residual gas concentrations due to valve overlap, and also affect the compression pressure and temperature by altering the effective compression ratio (eCR). In this study, it is shown that the fuel RON requirement for a non-knocking condition at a fixed operating point can vary significantly solely due to variations of the intake valve timing. At 2000 rpm and 6 bar IMEP, the fuel RON requirement ranges from 80 to 90 as a function of the intake valve timing, and the valve timing can change the RON requirement from 98 to 104 at 2000 rpm and 14 bar IMEP.
2017-09-04
Technical Paper
2017-24-0015
Luigi Teodosio, Vincenzo De Bellis, Fabio Bozza, Daniela Tufano
Abstract Nowadays different technical solutions have been proposed to improve the performance of internal combustion engines, especially in terms of Brake Specific Fuel Consumption (BSFC). Its reduction of course contributes to comply with the CO2 emissions legislation for vehicle homologation. Concerning the spark ignition engines, the downsizing coupled to turbocharging demonstrated a proper effectiveness to improve the BSFC at part load. On the other hand, at high load, the above solution highly penalizes the fuel consumption mainly because of knock onset, that obliges to degrade the combustion phasing and/or enrich the air/fuel mixture. A promising technique to cope with the above drawbacks consists in the Variable Compression Ratio (VCR) concept. An optimal Compression Ratio (CR) selection, in fact, allows for further improvements of the thermodynamic efficiency at part load, while at high load, it permits to mitigate knock propensity, resulting in more optimized combustions.
2017-09-04
Technical Paper
2017-24-0017
Emanuele Servetto, Andrea Bianco, Gennaro Caputo, Giuseppe Lo Iacono
Abstract Large pressure pulsations and a non-uniform distribution of charge air temperature along the intake manifold were detected on a large-bore marine Dual-Fuel engine. These two phenomena were found to impact negatively on the knock resistance of individual cylinders, when the engine is operated in gas-mode. As it happens with marine gas engines, the cylinder most prone to knocking drives the engine tuning for all the others, thus reducing the overall fuel conversion efficiency. In order to effectively tackle this issue, a comprehensive study was carried out, which included both experimental testing and fluid-dynamics simulation. A detailed GT-POWER 1D engine model was built, representing the laboratory 8L (i.e. inline eight-cylinder) engine configuration. The model was extensively correlated against measurements at different speeds and loads and it proved capable of closely reproducing both the pressure fluctuations and the temperature gradient along the intake manifold.
2017-09-04
Technical Paper
2017-24-0034
Michele Battistoni, Carlo N. Grimaldi, Valentino Cruccolini, Gabriele Discepoli, Matteo De Cesare
Abstract Water injection in highly boosted gasoline direct injection (GDI) engines has become an attractive area over the last few years as a way of increasing efficiency, enhancing performance and reducing emissions. The technology and its effects are not new, but current gasoline engine trends for passenger vehicles have several motivations for adopting this technology today. Water injection enables higher compression ratios, optimal spark timing and elimination of fuel enrichment at high load, and possibly replacement of EGR. Physically, water reduces charge temperature by evaporation, dilutes combustion, and varies the specific heat ratio of the working fluid, with complex effects. Several of these mutually intertwined aspects are investigated in this paper through computational fluid dynamics (CFD) simulations, focusing on a turbo-charged GDI engine with port water injection (PWI). Different strategies for water injection timing, pressure and spray targeting are investigated.
2017-09-04
Technical Paper
2017-24-0050
Anjan Rao Puttige, Robin Hamberg, Paul Linschoten, Goutham Reddy, Andreas Cronhjort, Ola Stenlaas
Abstract Improving turbocharger performance to increase engine efficiency has the potential to help meet current and upcoming exhaust legislation. One limiting factor is compressor surge, an air flow instability phenomenon capable of causing severe vibration and noise. To avoid surge, the turbocharger is operated with a safety margin (surge margin) which, as well as avoiding surge in steady state operation, unfortunately also lowers engine performance. This paper investigates the possibility of detecting compressor surge with a conventional engine knock sensor. It further recommends a surge detection algorithm based on their signals during transient engine operation. Three knock sensors were mounted on the turbocharger and placed along the axes of three dimensions of movement. The engine was operated in load steps starting from steady state. The steady state points of operation covered the vital parts of the engine speed and load range.
