• Journal of Environmental Science International
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• v.21 no.7
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• pp.769-778
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• 2012

Diesel DeNOx experiments using the SNCR process were performed by directly injecting NH3 into a simulated engine cylinder (966 $cm^3$) for which a diesel fuelled combustion-driven flow reactor was designed by simulating diesel engine geometry, temperature profiles, aerodynamics and combustion products. A wide range of air/fuel mixtures (A/F=20~45) were combusted for oxidizing diesel flue gas conditions where an initial NOx levels were 250~900 ppm and molar ratios (${\beta}=NH_3/NOx$) ranged from 0.5~2.0 for NOx reduction tests. Effective NOx reduction occurred over a temperature range of 1100~1350 K at cylinder injections where about 34% NOx reduction was achieved with ${\beta}$=1.5 and cylinder cooling at optimum flow conditions. The effects of simulated engine cylinder and exhaust parts, initial NOx levels, molar ratios and engine speeds on NOx reduction potential are discussed following temperature gradients and diesel engine environments. A staged injection by $NH_3$ and diesel fuel additive is tested for further NOx reduction, and more discussed for practical implication.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.193-199
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• 2002

According to the NOx level requirement of annex Vl to IMO(International Maritime Organization) MARPOL 73/78, this regulation shall apply to each diesel engine with a power output of more than 130 ㎾ which is installed on a ship constructed and undergoes a major conversion on or after 1 January 2000. It is inevitable to adopt IMO standard for marine engines. Therefore, most of diesel engines which are being currently built should be tested and surveyed in accordance with the NOx technical code. In this study, various technics of NOx reduction methods were investigated for the diesel engines and the methods of NOx measuring were introduced by the new and simplified field detecting equipment. These results can be utilized for the basic design and developement of diesel engine for NOx reduction.

• Environmental Engineering Research
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• v.11 no.3
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• pp.149-155
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• 2006

NOx reduction experiments were conducted by direct injection of urea into a diesel fueled, combustion-driven flow reactor which simulated a single engine cylinder ($966cm^3$). NOx reduction tests were carried out over a wide range of air/fuel ratios (A/F=20-40) using an initial NOx level of 530ppm, and for normalized stoichiometric ratios of reductant to NOx (NSR) of 1.5 to 4.0. The results show that effective NOx reduction with urea occurred over an injection temperature range of 1100 to 1350K. NOx reduction increased with increasing NSR values, and about a 40%-60% reduction of NOx was achieved with NSR=1.5-4.0. Most of the NOx reduction occurred within the cylinder and head section (residence time <40msec), since temperatures in the exhaust pipe were too low for additional NOx reduction. Relatively low NOx reduction is believed to be due to the existence of higher levels of CO and unburned hydrocarbons (UHC)inside the cylinder, and large temperature drops along the reactor. Injection of secondary combustible additives (diesel fuel/$C_2H_6$) into the exhaust pipe promoted further substantial NOx reduction (5%-30%) without shifting the temperature windows. Diesel fuel was found to enhance NOx reduction more than $C_2H_6$, and finally practical implications are further discussed.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.3
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• pp.373-380
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• 2003

According to the NOx regulations of annex Vi to IMO MARPOL 73/78, all diesel engines with a power output of more than 130 kW should be delivered so as to comply with the IMO speed dependent NOx limit. It is inevitable to adopt this regulations for marine engines Therefore, most of diesel engines which are being currently built should be designed and tested in accordance with the NOx technical code In this study, NOx concentrations of 4 type engines were measured with portable NOx measuring system recommended by ISO-8178. As the results NOx concentrations of each engine by variation of engine speed and engine load were visualized Also these results can be utilized for the basic design and development of diesel engine for NOx reduction.

• Journal of Power System Engineering
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• v.17 no.6
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• pp.149-155
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• 2013

Since bio-diesel oil has a merit that it satisfies both demand of substitution for fossil fuel and reduction in carbon dioxide emission, it is widely used in diesel engines by blending in gas oil in small quantity. It is needed to reduce in NOx emission in some way or others if blending ratio of bio-diesel oil is going to increase, because it is demerit that bio-diesel oil emits more NOx emission than gas oil. In this study, it was accomplished to optimize 3 factors what effect on NOx emission as blending ratio of bio-diesel oil, injection timing and common rail pressure with an introduction of a design of experiments, in order to minimize a number of tests. It was cleared that to introduce the design of experiments was very available in NOx optimization.

