• 한국자동차공학회논문집
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• 제13권4호
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• pp.90-96
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• 2005

The improvement of combustion stability is very important because it is closely related to the exhaust emission concentrations as well as the fuel consumption during the cold start of SI engine. In our previous studies, the spark and exhaust valve timings were retarded individually from the baseline case to increase the exhaust gas temperature far fast warmup of a close-coupled catalyst. In the study, it was found that combustion stability during cold start becomes worse when the valve timing is retarded from the baseline conditions. The spark and valve timings were simultaneously changed from the baseline conditions to find out the variation of combustion stability during cold start of an Sl engine. Through the study. retarded spark timing by $5^{\circ}$ CA helps improvement of $COV_{imep}$ by $2\%$ and $15^{\circ}C$ increase of exhaust temperature. Retarded exhaust valve timing makes the exhaust gas temperature increase by $30^{\circ}C$, but it also deteriorates the $COV_{imep}$ by $1\%$.

• Journal of Advanced Marine Engineering and Technology
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• 제40권5호
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• pp.429-436
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• 2016

Currently, many studies on green ships are under way. Fuel cell (FC) ships are of interest as future low-emission, fuel-efficient vessels. In this paper, a hybrid power management system for an FC ship was designed. The system consists of an FC, a battery, a unidirectional DC/DC converter, a bidirectional DC/DC converter, a filter, an inverter, and a propulsion component. To design the system, we analyze electric sources and converters, and create PLECS models of hybrid power management system. Then, we check the cold start sequence and perform a simulation to understand the characteristics of the hybrid power management system in an FC ship.

• 한국자동차공학회논문집
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• 제9권6호
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• pp.24-29
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• 2001

Adaptive valve timing control is one of the promising techniques to accomplish the optimized mixture formation and combustion depending on the load and speed, which is needed to meet the future challenges in reducing fuel consumption and exhaust emissions. The behavior and the effect of adaptive valve timing control system has been investigated by computer simulation, which simulates the gas dynamics in engines. Improved fuel economy can be achieved by reduction of pumping loss under low and mid load conditions. EIVC(Early Intake Valve Closing) strategy turns out to be superior to LIVC(Late Intake Valve Closing) strategy in reducing fuel consumption. Deterioration of combustion quality can be overcome by introducing LIVO(Late Intake Valve Opening) strategy, which increases turbulent intensity in cylinders. Furthermore, LIVO can reduce HC emission by decreasing the required amount of fuel to be injected during cold start.

• 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.

• 한국분무공학회지
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• 제28권3호
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• pp.150-155
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• 2023

Cold-start emissions are given great importance under the Euro-7 emission standard due to their significant impact on overall vehicle emissions. When an engine is started from a cold state, the combustion process is not yet optimized, leading to higher emissions. Hybrid vehicles, in particular, may face additional challenges, as their engine may remain inactive for extended periods, causing their catalysts to cool down and potentially become less effective in reducing emissions. In the present study, the performance of an electric heater was investigated as a means to enhance the catalyst heating during the start-up time. A simulation tool was utilized to develop a model for the gasoline exhaust aftertreatment system. The result indicates that the heater was able to increase the three-way catalyst temperature to 500℃ in 4 s using 20 kW power. In addition, the implementation of a secondary air supply resulted in reduced temperature overshoot and improved conversion efficiencies.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.150-155
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• 2000

Exhaust emissions from vehicles are the main source of air pollution. Many researchers are trying to find the way of reducing vehicle emissions, especially in the cold transient period of the FTP-75 test. In this study, UEGI (Unburned Exhaust Gas Ignition) technology, warming up the close-coupled catalytic converter (CCC) by igniting the unburned exhaust mixture using two glow plugs installed in the upstream of the catalyst, was developed. It was applied to an exhaust system with a hydrocarbon adsorber to ensure an effective reduction of HC emission during the cold start period. Results showed that the CCC reaches the light-off temperature (LOT) in a shorter time compared with the baseline exhaust system, and HC and CO emissions are reduced significantly during the cold start.

