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On Maximizing Argon Engines' Performance via Subzero Intake Temperatures in HCCI Mode at High Compression Ratios

King Abdullah University of Science & Technology-Ali Elkhazraji, Abdulrahman Mohammed, Sufyan Jan, Jean-Baptiste Masurier, Robert Dibble, Bengt Johansson
  • Technical Paper
  • 2020-01-1133
To be published on 2020-04-14 by SAE International in United States
Maximizing the indicated thermal efficiency with minimal amount of emissions is one of the main challenges to overcome in the field of internal combustion engines. The main obstacle that hinders achieving this goal is the typically low thermodynamic efficiency which is the ratio of the positive produced work on the piston to the amount of heat released inside the cylinder. Many concepts and technologies were innovated to maximize the thermodynamic efficiency. One of the main guidelines that have been followed to achieve so, is the ideal Otto’s cycle that predicts that increasing the compression ratio and/or the specific heat ratio of the combustion reactants, will maximize the thermodynamic efficiency. This study combines both high compression ratios and a high specific heat ratio via two of the main approaches used to maximize the thermodynamic efficiency. First, is the HCCI combustion mode. HCCI is typically operated at fuel-lean conditions, allowing to operate at higher compression ratios without having intense knock (pressure waves, generated by undesired autoignition, that can damage the engine). Second, air was replaced by an…
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Downsized-Boosted Gasoline Engine with Exhaust Compound and Lean Advanced Combustion

General Motors LLC-Jeremie Dernotte, Paul M. Najt, Russell P. Durrett
  • Technical Paper
  • 2020-01-0795
To be published on 2020-04-14 by SAE International in United States
This article presents the experimental results obtained with a disruptive engine platform, designed to maximize the engine efficiency through a synergetic implementation of downsizing, high compression-ratio, and importantly exhaust-heat energy recovery in conjunction with advanced lean/dilute low-temperature type combustion. The engine architecture is a supercharged high-power output, 1.1-liter engine with two-firing cylinders and a high compression ratio of 13.5:1. The integrated exhaust heat recovery system is an additional, larger displacement, non-fueled cylinder into which the exhaust gas from the two firing cylinders is alternately transferred to be further expended. The main goal of this work is to implement advanced lean/dilute combustion while minimizing NOx emissions and addressing the transition between the operating modes. The combustion modes include well-mixed charge compression-ignition at low-load, and a mixed-mode combustion strategy at higher loads. The mixed-mode combustion strategy is composed of a deflagration of a stratified mixture, triggering a controlled autoignition of the surrounding gas. The paper describes the key features of the engine and details regarding the combustion and multi-mode valve strategies. The experiments were performed under steady-state…
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High-pressure laminar burning velocity measurements of ethanol- a Co-Optima fuel candidate

Public Authority for Applied Education & Training-Bader Almansour
University of Central Florida-Gihun Kim, Anthony Terracciano, Subith Vasu
  • Technical Paper
  • 2020-01-0332
To be published on 2020-04-14 by SAE International in United States
Co-Optimization of Fuels and Engines initiative (Co-Optima) of the U.S Department of Energy initiated investigations on several candidates of biofuels and blends for internal combustion engines. Several biofuels were selected by screening criteria, which were boiling point, toxicity, research octane number, octane sensitivity, laminar flame speed, and economical distribution system, etc. In this study, we focused our investigation on ethanol – a key fuel candidate. Measurements of properties such as ignition delay time and laminar burning velocity (LBV) are necessary for these fuels in order to understand their performance and applicability in engines. One key combustion metric is the fuel’s LBV in air over a range of equivalence ratios. LBV is dependent on reactive mixture composition, temperature, and pressure, but it is independent of hydrodynamic conditions, such as stretch rate, turbulent intensity, and Reynolds number. LBV is useful as it: (i) gives a measure of combustion efficiency and heat release rate; (ii) enables validation of chemical kinetic mechanisms; (iii) and gives engine design engineers a metric for the expected time required to burn the fuel…
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Stability of Flowing Combustion in Adaptive Cycle Engines

