• 한국자동차공학회논문집
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• 제4권4호
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• pp.140-146
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• 1996

A large portion(above 70%) fo the hydrocorbon and NOx emissions for a typical vehicle occur mainly before the conventional underbody catalyst reaches activation temperature. To meet the stringent regulation as EC stage 2, the emissions produced during this period must be reduced. One of alternative techniques is to place CCC(Close-Coupled Catalyst) near the exhaust manifold. In this study, the characteristics of CCC are observed through EEC mode.

• 대한기계학회논문집B
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• 제27권7호
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• pp.837-844
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• 2003

The exhaust gas flow in the inlet collector of close coupled catalyst(CCC) adapted to the exhaust manifold is very complex flow because the exhaust gas is a pulsation flow with several port flow. The distribution of gas flow and temperature in inlet collector effect to the efficiency of catalytic converter. In this study, it measures temperatures on several point in inlet collector with two kind of inlet collector volume. And it analyzes with CFD to exhaust manifold and close coupled catalyst for temperature and flow. Comparing to measured and analyzed result, it find increasing of collector volume effects to catalyst temperature distribution and uniformity of catalytic converter

• International Journal of Automotive Technology
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• 제6권5호
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• pp.445-451
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• 2005

Most of the pollutants from passenger cars are emitted during the cold-transient phase of the FTP-75 test. In order to reduce the exhaust emissions during the cold-transient period, it is essential to warm up the catalyst as fast as possible after the engine starts, and the Unburned Exhaust Gas Ignition (UEGI) technology was developed through our previous studies to help close-coupled catalytic converters (CCC) reach the light-off temperature within a few seconds after cold-start. The UEGI system operates by igniting the unburned exhaust mixture by glow plugs installed upstream of the catalyst. The flame generates a high amount of heat, and if the heat is concentrated on a specific area of monolith surface, then thermal crack or failure of the monolith could occur. Therefore, it is very important to monitor the temperature distribution in the CCC during the UEGI operation, so the local temperatures in the monolith were measured using thermocouples. Experimental results showed that the temperature of CCC rises faster with the UEGI technology, and the CCC reaches the light-off temperature earlier than the baseline case. Under the conditions tested, the light-off time of the baseline case was 62 seconds, compared with 33 seconds for the UEGI case. The peak temperature is well under the thermal melting condition, and temperature distribution is not so severe as to consider thermal stress. It is noted that the UEGI technology is an effective method to warm up the catalyst with a small amount of thermal stress during the cold start period.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.335-340
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• 2000

Most vehicle's exhaust emissions come from the cold transient period of the FTP-75 test. In this study, UEGI technology was developed to help close-coupled catalytic converter (CCC) reach light-off temperature within a few seconds after cold-start. In the UEGI system, unburned exhaust mixture is ignited by four glow plugs installed upstream of the catalyst. Experimental results showed that the temperature of CCC rises faster with the UEGI technology, and the CCC reaches light-off temperature earlier. Under the conditions tested, the light-off time of the baseline case was 62 seconds and that of the UEGI case was 33 seconds.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.9-16
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• 2004

Close-coupled catalyst (CCC) can reduce the engine cold-start emissions by utilizing the energy in the exhaust gas. However, in case the engine is operated at high engine speed and load condition, the catalytic converter may be damaged and eventually deactivated by thermal aging. Excess fuel is sometimes supplied intentionally to lower the exhaust gas temperature avoiding the thermal aging. This sacrifices the fuel economy and exhaust emissions. This paper describes the results of an exhaust heat exchanger to lower the exhaust gas temperature mainly under high load conditions. The heat exchanger was installed between the exhaust manifold and the inlet of close-coupled catalytic converter. The exhaust heat exchanger successfully decreased the exhaust gas temperature, which eliminated the requirement of fuel enrichment under high load conditions. However, the cooling of the exhaust gas through the heat exchanger may cause the deterioration of exhaust emissions at cold start due to the increment of catalyst light-off time.

