• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.8
• /
• pp.665-670
• /
• 2014

Because reducing atmospheric pollution is becoming a serious issue, studies are actively focusing on exhaust gas reduction. This study was conducted to determine the emission characteristics when applying an EGR system, the main approach used for NOx reduction, to an off-road mechanical diesel engine. For the application of the EGR system, the emission characteristics in consideration of the engine conditions were analyzed. The optimum EGR ratio for NOx emission reduction was determined by applying variable EGR conditions for each engine speed condition. Considering the above process, the emission characteristics of the modified EGR condition are compared with those of other conditions (non-EGR and existing EGR condition) in the NRTC mode. Consequently, NOx emission was reduced by around 42 compared with the non-EGR condition when using the modified EGR map.

• International Journal of Automotive Technology
• /
• v.8 no.2
• /
• pp.137-147
• /
• 2007

Homogenous Charge Compression Ignition (HCCI) combustion systems can be broadly divided for the process applied to 4-stroke and 2-stroke engines. The former process is often referred to as simply HCCI combustion and the latter process as Active Thermo-Atmosphere Combustion (ATAC). The region of stable engine operation tends to differ greatly between the two processes. In this study, it was shown that the HCCI combustion process of a 4-stroke engine, characterized by the occurrence of autoignition under a high compression ratio, a lean mixture and wide open throttle operation, could be simulated by operating a 2-stroke engine at a higher compression ratio. On that basis, a comparison was made of the combustion characteristics of high-compression-ratio HCCI combustion and ATAC, characterized as autoignited combustion in the presence of a large quantity of residual gas at a low compression ratio and part throttle. The results showed that one major difference between these two combustion processes was their different degrees of susceptibility to the occurrence of cool flame reactions. Compared with high-compression-ratio HCCI combustion, the ignition timing of ATAC tended not to change in relation to different fuel octane numbers. Furthermore, when internal EGR was applied to high-compression-ratio HCCI combustion, it resulted in combustion characteristics resembling ATAC. Specifically, as the internal EGR rate was increased, the ignition timing showed less change in relation to changes in the octane number and the region of stable engine operation also approached that of ATAC.

• 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).

• Environmental and Resource Economics Review
• /
• v.30 no.3
• /
• pp.471-501
• /
• 2021

We measure Environmental Efficiency (EE) based on CO₂ in four income groups from 1998 to 2018, using the Meta Stochastic Frontier Analysis method by Input Distance Function. Our results showed that economic growth and energy consumption would increase carbon dioxide emissions, and increasing labor and capital input will reduce it. Moreover, we compared Group Environmental Efficiency (GEE), Meta Environmental Efficiency (MEE), and Environmental Gap Ratio (EGR). The results showed that GEEs were be overestimated. Furthermore, the MEE showed a downward trend during this period. The lower-middle-income group had the highest EGR performance. High-income and upper-middle-income groups showed less efficiency in MEE and EGR. To improve environmental efficiency, we must reduce fossil fuels and find more scientific and technological ways to solve existing environmental problems as soon as possible.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.9
• /
• pp.1064-1069
• /
• 2014

The use of emulsified fuel and EGR (Exhaust gas recirculation) system are effective methods to reduce NOx emission from diesel engines. In general, it is considered that EGR method influences diesel engine combustion in three different ways: thermal, chemical and dilution effect. Among others, the thermal effect is related to the increase of specific heat capacity due to the presence of $CO_2$ and $H_2O$ in inlet air. Meanwhile, emulsified fuel method of utilizing latent heat of vaporization and miro-explosion has been recognized as an effective technique for reducing diesel engine emissions. In this paper, an author studied on combustion and emission characteristics by using emulsified fuel (EF, Light oil : 80% + Water : 20%) and EGR (30% EGR ratio) system. And the effect of fuel injection pattern control was investigated.

