• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.39-44
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• 2004

As air pollution has become an important issue across the world, studies of clean fuel are on going to reduce combustion emissions. One example is development of the LPLi(Liquefied Phase LPG injection) engine. Some problems are occurred during development. One of the problems is icing phenomenon at injector tip due to evaporation potential heat when liquid LPG is injected. If the Icing is raised at injector tip or injector inserting hole, it disturbs fuel injection. And if the ice particles are inducted into cylinder, it brings problems associated with control of emission and air/fuel ratio. In order to solve the problems, a rig system was set up and observed Icing of injector tip. Engine test was carried out for visualization of injector tip icing and its effects on combustion and emissions.

• International Journal of Automotive Technology
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• v.6 no.3
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• pp.215-219
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• 2005

Liquefied petroleum gas (LPG) has been used as motor fuel due to its low emissions and low cost. A liquid direct injection system into a cylinder was suggested as a next generation system to maximize a fuel economy as well as a power. This study addresses the analysis of the LPG spray injecting from single hole injector. Two different test conditions are given, which are a fully developed spray case with various injection pressures and a developing spray case with ambient pressure variation. The LPG spray photographs are compared with the sprays of gasoline and diesel fuel at the same conditions, and the spray angles and penetration lengths are also compared, and then the spray behavior is analyzed. The LPG spray photos show that the dispersion characteristic depends very sensitively on the ambient pressure soon after injection. The spray angle is very wide in a low ambient pressure condition until the saturated pressure, but the angle is quickly reduced at the condition over the pressure. However, the down stream of the LPG spray shows much wider dispersion and less penetration than those of gasoline and diesel sprays regardless ambient pressure condition.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.77-85
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• 2000

LPG gains many advantages of a high octane number low emissions and low cost over conventional fuel. The fuel has been naturally used in engines to save running cost but the first generation fuel feeding system was not satisfied with stringent requirement for exhaust emissions, A liquid direct injection system into a cylinder has been suggested as a next generation system to maximize a fuel economy as well as to reduce emissions. In this paper LPG sprays are compared with diesel sprays in a high pressured surrounding condition in order to understand the high pressure spray characteristics, The spray images show that LPG spray penetrates further soon after the injection then the sprays stays in a distant. it may explain the flashing effect of LPG.

• Journal of the Korean Society of Combustion
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• v.4 no.2
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• pp.43-50
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• 1999

Liquefied petroleum gas (LPG) has been used as motor fuel due to its low emissions and low cost. The fuel feeding system has been improved with stringent requirement for exhaust emissions. LPG carburetion system was first introduced, then the system has been changed to a precisely controlled gas injection system, but this gas feeding system has a limitation on improving power output. In order to improve an engine performance, a multi-point port injection system was introduced recently, and a liquid direct injection system into a cylinder was suggested as a next generation system to maximize a fuel economy as well as a power. This study addresses the analysis of the LPG spray from diesel injectors. The spray images are visualized and compared with diesel sprays in a wide injection pressure range. The photographs show much wider dispersion of LPG sprays.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.7-14
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• 2003

Exhaust Gas Recirculation (EGR) system is used to reduce NOx emission, to improve fuel economy, and to suppress knock since it offers the benefits of the inlet charge dilution. The effects of EGR was investigated on the performance and emission to reduce exhaust thermal load with a single cylinder liquid-phase LPG injection engine, in a wide range of EGR rate, engine conditions and LPG proportions. As EGR rate was increased, NOx was reduced while HC was increased. Pumping loss reduction by EGR improved bsfc and increased EGR lowered exhaust gas temperature. And, LPG proportions were made a difference on the performance and emission characteristics.

• International Journal of Automotive Technology
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• v.6 no.2
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• pp.133-139
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• 2005

In this study, a three-dimensional transient simulation with a knock model was performed to predict knock occurrence and autoignition site in a heavy-duty LPG engine. A FAE (Flame Area Evolutoin) premixed combustion model was applied to simulate flame propagation. The coefficient of the reduced kinetic model was adjusted to LPG fuel and used to simulate autoignition in the unburned gas region. Engine experiments using a single-cylinder research engine were performed to calibrate the reduced kinetic model and to verify the results of the modeling. A pressure transducer and a head-gasket type ion-probe circuit board were installed in order to detect knock occurrences, flame arrival angles, and autoignition sites. Knock occurrence and position were compared for different piston bowl shapes. The simulation concurred with engine experimental data regarding the cylinder pressure, flame arrival angle, knock occurrence, and autoignition site. Furthermore, it provided much information about in-cylinder phenomena and solutions that might help reducing the knocking tendency. The knock simulation model presented in this paper can be used for a development tool of engine design.

• Journal of the Korean Institute of Gas
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• v.11 no.1 s.34
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• pp.23-28
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• 2007

This paper presents an experimental investigation on the sealing defects and cracks of O-rings and a valve packing of a gas valve for a LPG cylinder. O-ring in which stops a gas leakage of a liquefied petroleum gas is very important for a LPG valve safety. Valve packing is to open and close a gas flow port for supplying and charging a LPG fuel. The sealing performance of two sealing units ism related to the leak safety and long lift of a gas valve. The investigated results show that most of O-rings was failed due to a circumferential crack in which is caused by partial press bonding failure near the partition zone and an excess compression rate. Some of the O-ring failure was originated by an extrusion of an excessive leak pressure of a LP gas. Thus, this paper strongly recommends a tight quality control and a safety guarantee system of O-rings and valve packing to guarantee a leak safety and to extend a service lift of a gas valve. At the end, a warranty policy of the sealing units should be adopted for increasing a product quality and safety of a gas valve.

• Journal of the Korean Institute of Gas
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• v.7 no.2 s.19
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• pp.33-41
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• 2003

There exists high hazard when transporting LPG as well as using, storing, and producing. For small scale LPG consumer, retailers deliver LPG to customers via a truck loading many LPG cylinders. Suppose there occurred a accident during LPG cylinder transfer, this could result in serious damages to the life and properties in the near or neighbor of the accident spot. In this regard, we made a quantitative risk analysis to estimate the possible damages and the probability through the identification of accidents causes and the simulation of the possible scenario. In this study, we made the Excel & Visual Basic computer program to perform quantitative LPG accident analysis. The simulation showed the following results. In case of UVCE(Unconfined Vapor Cloud Explosion), the effect within l0m of the accident spot showed very severe structural damages and even the accident can break the window glasses of the area of 150 m apart from accident spot. In case of TNT corresponding probit analysis, after 10 minutes LPG leaking, $75\%$ window glasses of 40 m distance was expected to be broken. And $16\%$ frames of 20m distance, $10\%$ frames of 40m distance was expected to be collapsed.

• 한국가스학회:학술대회논문집
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• 2006.11a
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• pp.81-89
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• 2006

• 한국가스학회:학술대회논문집
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• 2006.11a
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• pp.49-54
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• 2006