• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.9-16
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• 2007

Since the liquid phase LPG injection(LPLI) system has an advantage of higher power and lower emission characteristics than the mixer type fuel supply system, many studies and applications have been conducted. However, the heat extraction, due to the evaporation of liquid fuel, causes not only a dropping of LPG fuel but also icing phenomenon that is a frost of moisture in the air around the nozzle tip. Because both lead to a difficulty in the control of accurate air fuel ratio, it can result in poor engine performance and a large amount of HC emissions. The experimental investigation was carried out on the bench test rig in this study. It was found that n-butane, that has a relatively high boiling point($-0.5^{\circ}C$), was a main species of droplet composition and also found that the droplet problem was improved by the use of a large inner to outer bore ratio nozzle whose surface roughness is smooth. The icing phenomena were decreased when the an engine head temperature was increased, although a large amount of icing deposit was still observed in the case of $87^{\circ}C$. Also, it was observed that the icing phenomenon is improved by using anti-icing bushing.

• Journal of ILASS-Korea
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• v.8 no.1
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1103-1106
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• 2005

The research and development for LPLI system to replace the conventional LPG fuel supply system has been processed with a view to enhancing the environmental status and the efficiency for LPG cars. Part of the small sized cars are under commercialization with the LPLI application already. And yet, most of the technologies are relied upon the advanced countries and as part of the application for large scaled engines, many researches are on the increase. This study shows the technology development to make use of LPLI system for those large engines and reviews the controllers, which were manipulated through experiments for their work, reliability and possibility for commercialization.

• Journal of Institute of Convergence Technology
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• v.3 no.1
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• pp.25-29
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• 2013

The purpose of this paper is to determine the fuel change and weight change impact on the fuel economy and emission characteristic of ICE (Internal Combustion Engine) vehicle. According to fuel type, fuel consumption and emission characteristics were measured and fuel used in this paper was gasoline, diesel, and LPG. Four vehicles with different weight were tested and the fuel economy were compared and analyzed by using scatter graph. Test was carried out using chassis dynamometer, CVS (Constant Volume Sampler), and emission measurement system. Diesel vehicle less emited $CO_2$ compared to gasoline and LPG. Even if same $CO_2$ between gasoline and LPG, there are difference fuel economy depending on carbon proportion of specific fuel. The heavier weight of vehicle, the worse of fuel economy and Better fuel economy performance on highway driving mode.

• Journal of the Korean Institute of Gas
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• v.19 no.4
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• pp.22-28
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• 2015

In order to keep the competitiveness of LPG fuel for transportation fuel, the difference in fuel consumption with gasoline and cost for an aftertreatment system should be reduced with continuous development of technology for LPG engine. In the present study, spray-guided type direct injection combustion system, whose configuration is composed of direct injector in the vicinity of spark plug, was employed to realize stable lean combustion. A certain level of nitrogen oxides($NO_x$) emits due to a locally rich mixture regions in the stratified mixture. With the application of EGR system for the reduction of $NO_x$, 15% of $NO_x$ reduction was achieved whereas fuel consumption and hydrocarbon emission increased. By the application of EGR, the combustion speed reduced especially appeared at initial flame development period and peak heat release rates and increasing rates for heat release rate decreased as EGR rate increased due to the dilution effect of intake air.

• Journal of ILASS-Korea
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• v.12 no.1
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• pp.38-44
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• 2007

