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Potential to Reduce Nano-Particle Emission in SG-DISI Engine with Normal Butane

Korea Advanced Inst of Science & Tech-Sangjae Park, Sanguk Lee, Yonghyun Na, Choongsik Bae
  • Technical Paper
  • 2019-24-0022
Published 2019-09-09 by SAE International in United States
Lean stratified combustion is a mean to dilute the fuel-air mixture leaner than stoichiometric ratio, by using stratification of fuel gradient in a spark ignition engine. Under the lean stratified combustion, differed from the stoichiometric homogeneous charge combustion, flame could propagate through extremely rich air-fuel mixture, while the global air-fuel mixture is under lean condition. The rich mixture causes considerable amount of particulate matter, but, due to large effect of efficiency improvement, the attractive point is on fuel economy compare to homogeneous charge SI combustion. The easiest way to reduce particulate matter is changing fuel to gaseous hydrocarbon, to minimize evaporating and mixing period. In this study, to reduce the particulate emission and to develop the way to mitigation of emission, the emission data of particulate under low and medium-low load conditions from normal butane fueled research engine are dealt to optimize combustion strategies, with respect to injection and ignition. Especially, particulate number density were collected in the research engine, and the causes of particulate formation were studied with visualized combustion data. Through visualization data,…
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Particle Reduction in LPG Lean Stratified Combustion by Intake Strategies

Korea Advanced Institute of Science & Technology-Sanguk Lee, Sangjae Park, Choongsik Bae
Published 2019-04-02 by SAE International in United States
Lean stratified combustion shows high potential to reduce fuel consumption because it operates without the intervention of a throttle valve. Despite its high fuel economy potential, it emits large amounts of particulate matter (PM) because the locally rich mixture is formed at the periphery of a spark plug. Furthermore, the combustion phasing angle is not realized at MBT ignition timing, which can bring high work conversion efficiency. Since PM emission and work conversion efficiency are in a trade-off relation, this research focused on reducing PM emission through achieving high work conversion efficiency. Two intake air control strategies were examined in this research; throttle operation and late intake valve closing (LIVC). The experiment was conducted in a single cylinder spray-guided direct injection spark ignition (SG-DISI) engine with liquefied petroleum gas (LPG). The injected fuel amount was fixed so as to investigate the effect of each strategy. The throttle valve strategy decreased the filter smoke number (FSN) as the restriction of inhaled air was increased. By contrast, the number of particles was increased. When the LIVC strategy…
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The Fuel Economy Improvement through the Knock Margin Expansion in a Turbocharged Gasoline Direct Injection Engine

Korea Advanced Inst. of Science & Tech.-Ji Yong Shin, Chansoo Park, Jinyoung Jung, Choongsik Bae
Published 2018-09-10 by SAE International in United States
Knocking combustion limits the downsized gasoline engines’ potential for improvement with regard to fuel economy. The high in-cylinder pressure and temperature caused by the adaptation of a turbocharger aggravates the tendency of the end-gas to autoignite. Thus, the knocking combustion does not allow for further advancing of the combustion phase. In this research, the effects of the ignition and valve timings on knocking combustion were investigated under steady-state conditions. Moreover, the optimal ignition and valve timings for the transient operations were derived with the aim of a greater fuel economy improvement, based on the steady-state analysis. A 2.0 liter turbocharged gasoline direct injection engine with continuously variable valve timing (CVVT), was utilized for this experiment. 2, 10, and 18 bar brake mean effective pressure (BMEP) load conditions were used to represent the low, medium, and high load operations, respectively. The engine speed was set at 1,500 RPM since the low speed conditions were more vulnerable to knocking combustion than the high speed conditions. Both the intake and the exhaust valve timings were controlled from the…
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Effects of Hot and Cooled EGR for HC Reduction in a Dual-Fuel Premixed Charge Compression Ignition Engine

