• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.75-81
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• 2001

MCVD(modified chemical vapor deposition) used in making optical-fiber currently utilizes the hydrogen-oxygen burner as a energy supply source. To improve the productivity and to reduce the manufacturing cost of optical-fiber, a natural gas-oxygen burner has been developed. The manufacturing processes of optical-fiber consist of vapor deposition, collapse and drawing processes. Among these processes, the vapor deposition and the collapse processes are important in terms of improving the productivity and saving the production cost. The vapor deposition and collapse processes are performed by combustion heat and flame force supplied by a burner. So the flame force of the burner used in these processes is required to have an optimal and consistent value in order to allow uniform heating and collapse of quartz tube. In this regard, the momentum ratio of natural gas and oxygen has been optimally determined by modification of a burner and the inlet flow pass also has been modified.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.05a
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• pp.95-100
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• 1999

One of the unsolved problems of the natural gas dual fuel engine is that there is too much exhaust of Total Hydrogen Carbon(THC) at a low equivalent mixture ratio. To fix it, a natural gas mixed with hydrohen 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 nocking limit decreases and the produce of NOx increases.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.275-277
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• 2011

KOGAS(Korea Gas Corporation) uses two-type vaporizers to send customers natural gas with imported LNG. In winter season, SMVs(SubMerged combustion Vaporizers) are mainly operated due to low seawater temperature. SMVs consume the natural gas of 1,520 $Nm^3/hr$ and emit a lot of $CO_2$ in winter time. If carbon taxes are activated on climate change, the tax burden will be severely heavy. Accordingly this work carried out numerical simulation with a commercail CFX code to investigate its possibility on the practical use of pure oxygen combustion of SMVs to reduce $CO_2$ and to improve its efficiency. First, a nozzle of a SMV's combustor is modelled. The combustion characteristics of Air/Fuel and Oxygen/Fuel are analyzed under folly insulated condition. Although we couldn't find the carbon reduction and the efficient elevation when the pure oxygen/fuel type was compared to the existing air/fuel one, we need a further study to investigate the effect of $CO_2$ recirculation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.8
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• pp.545-552
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• 2010

Research and development efforts to reduce $CO_2$ emission are in progress to cope with global warming. $CO_2$ emission from fossil fuel fired power plants is a major greenhouse gas source and the post-combustion $CO_2$ capture is considered as a short or medium term option to reduce $CO_2$ emissions. In this study, the application of the post-combustion $CO_2$ capture system, which is based on chemical absorption and stripping processes, to typical fossil fuel fired power plants was investigated. A coal fired plant and a natural gas fired combined cycle plant were selected. Performance of the MEA-based $CO_2$ capture system combined with power plants was analyzed and overall plant performance including the energy consumption of the $CO_2$ capture process was investigated.

• Journal of the Korean Society of Combustion
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• v.17 no.4
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• pp.5-10
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• 2012

The reformer system is a chemical device that drives the conversion of hydrocarbon to hydrogen rich gas under high temperature environment($600-1,000^{\circ}C$). Generally, NG(Natural Gas) or AOG(Anode Off Gas) is used as fuel of fuel cell reformer combustion system. The experimental study to analyze the combustion characteristics of a premixed ceramic burner used for 0.5-1.0 kW fuel cell reformer was performed. Ceramic burner experiments using NG and AOG were carried out to investigate the flame stability characteristics by heating capacity, equivalence ratio and different fuels respectively. The results show that surface flames can be classified into green, red, blue and lift-off flames as the equivalence ratio of methane-air mixture decreases. And the stable flames can be established using NG and AOG as reformer fuel in the perforated ceramic burner. In particular, the blue flame is found to be stable at a lean equivalence ratio under different mixture conditions of NG and AOG for the 0.5 to 1.0 kW fuel cell system power range. NOx emission is under 60 ppm between 0.70 to 0.78 of equivalence ratio and CO emission is under 50 ppm between 0.70 to 0.84 of equivalence ratio.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.7
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• pp.693-699
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• 2011