2017-09-04
Technical Paper
2017-24-0039
Daniele Piazzullo, Michela Costa, Youngchul Ra, Vittorio ROCCO, Ankith Ullal
Abstract Bio-derived fuels are drawing more and more attention in the internal combustion engine (ICE) research field in recent years. Those interests in use of renewable biofuels in ICE applications derive from energy security issues and, more importantly, from environment pollutant emissions concerns. High fidelity numerical study of engine combustion requires advanced computational fluid dynamics (CFD) to be coupled with detailed chemical kinetic models. This task becomes extremely challenging if real fuels are taken into account, as they include a mixture of hundreds of different hydrocarbons, which prohibitively increases computational cost. Therefore, along with employing surrogate fuel models, reduction of detailed kinetic models for multidimensional engine applications is preferred. In the present work, a reduced mechanism was developed for primary reference fuel (PRF) using the directed relation graph (DRG) approach.
2017-09-04
Technical Paper
2017-24-0065
Helmut Ruhland, Thomas Lorenz, Jens Dunstheimer, Albert Breuer, Maziar Khosravi
Abstract An integral part of combustion system development for previous NA gasoline engines was the optimization of charge motion towards the best compromise in terms of full load performance, part load stability, emissions and, last but not least, fuel economy. This optimum balance may potentially be different in GTDI engines. While it is generally accepted that an increased charge motion level improves the mixture preparation in direct injection gasoline engines, the tradeoff in terms of performance seems to become less dominant as the boosting systems of modern engines are typically capable enough to compensate the flow losses generated by the more restrictive ports. Nevertheless, the increased boost level does not come free; increased charge motion generates higher pumping- and wall heat losses. Hence it is questionable and engine dependent, whether more charge motion is always better.
2017-09-04
Technical Paper
2017-24-0092
Francesco Catapano, Silvana Di Iorio, Paolo Sementa, Bianca Maria Vaglieco
Abstract Fuel depletion as well as the growing concerns on environmental issues prompt to the use of more eco-friendly fuels. The compressed natural gas (CNG) is considered one of the most promising alternative fuel for engine applications because of the lower emissions. Nevertheless, recent studies highlighted the presence of ultrafine particle emissions at the exhaust of CNG engines. The present study aims to investigate the effect of CNG on particle formation and emissions when it was direct injected and when it was dual fueled with gasoline. In this latter case, the CNG was direct injected and the gasoline port fuel injected. The study was carried out on a transparent single cylinder SI engine in order to investigate the in-cylinder process by real time non-intrusive diagnostics. In-cylinder 2D chemiluminescence measurements from UV to visible were carried out.
2017-09-04
Technical Paper
2017-24-0115
Martin Pechout, Jan Czerwinski, Martin Güdel, Michal Vojtisek-Lom
Abstract In this study, the combustion of butanol, neat and mixed with gasoline, was investigated on a 0.6 liter two-cylinder spark ignition engine with fully adjustable fuel injection and spark timing, coupled with an eddy current dynamometer. Two isomers of butanol, n-butanol and iso-butanol, were examined. This basic parameter study gives information about potential requirements of engine control systems for butanol FFV. Compared to the traditionally used ethanol, butanol does not exhibit hygroscopic behaviour, is chemically less aggressive and has higher energy density. On other hand, different laminar burning velocity and higher boiling temperature of butanol, compared to gasoline, requires some countermeasures to keep the engine operation reliable and efficient.
2017-09-04
Technical Paper
2017-24-0060
Nicolo Cavina, Nahuel Rojo, Lorella Ceschini, Eleonora Balducci, Luca Poggio, Lucio Calogero, Ruggero Cevolani
Abstract The recent search for extremely efficient spark-ignition engines has implied a great increase of in-cylinder pressure and temperature levels, and knocking combustion mode has become one of the most relevant limiting factors. This paper reports the main results of a specific project carried out as part of a wider research activity, aimed at modelling and real-time controlling knock-induced damage on aluminum forged pistons. The paper shows how the main damage mechanisms (erosion, plastic deformation, surface roughness, hardness reduction) have been identified and isolated, and how the corresponding symptoms may be measured and quantified. The second part of the work then concentrates on understanding how knocking combustion characteristics affect the level of induced damage, and which parameters are mainly responsible for piston failure.
