Criteria

Text:
Sector:
Display:

Results

Viewing 391 to 420 of 86934
2018-04-03
Technical Paper
2018-01-0215
Zhuyong Yang, Sandesh Rao, Yanyu Wang, Jaideep Harsulkar, Ehsan Ansari, Niranjan Miganakallu Narasimhamurthy, Paul Dice, Jeffrey Naber, Yashodeep Lonari, Stanislaw Szwaja
The characteristics of knock metrics over a number of engine cycles can be an important reference for knock detection and control in internal combustion engines. In a spark-ignition (SI) engine, the stochastic nature of combustion knock has been shown to follow a log-normal distribution. However, this has been derived from experiments done with gasoline only and applicability of log-normal distribution to dual-fuel combustion knock has not been explored. Natural gas (NG) features itself with relatively high methane and octane numbers, hence, it can be applied as additional fuel blended with gasoline, which enables to increase knock limited spark advance thereby increasing thermal efficiency. To evaluate the efficacy and accuracy of log-normal distribution model for NG-gasoline blended fuel, a sweep of NG-gasoline fueling blending ratio by energy was conducted at two different speeds.
2018-04-03
Technical Paper
2018-01-0217
David Vuilleumier, Xun Huan PhD, Tiernan Casey PhD, Magnus Sjöberg
The Octane Index framework and Co-Optimization of Fuels and Engines (Co-Optima) Central Fuels Hypothesis are evaluated using seven fuels operated under stoichiometric, knock-limited conditions in a directly injected spark ignition (DISI) engine. Of the seven tested fuels, three fuels are “Tier III” fuel blends, meaning that they are blends of molecules which have passed two levels of screening, and have been evaluated to be ready for tests in a research engine. These molecules have been blended into a 4-component gasoline surrogate at varying volume fractions in order to achieve a Research Octane Number (RON) rating of 98. The four molecules under consideration are: isobutanol, 2-butanol, and Diisobutylene. Research engine tests measured knock limits at heated and unheated intake temperature conditions, as well as throttled and boosted intake pressures.
2018-04-03
Technical Paper
2018-01-0213
Seokwon Cho, Chiheon Song, Sechul Oh, Kyoungdoug Min, Kyoung-Pyo Ha, Back-Sik Kim
Increasing compression ratio is essential to develop the future high-efficiency spark-ignited engines. However, it inevitably involves the knock occurrence during the combustion. Among a lot of methods, efficient cooling strategy of the engine components is considered as one of the practical ways to suppress knock occurrence. In this study, the effect of thermal boundary conditions on knock phenomena was observed while the temperatures of the cylinder thermal boundaries (head, liner and piston) were controlled independently. While controlling independently, by measuring the temperatures of each of them, the expansion of the detonation border line (DBL) and the advance of the ignition timing were investigated. The effect of the piston oil-cooling gallery was also investigated for further knock mitigation. In addition, the difference of the effect on two different type of single cylinder engines which are MPI and GDI type (CR=12) was also observed in this study.
2018-04-03
Technical Paper
2018-01-0214
Saif Salih, Dan DelVescovo
Developments in modern spark ignition (SI) engines such as intake boosting, direct-injection, and engine downsizing techniques have demonstrated improved performance and thermal efficiency, however, these strategies induce significant deviation in end-gas pressure/temperature histories from those of the traditional Research and Motor Octane Number (RON and MON) standards. Attempting to extrapolate the anti-knock performance of fuels tested under the traditional RON/MON conditions to boosted operation has yielded mixed results in both SI and advanced compression ignition (ACI) engines. This consideration motivates the present work with seeks to establish a pathway towards the development of the test conditions of a boosted octane number, which would better correlate to fuel performance at high intake pressure conditions.
2018-04-03
Technical Paper
2018-01-0211
Mitsuaki Ohtomo, Tetsunori Suzuoki, Seiji yamamoto, Hiroshi Miyagawa
Suppression of knock induced by the auto-ignition of the end gas in spark ignition engines is very important for improvement of thermal efficiency. Occurrence of knock is usually suppressed by inhibiting the auto-ignition of the fuel-air mixture. However, knock does not occur if the pressure oscillation induced by the auto-ignition is sufficiently reduced. It is thought that the pressure oscillation occurs when the rising of the pressure by the auto-ignition of the local mixture is not adequately decreased by the expansion of the gas to the surroundings. It indicates that a reaction rate of the auto-ignition affects the pressure oscillation, namely knock intensity. In this paper, the knock intensity of the diluted fuel-air mixture was measured with varying the dilution ratio and the dilution gas in order to change a reaction rate of the auto-ignition of the mixture by using a rapid compression machine and a singly cylinder spark ignition engine.