Korea Advanced Inst. of Science & Tech.-Eui joon Shim, Hyunwook Park, Choongsik Bae
Published 2018-09-10 by SAE International in United States
Most internal combustion engine makers have adopted after-treatment systems, such as selective catalytic reduction (SCR), diesel particulate filter (DPF), and diesel oxidation catalyst (DOC), to meet emission regulations. However, as the emission regulations become stricter, the size of the after-treatment systems become larger. This aggravates the price competitiveness of engine systems and causes fuel efficiency to deteriorate due to the increased exhaust pressure. Dual-fuel premixed charge compression ignition (DF-PCCI) combustion, which is one of the advanced combustion technologies, makes it possible to reduce nitrogen oxides (NOx) and particulate matter (PM) during the combustion process, while keeping the combustion phase controllability as a conventional diesel combustion (CDC). However, DF-PCCI combustion produces high amounts of hydrocarbon (HC) and carbon monoxide (CO) emissions due to the bulk quenching phenomenon under low load conditions as a huddle of commercialization. In this study, the effects of exhaust gas recirculation (EGR) rate and EGR temperature were investigated to overcome the bulk quenching phenomenon under low load conditions in the DF-PCCI combustion. Natural gas (NG) and diesel were selected for low reactivity…
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Near Nozzle Flow and Atomization Characteristics of Biodiesel Fuels

Indian Institute of Technology-Chetankumar Patel, Avinash Kumar Agarwal, Tarun Gupta
Korea Advanced Inst of Science & Tech-Joonsik Hwang, Choongsik Bae
Published 2017-10-08 by SAE International in United States
Fuel atomization and air-fuel mixing processes play a dominant role on engine performance and emission characteristics in a direct injection compression ignition engine. Understanding of microscopic spray characteristics is essential to predict combustion phenomena. The present work investigated near nozzle flow and atomization characteristics of biodiesel fuels in a constant volume chamber. Waste cooking oil, Jatropha, and Karanja biodiesels were applied and the results were compared with those of conventional diesel fuel. The tested fuels were injected by a solenoid injector with a common-rail injection system. A high-speed camera with a long distance microscopic lens was utilized to capture the near nozzle flow. Meanwhile, Sauter mean diameter (SMD) was measured by a phase Doppler particle analyzer to compare atomization characteristics. The experimental results showed that the biodiesels had poor macroscopic spray characteristics showing longer liquid tip penetration length and narrower spray angle than those of diesel. Based on microscopic imaging, biodiesels exhibited longer injection delay and resisted formation of ligaments compared to baseline diesel due to higher viscosity and surface tension. In addition, the estimation…
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Spray and Combustion of Diesel Fuel under Simulated Cold-Start Conditions at Various Ambient Temperatures

Korea Advanced Inst of Science & Tech-Hyunwook Park, Choongsik Bae
Korea Electric Power Research Institute-Jugon Shin
Published 2017-09-04 by SAE International in United States
The spray and combustion of diesel fuel were investigated to provide a better understanding of the evaporation and combustion process under the simulated cold-start condition of a diesel engine. The experiment was conducted in a constant volume combustion chamber and the engine cranking period was selected as the target ambient condition. Mie scattering and shadowgraph techniques were used to visualize the liquid- and vapor-phase of the fuel under evaporating non-combustion conditions (oxygen concentration=0%). In-chamber pressure and direct flame visualization were acquired for spray combustion conditions (oxygen concentration=21%). The fuel was injected at an injection pressure of 30 MPa, which is the typical pressure during the cranking period. The liquid length of the fuel at an ambient temperature of 573 K increased by about 14% compared to that at 663 K due to the lower ambient temperature and fuel temperature as well as the increased fuel density and viscosity from the lower fuel temperature. The vapor penetration of the fuel was also slightly increased at 573 K. However, the vapor phase area was reduced by about…
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Effect of Injector Nozzle Hole Geometry on Particulate Emissions in a Downsized Direct Injection Gasoline Engine

