• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.393-396
• /
• 2007

EGR is well established and efficient means to reduce NOx emissions. The increase of EGR rate affects the ignition delay of the combustion due to the lower oxygen availability. The increasing of the ignition delay period causes large combustion noise. In this study, the effects of EGR and Induction Point on combustion noise are investigated by measuring cylinder pressure and noise. As a result, The Combustion noise is markedly increased under the application of EGR. The increased premixed distance by displacing EGR Induction point in flow direction causes the uniform EGR distribution and the modulation level of the combustion noise is reduced slightly.

• Proceedings of the KAIS Fall Conference
• /
• 2009.12a
• /
• pp.534-537
• /
• 2009

최근 자동차 배기가스 규제가 더욱 강화됨에 따라 완전 연소를 통한 배기가스 저감에 관하여 많은 연구가 진행되고 있다. 특히, 고온 연소시 문제가 되는 질소 산화물의 저감을 위해 많은 노력을 기울이고 있다. 질소 산화물을 저감하는데 효과적인 EGR 기술의 도입이 보편화되고 있지만, 각 실린더별 EGR 분배 특성에 따라 엔진의 성능이 달라지는 역효과가 발생한다. 시제품을 동한 EGR 분배특성 파악은 비용과 시간 측면에서 상당한 난제가 산재해있다. 본 연구에서는 이러한 실험시간과 비용 절감을 위하여 1D 성능해석 프로그램인 GT-Power를 적용 EGR의 분배특성을 예측하였다.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.4
• /
• pp.7-14
• /
• 2003

Recently, LPG has been considered as more environmental friendly fuel than liquid fuels for vehicles. However because LPLi engine has the strong point that not only increases the volumetric efficiency and cold startability, but also decreases unburned hydrocarbon exhaust emission in warm-up condition, much attention has moved to development of the Liquid Phase LPG injection (LPLi) system from the mixer type LPG engine. To reduce exhaust NOx, this study investigated the effect of EGR with LPLi engine and determined optimized EGR feeding position and distribution. In addition, engine stability, performance, and exhaust emission level were evaluated.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.6
• /
• pp.98-104
• /
• 2010

An experimental investigation was conducted to analyze the effects of EGR ratio on the combustion, exhaust emissions characteristics and size distributions of particulate matter in a single cylinder diesel engine with common-rail injection system fueled with biodiesel derived from soybean. In order to analyze the combustion, exhaust emissions and measurement of size distributions of particulate matter were carried out under various EGR ratio which was varied from 20~60% and the results were compared to those of results without EGR. The experimental results show that ignition delay was extended and maximum value of rate of heat release (ROHR) was decreased according to increasing of EGR ratio. In addition, oxidies of nitrogen ($NO_x$) emissions were reduced but soot emissions were increased under increasing of EGR ratio. However, under higher EGR ratio region, soot was slightly decreased. And then the particulate size distribution shows that high exhaust gas temperature restrain the formation of soluble organic fraction (SOF) which were beyond the accumulation mode (100~300nm) and lead to increase of nuclei mode particles.

• Journal of the Korean Society of Combustion
• /
• v.20 no.2
• /
• pp.28-35
• /
• 2015

In this study, the CH4/air lean-rich combustion system with exhaust gas recirculation (EGR) was investigated to explore the potential for lowering pollutant emissions. To achieve this purpose, experiments of lean-rich combustion system with EGR were conducted to measure the changes in the characteristics of the pollutant emission and flame shape with various equivalence ratios and EGR rates. Here, this study was applied to the fuel distribution ratio of 3:1 for the formation of the lean and rich flames. Additionally, the results were compared with $CH_4$/air lean premixed combustion system. The results show that flame shape of lean-rich combustion system was determined by lean and rich equivalence ratios (${\Phi}_L$ and ${\Phi}_R$) and stratified flame was formed with increasing ${\Phi}_R$. According to the pollutant emission characteristics based on experimental results, the NOx and CO emission index (EINOx and EICO) decreased with increasing EGR rate. Especially, in the range needed to form a stable flame, the reduction rates of EINOx and EICO were approximately 47% and 48% for an EGR rate of 25%, global equivalence ratio of 0.85 and ${\Phi}_L$ of 0.80 compared with lean premixed combustion system (${\Phi}$ = 0.78).