2018-04-03
Technical Paper
2018-01-0212
Jaeyoung Cho, Han Ho Song
As fuel injection strategy in spark-ignition (SI) engine has been diversified, inhomogeneous mixing of fuel-air mixture can occur to the various extents during mixture preparation. In this study, we analyzed the effect of inhomogeneous mixing on the knocking characteristics of iso-octane and air mixture in a standardized fuel testing condition for research octane number, based on ASTM D2699. For this purpose, we assumed that both lean spots and rich spots existed in unburned gas during compression stroke and flame propagation, and calculated the thermodynamic state of the spots using in-house multi-zone, zero-dimensional SI engine model. Then, the ignition delay was measured over the derived thermodynamic profiles by using rapid compression machine (RCM), and we calculated ξ, the ratio of sound speed to auto-ignition propagation speed, based on Zel'dovich and Bradley's ξ-ϵ theory to estimate knock intensity.
2018-04-03
Technical Paper
2018-01-0209
Jose V. Pastor, Jose M Garcia-Oliver, Antonio Garcia, Leonardo Pachano
Ever decreasing permitted emission levels and the necessity of more efficient engines demand a better understanding of in-cylinder phenomena. In swirl-supported compression ignition (CI) engines mean in-cylinder flow structures formed during the admission stroke deeply influence mixture preparation prior combustion, heat transfer and pollutant oxidation all of which could potentially improve engine performance. Therefore, the ability to characterize these mean flow structures is relevant for achieving performance improvements. CI mean flow structure is mainly described by a precessing vortex. The location of the vortex center is key for the characterization of the flow structure. Consequently, this work aims to evaluate algorithms that allows for the efficient location of the vortex center. The study is carried out on velocity fields measured using Particle Image Velocimetry (PIV) in an optical light-duty CI engine operated under motored conditions.
2018-04-03
Technical Paper
2018-01-0207
Zhenghao Liu, Kwee-Yan Teh, Penghui Ge, Fengnian Zhao, David Hung
Rotating flow inside an internal combustion engine cylinder is deliberately engineered for improved fuel-air mixing and combustion. The details of the rotating flow structure vary temporally over an engine cycle as well as cyclically at the same engine phase. Algorithms in the literature to identify these structural details of the rotating flow invariably focus on locating its center and, on occasion, measuring its rotational "strength" and spatial extent. In this paper, these vortex parameters are evaluated by means of complex moments, which have been adapted from image (scalar field) recognition applications to two-dimensional flow pattern (vector field) analysis. Several additional detailed characteristics of the rotating flow --- including the type and extent of its deviation from the ideal circular vortex, its rotational and reflectional symmetry (if exist), and thus its orientation --- are also shown to be related to the first few low-order complex moments of the flow pattern.
2018-04-03
Technical Paper
2018-01-0204
Daniele Farrace, David Sakellarakis, Michele Bolla, Yuri M. Wright, Konstantinos Boulouchos
Formation of soot in an auto-igniting n-dodecane spray under diesel engine relevant conditions has been investigated numerically. The bulk of research thus far has addressed turbulence-chemistry interaction by coupling highly diffusive turbulence models with more sophisticated combustion models. Instead, this study employs the advanced sub-grid scale k-equation model in the framework of a Large Eddy Simulation (LES) together with the uninvolved Direct Integration approach. A reduced n-heptane chemical mechanism has been employed and artificially accelerated in order to predict the ignition for n-dodecane accurately. Soot processes have been modelled with an extended version of the semi-empirical, two-equation model of Leung, which considers C2H2 as the soot precursor and accounts for particle inception, surface growth by C2H2 addition, oxidation by O2, oxidation by OH and particle coagulation.
2018-04-03
Technical Paper
2018-01-0203
Insuk Ko, Kyoungdoug Min, Stefano Fontanesi, Federico Rulli
Large Eddy Simulation (LES) applications to Internal Combustion Engine (hereafter ICE) flows are constantly growing, due to the increase of computing resources and the availability of suitable CFD codes, methods and practices. LES superior capability to model spatial and temporal evolution of turbulent flow structures with reference to RANS makes it a promising tool to describe, and possibly motivate, ICE cycle-to-cycle variability (CCV) and cycle-resolved events such as knock and misfire. Despite the growing interest towards LES in the academic community, applications to ICE flows are still limited. One of the reasons for such discrepancy is to be found in the uncertainty in the estimation of the computational cost of LES. This in turn is mainly dependent on grid density, CFD domain extent, time step size and overall number of cycles to be run. Grid density is directly linked to the possibility to reduce modelling assumptions for sub-grid scales.
