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Influence of port water injection on the combustion characteristics and exhaust emissions in a spark-ignition direct-injection engine

Shanghai Jiao Tong Univ-Tianbao Wu, Xuesong Li
Shanghai Jiao Tong Univ.-Yadong Fan
  • Technical Paper
  • 2020-01-0294
To be published on 2020-04-14 by SAE International in United States
It is well known that spark-ignition direct-injection (SIDI) gasoline engines have a huge advantage in fuel economy due to their good anti-knock performance compared to port fuel injection engines. However, higher particle number (PN) emissions associated with fuel impingement make the SIDI engines have additional difficulties to meet the upcoming China VI emission standards. In this study, the port water injection (PWI) techniques on a 1.0-L turbocharged, three cylinder, SIDI engine were investigated. PWI strategies were optimized to quantify port water injection as a means of mitigating the knock and improving the combustion performance by sweeping water-fuel mass ratios and PWI timing at different operating conditions. Measurements indicate that regardless of engine load, PWI induced a worsening of the maximum in-cylinder pressure (P-Max) and cycle-to-cycle variations (IMEPN-COV ) , which mainly due to the effects of water dilution and slower burning velocities. But by the advance of spark timing with knock mitigation, we find that the improvement of combustion phasing finally makes it possible to eliminate fuel enrichment, which bring the potential advantages on the…
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Downsized-Boosted Gasoline Engine with Exhaust Compound and Lean Advanced Combustion

General Motors-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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A path towards high efficiency SI combustion in a CFR engine: Cooling the intake to sub-zero temperatures

King Abdullah Univ of Science & Tech-Abdulrahman Mohammed, Ali Elkhazraji, Jean-Baptiste Masurier
King Abdullah Univ. of Science & Tech.-Sufyan Mohammad Jan
  • Technical Paper
  • 2020-01-0550
To be published on 2020-04-14 by SAE International in United States
Textbook engine thermodynamics predicts that SI (Spark Ignition) engine efficiency η is a function of both the compression ratio CR of the engine and the specific heat ratio γ of the working fluid. In practice the compression ratio of the SI engine is often limited due to “knock”. When this knock limit is reached, increase in heat transfer losses result in reduction in efficiency. One way to lower the end-gas temperature is to cool the intake gas before inducting it into the combustion chamber. With colder intake gases, higher CR can be deployed, resulting in higher efficiencies. In this regard, we investigated the indicated efficiency of the standard Waukesha CFR engine. The engine is operated in the SI engine mode. The engine was operated with three different mediums using the same fuel Methane (Gas). First is Air + Methane at room temperature, second was O2 + Argon + Methane gas mixture at room temperature, and lastly O2 + Argon +Methane at sub-zero conditions. We replace the Air by an Oxygen-Argon mixture to increase the specific…
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Combustion Characterization of Neat n-Butanol in an SI Engine

Univ of Windsor-Navjot Singh Sandhu, Simon Leblanc, Xiao Yu, David Ting, Ming Zheng
  • Technical Paper
  • 2020-01-0334
To be published on 2020-04-14 by SAE International in United States
Increasingly stringent emission standards have promoted the interest in alternative fuel sources. Because of the comparable energy density to the existing fossil fuels and renewable production, alcohol fuels may be a suitable replacement or an additive to the gasoline/diesel fuels to meet the future emission standards with minimal modification to current engine geometry. Extensive research is published on n-Butanol and gasoline fuel blends in a spark-ignition (SI) engine operation. In this research, the combustion characteristics of neat n-Butanol are analyzed under spark ignition operation using a single cylinder SI engine. The fuel is injected into the intake manifold using a port-fuel injector. Two modes of charge dilution were used in this investigation to test the limits of stable engine operation, namely lean burn using excess fresh air and exhaust gas regeneration (EGR). The in-cylinder pressure measurement and subsequently, heat release analysis are used to investigate the combustion characteristics of the fuel under low load SI engine operation. Additionally, a comprehensive emission analysis is performed using the Fourier transform infrared (FTIR) spectroscopy technique to study the…
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Extend Syngas Yield through Increasing Rich Limit by Stratified Air Injection in a Single Cylinder Engine

Southwest Research Institute-Yanyu Wang, Graham Conway, D. Ryan Williams, Christopher Chadwell
  • Technical Paper
  • 2020-01-0958
To be published on 2020-04-14 by SAE International in United States
Southwest Research Institute (SwRI)’s dedicated exhaust gas recirculation (D-EGR®) concept has demonstrated a thermal efficiency increase on many spark-ignited engines at both low and high load conditions. The syngas (H2+CO) produced in the dedicated cylinder (D-cyl) by rich combustion helps to stabilize combustion at highly dilute conditions at low loads and mitigate knock at high loads. The dedicated cylinder with 25% EGR can typically run up to 1.4 equivalence ratio, beyond which the combustion becomes unstable. By injecting fresh air near the spark plug gap at globally rich conditions, a locally lean or near-stoichiometric mixture can be achieved, thus facilitating the ignitability of the mixture and increasing combustion stability. With more stable combustion a richer global mixture can be introduced into the D-cyl to generate higher concentrations of syngas. This in turn can further improve the engine thermal efficiency. This study investigated the possibility of extending the rich limit by stratified air injection in a single cylinder engine. A custom modified spark plug with air passage was used to realize stratified air injection. The emissions…
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Determination of Octane Index and K in a 2L, 4-cylinder turbocharged SI engine using the PRF method

