• 에너지공학
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• 제21권4호
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• pp.378-384
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• 2012

Higher compression ratio is required in diesel engine to ignite the fuel that leads to better efficiency. For complete combustion inside the cylinder it is important to ensure the clean air flow with free of debris and as cool as possible. In this manner, modification of intake valve arrangements is taken in to consideration importantly. In this paper, the intake valve arrangements are modified with newly designed valve mixer. It causes swirl flow of air through the intake port that mixing with the fuel followed by complete combustion. The use of valve mixer reduces the carbon sediment formation on valve fillet and its face area as the carbon particles gradually take place on it after certain running period. It therefore, helps to increase the valve lifetime. And at the same time it reduces the exhaust elements i.e. soot from the automobiles to a significant level.

• 한국소음진동공학회논문집
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• 제17권3호
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• pp.213-219
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• 2007

Column mixer Is one of the facilities to mix fluids at petrochemical plants. The vibration of column mixer is usually caused by pumps for fluid inflow and mixing of inside fluids. This fluid induced nitration is mainly responsible for the reduction of column life. Measurements were performed for understanding the vibration characteristics of the column. First measurement results showed the need of stiffness reinforcement. After the reinforcement work, second measurement confirmed the difference between two results. Modal analysis was also performed to investigate the resonance of the column vibration and the damage of the rib plate. To confirm fluid induced vibration at the column mixer fluid structure interaction analysis using ADINA/FSI was performed, which showed the necessity of the modification of the rotary valve.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.916-921
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• 2006

Column mixer is one of the facility to mix fluids at petrochemical plants. The column vibration is caused by pumps for fluid inflow and mixing of inside fluids. This fluid induced vibration is mainly responsible for the reduction of column life. Measurements were performed three times for understanding the vibration characteristics of the column. First experimental results showed the need of stiffness reinforcement. After the reinforcement work, second measurement conformed the difference between two results. Modal analysis was also performed to investigate the resonance of the column vibration and the damage of the rib plate. To confirm the generation of the fluid instability in the column mixer fluid structure interaction analysis using ADINA/FSI was performed which showed the necessity of the modification of the rotary valve.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2009년도 추계학술대회
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• pp.223-229
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• 2009

The engine backfire leading to the damage to the intake system is observed in the mixer-type LPG engines. The hot spot flowing back into the intake manifold from the engine cylinder during the valve overlap period is known to give rise to the backfire. This backfire is known to be the main cause of the abrupt stop of the vehicle leading to the accidents on the streets. In this study, the cylinder pressure buildup at the later stage of combustion due to the prolonged burning is presumed to be the main cause of the backflow leading to the backfire. This is experimentally observed by creating the engine misfire using the ill-conditioned ignition systems.

• 한국자동차공학회논문집
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• 제21권2호
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• pp.146-153
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• 2013

CNG buses has contributed to improve air quality in cities. But it is difficult to meet the next emission regulations such as EURO-VI without the help of additional post-processing device. Hydorgen has higher flame speed and lower combustion temperature that make it thermal efficiency increase with leaner operation. Using hydrogen natural gas blend (HCNG) fuel is promising technology which can reduce $NO_x$ and $CO_2$ emissions for a natural gas vehicle. However, fuel flow rate of HCNG should be increased since hydrogen's energy density per volume is much smaller than natural gas. In the present study, the characteristics of fuel supply system and its applicability were evaluated in a heavy duty natural gas engine. The results showed that the potential of fuel pressure regulator and fuel metering valve had enough capacity with HCNG. Employed mixer did not affect the distribution characteristics of mixture.