2018-04-03
Technical Paper
2018-01-0202
Devyani Patil, Yue Wang, Long Liang, Karthik Puduppakkam, Ahmed Hussein, Chitralkumar Naik, Ellen Meeks
Advanced research in Spark Ignition (SI) engine has been focused on dilute combustion concepts. For example, exhaust gas recirculation is used to lower both fuel consumption and pollutant emissions while maintaining or enhancing engine performance, durability and reliability. These advancements achieve higher engine efficiency but may deteriorate combustion stability. One symptom of instability is a large Cycle to Cycle Variations (CCV) in the in-cylinder flow and combustion metrics. Large-Eddy Simulation (LES) is a Computational Fluid Dynamics (CFD) method that may be used to quantify CCV through numerical prediction of the turbulent flow and combustion processes in the engine over many engine cycles. In this study, we focus on evaluating the capability of LES to predict the in-cylinder flows and gas exchange processes in a motored SI engine installed with a transparent combustion chamber (TCC), comparing with recently published data.
2018-04-03
Technical Paper
2018-01-0201
Yashas Karaya, Srinivasa Krishna Addepalli, J M Mallikarjuna
Gasoline direct injection (GDI) engines have gained popularity in the recent times because of lower fuel consumption and exhaust emissions. But in these engines, the mixture preparation plays an important role which affects combustion, performance and emission characteristics of the engine. The mixture preparation, in turn, depends mainly upon fuel injector location and orientation. Therefore, in this study, an attempt has been made to understand the effect of fuel injector location and nozzle-hole orientation on the mixture preparation, performance and emission characteristics of a GDI engine. The mixture stratification inside the combustion chamber is characterized by a parameter called “stratification index” which is based on average equivalence ratio at different zones in the combustion chamber. The analysis is carried out on a four-stroke wall-guided GDI engine by computational fluid dynamics (CFD) analysis using the CONVERGE software.
2018-04-03
Technical Paper
2018-01-0200
Corinna Netzer, Tim Franken, Lars Seidel, Harry Lehtiniemi, Fabian Mauss
Water injection is a promising technology to improve the fuel efficiency of turbo-charged gasoline engines. Additionally, this technology is believed to enable the efficient operation of the three-way-catalyst also at high load conditions. In this numerical analysis, we investigate the effect of water on the combustion chemistry and the thermodynamics using 3D CFD RANS. In the first step, the influence of different amounts of steam on ignition delay time, laminar flame speed and heat capacity is investigated. In the second step, the impact of water vaporization is analyzed for different injection strategies, such as port and direct injection. Therefore, the water mass flow and the injection pressure are varied. A steady-state, medium speed, high-load operating point is investigated with focus on the effect of water injection on fuel efficiency, knock tendency and exhaust temperature.
2018-04-03
Technical Paper
2018-01-0198
Riccardo Scarcelli, Anqi Zhang, Thomas Wallner, Douglas Breden, Anand Karpatne, Laxminarayan Raja, Isaac Ekoto, Benjamin Wolk
While the spark-ignition (SI) engine technology migrates towards challenging combustion regimes (dilute and boosted operation), advanced ignition technologies generating non-equilibrium types of plasma have continued to receive significant attention from the automotive industry as a potential replacement for conventional spark-plugs. However there are no models currently that can describe the non-thermal plasma ignition process in the computational fluid dynamics (CFD) codes that are widely used in the engine multi-dimensional modeling community. A key question for the engine modelers that are trying to describe the non-equilibrium ignition physics concerns the characteristics of the non-equilibrium plasma. A key challenge is represented by the plasma formation timescale (nanoseconds) that can hardly be resolved within a full engine cycle (milliseconds) simulation.
2018-04-03
Technical Paper
2018-01-0197
Raouf Mobasheri, Mahdi Seddiq
An advanced 3D-CFD computational study was done in order to study the simultaneous effects of diesel injection pressure and single injection timing on the amounts of pollutant emissions and engine performance in a heavy duty, single cylinder iso-butanol/Diesel reactivity controlled compression ignition (RCCI) engine. A reduced chemical n-heptane-n-butanol-PAH mechanism which consists of 76 species and 349 reactions was used to simulate the combustion process of the dual-fuel diesel engine. The baseline operation case was validated with Wang et al. research work and good agreements between in-cylinder mean pressure, the rate of heat release and amounts of pollutant emissions such as NOx, Particulate Matter (PM), unburnt hydrocarbons (UHC) and carbon monoxide (CO) was obtained. Twenty-one different strategies based on two variables (diesel direct injection timing and diesel injection pressure) have been investigated.