• Journal of ILASS-Korea
• /
• v.22 no.4
• /
• pp.197-202
• /
• 2017

The objective of this study is to investigate the effects of low-temperature combustion (LTC) on the correlations of combustion characteristics and reduction of exhaust emissions in a small DI diesel engine with biodiesel fuel. In order to analyze the combustion, exhaust emission characteristics and distribution of nano size particles for biodiesel were investigated. In addition, to evaluate the effect of LTC on the combustion and emission characteristics, 30 and 50% of cooled-EGR rates were investigated. From these results, it revealed that the influence of LTC on the combustion characteristics showed that the ignition delay significantly increased and reduces peak heat release rate of premixed combustion by lowering reaction rate. With 50% EGR and advanced injection timing, soot and $NO_x$ emissions were simultaneously reduced.

• KDI Journal of Economic Policy
• /
• v.29 no.3
• /
• pp.1-28
• /
• 2007

Upon analyzing several Korean Income data sets, it is confirmed that the relationship between Gini coefficient and bi-polarization measure (EGR) is empirically not different although they each come from different theoretical basis. Furthermore, it is difficult to state that the degree of polarization of income distribution, measured by DER, in Korea has deepened more than that of income inequality, estimated by Gini coefficient, in the periods of before and after the economic crisis.

• Journal of Power System Engineering
• /
• v.22 no.6
• /
• pp.74-79
• /
• 2018

Compressed natural gas has a high octane number and low particulate emission characteristics as compared with petroleum-based fuels, so it can respond to exhaust gas regulations positively. A natural gas engine has been introduced to improve the quality of the atmosphere, a diversity of fuel, a stable supply, and it has widely been used in city buses and garbage trucks. Recently, the natural gas engine has received attention by overcoming the disadvantage of the theoretical air-fuel ratio method through the development of EGR cooler and engine parts with the development of LP-EGR technology. In this study, we try to develop the cogeneration system that can simultaneously generate electric power and heat by remodeling the gasoline engine to the mixer type CNG engine. As a result, it was able to reduce the NOx (approximately 77%) compared to the diesel engines with same displacement.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.11
• /
• pp.1509-1517
• /
• 2001

An experimental and numerical analysis were conducted to investigate the transient temperature distribution and flame propagation characteristics over an inline polystyrene spheres under microgravity. From the experimental, a self-ignition temperature of polystyrene bead was 872 K under gravity. Flame spread rates were 4.7-5.1 mm/s with ambient gas N$_2$and 2.3-2.5 mm/s with ambient gas CO$_2$, respectively. Flame radius diameters were 17 mm with ambient gas N$_2$and 9.6 mm with ambient gas CO$_2$, respectively. These results suggest that the flame propagation speed could be affected in the Diesel engine and the boiler combustor by EGR. In terms of the flame spread rate and the transient temperature profile, numerical results have the qualitative agreement with the experiment.

• Tribology and Lubricants
• /
• v.34 no.6
• /
• pp.292-299
• /
• 2018

The objective of this research is to investigate the impact of engine oil aging on PM(Particulate Matter), exhaust gases, and DPF. It is widely known that the specification of a lubricant and its consumption in an ICE considerably influences the release of regulated harmful emissions under normal engine operating conditions. Considering DPF clogging phenomena associated with lubricant-derived soot/ash components, a simulated aging mode is designed for DPF to facilitate engine dynamometer testing. A PM/ash accumulation cycle is developed by considering real-world engine operating conditions for the increment of engine oil consumption and natural DPF regeneration for ash accumulation. The test duration for DPF aging is approximately 300 h with high- and low-SAPs engine oils. Detailed engine lubricant properties of new and aged oils are analyzed to evaluate the effect of engine oil degradation on vehicle mileage. Furthermore, physical and chemical analyses are performed using X-CT, ICP, and TGA/DSC to quantify the engine oil contribution on the PM composition. This is achieved by sampling with various filters using specially designed PM sampling equipment. Using high SAPs engine oil causes more PM/ash accumulation compared with low SAPs engine oils and this could accelerate fouling of the EGR in the engine, which results in an increase in harmful exhaust gas emissions. These test results on engine lubricants under operating conditions will assist in the establishment of regulated and unregulated toxic emissions policies and lubricant quality standards.