Internal combustion engines running on syngas, which can be obtained from biomass or organic wastes, are expected to be one of the suitable alternatives for power generation, because they are environment-friendly and do not contribute to the depletion of fossil fuels. However, syngas has variable compositions and a lower heating value than pure natural gas, owing to which the combustion conditions need to be adjusted in order to achieve stable combustion. In this study, a gas that has the same characteristics as syngas, such as low heating value (LHV), was produced by mixing $N_2$ with compressed natural gas (CNG). In addition, this study investigates the combustion characteristics of syngas when it is mixed with hydrogen in a ratio ranging from 10% to 30% with a constant LHV of total gas.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.166-177
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• 1998

Combustion characteristics of natural gas premixed flames is studied experimently and numerically by adopting a counterflow as a flamelet model in turbulent flames. Flame speeds are measured by employing LDV, and the results show that flame speed increases linearly with strain rate, which agrees well with numerical results. Parametric dependences of extinction strain rates are studied numerically with detailed kinetic mechanism to show that the addition of ethand to a methane premixed flame makes the flame more resistant to strain rate. The effect of pressure on the extinction strain rate is that the extinction strain rate increases up to 10 atm and them decreases, which is explained by competition of chain branching H+O2=OH+O and recombination reaction H+O2+M=HO2+M. Detailed mechanism having seventy-four step is systematically reduced to a nine-step and a five-step thermal NOx chemistry is reduced to two-step. Comparison between the results of the detailed and the reduced mechanisms demonstrates that the reduced mechanism successfully describes the essential features of natural gas premixed flames including extinction strain rate and NOx production.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.3
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• pp.267-281
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• 1994

The Combustion gas behavior induced by fire in a building is numerically investigated. The typical building for this analysis is partially divided by a vertical baffle projecting from the ceiling. The solution procedure includes the low Reynolds number ${\kappa}-{\varepsilon}$ model for the turbulent flow and the discrete ordinates method is used for the calculation of radiative heat transfer equation. The effects of the location and size of fire source and baffle length on velocity and temperature distributions, species mass fraction and flame location are analyzed. As the results of this study, it is found that the case when the fire source is located at the vertical wall is more dangerous than at the bottom wall in view of the combustion products and flame location. It is also found that the radiation effect cannot be neglected in analyzing the building in fire.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.700-707
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• 2017

In the international natural gas market, natural gas has markedly low calories. The domestic calories standard of natural gas was changed and the performance and efficiency of many industrial machines using natural gas were affected because of low caloric natural gas. Therefore, in this study, a dual fuel engine fueled with natural gas and diesel was tested to examine the effects of the CNG substitution rate on the combustion characteristics, such as thermal efficiency, COVimep and heat release rate. The CNG substitution rate was defined as the ratio of CNG instead of diesel, which was calculated as the total energy. The conditions of the tested engine were fixed $1800rpm/500N{\cdot}m$. In addition, diesel fuel was injected at $16^{\circ}CA$ BTDC and the fuel pressure was fixed at 85 MPa; the lower heating value of CNG was $10,400kcal/Nm^3$. The results of the engine test showed that the amount of diesel fuel was changed according to the CNG substitution rate. Therefore, when the substitution rate was increased, the amount of diesel fuel was decreased, which affected the energy for ignition. In addition, the ignition delay duration was increased, which affected the thermal efficiency and torque. On the other hand, the COVimep was less than 5% and a stable combustion state of the engine was shown.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1248-1253
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• 1999

This study is concerned about the combustion characteristics of methane-air and methane/hydrogen-air mainly the behavior of burning velocity including the effect of the ignition energy. The experiments were conducted in a spherical combustion bomb designed in this laboratory. The burning velocities were measured by the pressure-time history and the reaction rates were estimated theoretically. The experimental results showed that the burning velocity increased by 25 to 50 percent when hydrogen is added to methane by 20 percent.