2018-04-03
Technical Paper
2018-01-0196
Noah Van Dam, Magnus Sjöberg, Sibendu Som
Large-eddy Simulations (LES) have been carried out to investigate spray variability and its effect on cycle-to-cycle flow variability in a direct-injection spark-ignition (DISI) engine under non-reacting conditions. Initial simulations were performed of an injector in a constant volume spray chamber. Detailed measurements of the spray including quantitative mixing data are used to validate a simulation spray set-up for the stepped-bore multi-hole gasoline direct injection (GDI) injector. A random seed perturbation methodology was used to generate shot-to-shot spray variability in the LES, and comparisons of both mean and standard deviations were made for quantities with sufficient experimental data. After validation, the same spray set-up was used to simulate the same injector in an optically accessible DISI engine.
2018-04-03
Technical Paper
2018-01-0195
Federico Perini, Kenji Hiraoka, Yuji Oda, Akihiro Yuuki, Christopher Rutland, Rolf Reitz
Modeling ignition kernel development in spark ignition engines is crucial to capturing the sources of cyclic variability, both with RANS and LES simulations. Appropriate kernel modeling must ensure that energy transfer from the electrodes to the gas phase has the correct timing, rate and locations, until the flame surface is large enough to be represented on the mesh by the G-Equation level-set method. However, in most kernel models, geometric details driving kernel growth are missing: either because it is described as Lagrangian particles, or because its development is simplified, i.e., down to multiple spherical flames. In this work, we focused on the geometry of kernel development, and developed a new, Triangulated Lagrangian Ignition Kernel model. One (or multiple, if it restrikes) spark channel is initialized as a one-dimensional Lagrangian particle thread.
2018-04-03
Technical Paper
2018-01-0194
Haiwen Ge, Nam Hyo Cho
Pressure ringing in internal combustion engine is observed in in-cylinder pressure measurement, which may be due to combustion dynamics, pressure oscillation inside the combustion chamber, and inside a recessed drilled hole for cylinder pressure sensor installation. In the present study, combustion process of a production diesel engine instrumented with pressure sensors in the cylinder head was analyzed using 3D CFD software CONVERGE. The engine utilized in this analysis is a 2-valve 4.5L 4-cylinder heavy-duty direct-injection diesel engine for off-road applications. Various combustion models such as Shell/CTC ignition-combustion model, SAGE model with n-Heptane mechanism of Chalmers University, and ECFM-3Z model were employed to review their capability in capturing pressure ringing phenomena. The raw pressure signal from measurement and simulation was analyzed by FFT.
2018-04-03
Technical Paper
2018-01-0193
Alberto Broatch, Ricardo Novella, Josep Gomez-Soriano, Pinaki Pal, Sibendu Som
It is challenging to develop highly efficient and extremely clean engines, while meeting user expectations in terms of performance, comfort and driveability. One of the critical aspects in this regard is combustion noise control. Combustion noise represents about 40 percent of the overall engine noise in typical turbocharged diesel engines. The understanding of noise generation is intricate due to its inherent complexity and measurement limitations. Therefore, current efforts are focused on developing efficient strategies to understand the combustion noise mechanisms in order to reduce engine noise while maintaining high efficiency and low pollutant emissions.
2018-04-03
Technical Paper
2018-01-0242
Adam B. Dempsey, Patrick Seiler, Kenth Svensson, Yongli Qi
In this study single-cylinder engine experiments and computational fluid dynamics (CFD) modeling were used to evaluate the classic two-step Hiroyasu soot model. A broad range of direct injected (DI) combustion systems were investigated to assess the predictive accuracy of the soot model as a design tool for modern DI diesel engines. Experiments were conducted on a 2.5 liter single-cylinder engine. Combustion system combinations included 3 unique piston bowl shapes and 7 variants of a common rail fuel injector. The pistons were a Tier 4 final production piston, a re-entrant piston, and a Volvo WAVE-like piston. The injectors featured 6 or 7 holes and systematically varied included spray angle from 120 to 150 degrees and hole size from 170 to 273 microns. Two nominal operating conditions were studied: 25% and 100% load at 1800 rpm. Start of injection timing sweeps at varied injection pressures were run at two exhaust gas recirculation (EGR) levels at each load condition.
