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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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A new efficient combustion method for ICEs

Revolutionary Engines LLC-Peter C. Cheeseman
  • Technical Paper
  • 2020-01-1314
To be published on 2020-04-14 by SAE International in United States
Current methods for combustion in Internal Combustion Engines (ICEs) are: Spark Ignition (SI), Compression Ignition (CI) and Homogeneous Charge Compression Ignition (HCCI). Each of these combustion methods has well known limitations for efficiency and clean exhaust. This paper presents a new method of combustion, called Entry Ignition (EI), that overcomes these limitations. EI burns a homogeneous fuel air mixture at constant pressure with combustion occurring at the inlet where the unburned mixture flows into the combustion chamber. Combustion results from the unburned mixture mixing with the much hotter already burned gases already in the combustion chamber. EI can operate in a conventional piston-type engine, with the only major change being in the valving. EI’s efficiency gain results from the following. Firstly, EI is not subject to “knocking” and so can operate at CI level compression ratios or higher. Secondly, EI allows lean burn, which improves efficiency for basic thermodynamic reasons. Thirdly, an engine that using EI can fully expand the combustion gases (Brayton cycle), and finally, EI has reduced heat loss relative to the other…
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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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Analytical approach to characterize the effect of engine control parameters and fuel properties on ACI operation in a GDI engine

Argonne National Laboratory-Johannes Rohwer, Ashish Shah, Toby Rockstroh
  • Technical Paper
  • 2020-01-1141
To be published on 2020-04-14 by SAE International in United States
Advanced compression ignition (ACI) operation in gasoline direct injection (GDI) engines is a promising concept to reduce fuel consumption and emissions at part load conditions. However, combustion phasing control and the limited operating range in ACI mode are a perennial challenge. In this study the combined impact of fuel properties and engine control strategies are investigated. A design of experiments method was implemented using a three level orthogonal array to determine the sensitivity of five engine control parameters on four engine response variables under low load ACI operation for three 98 RON gasoline fuels, exhibiting disparate chemical composition. Furthermore, the thermodynamic state of the compression histories was studied with the aid of the pressure-temperature framework and correlations were drawn to analogous HCCI experiments conducted in an instrumented CFR engine. Due to the compression ratio constraints imposed by knock limited SI operation, considerable intake temperature heating was required resulting in advanced compression ignition mode resulting in the intermediate to high temperature autoignition regime. The olefin containing fuel was found to require the least amount of intake…
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Machine Learning Techniques for the Prediction of Combustion Events in Cooperative Fuel research Engine (CFR) at Homogeneous Charge Compression Ignition (HCCI) conditions.

Aramco Services Co.-Alexander Voice
King Abdullah University of Science &Technology-Fabiyan Angikath Shamsudheen, Kiran Yalamanchi, Mani Sarathy
  • Technical Paper
  • 2020-01-1132
To be published on 2020-04-14 by SAE International in United States
This research assesses the capability of data-science models to predict the combustion events occurring for certain input conditions in Cooperative Fuel Research Engine (CFR) at Homogeneous Charge Compression Ignition (HCCI) conditions. The experimental data from CFR engine of University of Michigan (UM), operated at different input conditions for various gasoline type fuels was utilized for the study. The current study developed a capable machine learning framework to predict the auto-ignition propensity of a fuel under HCCI conditions. The combustion events happening at HCCI conditions in CFR engine are primarily classified into four different classes depending on the combustion phasing and pressure rise during the combustion in engine. The classes are: no ignition, normal combustion, high MPRR and early CA 50. Two machine learning (ML) models, K-nearest neighbors and Support Vector Machines, are compared for their classification capabilities of combustion events. Seven conditions are used as the input features for this ML models viz. Research Octane Number (RON) of fuel, Sensitivity of fuel (S), fuel rate (J/L/cycle), oxygen mole fraction, intake temperature and pressure, and compression…
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Study on the effects of fuel reforming on fuel properties and the following potential influences on ICEs

CATARC-Feng Yan
  • Technical Paper
  • 2020-01-1315
To be published on 2020-04-14 by SAE International in United States
A high temperature and no oxygen atmosphere fuel reforming has been proposed for the purpose of exergy saving by theoretical analyzing the detailed exergy loss events of combustion process, the correctness and feasibility of this fuel reforming have been verified through experiments. The exergy behaviors of high temperature and no oxygen atmosphere fuel reforming have been extensively studied, and many benefits had been observed including: (1) simplifying the reforming device where catalysts are not necessary; (2) improving the total chemical exergy while effectively converting large moleculae to small moleculae; (3) improving the mixture’s ratio of specific heat that can promote work-extraction; and (4) lengthening the ignition delay that buys time for better mixing process. All of these benefits are conducive to a better organized HCCI combustion that may improve the engine second law efficiency.
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Experimental Investigation of Low Cost, Low Thermal Conductivity Thermal Barrier Coating on HCCI Combustion, Efficiency, and Emissions