• 한국분무공학회지
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• 제8권1호
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• pp.9-15
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• 2003

The liquid phase LPG injection (LPLI) system is considered as one of the next generation fuel supply systems for LPG, vehicles, since it can accomplish the higher power, higher efficiency, and lower emission characteristics than the existing mixer type fuel supply system. However, during the injection of liquid LPG fuel into the inlet duct of an engine, a large quantity of heat is extracted due to evaporation of fuel. A problem is that the moisture in the air freezes around the outlet of a nozzle, which is called icing Phenomenon. It may cause damage to the outlet nozzle of an injector. The frozen ice deposit detached from the nozzle also may cause a considerable damage to the inlet valve or valve seat. In this work, the experimental investigation of the icing phenomenon was carried out. The results showed that the icing phenomenon and process were mainly affected by humidity of inlet air instead of the air temperature in the inlet duct. Also, it was observed that the icing occurs first in the inlet of a nozzle, and grows considerably at the upper part of the nozzle inlet and the opposite side of the nozzle entrance. An LPG fuel, mainly consisting of butane, has lower latent heat of vaporization than that of propane, which is an advantage in controlling the icing phenomenon.

• Journal of Advanced Marine Engineering and Technology
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• 제21권4호
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• pp.356-363
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• 1997

Many research works have been carried out to investigate the factors governing the performance of diesel engine. The area of the study has been focused on reducing both of NOx and smoke because of many difficulties to reduce them simultaneously in diesel engines. One of the efforts is an application of EGR technology to reduce NOx emission, which is very effective, but increases other emissions and makes fuel economy worse. In order to solve the problem, EGR is employed with water emulsified fuel and tested in this paper. Emulsified fuel is produced by centrifugal mixer and the amount of water is controlled by water injector and pulse generator, and EGR rate is controlled with 6-step control valve. The chamber pressure, fuel consumption and emissions are measured with various values of both EGR and water mixing rate, The results show that NOx emission is reduced much rather and smoke is also reduced simultaneously.

• 한국분무공학회지
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• 제8권2호
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• pp.1-6
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• 2003

The liquid phase LPG injection (LPLI) system (the third generation technology) has been considered as one of the next generation fuel supply systems for LPG vehicles, since it has a very strong potential to accomplish the higher power, higher efficiency, and lower emission characteristics than the mixer type(the second generation technology) fuel supply system However. when a liquid LPG fuel is injected into the inlet duct of an engine, a large quantity of heat is extracted due to evaporation of fuel. This leads to freezing of the moisture in the air around the outlet of a nozzle, which is called icing phenomenon. It may cause damage to the outlet nozzle of an injector or inlet valve seat. In this work, the experimental investigation of the icing phenomenon was carried out The results showed that the icing phenomenon and process were mainly affected by humidity of inlet air instead of air temperature in the inlet duel. Also, it was observed that the total ice formed around the nozzle weighs at about $150mg{\sim}260mg$ after injection for ten minutes. And some fuel species were found in the ice attached at the front side of a nozzle, while frozen ice attached at the back of a nozzle was mostly' consisted of moisture of inlet air. Therefore, some frozen ice deposit. detached from front nozzle of an injector, may cause a problem of unfavorable air fuel ratio control in the small LPLI engine.

• 대한기계학회논문집B
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• 제36권3호
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• pp.343-350
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• 2012

본 연구에서는 외부 개질기에 열원을 공급하기 위한 시스템 내에 가용한 열에너지의 활용 및 확보에 대한 해석을 위해서 외부 개질기를 연계한 평판형 SOFC 시스템의 해석 모델을 구축하고자 한다. 이러한 해석을 위한 모델 구축을 위해 Matlab simulink$^{(R)}$ 기반의 ThermoLib module을 사용하였으며, 구축된 해석 모델을 통하여 시스템의 성능 향상을 위한 구성 기법에 대해서 연구를 하였다. 시스템 구성 방법은 기존 시스템의 layout을 바꾸기 위해 공기극 출구가스 재순환 및 외부개질기와 촉매연소기를 통합한 개질반응시스템 적용, 개질기에 공급되는 혼합연료의 예열, 연료극 출구가스의 응축을 통한 연료 농도 향상 등을 고려하였다. 시뮬레이션의 해석 결과에서는 SOFC 시스템에 있어서 일반 연소기를 적용한 기준 시스템에 비하여 촉매 연소기를 사용한 시스템의 전기 효율이 12.13% 향상되었으며, 연료극 출구 가스를 응축시켜 버너로 연소시킨 시스템에서는 열효율이 76.12%로 가장 높았다.