2018-04-03
Technical Paper
2018-01-0244
Puneet Valecha, Chinmaya Mishra, PMV Subbarao, Pranab Das
The rising expectation from engine designers to address the increasingly stringent emission norms while retaining and enhancing the engine performance, demands a comprehensive understanding of critical in-cylinder combustion parameters. In this context, experimental research has been the traditional favourite vis-à-vis analytical modelling due to the inherent entanglement associated with the complex chain chemical reactions with the fuel burning rate. Besides, the complexity of modelling the interlinked set of chemical reactions to determine heat release and other combustion characteristics has been prohibitive. In this context, Wiebe function has been a pathfinder for engineering applications as it bypasses the simultaneous and sequential interdependent chain and branching reactions by a continuous, general macroscopic reaction rate expression. However, the suitability of single Wiebe functions were restricted to mostly SI engines.
2018-04-03
Technical Paper
2018-01-0247
Ricardo Novella
A genetic algorithm optimization methodology is applied to the design of the combustion system of a heavy-duty (HD) Diesel engine fueled with dimethyl ether (DME). The study has two objectives, the optimization of a conventional diesel combustion system aiming to achieve US2010 targets and the optimization of a stoichiometric combustion system coupled with a three way catalyst (TWC) to further control NOx emissions and achieve US2030 emission standards. These optimizations include the key combustion system related hardware, bowl geometry and injection nozzle design as input factors, together with the most relevant air management and injection settings. The GA was linked to the KIVA CFD code and an automated grid generation tool to perform a single-objective optimization. The target of the optimizations is to improve net indicated efficiency (NIE) while keeping NOx emissions, peak pressure and pressure rise rate under their corresponding target levels.
2018-04-03
Technical Paper
2018-01-0246
Hu Chien Su, Harsh Goyal, Lewis Clark, Sanghoon Kook, Evatt Hawkes, Qing Nian Chan, Srinivas Padala, Minh Khoi Le, Yuji Ikeda
The present study explores the effect of in-cylinder generated non-thermal plasma on hydroxyl and soot development. Three optical diagnostics of electronically excited hydroxyl (OH*) chemiluminescence, Planar Laser Induced Fluorescence of OH (OH-PLIF) and Planar Laser Induced Incandescence (PLII) are performed in a single-cylinder optical diesel engine. Plasma was generated using a newly developed Microwave Discharge Igniter (MDI), which has the potential to accentuate the formation of active radical pools as well as suppress soot formation while stimulating soot oxidation. Methyl Decanoate fuel was specifically selected for diagnostics due to its low beam attenuation which is required for OH-PLIF and PLII.
2018-04-03
Technical Paper
2018-01-0249
Jonathan Martin, Andre Boehman, Rutvik Topkar, Sumit Chopra, Uday Subramaniam, Heng Chen
In recent years, several unconventional fueling modes have been developed for dual-fuel compression-ignition (CI) engines. One such mode is reactivity controlled compression ignition (RCCI), which utilizes both a high-octane fuel (HOF) and a high-cetane fuel (HCF) via separate injection systems. RCCI has been tested with many fuels, but there have been relatively few tests on the intermediate modes that exist in between RCCI and conventional diesel combustion. For this purpose, a quantitative classification system of fueling modes was created and used to test incremental changes in the fueling mode of a 1.9L GM turbodiesel engine, shifting between conventional diesel combustion (CDC) and RCCI at a single speed/load point. This engine used a 5:2 mass ratio blend of propane and dimethyl ether (DME) as its HOF and ultra-low-sulfur diesel (ULSD) as its HCF.
2018-04-03
Technical Paper
2018-01-0248
Jonathan M. S. Mattson, Chenaniah Langness, Christopher Depcik
The recent increase in natural gas availability has made compressed natural gas (CNG) an option for fueling the transportation sector of the United States economy, particularly in dual-fuel operation alongside ultra low sulfur diesel in standard compression ignition engines. This work investigates the usage of natural gas mixtures at varying Energy Substitution Rates (ESR) within a high compression ratio single-cylinder engine, including performance and heat release modeling of dual-fuel combustion. Results from this work demonstrate the differing behavior of utilizing CNG at various substitution rates, including low-ESRs (7-18%) where operation is not dissimilar from that of normal operation, moderate-ESRs (40-50%) where combustion begins to change but significant changes to engine operation (i.e. injection timing) are not required, and high-ESRs (60-85%) where relatively large changes to injection behavior are required to achieve optimized operation.