Hyundai Kefico Corporation-Jungho Lee, In Keun Seo, Sung Jae Kim
Hyundai Motor Company-Heechang Oh, JuHun Lee, Seungkook Han
Published 2017-09-04 by SAE International in United States
In this study, the effect of the nozzle tip geometry on the nozzle tip wetting and particulate emissions was investigated. Various designs for the injector nozzle hole were newly developed for this study, focusing on the step hole geometry to reduce the nozzle tip wetting. The laser induced fluorescence technique was applied to evaluate the fuel wetting on the nozzle tip. A vehicle test and an emissions measurement in a Chassi-Dynamo were performed to investigate the particulate emission characteristics for injector nozzle designs. In addition, the in-cylinder combustion light signal measurement by the optical fiber sensor was conducted to observe diffusion combustion behavior during the vehicle test. Results showed that the step hole surface area is strongly related to nozzle tip wetting and particulate emissions characteristics. Injectors without the step hole and with a smaller step hole geometry showed significant reduction of nozzle tip wetting and number of particulate emissions.
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Influence of the Injector Geometry at 250 MPa Injection in a Light-Duty Diesel Engine

Hyundai Motor Company-Youngho Kim
Korea Advanced Institute of Science and Technology-Seungwoo Kang, Wonkyu Cho, Choongsik Bae
Published 2017-03-28 by SAE International in United States
This paper investigated the influence of the injector nozzle geometry on fuel consumption and exhaust emission characteristics of a light-duty diesel engine with 250 MPa injection. The engine used for the experiment was the 0.4L single-cylinder compression ignition engine. The diesel fuel injection equipment was operated under 250MPa injection pressure. Three injectors with nozzle hole number of 8 to 10 were compared. As the nozzle number of the injector increased, the orifice diameter decreased 105 μm to 95 μm. The ignition delay was shorter with larger nozzle number and smaller orifice diameter. Without EGR, the particulate matter(PM) emission was lower with larger nozzle hole number. This result shows that the atomization of the fuel was improved with the smaller orifice diameter and the fuel spray area was kept same with larger nozzle number. However, the NOx-PM trade-offs of three injectors were similar at higher EGR rate and higher injection pressure. The effect of high injection pressure was dominant for reducing PM emissions, and the effect of nozzle geometry on the PM emissions wasn’t distinguishable at…
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An Experimental Investigation on Spray Characteristics of Waste Cooking Oil, Jatropha, and Karanja Biodiesels in a Constant Volume Combustion Chamber

Indian Institute of Technology - Kanpur-Chetankumar Patel, Avinash Kumar Agarwal, Tarun Gupta
Korea Advanced Inst of Science & Tech-Joonsik Hwang, Choongsik Bae
Published 2016-10-17 by SAE International in United States
In this study, macroscopic spray characteristics of Waste cooking oil (WCO), Jatropha oil, Karanja oil based biodiesels and baseline diesel were compared under simulated engine operating condition in a constant volume spray chamber (CVSC). The high pressure and high temperature ambient conditions of a typical diesel engine were simulated in the CVSC by performing pre-ignition before the fuel injection. The spray imaging was conducted under absence of oxygen in order to prevent the fuels from igniting. The ambient pressure and temperature for non-evaporating condition were 3 MPa and 300 K. Meanwhile, the spray tests were performed under the ambient pressure and temperature of 4.17 MPa and 804 K under evaporating condition. The fuels were injected by a common-rail injection system with injection pressure of 80 MPa. High speed Mie-scattering technique was employed to visualize the evaporating sprays. Liquid tip penetration length, spray cone angle and spray area were determined from captured images. The equivalence ratio along the axial direction of the spray was also calculated based on mathematical correlations. Results showed that biodiesels had longer…
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Effects of High-Response TiAl Turbine Wheel on Engine Performance under Transient Conditions

Korea Advanced Institute of Science and Technology-Jinyoung Jung, Chansoo Park, Choongsik Bae
Published 2015-09-01 by SAE International in United States
Transient tests in a 2.0 liter in-line 4 cylinder downsizing gasoline direct injection engine were conducted under various transient conditions in order to investigate effects of lower rotational inertia of titanium aluminide alloy (TiAl) turbine wheel on engine and turbocharger performances. As a representative result, fast boost pressure build up was achieved in case of TiAl turbocharger compared to Inconel turbocharger. This result was mainly due to lower rotational inertia of TiAl turbine wheel. Engine torque build up response was also improved with TiAl turbocharger even though engine torque response gap between both turbochargers was slightly reduced due to retarded combustion phase. In addition, with advanced ignition timing, fuel consumption became less than that of Inconel turbocharger with similar engine torque response.
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