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Methods of Pegging Cylinder Pressure to Maximize Data Quality

Michigan Tech APS LABS-Jeremy Worm
Michigan Technological Univ-Darrell Robinette
  • Technical Paper
  • 2019-01-0721
To be published on 2019-04-02 by SAE International in United States
Engine cylinder pressure measured with piezo-electric pressure transducers must be referenced or pegged to a known pressure at some point in the engine cycle. Traditionally, the pressure has been pegged to the pressure in the intake manifold plenum at Bottom Dead Center (BDC) at the end of the intake stroke. However, an error in pegging induces an error in the cylinder pressure trace, which has an adverse effect on the entire combustion analysis. This research is focused on assessing the pegging error for several pegging methods across a wide range of engine operating conditions, and ultimately determining best practices to minimize error in pegging and its propagation to calculated combustion metrics. The study was conducted through 1D simulations run in the commercially available GT-Power. The points studied included variations of speed, load, intake runner length and intake valve timing (including Late Intake Valve Closing (LIVC) and Early Intake Valve Closing (EIVC)). Five different pegging locations were compared (intake manifold plenum, intake port, intake valve, exhaust valve, and exhaust manifold runner). For each of the five…

A Quasi-Dimensional Model of Pre-Chamber Spark-Ignition Engines

FEV Engine Technology-Knut Habermann
University of Naples-Fabio Bozza, Vincenzo De Bellis, Daniela Tufano, Enrica Malfi
  • Technical Paper
  • 2019-01-0470
To be published on 2019-04-02 by SAE International in United States
Increasingly stringent legislations are inducing the car manufacturers to investigate innovative solutions to improve the vehicle fuel economy. Some of them act on the vehicle/engine interaction, such as the powertrain electrification, while other techniques directly affect the engine thermal efficiency. Among them, concerning the spark-ignition engines, a lean combustion showed the potential to improve the fuel consumption. This approach, on the other hand, causes some drawbacks, such as a combustion stability worsening and the impossibility for the TWC to optimally operate. A pre-chamber ignition system could represent an interesting solution to overcome the above issues. Especially in the case of an active system, a high fuel-air mixture ignitability, and an adequate combustion speed can be obtained even with a very lean mixture. In this work, a research single-cylinder SI engine equipped with an active pre-chamber is analyzed. A conventional gasoline fuel is injected in the main chamber while the pre-chamber is fed with CNG. In a first stage, an experimental campaign is carried out under various operating conditions, at various speeds, spark timings and air-fuel…

Experimental investigations on the influence of valve timing and multi-pulse injection on GCAI Combustion

Indian Institute of Technology Madras-Jensen Samuel, Santhosh Mithun, Kasinath Panda, A Ramesh
MSCE, RWTH Aachen University-Maximilian Wick, Jakob Andert
  • Technical Paper
  • 2019-01-0967
To be published on 2019-04-02 by SAE International in United States
Gasoline Compressed Auto-Ignition (GCAI) technology, which can be categorized under Homogeneous Charge Compression Ignition (HCCI), is a low-temperature combustion system with promising benefits such as ultra-low in-cylinder NOx emissions and reduced brake-specific fuel consumption, which are the critical parameters in any modern engine. Since this technology is based on uncontrolled auto-ignition of a premixed charge, it is very sensitive to any change in boundary conditions during engine operation. Adopting real time valve timing and fuel-injection strategies can enable improved control over GCAI combustion. This work discusses the outcome of collaborative experimental research by the partnering institutes in this direction. Experiments were performed in a single cylinder GCAI engine with variable valve timing and Gasoline Direct Injection (GDI) at constant indicated mean effective pressure (IMEP). In the first phase, intake and exhaust valve timing sweeps were investigated. It was found that the Intake Valve Closing (IVC) timing and Exhaust Valve Closing (EVC) timing have a dominant influence on combustion, performance and emission parameters. Retarding the IVC timing to a certain extent increased the mass of air…

TSCI with Wet Ethanol: an Investigation of the Effects of Injection Strategy on a Diesel Engine Architecture