2017-09-04
Journal Article
2017-24-0061
James P. Szybist, Scott W. Wagnon, Derek Splitter, William J. Pitz, Marco Mehl
Abstract Numerous studies have demonstrated that exhaust gas recirculation (EGR) can attenuate knock propensity in spark ignition (SI) engines at naturally aspirated or lightly boosted conditions [1]. In this study, we investigate the role of cooled EGR under higher load conditions with multiple fuel compositions, where highly retarded combustion phasing typical of modern SI engines was used. It was found that under these conditions, EGR attenuation of knock is greatly reduced, where EGR doesn’t allow significant combustion phasing advance as it does under lighter load conditions. Detailed combustion analysis shows that when EGR is added, the polytropic coefficient increases causing the compressive pressure and temperature to increase. At sufficiently highly boosted conditions, the increase in polytropic coefficient and additional trapped mass from EGR can sufficiently reduce fuel ignition delay to overcome knock attenuation effects.
2017-09-04
Journal Article
2017-24-0085
Jesus Benajes, Antonio Garcia, Javier Monsalve-Serrano, Vicente Boronat
Abstract This work investigates the particulates size distribution of reactivity controlled compression ignition combustion, a dual-fuel concept which combines the port fuel injection of low-reactive/gasoline-like fuels with direct injection of highly reactive/diesel-like fuels. The particulates size distributions from 5-250 nm were measured using a scanning mobility particle sizer at six engine speeds, from 950 to 2200 rpm, and 25% engine load. The same procedure was followed for conventional diesel combustion. The study was performed in a single-cylinder engine derived from a stock medium-duty multi-cylinder diesel engine of 15.3:1 compression ratio. The combustion strategy proposed during the tests campaign was limited to accomplish both mechanical and emissions constraints. The results confirms that reactivity controlled compression ignition promotes ultra-low levels of nitrogen oxides and smoke emissions in the points tested.
2017-09-04
Journal Article
2017-24-0099
Francesco Catapano, Paolo Sementa, Bianca Maria Vaglieco
Abstract Gasoline direct injection (GDI) allows knock tendency reduction in spark-ignition engines mainly due to the cooling effect of the in-cylinder fuel evaporation. However, the charge formation and thus the injection timing and strategies deeply affect the flame propagation and consequently the knock occurrence probability and intensity. In particular, split injection allows a reduction of knock intensity by inducing different AFR gradient and turbulent energy distribution. Present work investigates the tendency to knock of a GDI engine at 1500 rpm full load under different injection strategies, single and double injections, obtained delivering the same amount of gasoline in two equal parts, the first during intake, the second during compression stroke. In these conditions, conventional and non-conventional measurements are performed on a 4-stroke, 4-cylinder, turbocharged GDI engine endowed of optical accesses to the combustion chamber.
2017-09-04
Journal Article
2017-24-0055
Enrico Corti, Claudio Forte, Gian Marco Bianchi, Lorenzo Zoffoli
Abstract The performance optimization of modern Spark Ignition engines is limited by knock occurrence: heavily downsized engines often are forced to work in the Knock-Limited Spark Advance (KLSA) range. Knock control systems monitor the combustion process, allowing to achieve a proper compromise between performance and reliability. Combustion monitoring is usually carried out by means of accelerometers or ion sensing systems, but recently the use of cylinder pressure sensors is also becoming frequent in motorsport applications. On the other hand, cylinder pressure signals are often available in the calibration stage, where SA feedback-control based on the pressure signal can be used to avoid damages to the engine during automatic calibration. A predictive real-time combustion model could help optimizing engine performance, without exceeding the allowed knock severity.
Viewing 1 to 30 of 2213

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