• Journal of ILASS-Korea
• /
• v.21 no.3
• /
• pp.130-136
• /
• 2016

NOx and PM are important air pollutants as vehicle management policy aspect. Medium-duty truck is the main source of the pollutants although the vehicle market share is only 3.5%. National emission portion of NOx and PM form the mobile sourece are 14% and 16% respectively. In this study it was investigated that characteristics of air pollutants emission on medium duty truck equipped with EGR and SCR system. Vehicle's test reflected driving cycle on the chassis dynamometer, and applied test cycle was WHVC(World Harmonized Vehicle Cycle) mode. The test cycle include three segments, represent urban, rural and motorway driving. Based on the test results NOx, PM, HC were less emitted form SCR vehicle than EGR vehicle. And CO was less emitted form EGR vehicle than SCR vehicle due to CO oxidation reaction on DPF surface. And most air pollutants reduced as average vehicle speed increased. Pollutants were less emitted on motorway section than urban and rural sections. But highly NOx emission on motorway section was verified according to increased EGR ratio on fast vehicle speed. HC and CO additional emission was identified as 68%, 58% respectively during SCR vehicle's cold engine start emission test. NOx additional emission was detected by 24% on SCR vehicle's condition of engine cold start while not detected on vehicle equipped with EGR. SCR vehicle's additional NOx emission was derived from low reaction temperature during engine cold start condition. medium-duty truck emission characteristics were investigated in this study and expected to used to improve air pollutants management policy of medium-duty truck equipped with SCR & EGR.

• Journal of Nutrition and Health
• /
• v.29 no.9
• /
• pp.1003-1012
• /
• 1996

We examined the relationship among riboflavin intake, work activity, erythrocyte glutathione reductase activity coefficient(EGR AC)and urinary riboflavin excretion. We also attempted to determine factors affecting seasonal riboflavin status of rural women. All information about nutrient intake, work activity and riboflavin biochemical status was repeatly collected in three seasons ; farming season(June), harvest season(October), nonfarming season(February). EGR AC was negatively correlated with riboflavin intake(P<0.005) and positively correlated with the duration(min) of farming activity(P<0.005) and the percentage of lean body mass(LBM) (%) representing long term physical activity(P<0.05) in harvestseason. Urinary riboflavin excretion was positively correlated with the ratio of riboflavin intake to 1,000kcal of energy expenditure (P<0.05) in farming season and negatively correlated with the duration(min) of farming activity (P<0.05) and crude nitrogen balance(P<0.005) in harvest season. It appeared that EGR AC seems to increase and urinary riboflavin excretion seems to decrease as work activity increase. Therefore work activity would be expected to deteriorate riboflavin status. Multiple regression analysis of variables showed that in general EGR AC was affected by riboflavin and energy intakes, energy expenditure, energy balance, the duration(min) of farming activity, LBM (%). Urinary riboflavin excretion was affected by riboflavin and protein intakes, LBM(kg) and crude nitrogen balance. Crude nitrogen balance affected urinary riboflavin excretion in all seasons. The result indicated that work activity as well as nutrient intake seemed to affect riboflavin status, especially EGR AC was affected preferentially be work activity in all seasons.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.7
• /
• pp.857-862
• /
• 2004

HCCI engines take advantage of high compression ratio and heat release rate, they exhibit high efficiency in compression ignition engines. HCCI engines also utilize a lean air/fuel ratio resulting in low emissions of NOx and particulate matter(PM). The objective of this research is to determine the effects of EGR rate on the combustion processes of HCCI. For this purpose, a 4-cylinder, compression ignition engine was converted into a HCCI engine, and a heating device was installed to raise the temperature of the intake air and also to make it more consistent. In addition, a pressure sensor was inserted into each of the cylinders to investigate the differences in characteristics among the cylinders.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.7
• /
• pp.84-89
• /
• 2014

Not only the emission regulation of on-road vehicle engine, but also emission regulation of off-road engine have been reinforced. It is the reason of wide application of emission reduction technology for off-road engines. In this study, optimization of engine parameters (Injector hole number, Injection timing and EGR rate) for reduction of NOx and smoke emissions were conducted by using the analysis of sensitivity and S/N ratio of Taguchi method(DOE). As results, this paper shows optimum value of the parameters for NOx and smoke emission reduction. From the result of reproducibility verification, it is final that the prediction value of NOx and smoke has the error of below 10%. Consequently, the method and results of this study will be used for quantitative reference to EGR control mapping in next study.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.4
• /
• pp.34-41
• /
• 2000

The purpose of this research was to investigate the effects of exhaust gas recirculation(EGR) with diesel particulate filter(DPF) on heavy duty diesel engine. The exhaust gas was recirculated to the intake manifold after the smoke was eliminated in the DPF, The major conclusions of this research are i)at each engine speed EGR ratio was able to 60% maximum ii) the amount of NOx emissions was decreased to 90% at high engine load and to more than 60% at low engine load and iii) the amout of NOx emissions was increased to five times according to the increase of engine load but the effect of EGR is more effective at high engine load.