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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 University-Yadong Fan, Tianbao Wu, Xuesong Li, Min Xu, David Hung
  • 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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Studying Ignition Delay Time of Lubricant Oil Mixed with Alcohols, Water and Aromatics in IQT and CVCC

Abu Dhabi Polytechnic-Hatsari Mitsudharmadi
King Abdullah University of Science & Technology-Sumit Maharjan, Ayman Elbaz, William Roberts
  • Technical Paper
  • 2020-01-1422
To be published on 2020-04-14 by SAE International in United States
The auto-ignition of liquid fuel and lubricant oil droplets is considered as one of the possible sources of pre-ignition. Researchers are constantly finding new ways to form advanced lubricant oil by changing its composition and varying different oil additives to prevent the occurrence of this event. In this study, three sets of mixtures are prepared. First set of mixtures was prepared by adding different alcohols namely ethanol, methanol and propanol, to the commercial lubricant oil (SAE 15W-40) in ratio of 1 % - 5 % by volume to investigate the mixtures’ ignition delay time (IDT) following standard ASTM D6890 procedure in an Ignition Quality Tester (IQT) and a custom built 4 liters constant volume combustion chamber (CVCC). For the CVCC, experiments were carried out in ambient air environment at 300 °C with varying pressure ranging from 4 bar - 22 bar at 6 bar interval pressures. Second set of mixtures were prepared by mixing SAE 15W-40 with aforementioned alcohols (1 % vol.) and H2O (1 % vol.). Lastly, third set of mixtures were prepared by…
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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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A path towards high efficiency SI combustion in a CFR engine: Cooling the intake to sub-zero temperatures

King Abdullah University of Science & Technology-Sufyan M. Jan, Abdulrahman Mohammed, Ali Elkhazraji, Jean-Baptiste Masurier
University of California-Robert Dibble
  • 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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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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Study of thermal efficiency improvement by multi-hole nozzle

Hino Motors Ltd.-Kazunori Yoshitomi, Yoshihiro Funayama, Mori Ishii, Hiroshi Nakajima
  • Technical Paper
  • 2020-01-0304
To be published on 2020-04-14 by SAE International in United States
A truck and bus transportation which support logistics and people, diesel engines are highly expected to have high thermal efficiency and low exhaust emissions over the next few decades. Effective methods to achieve even higher thermal efficiency are to reduce a cooling loss from combustion chamber wall. A multi-hole diesel injector has a significant impact on improving engine thermal efficiency by enhancing a combustion activity and reducing a cooling loss. In this study, two types of diesel injectors – 8-hole and 14-hole - with the same flow rate were tested under heavy-duty diesel engine condition. Heat release rate, energy balance and engine emissions were investigated using the single-cylinder engine with displacement of 1,478 cc. Furthermore, an optical engine was used to observe quantitative spray penetration and flame development from shadowgraph imaging and analyze flame temperature by a two-color method. The results of the single-cylinder engine showed that the 14-hole injector exhibited higher indicated thermal efficiency thanks to lower cooling loss than 8-hole results. However, we observed a slightly higher exhaust loss in the case of…
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Effect of changing compression ratio on ignition delay times of iso-octane in a rapid compression machine

Michigan State University-Chaitanya Wadkar, Prasanna Chinnathambi, Elisa Toulson
  • Technical Paper
  • 2020-01-0338
To be published on 2020-04-14 by SAE International in United States
Previous studies have shown that several facility dependent factors can influence ignition delay times measured in a rapid compression machine. Compression ratio variation can have a major impact on measured delay times due to the change in surface-area-to-volume ratio even when the same compressed conditions are maintained. In this study, iso-octane, which exhibits two stage ignition delay and has a pronounced negative temperature coefficient (NTC) region, is used to investigate the effects of several facility dependent factors on ignition delay. Resulting trends are also compared to previous results obtained with ethanol, which has very different combustion properties. In addition to the experimental results, numerical analysis is also used to gain a deeper understanding of the complex processes occurring inside the combustion chamber at a variety of different compression ratio conditions. Experiments and simulations were carried out for stoichiometric mixtures of iso-octane and air over a compressed temperature range of 700–900 K at 20 bar compressed pressure. The compression ratio was varied from 9.58 to 17.07 which also led to changes in initial conditions, compression time…
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Characteristics of Auto-ignition for Lubricants and Lubricant/Gasoline based on An Innovative Single Droplet Combustion System