Since the Liquid Phase LPG injection (LPLI) system has Advantages in power generation and emission characteristics compared to the mixer-type fuel-supply system, a variety of studies regarding LPLi system has been conducted and its applications are made in automobile industry. However, the heat extraction due to the evaporation of liquid fuel, causes not only a post-accumulation of fuel but also an icing phenomenon which is a frost of moisture in the air around the nozzle tip. Since there exists a difficulty in the accurate control of air fuel ratio in both fuel supply systems, it can result in poor engine performance and a large amount of harmful emissions. This research examines the characteristics of icing phenomenon and develops anti-icing bushing to prevent an icing on the surface of the injection tip. It was found that n-butane, which has a relatively high boiling point ($-0.5^{\circ}C$), was a main species of post-accumulation. Also the results show that the post-accumulation problem was allevaited the utilization of a large inner to outer bore ratio and smooth surface roughness. In addition, an icing phenomenon and its formation process were found to be mainly affected by the humidity and the temperature of inlet air in an inlet duct. Also, it was observed that an icing phenomenon is lessened using aluminum bushing whose end coincides with the end of fuel injection tip in length.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.963-970
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• 1987

It has been a long time that black smoke emitted from buses and trucks powered with diesel engines, especially city-buses, came to be a serious air pollution problems in large cities as Seoul and Pusan. Therefore, proper means to reduce black smoke from diesel engines have to be considered as soon as possible, because it will take quite a long time to replace major passenger transportation system in cites from city-buses to subway. This paper, as a study on the reduction of diesel black smoke, showes how the black smoke of diesel engines can be reduced at various loads and engine speed by supplying small amount of gaseous fuel as LPG into the intake manifold. Thermal efficiency has been also considered for users, and confirmed through the engine test.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.6
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• pp.607-614
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• 2013

Nowadays, automotive manufacturers have developed various technologies to improve fuel economy and reduce harmful emissions. The ultra-lean direct injection engine is a promising technology because it has the advantage of improving thermal efficiency through the deliberate control of fuel and ignition. This study aims to investigate the development of a spray-guided-type lean-burn LPG direct injection engine through the redesign of the combustion system. This engine uses a central-injection-type cylinder head in which the injector is installed adjacent to the spark plug. Fuel consumption and combustion stability were estimated depending on the ignition timing and injection timing at various air-fuel ratios. The optimal injection timing and ignition timing were based on the best fuel consumption and combustion stability.

• Journal of ILASS-Korea
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• v.14 no.4
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• pp.184-189
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• 2009

Recently, ultrafine particles emitted from internal combustion engine is main concern because of its well known adverse health effects. So Europe decided to start the regulation about diesel engine particle number emissions. The nanoparticles smaller than 50nm in diameter have the ability to penetrate deep into interstitial tissue of luge, where they may cause severe respiratory inflammation and acute pulmonary toxicity. Recent studies have showed that spark ignition engines emit particles number concentration comparable to those from diesel engines with DPF under high load and rich mixture conditions, including cold starts and acceleration. So this study investigated emission characteristics of ultrafine particles according to fuel injection type in gasoline vehicles and LPG vehicles. The test vehicles were tested on CVS-75 and NEDC vehicle test mode using the chassis dynamometer, CPC system applied as a particle measuring instrument at the end of dilution tunnel. As a result, the correlation between fuel injection type and particulate emission was determined. GDI vehicle emitted 10 times higher particles than PFI vehicles, and compared to Mixer and LPGI type LPG vehicle, LPLI vehicle emitted particles high.

• Journal of ILASS-Korea
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• v.12 no.4
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• pp.204-210
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• 2007

The worldwide energy problem and global warming cause the need of alternative fuels which feature low carbon-dioxide emission and another energy source. Liquefied Petroleum Gas (LPG) is one of the alternative fuels widely used as domestic and transportational fuel. The third generation LPLi fuel supply system has merits in the increase of engine power and low emissions. The injectors used in LPLi system should overcome a leakage problem and satisfy the durability conditions. Therefore, 1000 hour durability test of the injectors was carried out throughout this research. First, the spray pattern and the penetration length of the selected injectors is graphically shown. Next, the leakage amount with respect to the injection cycle is introduced. Finally, the shapes of nozzle holder and nozzle tip after durability test was investigated by analyzing the microscopic image of the injector tip. The variation in the shape of nozzle tip mainly due to the residue of rubber materials is found to be the reason for leakage.