• Journal of ILASS-Korea
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• v.23 no.3
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• pp.136-148
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• 2018

Major countries have tighten their NOx regulation of diesel passenger cars. In the case of the EU, the regulation has been toughen up to 6.25 times since 2000. Despite the regulation the NOx concentration of the ambient has not been reduced proportionally. As these issues, to reduce NOx emission practically, Korea and the EU introduced the real-world driving emission (RDE) regulation and the test method that will be applied after 2017. In this paper, for the regulation to make a soft landing in Korea, 6 diesel passenger cars which met Euro 6a~6d regulation and were equipped with LNT/SCR were tested at a chassis dynamometer with environmental chamber applying the off-cycles (FTP, US06, SC03, HWFET and CADC) and several ambient conditions (-7 and $14^{\circ}C$) as well as certification modes (NEDC, WLTC@ $23^{\circ}C$). The result of the test showed that the ambient temp. and the engine load as a test mode impacted the NOx emission of the cars while the vehicles with SCR emitted NOx lower than with LNT. Additionally, to propose an effective RDE test method, the above result was compared with the results of the other papers which tested RDE using the same cars.

• Journal of Power System Engineering
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• v.7 no.4
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• pp.12-18
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• 2003

Various measures have been tried to reduce the NOx emission from diesel engine, but with partial success because the mechanisms of NOx and PM formations appear to have trade-off relation between each other. Therefore it has been known to be difficult to reduce NOx emission and PM emission simultaneously. Two stage combustion method i,e. a combustion process which has rich combustion stage and lean combustion stage one by one, has been developed successfully to reduce NOx formation in the continuous combustion chambers such as in the boilers. But until yet it is not successful to apply the same method in intermittent combustion chamber like in the diesel engine cylinder, as it was, only several research works were carried out. In this study, devised was a uniquely shaped combustion chamber with reformed piston crown intended to keep fuel-rich condition during early stage of combustion and fuel-lean condition during next stage. It was found that the NOx emission decreased significantly at various conditions of operation with the two stage combustion type engines of PR20 type, but other values such as smoke, CO and specific fuel consumption deteriorated as usual.

• Journal of Energy Engineering
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• v.18 no.3
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• pp.163-168
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• 2009

This paper describes the homogeneous charge compression ignition (HCCI) engine for a new concept. HCCI engines are being considered as a future alternative for diesel and gasoline engines. HCCI engines have the potential for high indicated thermal efficiency under part load and very low NOx emissions. The objective of this paper is to clear the effects of exhaust gas recirculation (EGR) rate on the HCCI. For this purpose, a 4-cylinder, compression ignition engine was converted into a HCCI engine This work has been run with propane and butane fuels at a constant speed.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.73-83
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• 2014

CFD(computational fluid dynamics) model is developed to simulate direct injection of ammonia gas phase from ammonia transporting materials into the SCR catalyst in the exhaust pipe of the engine with solid SCR. Configurations of one-hole and four-hole nozzle, circumferential type, porous tube type, and the effect of mixer configurations which commonly used in liquid injection of AdBlue are considered for complex geometries. Mal-distribution index related to concentration of ammonia gas, flow uniformity index related to velocity distribution, and pressure drop related to flow resistance are compared for different configurations of complex geometries at the front section of SCR catalyst. These results are used to design the injection system of ammonia gas phase for solid SCR of target vehicle.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.308-315
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• 2013

Water emulsion technology has the problem of unstable combustion due to the rapid separation of water. To solve the problem, a hybrid mixing device was developed. The device attached on the burner was tested. As a result, the fuel consumption reduced to 12% in the similar condition of exhaust emissions and flame temperature, and 45.5%, 98.5% and 97.2% of NOx, CO, and smoke were reduced at the same inlet air and fuel flow rate.