SUNY-Stonybrook-Ziming Yan
Stony Brook Univ.-Brian Gainey, James Gohn, Mozhgan Rahimi Boldaji, Benjamin Lawler
  • Technical Paper
  • 2019-01-1146
To be published on 2019-04-02 by SAE International in United States
Thermally Stratified Compressions Ignition (TSCI) is a new advanced, low temperature combustion concept that aims to control the thermal stratification in the cylinder in order to control the heat release process in a lean, compression-ignition combustion mode. This work in particular uses “wet ethanol”, a mixture of 80% ethanol and 20% water by mass, to increase thermal stratification beyond what naturally occurs, via evaporative cooling. TSCI with wet ethanol has previously shown the potential to increase the high-load limit when compared to HCCI. The experiments conducted in this paper aim to fundamentally understand the effect that injection strategy has on the heat release process in TSCI. TSCI employs a split-injection strategy in which an injection during the intake stroke allows the majority of the fuel to premix with the air and an injection during the compression stroke introduces the desired level of thermal stratification to control the heat release rate. Using a single injection at -350 deg aTDC was found to be the most effective way to introduce the fuel during the intake stroke. The…

The Physical and Chemical Effects of Fuel on Gasoline Compression Ignition

King Abdullah Univ of Science & Tech-Ponnya Hlaing, Abdullah S. AlRamadan, Yanzhao An, Bengt Johansson
Saudi Aramco-R. Vallinayagam, Jaeheon Sim, Junseok Chang
  • Technical Paper
  • 2019-01-1150
To be published on 2019-04-02 by SAE International in United States
In the engine community, gasoline compression ignition (GCI) engines are at the forefront of research and efforts are being taken to commercialize an optimized GCI engine in the near future. GCI engines are operated typically at Partially Premixed Combustion (PPC) mode as it offers better control of combustion with improved combustion stability. While the transition in combustion homogeneity from convectional Compression Ignition (CI) to Homogenized Charge Compression Ignition (HCCI) combustion via PPC has been compressively investigated, the physical and chemical effects of fuel on GCI are rarely reported at different combustion modes. Therefore, in this study, the effect of physical and chemical properties of fuels on GCI is investigated. In-order to investigate the reported problem, low octane gasoline fuels with same RON = 70 but different physical properties and sensitivity (S) are chosen. Fuels with comparable sensitivity and RON are chosen to study the impact of physical properties on GCI. On the other hand, by keeping the same RON and physical properties, the effect of sensitivity on GCI is investigated. In this regard, three test…

HYDROGEN-DIESEL ENGINE: PROBLEMS AND PROSPECTS OF IMPROVING THE WORKING PROCESS

Bauman Moscow Technical University-Revaz Kavtaradze
Institute of Machine Mechanics-Tamaz Natriashvili
  • Technical Paper
  • 2019-01-0541
To be published on 2019-04-02 by SAE International in United States
The diesel engine with direct injection of hydrogen gas has clear advantages over the hydrogen engine with forced ignition of a hydrogen-air mixture. Despite of this, the concept of hydrogen-diesel engine has not investigated until now. In the paper, a detailed study of the working process of hydrogen-diesel engine carried out for the first time. Based on the results of the experimental studies and mathematical modeling, it has established that the behavior of thermophysical processes in the combustion chamber of hydrogen-diesel engine, in a number of cases, differs fundamentally from the processes that take place in the conventional diesel engines. There have been identified the reasons for their difference and determined the values of the operating cycle parameters of hydrogen diesel engine, which provide the optimal correlation between the indicator values and the environmental performance. For a single-cylinder hydrogen-diesel engine MAN (S/D=300/240 mm/mm) the concentration of nitrogen oxides in combustion products is: [NOx] = 920 ppm, the mean effective pressure pe=9.0 bar, and the indicator efficiency of hydrogen diesel engine ηi=0.48. Overall, it can be…

Effect of Turbulence-Chemistry Interaction on Spray Combustion: a Large Eddy Simulation Study

Dalian University of Technology-Ming Jia
Tianjin University-Junqian Cai, Tianyou Wang, Kai Sun, Zhen Lu, Gang Xiao, Shiquan Shen
  • Technical Paper
  • 2019-01-0203
To be published on 2019-04-02 by SAE International in United States
Although turbulence plays a critical role in engines operated within low temperature combustion (LTC) regime, its interaction with chemistry on auto-ignition at low-ambient-temperature and lean-oxygen conditions remains inadequately understood. Therefore, it is worthwhile taking turbulence-chemistry interaction (TCI) into consideration in LTC engine simulation by employing advanced combustion models. In the present study, large eddy simulation (LES) coupled with linear eddy model (LEM) is performed to simulate the ignition process in n-heptane spray under engine-relevant conditions, known as Spray H. With LES, more details about unsteady spray flame could be captured compared to Reynolds-averaged Navier-Stokes equations (RANS). With LEM approach, both scalar fluctuation and turbulent mixing on sub-grid level are captured, accounting for the TCI. A skeletal mechanism is adopted in this numerical simulation, including 41 species and 124 reactions. Validations is carried out and numerical results show good agreement with experimental data. It is found that, Damköhler number (Da) at the onset of high temperature reaction evidently decreases as ambient temperature and oxygen reduces. Consequently, combustion mode varies from flamelet regime to slow chemistry regime,…

