• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.28-35
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• 2002

The objective of this paper is to quantitatively investigate the effects of alcohol mixture on the combustion improvement of main fuel in supplying alcohol to direct injection diesel engine by auxiliary injection method and blend method. If alcohol is supplied, engine performance greatly improves in high load range. In case of supplying ethanol, BSFC improves, the emission of smoke and NO decreases by delaying main fuel injection timing 5$\^{C}$A. The maximum delivery quantity of alcohol is limited to approximately 50% of total fuel delivery due to misfire and knocking. The limit quantity of main fuel injection that does not accompany misfire and the deterioration of BSFC was approximately 15∼18.5mg/st.

• Journal of the Korean Institute of Gas
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• v.17 no.1
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• pp.7-12
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• 2013

As emission regulation for vehicle has been reinforced, many researches carried out for HCNG(hydrogen-natural gas blends) fuel to the conventional compressed natural gas (CNG) engine. However, abnormal combustion such as backfire, pre-ignition or knocking can be caused due to high combustion speed of hydrogen and it can result in over heating of engine or reduction of thermal efficiency and power output. In the present study, improvement of combustion performance was observed with HCNG fuel since it can extend a flammability limit. Knocking characteristics for CNG and HCNG fuel were investigated. Feasibility of HCNG fuel was evaluated by checking the knock margin according to excess air ratio. The operation of engine with HCNG was stable at minimum advance for best torque(MBT) spark timing and knock phenomena were not detected. However, it is necessary to prepare higher knock tendency since possibility of knock is higher with HCNG fuel.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.9-16
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• 2006

Variable valve timing is one of the attractive ways to control homogeneous charge compression ignition (HCCI) engine. Hot internal residual gas which can be controlled by variable valve timing(VVT) device, makes fuel evaporated easily, and ignition timing advanced. Regular gasoline was used as main fuel and di-methyl ether(DME) was used as ignition promoter in this research. HCCI engine operating range is limited by high combustion peak pressure and engine noise. High combustion pressure can damage the engine during operation. To avoid engine damage, the rich limits have to define using various methods. Peak combustion pressure, rate of cylinder pressure rise was considered to determine rich limit of engine operating range. Knock probability was correlated with the rate of cylinder pressure rise as well as the peak combustion pressure.

• Journal of Energy Engineering
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• v.9 no.2
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• pp.83-88
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• 2000

In this study, the performance and pollutant emission of CNG engine using diesel oil as a source of ignition, so called CNG dual fuel diesel engine is considered by experiment. One of the unsolved problems of the natural gas dual fuel engine is that there is too much exhaust of total hydrocarbon (THC) at a low equivalent mixture ratio. To fix it, a natural gas mixed with hydrogen was applied to engine test. The results showed that the higher the mixture ratio of hydrogen to natural gas, the higher the combustion efficiency. and when the amount of the intake air is reached to 90% of WOT, the combustion efficiency was promoted. But, like a case making the injection timing earlier, the equivalent mixture ratio for the knocking limit decrease and the produce of NOx increases.

• Journal of ILASS-Korea
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• v.9 no.4
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• pp.9-16
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• 2004

A study of the propeny and performance effect of Indolene - Methanol Plus High Alcolhols (MPHA) has been completed. This study invested the measurement of fuel properties and performance parameters. The fuel properties investigated are distillation characteristics, heating valuer flash point, specific gravity and water tolerance. The performance parameters measured are minimum advance for best torque (MBT) spark timing, power output. The alcohol concentration was varied from 0 to 100 percent by volume in clear Indolene. The measurement of fuel properties indicated that, in general, Indolene - MPHA blends have higher water tolerance, similar specific gravity, similar flash point and different distillation characteristics compared to Indolene - Methanol blends. The performance parameters were measured using a single cylinder spark ignition engine at different compression ratios. The results of the performance measurements indicated that Indolene - MPHA blends have a higher MBT spark advance, similar power output.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.386-394
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• 1987

The method of methanol using in diesel engines hasn't been established yet because of it's low ignition characters. But many studies about it with many methods have been doing recently. If alcohol can be used in diesel engines, smoke and NO$\sub$x/, which is a big problem in diesel engines, can be reduced large. The purpose of this study is to establish using method of alcohol, as a substitute fuel. In this study, Combustion characters, engine performance and exhaust gas emissions are checked by using gasfication diesel method. Concluding remarks of this study are as follows. (1) Methanol can be used within 30% of total inducing energy, if above that rate, it can't be used because of knocking and bad operating condition. (2) Under the low load, the effect of methanol inducing of fuel consumption is somewhat bad, but under the high load, the effect is very good. (3) Under the high load, smoke limit is a marked improvement with methanol inducing.

• Journal of ILASS-Korea
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• v.28 no.2
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• pp.55-61
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• 2023

Natural gas is a high-octane fuel that is effective in controlling knocking combustion. In addition, as a low-carbon fuel with a high hydrogen-carbon ratio, it emits less carbon dioxide and almost no particulate matter compared to conventional fossil fuels. Stoichiometric combustion engines equipped with a three-way catalyst are useful in various fields such as transportation and power generation because of their excellent exhaust emission reduction performance. However, stoichiometric combustion engines have a disadvantage of lower thermal efficiency compared to lean combustion engines. In this study, a combination of high compression ratio and Atkinson cycle was implemented in a 11 liter, 6-cylinder, spark-ignition engine to improve the thermal efficiency of the stoichiometric engine. As a result, pumping and friction losses were reduced and the operating range was extended with optimized Atkinson camshaft. Based on the exhaust gas limit temperature of 730℃, the maximum load and thermal efficiency were improved to BMEP 0.66 MPa and BTE 35.7% respectively.