2018-04-03
Technical Paper
2018-01-0251
Jaykumar Yadav, Dr A Ramesh
Butanol can be produced from renewable sources and is a promising alternative engine fuel. Experiments were conducted on a turbocharged three cylinder automotive common rail diesel engine that was modified to accommodate solenoid based butanol port fuel injectors. The engine was run in the dual fuel mode with diesel being directly injected. Blends of water and butanol (up to 30% water by mass) were injected. Initially diesel was injected as a single pulse per cycle and the timing was always set at the one for best efficiency. The engine speed was kept at 1800 rpm at different fixed load conditions. Open engine controllers were used for varying the injection parameters of diesel and butanol. Standard instrumentation was used for emissions. Combustion parameters were obtained from average cylinder pressure crank angle data processed using in-house developed software.
2018-04-03
Technical Paper
2018-01-0253
Vittorio Ravaglioli, Fabrizio Ponti, Federico Stola, Matteo De Cesare, Filippo Carra
The continuous development of modern Internal Combustion Engine (ICE) management systems is mainly aimed at complying with upcoming more stringent regulations throughout the world. Performing an efficient combustion control is crucial for efficiency increase and pollutant emissions reduction. These aspects are even more crucial for innovative Low Temperature Combustions (such as RCCI), mainly due to the high instability and the high sensitivity to slight variations of the injection parameters that characterize this kind of combustion. Optimal combustion control can be achieved through a proper closed-loop control of the injection parameters. The most important feedback quantities used for combustion control are engine load (Indicated Mean Effective Pressure or Torque delivered by the engine) and center of combustion (CA50), i.e. the angular position in which 50% of fuel burned within the engine cycle is reached.
2018-04-03
Technical Paper
2018-01-0250
Jesus Benajes, Antonio Garcia, Javier Monsalve-Serrano, Vicente Boronat
The dual-fuel combustion mode known as reactivity controlled compression ignition (RCCI) allows an effective control of the combustion process by means of modulating the in-cylinder fuel reactivity depending on the engine operating conditions. This strategy has been found to be able to avoid the NOx-soot trade-off appearing during conventional diesel combustion (CDC), with diesel-like or better thermal efficiency in a great part of the engine map. The role of the low reactivity fuel properties and engine settings over RCCI combustion has been widely investigated in literature, concluding that the direct-injected fuel injection timing is a key parameter for controlling the in-cylinder fuel stratification. From this, it can be inferred that the physical and chemical characteristics of the direct-injected fuel should have also an important role on the RCCI combustion process.
2018-04-03
Technical Paper
2018-01-0252
Zeeshan Ahmad, Janak Aryal, Olli Ranta, Ossi Kaario, Ville Vuorinen, Martti Larmi
A developing practical approach of dual fuel combustion facilitates the fuel flexibility and provide a base to utilize diverse fuels in internal combustion engines. The abundance of natural gas and its clean burning property due to its lower C/H ratio has drawn the interest toward it. In addition, natural gas has high octane number and high auto-ignition temperature, which makes it a potential fuel to employ as a primary fuel in typical diesel engines with high compression ratio resulting in diesel like efficiency. In this study, DF-combustion involving methane (99.8% pure) as a primary fuel and diesel as a pilot fuel is subjected. In diesel-methane DF combustion, the combustion of lower reactivity fuel methane initiates through the energy provided by compression ignited pilot amount of high reactivity diesel fuel. The experimental investigation of DF-combustion was carried out by a natural luminosity optical method.
2018-04-03
Technical Paper
2018-01-0255
John Roberts, Sage Kokjohn, Deyang Hou, Yiqun Huang
Gasoline compression ignition (GCI) combustion is a promising solution to address increasingly stringent efficiency and emissions regulations imposed on the internal combustion engine. However, the high resistance to auto-ignition of modern market gasolines makes low load compression ignition (CI) operation difficult. Accordingly, a method that enables the variation of the fuel reactivity on demand is an ideal solution to address low load stability issues. Metal engine experiments were conducted on the single cylinder medium duty research engine. The fuels used for this study were 87 octane gasoline (primary fuel stream) and diesel fuel (reactivity enhancer). Initial tests demonstrated load extension down to idle conditions with only 20% diesel by mass, which was reduced to 0% at loads above 3 bar IMEPg.
Viewing 391 to 420 of 86934