• Journal of Environmental Science International
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• v.27 no.10
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• pp.809-820
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• 2018

DeNOx experiments for the effects of hydrocarbon additives on diesel SNCR process were conducted under oxidizing diesel exhaust conditions. A diesel-fueled combustion system was set up to simulate the actual cylinder and head, exhaust pipe and combustion products, where the reducing agent $NH_3$ and $C_2H_6/diesel$ fuel additives were separately or simultaneously injected into the exhaust pipe, used as the SNCR flow reactor. A wide range of air/fuel ratios (A/F=20~40) were maintained, based on engine speeds where an initial NOx level was 530 ppm and the molar ratios (${\beta}=NH_3/NOx$) ranged between 1.0~2.0, together with adjusting the amounts of hydrocarbon additives. Temperature windows were normally formed in the range of 1200~1350K, which were shifted downwards by 50~100K with injecting $C_2H_6/diesel$ fuel additives. About 50~68% NOx reduction was possible with the above molar ratios (${\beta}$) at the optimum flow #1 ($T_{in}=1260K$). Injecting a small amount of $C_2H_6$ or diesel fuel (${\gamma}=hydrocarbon/NOx$) gave the promising results, particularly in the lower exhaust temperatures, by contributing to the sufficient production of active radicals ($OH/O/HO_2/H$) for NOx reduction. Unfortunately, the addition of hydrocarbons increased the concentrations of byproducts such as CO, UHC, $N_2O$ and $NO_2$, and their emission levels are discussed. Among them, Injecting diesel fuel together with the primary reductant seems to be more encouraging for practical reason and could be suggested as an alternative SNCR DeNOx strategy under diesel exhaust systems, following further optimization of chemicals used for lower emission levels of byproducts.

• Journal of ILASS-Korea
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• v.2 no.1
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• pp.29-35
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• 1997

Many technologies have been developed to improve diesel emissions or performance, however NOx/PM trade-off occurs because normal methods that reduce NOx emissions tend to increase PM emissions. On the other hand many measures used to control PM emissions tend to increase NOx emissions. Thus, simultaneously controlling both NOx and PM emissions has become a significant challenge for diesel engine manufacturers. As one of the measures, the technology using emulsified fuel has recently become important under the stringent emission regulations of diesel engines. This paper investigates injection characteristics of emulsified fuel and its effect on a combustion performance in a diesel engine. In order to supply emulsified fuel into injection system a mixing unit produced by Harrier is used, then the fuel mixed with water is supplied into injector directly. The spray injected is investigated with a shadowgraph photo system and injection analyzing apparatus, then applied into a diesel engine. Those results showed that the emulsified fuel has an effect on reducing both NOx and PM.

• Journal of ILASS-Korea
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• v.21 no.4
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• pp.207-213
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• 2016

To protect air pollution of urban area from motor vehicles, emission limits for diesel vehicles have been dramatically lowered in short period. But recent studies have shown that on-road NOx emissions of light-duty diesel vehicles are considerably higher than the values measured with laboratory test procedures used for emission certification. To tackle with this issue, Ministry of Environment have a plan to introduce EU RDE-LDV (Real-driving Emission-Light-duty Vehicle) regulation. In this study, 4 Euro 6 diesel vehicles have been tested with the new test procedures published by EU to estimate on-road NOx emissions using PEMS (Portable Emission Measurement System). The results have shown that the requirements of EU RDE-LDV could be met in driving condition of metropolitan area for constitution of test routes and validity of test results. In analysing with Moving Averaging Window method the completeness and normality of test data were validated with the requirement. On-road NOx emissions were quite deviated as test vehicles and higher than the new limit of on-road NOx emission enforced from Sept. 2017, which means that RDE-LDV can effectively reduce NOx emission of diesel vehicles in real driving conditions of Korea.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.12
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• pp.952-960
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• 2009

Selective Catalytic Reduction (SCR) system is a high-effective NOx reduction technology in diesel engines. As the emission standard of diesel engines is more stringent, vehicle manufactures makes efforts on emission technologies. This paper discusses the performance of Urea-SCR system according to the engine operating conditions in a passenger diesel engine. Engine test results in this paper show that it is important to consider the catalyst temperature and space velocity to obtain high NOx conversion efficiency. In condition of high catalyst temperature, over 90% NOx conversion efficiency is indicated. However, when catalyst temperature is low, NOx conversion efficiency was decreased. Also, it was shown that space velocity mainly effects on the DeNOx performance under 220 degree celsius of SCR catalyst temperature. As the urea injection pressure was decreased, NOx conversion efficiency was declined. It is concerned about urea droplet atomization. This work shown in this paper can lead to improved overall NOx conversion efficiency.

• Journal of Biosystems Engineering
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• v.24 no.6
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• pp.465-472
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• 1999

To remove nitrogen oxides(NOx) in exhaust gas of diesel engine, three-way catalytic process with plasma discharger has great possibilities. Characteristics of NOx removal depends on NO conversion to NO$_2$and/or HNO$_3$due to high activation energies for NO oxidation and reduction. NOx removal efficiency by using three-way catalytic with plasma discharger indicated about 50% at 40watt power consumption condition.