• International Journal of Automotive Technology
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• 제8권5호
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• pp.575-581
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• 2007

As current and future automobile emission regulations become more stringent, the research on flow distribution for an exhaust manifold and close-coupled catalyst(CCC) has become an interesting and remarkable subjects. The design of a CCC and exhaust manifold is a formidable task due to the complexity of the flow distribution caused by the pulsating flows from piston motion and engine combustion. Transient flow at the exhaust manifold can be analyzed with various computational fluid dynamics(CFD) tools. However, the results of such simulations must be verified with appropriate experimental data from real engine operating condition. In this study, an experimental approach was performed to investigate the flow distribution of exhaust gases for conventional cast types and stainless steel bending types of a four-cylinder engine. The pressure distribution of each exhaust sub-component was measured using a simulated dynamic flow bench and five-hole pitot probe. Moreover, using the results of the pitot tube measurement at the exit of the CCC, the flow distribution for two types of manifolds(cast type and bending type) was compared in terms of flow uniformity. Based on these experimental techniques, this study can be highly applicable to the design and optimization of exhaust for the better use of catalytic converters to meet the PZEV emission regulation.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 춘계학술대회 논문집(Proceeding of the KOSME 2000 Spring Annual Meeting)
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• pp.52-59
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• 2000

Experimental studies were performed to improve the THC emission characteristics by optimizing the flow in the exhaust manifold and CCC in a SI engine. For this purpose the flow characteristics in the exhaust manifold and CCC were measured by using LDV technique under various engine conditions, Referring to these data a new type exhaust manifold was designed to improve the cold-start emission characteristics and the response characteristics of {{{{ OMICRON _2}}}} sensor by optimizing the flow pattern and reducing the thermal inertia of the exhaust manifold system. It was found through the vehicle emission tests that the emission characteristics of THC of the new type exhaust manifold was improved by 12% through the optimizing the flow pattern in the exhaust manifold.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.39-47
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• 2003

UEGI (Unburned Exhaust Gas Ignition) is an alternative method for fast light-off of a catalyst. It ignites the unburned exhaust mixture using two glow plugs installed in the upstream of the close-coupled catalysts. In addition, a hydrocarbon adsorber was applied to the UEGI, for more effective reduction of HC emission. Engine bench tests show that the CCC reaches the light-off temperature laster than the baseline exhaust system and HC and CO emissions are reduced significantly during the cold start. From the vehicle test, it was observed that a few amount of HC emission was reduced even the catalysts were aged. It is expected to develop a solution kit applicable to a new vehicle or used one, to meet the emission regulation

• Journal of Advanced Marine Engineering and Technology
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• 제24권5호
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• pp.111-118
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• 2000

Experimental studies were performed to understand the flow characteristics in the exhaust system and improve the THC emission characteristics by optimizing the flow in the exhaust manifold and CCC in a SI engine. For this purpose, the flow characteristics in the exhaust systems with two types of exhaust manifolds(STD and New Type) were measured by using LDV technique under various engine condition. It was found that the flow characteristics in the New Type exhaust manifold was more desirable in a view point of heat loss reduction from the exhaust gases. The vehicle emission tests showed that the THC emission in the New Type exhaust manifold was decreased by 12%.

• 한국자동차공학회논문집
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• 제10권3호
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• pp.61-69
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• 2002

To meet stringent LEV and ULEV emission standards, a considerable amount of development work was necessary to ensure suitable efficiency and durability of catalyst systems. The main challenge is to cut off the engine cold-start emissions. It is known that up to 80% of the total hydrocarbons(THC) are exhausted within the first five minutes in case of US FTP 75 cycle. Close-Coupled Catalyst(CCC) provides fast light-off temperature by utilizing the energy in the exhaust gas. However, if some malfunction occurred at engine operation and the catalyst temperature exceeds 1050$\^{C}$, the catalytic converter is deactivated and shows the poor conversion efficiency. This paper presents effEcts of engine operating conditions on catalytic converter temperature in a SI engine, which are the indications of catalytic deactivation. Exhaust gas temperature and catalyst temperature were measured as a function of air/fuel ratio, ignition timing and misfire rates. Additionally, light-off time was measured to investigate the effect of operating conditions. It was found that ignition retard and misfire can result in the deactivation of the catalytic converter, which eventually leads the drastic thermal aging of the converter. Significant reduction in light-off time can be achieved with proper control of ignition retard and misfire, which can reduce cold-start HC emissions as well.