Auburn University-Mark Hoffman
Bosch Packaging Technology Inc.-Ryan O'Donnell
  • Technical Paper
  • 2020-01-1140
To be published on 2020-04-14 by SAE International in United States
In-cylinder surface temperature is of heightened importance for Homogeneous Charge Compression Ignition (HCCI) combustion, as the combustion mechanism is thermo-kinetically driven. Thermal Barrier Coatings (TBCs) selectively manipulate the in-cylinder surface temperature, providing an avenue for improving thermal and combustion efficiency. This thermal phenomenon sidesteps charge preheating during gas exchange, while a surface temperature swing during combustion/expansion reduces heat transfer losses, leading to more complete combustion and reduced emissions. The magnitude and profile of the dynamic surface temperature swing was found to be affected by the material properties and TBC thickness. This study is the continuation of the author’s work to systematically engineer coatings that are best suited for HCCI. A parametric study was used to assess the impacts of various TBC material properties (density, specific heat, thermal conductivity) on the temperature swing effect. Previous work investigated the effect of reducing TBC density via increased porosity, however fuel entrapment and durability concerns found this route initially unattractive for robust TBC performance. Shifting focus to the remaining material properties, this study experimentally investigates the impact of lower…
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Measurements and Correlations of Local Cylinder-Wall Heat-Flux Relative to Near-Wall Chemiluminescence across Multiple Combustion Modes

Zachary Shechtman
Sandia National Laboratories-Zheming Li, Mark Musculus
  • Technical Paper
  • 2020-01-0802
To be published on 2020-04-14 by SAE International in United States
Minimizing heat transfer (HT) losses is important for both improving engine efficiency and increasing exhaust energy for turbocharging and exhaust aftertreatment management, but engine combustion system design to minimize these losses is hindered by significant uncertainties in prediction. Empirical HT correlations such as the popular Woschni model have been developed and various attempts at improving predictions have been proposed since the 1960s, but due to variations in facilities and techniques among various studies, comparison and assessment of modelling approaches among multiple combustion modes is not straightforward. In this work, simultaneous cylinder-wall temperature and OH* chemiluminescence high-speed video are all recorded in a single heavy-duty optical engine operated under multiple combustion modes. The cylinder-wall HT is derived from the measured transient temperature and compared with Woschni HT correlation predictions using both bulk and estimated local gas-temperatures. The local Woschni correlation predictions of heat flux and the HT coefficient for spark ignition (SI) and homogeneous charge compression ignition (HCCI) match surprisingly well with measurements. Uncertainty analysis shows that the modeled results falls in the measurements uncertainty. For…
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Influence of Oxy-Fuel Combustion on Engine Operating Conditions and Combustion Characteristic in a High Speed Direct Injection (HSDI) Diesel Engine under Homogenous Charge Compression Ignition (HCCI) Mode

University of Bedfordshire-Zhijun Peng, Xiang Li
Yncréa Hauts-de-France-Raouf Mobasheri, Abdel Aitouche
  • Technical Paper
  • 2020-01-1138
To be published on 2020-04-14 by SAE International in United States
Oxyfuel combustion and nitrogen-free combustion coupled with Carbon Capture and Storage (CCS) techniques have been recently proposed as an efficient method to achieve carbon free emissions and to improve the combustion efficiency in diesel engines. In this study, a 3-D computational fluid dynamics model has been used to evaluate the influence of oxyfuel-HCCI combustion on engine operating conditions and combustion characteristics in a HSDI diesel engine. Investigations have conducted using four different diluent strategies based on the volume fraction of pure oxygen and a diluent gas (carbon dioxide). The first series of investigations has performed at a constant fuel injection rating at which 4.4 mg of fuel has injected per cycle. In the second part of analysis, the engine speed was maintained at 1500 rev/min while the engine loads were varied by changing the fuel injection rates in the range of 2.8 to 5.2 mg/cycle. Results showed that oxyfuel-HCCI combustion has brought CO and PM emissions to very ultra-low level while NOx emissions have been completely eliminated. It has found that by increasing the diluent…
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Control of Ignition Timing and Combustion Phase by means of Injection Strategy for Jet-Controlled Compression Ignition Mode in a Light Duty Diesel Engine

CATARC-Li Bo
Dalian University of Technology-Jingyu Zhu, Wuqiang Long
  • Technical Paper
  • 2020-01-0555
To be published on 2020-04-14 by SAE International in United States
Premixed charge low temperature combustion such as PCCI (Premixed charge compression ignition) and HCCI (Homogeneous charge compression ignition) has been considered as a promising way to simultaneously improve the fuel economy and reduce the NOx/soot emissions compared to the traditional combustion mode. However, how to realize the stable combustion phasing is still one of the main challenges since reaction of the premixed charge is sensitive to the intake air properties (temperature, oxygen concentration) and chemical kinetics. In this work, effects of multi-injection strategy on the controllability of premixed charge compression ignition were investigated in a light duty prototype diesel engine. Cylinder head was modified to ensure the configuration of two common rail direct injectors. One is for delivering the blended fuel of diesel and ethanol-gasoline to form the premixed charge, another is for injecting the jet-injection diesel fuel in order to trigger the ignition. Piston cavity shape was also optimized to reduce the THC and CO emission resulted from wall-wetting and incomplete combustion in the crevice. Several important factors including pre-injection timing, jet-injection timing, stratified…