• Journal of Biosystems Engineering
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• v.35 no.4
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• pp.239-243
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• 2010

Biodiesel (BD) can be effectively used as an alternative fuel in diesel engines. However, BD may affect the performance and exhaust emissions in diesel engines because it has different physical and chemical properties from diesel fuel such as viscosity, compressibility and so on. To investigate the effect of injection timing on the characteristics of engine performance and exhaust emissions with BD in an indirect injection diesel engine, BD derived from soybean oil was applied in this study. The engine was operated at six different injection timings from TDC to BTDC $12^{\circ}CA$ and five loads at various engine speeds. Below BD 30, there's similar trend compared with diesel fuel. But, the best injection timing was $4{\sim}6^{\circ}CA$ retarded compare with diesel fuel using BD 30. When the fuel injection timing was retarded, better results were showed, which may confirm by advantages of BD.

• Journal of Power System Engineering
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• v.19 no.3
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• pp.22-28
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• 2015

A compression ignition type of diesel engine makes fuel efficiency better and $CO_2$ in the exhaust gas lower. Also it is suitable to apply alternative fuels(blended fuel) to the engine. The objective of this study is the emissions reduction of diesel engine with EF(Emulsified fuel). The emulsified fuel consists of diesel and peroxide($H_2O_2$) and Soot reduction without worsening of NOx emissions can be achieved by using thermal decomposition of the peroxide, i.e. the chemical effect of the OH radical in actual engine. For manufacturing emulsified fuel, a surfactant which is comprised of span 80 and tween 80 mixed as 9:1, was mixed with a fixed with 3% of the total volume in the emulsion fuel. In addition, considering the mixing ratio of the surfactant, the mixing ratio of $H_2O_2$ in the emulsified fuel was set as EF0, EF2, EF12, EF22, EF32, and EF42, respectively. Consequently, this study aims to obtain the optimization of fuel design(mixing) for the emulsified fuel applying to the diesel engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.54-66
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• 2000

A gasoline direct injection single cylinder engine has been developed to study operational characteristics for highly stratified conditions. Parameters related to design and experiment were also studied to understand the characteristics of combustion and emissions at some part load conditions. It was found that optimal timings between the end of fuel injection and spark ignition were existed for stable combustion under the stratified modes, In a low engine speed, fuel spray behavior around piston bowl was important for stable combustion. The in-cylinder air motion affecting fuel spray behavior was found to be a dominant factor at higher engine speed as fuel injection timing had to be advanced to secure enough time for fuel evaporation and mixing with surrounding air. As swirl ratio increased, spark timing could be advanced for stable combustion and a higher compression ratio could be used for improved fuel consumption and stable combustion at the stratified mode. It was also observed that electrode geometry and piston bowl shape played an important role for combustion and emission characteristics and some results were shown for comparison.

• Journal of ILASS-Korea
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• v.17 no.3
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• pp.134-139
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• 2012

The main purpose of this study is to analyze and compare the nano-particle emission characteristics by 3-different biodiesel blending rates in a CI engine. Nano-particle number density emitted from various operating conditions of compression ignition engine can be investigated by using the PPS (Pegasor Particle Sensor) system. Namely, some particle charged through the corona discharge in real-time can be measured by PPS system. Under the steady state operation of the 2.0L CRDi diesel engine with different operating condition and biodiesel blending rates, the nano-particle number density was analyzed at the downstream position of DOC system. As this research result, more engine load speed and higher the concentration of biodiesel blending rate showed that the nano-particle number density decreases. Also we found that DOC system for clean diesel engine is effectively useful instrument to reduce diesel particulate matter as resource of nano-particle generation.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.313-316
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• 2012

In this study, the combustion and emission characteristics of waste cooking oil biodiesel was investigated. The fuel was injected from 5 CAD (Crank angle degree) ATDC (After top dead center) to -60 CAD ATDC by 5 CAD with 800 bar and 1600 bar injection pressure. Generally, the hydrocarbon, carbon monoxide and smoke emissions from biodiesel fuel were lower than the emission levels of diesel fuel. However, the emission characteristic of biodiesel got worse than diesel when the fuel was injected earlier than -30 CAD ATDC. $NO_x$ emission from biodeisel was higher than diesel fuel in all experimental conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.11
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• pp.878-883
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• 2008

The spray characteristics of a high pressure 6-hole injector were examined in a single cylinder optical direct injection spark ignition (DISI) engine. The effects of injection timing, in-cylinder charge motion, fuel injection pressure and coolant temperature were investigated using the 2-dimensional Mie scattering technique. It was confirmed that the in-cylinder charge motion played a major role in the fuel spray distribution during the induction stroke while the propagation of fuel spray was restrained during the compression stroke by the increasing pressure and the upward moving piston. In additions, it was confirmed that the liquid fuel droplets existing at the sprays edges were vaporized by the increase of the coolant temperature.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.12
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• pp.945-952
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• 2015

The autoignition characteristics of biosyngas were investigated both numerically and experimentally. The effects of the temperature, gas composition, and pressure on the autoignition characteristics were evaluated. A shock tube was employed to measure the ignition delay times of the biosyngas. The numerical study on the ignition delay time was performed using the CHEMKIN-PRO software to validate the experimental results and predict the chemical species in the combustion process. The results revealed that the ignition delay time increased with an increase in the hydrogen fraction in the mixture. Under most temperature conditions, the ignition delay time decreased with a pressure increase. However, the ignition delay time increased with an increase in pressure under relatively low temperature conditions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.501-511
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• 2014

Bio-oil derived from biomass through fast pyrolysis process has the potential to displace a significant amount of petroleum fuels. However, the use of bio-oil in a diesel engine is very limited because of its poor properties, e.g., its low energy density, low cetane number, and high viscosity. Therefore, bio-oil should be emulsified or blended with other fuels that have high centane numbers. Because bio-oil has poor miscibility with petroleum fuels, the most suitable candidate fuels for direct mixing are alcohol fuels. In this study, bio-oil was blended with ethanol, and two types of cetane improvers were added to a blended fuel to improve the self-ignition property. The two types of cetane improvers, PEG 400 and 2-EHN, made it possible for bio-oil blended fuels to combust in a diesel engine with a maximum bio-oil content of 15 wt%. A high-compression-ratio piston is also proposed for the combustion of bio-oil in a diesel engine.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1401-1406
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• 2004

In this paper, we present the theoretical and numerical results of scavenge characteristics in a small prechamber of an HCCI(Homogeneous Charge Compression Ignition) engine. Two theoretical models are proposed in prediction of the scavenge time and the efficiency ; one is the non-mixing models in which it is assumed that the input gas($CH_{4}$) and the existing gas(air) do not mix with each other, and the other is the fully-mixed model in which the two gases are assumed to mix completely before ejecting to the ambient air. Focus is also given to the effect on the scavenge performance of the size of the chamber oulet.

• Journal of Power System Engineering
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• v.15 no.1
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• pp.5-10
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• 2011

The spatial fuel vapor distribution of the homogeneous charge by a 6-hole injector was examined in a optically accessed single cylinder direct injection spark ignition(DISI) engine. The effects of in-cylinder charge motion, and fuel injection pressure, and coolant temperature were investigated using a planar LIF (Laser Induced Fluorescence) technique. It was confirmed that the in-cylinder tumble flow played a little more effective role in the spatial fuel vapor distribution than the swirl flow during the compression stroke at 10 mm and 2 mm planes under cylinder head gasket and the increased fuel injection pressure activated spatial distributions of the fuel vapor. In additions, richer mixtures were concentrated around the cylinder wall by the increase of the coolant temperature.