Illinois Institute of Technology-Prashanth Tamilselvam, Francisco Ruiz
  • Technical Paper
  • 2020-01-0296
To be published on 2020-04-14 by SAE International in United States
In an Adaptive Cycle Engine (ACE), thermodynamics favors combustion starting while the compressed, premixed air and fuel are still flowing into the cylinder through the transfer valve. Since the flow velocity is typically high, and is predicted to reach sonic conditions by the time the transfer valve closes, the flame might be subjected to extensive stretch, thus leading to aerodynamic quenching. It is also unclear whether a single spark, or even a succession of sparks, will be sufficient to achieve complete combustion. Given that the first ACE prototype is still being built, this issue is addressed by numerical simulation using the G-equation model, which accounts for the effect of flame stretching, over a 3D domain representing a flat-piston ACE cylinder, both with inward- and outward-opening valves. RNG K-Epsilon turbulence model was used to approximate the highly turbulent flow field. It was found that the flame would suffer local blow-off under most operating conditions, but the blow-off is never complete so that the regions affected are later re-ignited by the remaining parts of the flame, and…
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A Holistic Approach to Develop a Modern High Power Density Diesel Engine to Meet Best-in-class NVH levels.

Mahindra & Mahindra, Ltd.-Vikraman Vellandi, Prasad Namani, Rajkumar Bhagate, Madhu Chalumuru
  • Technical Paper
  • 2020-01-0406
To be published on 2020-04-14 by SAE International in United States
The ever-increasing customer expectations put a lot of pressure on car manufacturers to constantly reduce the noise, vibration and harshness (NVH) levels. This papers presents the holistic approach used to achieve best-in-class NVH levels in a modern high-power density 1.5 lit 4 cylinder diesel engine. The base engine architecture was designed with NVH reduction features such as crank-offset, cast iron crankcase, stiffened ladder frame, structural oil pan and front cover. Piston skirt profile was optimized to reduce the slapping noise by carefully studying the secondary motion and skirt contact pressure. The plastic parts such as cylinder head cover and intake manifold were designed with closely spaced ribs and high wall thickness. Natural frequency targets for different parts were set for the entire engine at component level and system level and confirmed through simulations. High frequency acoustic simulation was carried out to identify and improve the areas of high surface velocity. "Acoustic holography" technology was extensively used to identify the areas of high noise radiation in the running engine. Based on the measurements, it was identified…
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Numerical investigations on strong knocking combustion under compression ignition conditions

State Key Lab of Engines-Jiaying Pan
Tianjin University-Lin Chen, Jianfu Zhao
  • Technical Paper
  • 2020-01-1137
To be published on 2020-04-14 by SAE International in United States
Homogeneous charge compression ignition (HCCI) combined with high compression ratio is an effective way to improve engines’ thermal efficiency. However, the severe thermodynamic conditions at high load may induce knocking combustion thus damage engine body. In this study, compression ignition knocking characteristics were parametrically investigated through RCM experiments and simulation analysis. First, the knocking characteristics were optically investigated. The experimental results show that there even exists detonation when the knock occurs thus the combustion chamber is damaged. Considering both safety and costs, the effects of different initial conditions were numerically investigated and the results show that knocking characteristics is more related to initial pressure other than initial temperature. The initial pressure have a great influence on peak pressure and knock intensity while initial temperature on knock onset. Further analysis shows that knock intensity is mainly related to the energy density of the in-cylinder mixture and energy density is higher under higher pressure conditions. Then the effects of different cylinder wall temperature on the local auto-ignition thus knocking characteristics were further discussed. The results show that…
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Determination of Octane Index and K in a 2L, 4-cylinder turbocharged SI engine using the PRF method

Michigan Technological University-Siddharth Gopujkar, Jeremy Worm, Joel Duncan, William Hansley
  • Technical Paper
  • 2020-01-0552
To be published on 2020-04-14 by SAE International in United States
Research Octane Number (RON) and Motor Octane Number (MON) have traditionally been used to describe fuel anti-knock quality. The test conditions for MON are harsher than those for RON, causing the RON for a particular fuel to be higher than the MON. Researchers have proposed the anti-knock performance can be described using the Octane Index (OI), defined as OI=RON-K(RON-MON), where ‘K’ is a weighing factor between RON and MON. The K-factor indicates that at a particular operating condition, knock tolerance is better described by RON as K approaches a value of 1, and MON as K approaches a value of 0. Previous studies claim that K-factor is dependent only on the engine combustion system and the speed-load point, and that it is independent of fuel chemistry. In these studies, K was determined experimentally using linear regression. In this particular study, K was determined using the PRF method for two test fuels; EPA certification tier 2 and tier 3 fuel. K was calculated for these fuels at multiple test points and the results showed that the…
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Study on the Effect of Manifold Induction of Acetylene in a Dual-fuelled CI Engine

