• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.11a
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• pp.23-29
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• 1999

Experimental studies are conducted to investigate the flame stability and the thermal/fuel NOx formation characteristics of the low calorific value (LCV) coal derived gas fuel. Synthetic LCV fuel gas is produced by mixing carbon monoxide, hydrogen, nitrogen and ammonia on the basis that the thermal input of the syngas fuel into a burner is identical to that of natural gas. The syngas mixture is fed to and burnt with air on flat flame burner. With the variation of the equivalence ratio for specific syngas fuel, flame behaviors are observed to identify the flame instability due to blow-off or flashback and to define stable combustion range. Measurements of NOx content in combustion gas are made for comparing thermal and fuel NOx from the LCV syngas combustion with those of the natural gas one. In addition, the nitrogen dilution of the LCV syngas is preliminarily attempted as a NOx reduction technique, and its effects on thermal and fuel NOx production are discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.11-17
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• 1996

Many researches on natural gas engines, with lean mixtures are being conducted for the purpose of preservation of global environment. Lean combustion is one of the most promising method for increasing engine efficiency and reducing the emission from SI engines. Due to the possibility of partial burn and misfire, however, under lean burn operation, stable flame kernel formation and fast burn rate, by use of swirl or tumble flow, are needed to guarantee a successful subsequent combustion. Experimental data were obtained on a 4-stroke, natural gas fueled SI engine to investigate the effect of compression ratio, swirl and spark plug electrode rotation on efficiency and emission under lean burn condition. Experimental results have displayed that higher compression ratio, presence of swirl vane and favorable direction of electrode gap brougth about the improvements in engine efficiency and its operational stability.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.413-419
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• 2007

Experimental study of additives on the ignition performance of a compression ignition natural gas engine is introduced, followed by results of a simulation of its working mechanism. From the experimental results, it is understood that engine ignition performance can be improved when a certain amount of Di-tertiary-butyl peroxide additive is added. If the mass fraction of Di-tertiary-butyl peroxide additive reaches as high as 14.2%, engine ignition can be realized at ambient temperatures with a glow plug temperature of about $750^{\circ}C$. From the simulation results, we verify that the Di-tertiary-butyl peroxide additive, by cracking its radicals at lower temperature, can accelerate reaction rate. Therefore, the additive is able to improve the ignition performance of natural gas significantly.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3270-3275
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• 2007

DME (Dimethyl Ether, $CH_3OCH_3$) has highly attracted attention as an alternative fuel for transportation, power generation and LPG substitute owing to its easy transportation and cleanliness. This study was conducted to verify the combustion performance and to identify potential problems when DME is fuelled to a gas turbine. GE7EA gas turbine of Pyong-Tak power plant was selected as a target to apply the DME. Combustion tests were conducted by comparing DME with methane, which is a major component of natural gas, in terms of combustion instability, $NO_X$ and CO emissions, and the outlet temperature of the combustion chamber. The results of the performance tests show that DME is very clean but has a low combustion efficiency in low load condition. From the results of the fuel nozzle temperature we have ascertained that DME is easy to flash back, and this property should be considered when operating a gas turbine and retrofitting a burner.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.3
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• pp.358-370
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• 1997

In the present study, investigations were carried out to obtain data on combustion characteristics of methane gas and hydrogen supplemented methane gas in a constant volume combustion chamber. The main results obtained from the study can be summarized as follows. The maximum combustion pressure increases as the initial pressure and hydrogen supplement rate increase, the total burning time is shorten by lowering the initial pressure and by increasing the hydrogen supplement rate. The maximum flame temperature and NO concentration increase by the initial pressure and hydrogen supplement rate increase. The flame propagation processes in near stoichiometric mixture are propagated with a spherical shape, but in excess rich or lean mixtures are propagated with a elliptical shape. And, they are changed an unstable elliptical shape flame with very regular cells by increasing the hydrogen supplement rate.

• Journal of the Korean Institute of Gas
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• v.14 no.4
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• pp.12-17
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• 2010

Natural gas is one of the most promising alternatives to gasoline and diesel fuels because of its high thermal efficiency and lower harmful emissions, including $CO_2$. However, the possibility of partial burn and misfire makes the benefits of natural gas fueled engine worse under lean burn operation condition, Hydrogen addition can promote the combustion characteristics while reduces emissions extremely. In this study, the effect of hydrogen addition on an engine performance was investigated. The results showed that thermal efficiency was increased due to the expansion of lean operation range under stable operation. NOx emission can be significantly reduced with the small increase in HC or CO emissions.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.65-71
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• 2009

In this study, performance and economic analysis of natural gas/syngas fueled 100 MWth chemical-looping combustion (CLC) combined cycle plant were performed. Net efficiency of both cases was 53~54%, corresponding to previous research. We used Chemical Engineering Plant Cost Index and Guthrie method to evaluate plant cost. For syngas fueled CLC combined cycle plant, the plant cost was higher since lower heating value(LHV) of syngas was lower than that of natural gas and cost of electricity(COE) was also higher since the cost of syngas was higher than that of natural gas. By sensitivity analysis, it was shown that the cost of syngas should be less than 5.3 $/GJ in order to make COE lower than 5.8 ¢/kWh which was COE of natural gas fueled CLC combined cycle plant.

• 연구논문집
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• s.23
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• pp.121-126
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• 1993

In general, natural gas engine converted from gasoline engine has disadvantage of power decrease. In order to increase power output in natural gas engine, the improvement of in-cylinder flow motion has been believed as the most effective method. In this study, the geometry of combustion chamber in 4 valve DOHC natural gas engine is modified, and in-cylinder flow patterns are analyized. Also engine performance is evaluated according to the modification of in-cylinder flow motion.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.05a
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• pp.89-93
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• 1999

Experimental studies are conducted to investigate the flame stability and the thermal/fuel NOx formation characteristics of the low calorific value(LCV) gas fuel. Synthetic LCV fuel gas is produced through mixing carbon monoxide, hydrogen, nitrogen and ammonia on the basis that the thermal input of the syngas fuel into a burner is identical to that of natural gas, and then the syngas mixture is fed to and burnt with air on flat flame burner. Flame behaviors are observed to identify flame instability due to blow-off or flash-back when burning the LCV fuel gas at various equivalence ratio conditions. Measurements of NOx in combustion gas are made for comparing thermal and fuel NOx emissions from the LCV syngas combustion with those of the natural gas one, and for analyzing ammonia to NOx conversion mechanism. In addition, the nitrogen dilution of the LCV syngas is preliminarily attempted as a NOx reduction technique.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.2
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• pp.57-63
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• 2000

This paper deals with a study on combustion and emission characteristics of a direct injection diesel engine dual fueled with natural gas. Dual fuelling systems tend to emit high unburned fuel especially at low load, resulting in a decreased thermal efficiency. This is because natural gas-air mixtures are too lean for flame to propagate under low load conditions. Suction air quantity and injection timing controls are very useful to improve emissions and thermal efficiency at low load.