• 한국분무공학회지
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• 제22권4호
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• pp.185-189
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• 2017

In Korea, sales of passenger cars using diesel and LPG fuels were continuously increased in recent years. From now on 2030, the registrated vehicles will close in about twenty five million in Korea. From these reason, Investigation on the comparison of exhaust emission characteristics of passenger cars using LPG and Diesel fuel in variation of driving mode and ambient conditions were conducted in this study. Exhaust emission characteristics of test vehicles were measured and analyzed by using chassis dynamometer and emission analyzer. Also, test vehicles were selected on the diesel vehicle with 1.7L engine and LPG vehicle with 2.0L engine. In order to study on emission characteristics according to driving cycles, CVS-75, NEDC, US06, SC03, Cold-FTP and HWFET were applied and the test conditions were set up the cases of A/C on and hot start. From these results, it is revealed that the NOx emission of diesel vehicle was higher than that of LPG vehicle and the case of CO emission shows the opposite patterns. In the HC emission, the emission increasing patterns not showed but the NOx emission of diesel vehicle and CO emission of LPG vehicle were showed the variation patterns according to the various driving modes.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3317-3322
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• 2007

THC(Total Hydrocarbon) emissions during cold start and warm-up phase constitute the majority of THC emissions during the FTP-75 mode. As the basic approach to improve the emission performance of Gasoline engine during transient phase, the effect of spark timing retard from MBT on THC emission characteristics is studied by engine test using a Fast response Flame Ionization Detector(FFID). A cyclic analysis of the combustion process shows that high THC emissions are produced first few cycles during the transient phase. This paper presents the results of engine performance and emission of Gasoline engine with various spark timing. consequently, This paper was focused on the combustion phenomena with various spark timing during transient phase which was analyzed by Fast response Flame Ionization Detector (FFID) equipment to measure the cyclic THC emission characteristics.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.3079-3084
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• 2008

A fast response $CO_2$ analyzer has been developed for measuring the $CO_2$ concentration during transient condition of SI engine. The analyzer is based on the non-dispersive infrared absorption technique, electrical chopping system and water cooling system. The analyzer has good repeatability, linearity and permissible drift characteristic. Besides, it has 18ms with a response to measure the $CO_2$ concentration. The fast response $CO_2$ analyzer was applied to single cylinder SI engine and the $CO_2$ emission was examined during engine start. Simultaneously, the standard exhaust gas analyzer, which has slow response time, was used for considering the engine-out $CO_2$ characteristic. The developed analyzer showed much faster responsive characteristic than that of a standard analyzer and made cycle by cycle exhaust gas analysis possible. The transient engine operating characteristics will be estimated and the transient behaviors on engine-out emission and performance will be improved.

• 오토저널
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• 제14권6호
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• pp.67-73
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• 1992

This paper describes Hyundai's research and development work on a flexible fuel vehicle (FFV). The work on FFV has been conducted to evaluate its potential as an alternative to the conventional gasoline vehicle. Hyundai FFV described here can be operated on M85, gasoline, or any of their combinations, in which the methanol concentration is measured by an electrostatic type fuel sensor. For that operation, a special FFV ECU(Eletronic Control Unit) has been developed and incorporated in the FFV. The characteristics affecting FFV operation, such as FFV ECU control strategy and injector flow rate, have been investigated and optimized through the experiment. And various development tests have been performed in view of engine performance, durability, cold startability, and exhaust emissions reduction. The exhaust gas aftertreatment system consisting of manifold type catalyst and secondary air injection system shows good emission reduction performance including formaldehyde, and finally, the possibility of the FFVs as the low emission vehicles is evaluated by presenting NMOG(Non-Methane Organic Gases) levels with respect to M0 and M85. With these results, it is concluded that FFV can be a candidate for the low emission vehicles, but more works on its durability improvement is required.