Michigan Tech APS LABS-Jeremy Worm
Michigan Technological Univ-Joel Duncan
  • 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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RDE-compliant PEMS Testing of a Euro 6d-TEMP Passenger Car at Two Ambient Temperatures with a Focus on the Cold Start Effect

BOSMAL Automotive R&D Institute Ltd-Piotr Bielaczyc, Joseph Woodburn
Poznan University of Technology-Jerzy Merkisz, Jacek Pielecha
  • Technical Paper
  • 2020-01-0379
To be published on 2020-04-14 by SAE International in United States
European Union RDE (real driving emissions) legislation requires that new vehicles be subjected to emissions tests on public roads. Performing emissions testing outside a laboratory setting immediately raises the question of the impact of ambient conditions – especially temperature – on the results. In the spirit of RDE legislation, a wide range of ambient temperatures are permissible, with mathematical moderation (correction) of the results only permissible for very high and very low ambient temperatures. Within the standard range of temperatures, no correction for temperature is applied to emissions results and the applicable emissions limits have to be met. Given the well-known link between the thermal state of an engine and its emissions following cold start, ambient temperature can be of great importance in determining whether a vehicle meets emissions requirements during an RDE test. This paper reports the results of full RDE-compliant on-road emissions tests performed on a Euro 6d-TEMP passenger car with a direct injection spark ignition engine and a gasoline particle filter. Testing was performed at two temperatures, both lying within the “standard”…
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Potential analysis and virtual development of SI Engines operated with synthetic fuel DMC+

FKFS-Cornelius Wagner, Michael Grill, Mahir-Tim Keskin, Michael Bargende
RWTH Aachen University-Liming Cai, Heinz Pitsch
  • Technical Paper
  • 2020-01-0342
To be published on 2020-04-14 by SAE International in United States
On the way to emission-free mobility, future fuels must be CO2 neutral. To achieve this, synthetic fuels are being developed. In order to better assess the effects of the new fuels on the engine process, simulation models are being developed that reproduce the chemical and physical properties of these fuels. In this paper, the fuel DMC+ is examined. DMC+ (a mixture of DMC and MeFo mainly, characterized by the lack of C-C Bonds and high oxygen content) offers advantages with regard to evaporation heat, demand of oxygen and knock resistance. Furthermore, its combustion is almost particle free. With the aid of modern 0D/1D-Simulation methods, an assessment of the potential of DMC+ can be made. It is shown that the simulative conversion of a state-of-the-art gasoline engine to DMC+ (a mixture of DMC and MeFo mainly, characterized by the lack of C-C Bonds and high oxygen content) fuel offers advantages in terms of efficiency in many operating points even if the engine design is not altered. This is mainly due to the higher knock resistance and…
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Impact of plasma length on flame kernel development under flow condition

Univ of Windsor-Qingyuan Tan, Xiao Yu, Zhenyi Yang, Li Liang, Ming Zheng, Graham Reader
Univ. of Windsor-Hua Zhu
  • Technical Paper
  • 2020-01-1114
To be published on 2020-04-14 by SAE International in United States
Advanced ignition systems with enhanced discharge current level have been extensively investigated in research, since they are highly regarded to have potentials to overcome challenges arisen when spark-ignition engines are running under lean or EGR diluted conditions. Local flow field is also of particularly importance to improve the ignitability of the ignition system as spark plasma channel is stretched under flow conditions, leading to more thermal spark energy distribution to the air-fuel mixture in the vicinity of the spark plug. Research results have shown that a constantly high discharge current is considered to be effective to maintain stable discharge with less restrikes and longer plasma holding period. However, with the further increase of the discharge current, plasma channel becomes thicker, and the stretched plasma length becomes shorter under certain flow speed, which may suppress the advantages of the presence of air flow. In this work, the interaction between discharge current level and plasma length under flow conditions is investigated. Whether a thick but short plasma or a thin but stretched long plasma are more effective…
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Analysis Of The Passive Pre-Chamber Ignition Concept Combined With The EGR Dilution Strategy For Future Passenger Car SI Engines

DEA-IRP Groupe Renault-Chistou Panagiotis, Cedric Libert, Fano Rampanarivo, Maziar Dabiri
Universitat Politecnica de Valencia-Ricardo Novella, Josep Gomez-Soriano, Ibrahim Barbery, Jose Pastor
  • Technical Paper
  • 2020-01-0238
To be published on 2020-04-14 by SAE International in United States
Nowadays the combination of strict regulations for pollutant and CO2 emissions, together with the irruption of electric vehicles in the automotive market, is arising many concerns for internal combustion engine community. For this purpose, many research efforts are being devoted to the development of a new generation of high-performance spark-ignition (SI) engines for passenger car applications. Particularly, the pre-chamber ignition concept, also known as Turbulent Jet Ignition (TJI), is the focus of several investigations for its benefits in terms of engine thermal efficiency. The passive or un-scavenged version of this ignition strategy does not require an auxiliary fuel supply inside the pre-chamber; therefore, it becomes a promising solution for passenger car applications as packaging and installation are simple and straightforward. Moreover, combining this concept with EGR dilution is an interesting alternative for both improving the engine efficiency maintaining low pollutant emissions as this approach is perfectly compatible with the three-way catalyst for NOX control. However, previous researches focused on developing the technology rather than understanding the governing physical phenomena. Consequently, the knowledge about the characteristics…