• Journal of ILASS-Korea
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• v.17 no.2
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• pp.71-76
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• 2012

The aim of this work was to investigate the combustion and nanoparticle emission characteristics of premixed charge compression ignition (PCCI) combustion at various test conditions using a single cylinder common-rail diesel engine. In order to create the homogeneity of fuel-air mixture, the premixed fuel (gasoline) was injected into premixing chamber during the intake process and then the diesel fuel was directly injected into the combustion chamber as an ignition source for the gasoline premixture. From these results, it revealed that the ignition delays and combustion durations were gradually prolonged and the peak combustion pressure were increased because diesel fuel was injected early injection timing with the increase of premixed ratio. In addition, as the increase of premixed ratio, total particle number is generally decreased and particle volume also indicated low levels at the direct injection timing from BTDC $20^{\circ}$ to TDC. At further advanced injection timing, total particle number and volume were generally increased

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.4 s.247
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• pp.358-363
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• 2006

In this study, the effects of oxygenated fuel such as ethylene glycol mono-normal butyl ether(EGBE) was investigated both DI and IDI diesel engine. Because EGBE includes oxygen content approximately 27.1 %, it is a kind of oxygenated fuel that the smoke emission of EGBE blending fuel is reduced remarkably compared with commercial diesel fuel. The focus of this study was to investigate the effects of the addition of oxygenated fuel to diesel fuel on the engine-out emissions and the performance. Smoke emissions of all EGBE blends were reduced substantially in comparison with conventional diesel fuel. This study showed that remarkable reduction of smoke with oxygenate blending fuels in diesel engines including DI and IDI combustion method. Besides, this study showed that simultaneous reduction of smoke and NOx emissions could be achieved by oxygenated fuel and EGR method that was applied to decrease NOx emissions increasing with smoke emissions reduction.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.6
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• pp.896-902
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• 2009

EGR is applied in order to lower temperature of combustion chamber by using the specific heat of carbon dioxide in engine exhaust gas. However, the problem of EGR system in diesel engine is high PM concentration. Combined EGR system can be reduced it by mixing exhaust gas of gas engine into the intake air of diesel engine. This experimental study was designed for EGR system for both engines use. The results of EGR experimental study by using diesel engine and gas engine are as follows. 1) The pressure of combustion and rate of heat release decreased. 2) The specific fuel consumption increased. But, up to middle load, it little increased. 3) NO concentration has decreased up to 50% in almost all combustion area. 4) The variation of the PM concentration at low load is not so seen. But at high load, PM increased rapidly when concentration of oxygen is decreased and most of it caused the increasing of Dry Soot.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.16-23
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• 2011

Low temperature combustion is one of the advanced combustion technology in an internal combustion engine to reduce soot and nitrogen oxides simultaneously. In present experiment three kinds of injector were used to investigate the influence of injection angle and number of nozzle holes on the low temperature combustion in a heavy duty diesel engine. Low temperature diesel combustion is realized from the exhaust gas recirculation rate of 60%. Indicated mean effective pressure of low temperature combustion corresponds to the 70% level of conventional diesel engine combustion. Reduction of hydrocarbon and carbon monoxide, which are produced in low temperature combustion because of the low combustion temperature and a deficit of oxygen, was achieved by using various injector configuration. The result of experiment with $100^{\circ}$ injection angle and 8 holes showed that reductions in hydrocarbon and carbon monoxide could be achieved 58% and 27% respectively maintaining the 7% increased indicated mean effective pressure in low temperature diesel combustion compared with conventional injector.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.692-698
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• 2020

This paper examines the effects of a multi-stage pilot split injection strategy on combustion and exhaust emission factors in a single-cylinder diesel engine. One analysis noted that in the single-injection condition, the maximum in-cylinder pressure and rate of heat release were highest. The pilot injection quantity was evenly divided, showing a tendency to decrease as the number of injections increased. In another injection condition, when the multi-stage pilot split injection strategy was applied, IMEP, engine torque, and combustion increased. The COV_IMEP was greatest with the lowest combustion efficiency. The combustion ability was poor. In a single injection condition, the O₂ concentration in the exhaust gas was the lowest and the CO₂ was the highest. When the multi-stage split injection strategy was applied, the low temperature combustion process proceeded, and the oxidation rate of CO₂ decreased while the emission level increased. In a single injection condition in which a locally rich mixture was formed, the HC emission level showed the highest results. A 55.6% reduction of NOx emission occurred under a three-stage pilot injection condition while conducting a multi-stage pilot split injection strategy.