Tongji University-Yang Yu, Kaifeng Pan, Jun Deng, Zongjie Hu, Wei Xie, Zhijun Wu, Liguang Li
  • Technical Paper
  • 2020-01-1428
To be published on 2020-04-14 by SAE International in United States
Due to the advantages of low weight, low emission and good fuel economy, downsized turbocharged gasoline direct injection (GDI) engines are widely-applied nowadays. However, Low-Speed Pre-Ignition (LSPI) phenomenon observed in these engines restricts their improvement of performance. Some researchers have shown that auto-ignition of lubricant in the combustion chamber has a great effect on the LSPI frequency. To study the auto-ignition characteristics of lubricant, an innovative single droplet auto-ignition measurement system for lubricant and its mixture is designed and developed, with better accuracy and effectiveness. The experiments are carried out by hanging lubricant droplets on the thermocouple node under active thermo-atmosphere provided by a small Dibble burner. The auto-ignition process of lubricant droplets is recorded by a high-speed camera. Influences of different base oil types, viscosities, calcium contents, initial droplet diameters, co-flow speeds, new oil, used oil and blending ratios of lubricant and gasoline on the ignition delay time of droplets are investigated at different droplet temperatures. The co-flow field temperature varies from 823K to 1323K. Equivalent diameters of droplets, 0.99mm, 1.24mm and 1.63mm, generated…
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An Experimental Investigation of In-cylinder Flow Motion Effect on Dual-fuel Premixed Compression Ignition Characteristics

Hyundai Motor Group-Hyunsung Jung, Hyounghyoun Kim, Yohan Chi
Seoul National University-Sanghyun Chu, Hyungjin Shin, Kihong Kim, Sunyoung Moon, Kyoungdoug Min
  • Technical Paper
  • 2020-01-0306
To be published on 2020-04-14 by SAE International in United States
The combustion process using two fuels with different reactivity, known as dual-fuel combustion or RCCI is mainly studied to reduce emissions while maintaining thermal efficiency. Many studies have proven that dual-fuel combustion has a positive prospect in future combustion to achieve near-zero engine out emissions with high indicated thermal efficiency. However, a limitation on high-load expansion due to the higher maximum in-cylinder pressure rise rate (mPRR) is a main problem. Thus, it is important to establish the operating strategy and study the effect of in-cylinder flow motion with dual-fuel combustion to achieve a low mPRR and emissions while maintaining high-efficiency. In this research, the characteristics of dual-fuel combustion on different hardware were studied to verify the effect of the in-cylinder flow motion on dual-fuel combustion. To see such an effect, different head types (swirl and tumble) were used with different combustion chamber shapes (conventional vs bathtub). The higher thermal efficiency with swirl motion on low load combustion was shown with stable combustion due to the faster combustion occurred by air-fuel mixing of diesel fuel by…
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Evaluation of Trajectory Based Combustion Control for Electrical Free Piston Engine

University of Minnesota-Minal Nahin, Abhinav Tripathi, Zongxuan Sun
  • Technical Paper
  • 2020-01-1149
To be published on 2020-04-14 by SAE International in United States
Previously, the authors have proposed a novel strategy called trajectory based combustion control for the free piston engine where the shape of the piston trajectory between top and bottom dead centers is used as a control input to modulate the chemical kinetics of the fuel-air mixture inside the combustion chamber. It has been shown that in case of a hydraulic free piston engine, using active motion control, the piston inside the combustion chamber can be forced to track any desired trajectory, despite the absence of a crankshaft, providing reliable starting and stable operation. This allows for the use of optimized piston trajectory for every operating point which minimizes fuel consumption and emissions. In this work, this concept is extended to an electrical free piston engine as a modular power source. A dynamic model of a linear electrical free piston engine unit has been developed which consists of a single phase linear generator driven by a single cylinder engine. The linear generator unit not only provides the required electromagnetic force to ensure precise trajectory tracking for…