NIT Rourkela-Rakesh Kumar Sahoo, Akshat Jaiswal, Murugan Sivalingam
  • Technical Paper
  • 2020-01-0817
To be published on 2020-04-14 by SAE International in United States
The utilization of gaseous fuels in internal combustion (IC) engines is receiving more significant greater interest in recent years because of their better fuel mixing characteristics. Apart from potential gaseous fuels such as liquefied natural gas (LPG), compressed natural gas (CNG) and hydrogen, other gaseous fuels are being explored for their utilization in IC engines. The reason for this exploration is mainly because of the durability and robust nature of compression ignition (CI) engines, more research focuses on the utilization of a variety of gaseous fuels in CI engines. However, gaseous fuels need to be used in CI engines on dual fuel mode only. In this investigation, a single-cylinder, four-stroke, air-cooled diesel engine was converted into Acetylene run dual-fuel CI engine by changing the intake manifold of the test engine. Acetylene at three flow rates viz., 2lpm, 4lpm, and 6lpm were introduced into the intake port by manifold induction technique while Jatropha biodiesel was injected directly into the cylinder. In this paper, the effect of manifold induction of Acetylene on the performance and emission characteristics…
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Knock detection with series cylinder pressure sensors - Function principles – Realization in the engine control unit – vehicle measurement results from the chassis dyno -

Technical University of Munich-Matthias Gaderer
Vitesco Technologies GmbH-Harry Schuele, Johannes Beer
  • Technical Paper
  • 2020-01-1143
To be published on 2020-04-14 by SAE International in United States
Current legal requirements based on new driving cycles like WLTP or RDE focus on elevated power and torque from the engine. The gear ratios are chosen so as to permit low engine speeds to reduce fuel consumption and consequently CO2 emissions by shifting the operating point to higher loads with reduced throttling and friction losses at low engine speeds. To achieve the required acceleration values the engine tends to be operated more frequently close to its power and torque limits. Thus, the knock occurring at the load limits will increase in significance. Today, in series production, knock is detected via structure-borne sound sensors and eliminated via retarded ignition. New low-cost in cylinder-pressure sensors (ICPS) suitable for series-production now permit evaluation of every single combustion, thus detecting knock in the engine control unit at all speed and load ratios independent of parasitic noise. This paper presents the potential for knock detection and knock control using series-production capable cylinder-pressure sensors. First, the basic differences of the algorithm of a structure-borne sensor and a cylinder-pressure sensor and the…
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A novel design of engine misfire detection system suitable for small capacity S.I. engine for two wheeled vehicle

TVS Motor Co., Ltd.-Monika Jayprakash Bagade, Himadri Bhushan Das, Arjun Raveendranath Sr, S Jabez Dhinagar
  • Technical Paper
  • 2020-01-0267
To be published on 2020-04-14 by SAE International in United States
As per the OBD II regulations, it is essential to detect and monitor the misfire event in an I.C. engine. Misfiring of an I.C. engine affects the quality of combustion and degrades the performance of catalyst convertor which can lead to an increase of emissions. Misfire event can be categorized as partial or full, based on amount of combustion occurred during that particular engine cycle. Most of the production engine for non-two wheeler vehicle identifies misfire by monitoring angular acceleration of the engine crank-shaft. However, single cylinder engine with lower capacity (less than 200 cubic centimetre) provides challenges to identify misfire due to low mechanical inertia of the I.C. engine using the same approach. The problem of misfire identification for this category of I.C. engine turn out to be more challenging due to presence of various load disturbances on the powertrain. Ion current sensing is one of the alternate method to detect misfire, which received good attention during the last decade of the previous century. When the air-fuel mixture ignites inside the I.C. engine cylinder,…