Characterization of Particulate Matter Emissions from Heavy-Duty Partially Premixed Compression Ignition with Gasoline-Range Fuels

Aramco Research Center-Jong Lee
Aramco Services Co-Tom Tzanetakis, Yu Zhang, Michael Traver
  • Technical Paper
  • 2019-01-1185
To be published on 2019-04-02 by SAE International in United States
Low temperature combustion (LTC) engine technologies offer opportunities for higher efficiency and lower NOx emissions. Light-end distillate fuels have been shown to help promote LTC and produce very low soot emissions compared to ULSD fuel. In a previous study, a commercial 15L heavy-duty diesel engine was shown to produce lower PM emissions when using a light-end distillate fuel as a substitution for ULSD. In this study, the compression ratio of a commercial 15L heavy-duty diesel engine was lowered and the split injection strategy was developed to promote the partially premixed compression ignition (PPCI) combustion. Various gasoline-like light-end distillate fuels were compared with ULSD fuel for performance and emissions. The PM was characterized with particle mass, size, and number measurements, organic/elemental carbon analysis, chemical speciation and thermogravimetric analysis. Using light-end distillate fuels, engine-out PM emissions at the same engine-out NOx level were significantly reduced compared to ULSD fuels, while hydrocarbon and carbon monoxide emissions were only slightly increased. Light-end distillate PM samples were found to contain higher volatiles, organic carbon, and nitrogenated HC species, not typically…

An Experimental Study on the factors affecting Ignition Delay of Ethanol in a Rapid Compression Machine

Michigan State University-Chaitanya Wadkar, Prasanna Chinnathambi, Elisa Toulson
  • Technical Paper
  • 2019-01-0576
To be published on 2019-04-02 by SAE International in United States
Ignition Delay, using a RCM, is defined as the time period between the end of compression and the maximum rate of pressure rise due to combustion, at a given compressed condition of temperature and pressure. The same compressed conditions can be reached by a variety of combinations of compression ratio, initial temperature, initial pressure, diluent gas composition, etc. It has been assumed that the value of ignition delay, for a given fuel and at a given set of compressed conditions, would be the same, irrespective of the variety of the above mentioned combinations that were used to achieve the compressed conditions. In this study, a range of initial conditions and compression ratios are studied to determine their effect on ignition delay time and to show how ignition delay time can differ even at the same compressed conditions. Experiments were carried out at two compression ratio conditions (11.72 and 17.06) and ethanol was used as the fuel. Additionally, a study was undertaken to determine the effect of the charge preparation method on the ignition delay time.…

Method Development and Application of Thermal Encapsulation to Reduce Fuel Consumption of Internal Combustion Powertrains

Jaguar Land Rover-Richard Owen, Adam Price, Juan Diego Barril Boleto, Suresh Sivasankaran, Wilko Jansen
  • Technical Paper
  • 2019-01-0902
To be published on 2019-04-02 by SAE International in United States
During cold start of an internal combustion engine, fuel consumption (CO2 emissions) is higher due to increased engine friction (Friction Mean Effective Pressure) until the optimum operating temperature of the engine is achieved. With the introduction of the WLTP emissions drive cycle the impact of cold start is recorded twice; once at the start of the 23°C external ambient drive cycle, and a second time at the restart of the 14°C external ambient WLTP drive cycle after the vehicle has soaked for 9 hours at 14°C. By tackling the impact of the second cold start, the g CO2/km value for a vehicle can be reduced both on the cycle and in the real world. An approach is given to retain the heat generated during the first cycle and maintain engine and key fluid temperature (engine oil, transmission oil and engine coolant) until the start of the second cycle by using under bonnet thermal encapsulation. Alongside this, a CAE method was developed to simulate the temperature and movement of air within the under bonnet thermal encapsulation…