• Transactions of the Korean hydrogen and new energy society
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• v.33 no.6
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• pp.776-785
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• 2022

Hydrogen combustion in modern gas-turbine engine is the cutting edge technology as carbon-free energy conversion system. Flashback of hydrogen flame, however, is inevitable and critical specially for premixed hydrogen combustion. Therefore, this experimental investigation is conducted to understand flashback phenomenon in premixed hydrogen combustion. In order to investigate flashback characteristics in premixed hydrogen (H₂)/air flame, we focus on pressure conditions and nozzle shapes. In general, quenching distance reduces as pressure of combustion chamber increases, causing flashback from boundary layer near wall. The flashback regime for reference and modified candidate configurations can broadly appear with increasing combustion chamber pressure. The later one can improve flashback-resist by compensating flow velocity at wall. Also, improved wall flow velocity profile of suggested contraction nozzle prevents entire flashback but causes local flashback at nozzle exit.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.405-406
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• 2000

최근의 유가 상승으로 석유파동이 우려되며, 비산유국인 우리나라의 경우 석유를 대체할 에너지 개발의 필요성이 절실히 요구되고 있다. 한편 국내에서는 석탄의 지역적 편재성이 적고 풍부한 매장량을 가지고 있으면서도 이산화황 등의 대기오염문제를 해결하지 못해 사용량이 해마다 줄어들고 있다. 따라서 잉여탄의 관리 및 처분 문제가 대두되고 있으며, 잉여탄의 소모처 개발이 요구되고 있다. (중략)

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.712-714
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• 1998

Fuel cell systems offer high energy efficiencies for transportation application. In addition, they can use alcohols and alternative fuels as the fuel, while producing little or no noxious emissions. Fuel cell-powered vehicles should be competitive in performance characteristics and in capital and maintenance costs with internal combustion engine vehicles. The objective of the present study is to design a fuelcell/battery powered vehicles to analyze technical feasibity.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.264-266
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• 1997

Fuel cell systems offer high energy efficiencies for transportation application. In addition, they can use alcohols and alternative fuels as the fuel, while producing little or no noxious emissions. Fuel cell-powered vehicles should be competitive in performance characteristics and in capital and maintenance costs with internal combustion engine vehicles. The objective of the present study is to design a fuel cell-powered passenger car to analyze technical feasibility.

• Journal of the Korean Institute of Gas
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• v.27 no.4
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• pp.85-91
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• 2023

In this study, an experimental study was conducted on the flame behavior, combustion dynamics, and NOx emission characteristics for hydrogen co-firing with the EV burner which is the first stage combustor of GT24. It was confirmed that as the hydrogen co-firing rate increases, the NOx emission increases. This change was elucidate to be the result of a combination of changes in penetration depth due to changes in fuel density, reduction in fuel mixing due to changes in flame position due to increased flame propagation speed, and oscillation of fuel mixedness due to combustion instability. Through pressurization tests in the range of 1.3 to 3.1 bar, NOx emission characteristics under high-pressure operating conditions were predicted, and based on this, the hydrogen co-firing limits of the EV burner was evaluated.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.1
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• pp.63-71
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• 2017

Liquid methane ($CH_4$)/oxygen ($O_2$) bipropellants have been recently considered as a next-generation propellant due to eco-friendly and non-toxic properties, low cost and high performance. In this study, the combustion characteristics of gaseous $CH_4/O_2$ nonpremixed coflow flames in a model combustor with variation of internal pressure are investigated through measuring the combustion stability limits and visualizing flames. Results show that the combustion stability limits are extended and the reaction region is widened with increasing internal pressure of the combustion chamber for fuel-rich condition.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.35-43
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• 1998

Electrodes using for the anode electrode of direct methanol fuel cell with Pt/C and Pt/Ru/C catalyst were prepared and characterized by SEM, TEM, thermal analysis and electrochemical analysis. The half cell tests were carried out with 1 M $H_2SO_4$ electrolyte and 1 M $CH_3OH$ in order to evaluate the electrode performance. The employed electrochemical methods were cyclic vol-tammetry and potentiodynamic polarization experiments. It was found that 20 w% polytetrafluoroethylene (PTFE) content in catalyst showed the best performance due to the best platinum utilization on PTFE-containing catalyst layer. It was found that Pt/Ru/C binary catalyst inhibited the poisoning of anode electrode showing improved performance compared to the Pt/C catalyst by the adsorption of oxygen containing species on the electrode surface at same time. The apparent activation energy for methanol oxidation on the Pt/Ru/C and Pt/C catalyst layer was 11.60 kJ/mol and 26.85 kJ/mol, respectively.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.38-39
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• 2019

Optimal route planning is the route planning to minimize voyage time or fuel consumption in a given ocean environment. Unlike the previous studies on weather routing, this study proposes an optimization method for the route planning to avoid the grounding risk in the coast. The route way-points were searched using Dijkstra algorithm, and then the optimization was performed to minimize fuel consumption by setting the optimization design parameter to the engine rpm. To set the engine rpm, a method to use the fixed rpm from the departure point to the destination point, and a method to use the rpm for each section by dividing the route were used. The ocean environmental factors considered for route planning were wind, wave, and current, and the depth information was utilized to compute grounding risk. The proposed method was applied to the ship passing between Mokpo and Jeju, and then it was confirmed that fuel consumption was reduced by comparing the optimum route and the past navigated route.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.4
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• pp.86-94
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• 2015

Torrefaction is a thermochemical process proceeded at the temperature around $250^{\circ}C$ in an inert gas condition. By torrefaction, the hemicellulose portions contained in biomass are broken down to change into the volatile gas which is removed from biomass eventually. The main purpose of biomass torrefaction is to improve the energy density of the biomass to minimize the transport energy consumption, though the flammability can be elevated for transportation. In this study two types of solid biomass fuel, waste wood and rice straw, were torrefied at various temperature range from $200^{\circ}C$ to $300^{\circ}C$ to evaluate the torrefied biomass characteristics. In addition torrefied biomass were tested to evaluate the combustion characteristics using TGA (Thermogravimetric Analysis). After the torrefaction of biomass, the C/H (carbon to hydrogen ratio) and C/O (carbon to oxygen ratio) were measured for aquisition of bio-stability as well as combustion pattern. Generally C/H ratio implies the soot formation during combustion, and the C/O ratio for bio-stability. By torrefaction temperature at $300^{\circ}C$, C/H ratio and C/O ratio were increased by two times for C/H and three times for C/O. The torrefied biomass showed similar TGA pattern to coal compared to pure biomass; that is, less mass decrease at lower temperature range for torrefied biomass than the pure biomass.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.834-840
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• 2018

In this study, the characteristics of air pollutant emissions from ships' engines have been investigated by conducting E2 and E3 cycle mode tests. A engine 360Ps (Doosan L126TIH engine) and 400kW dynamometer Horiba-Schenck were utilized for engine tests. The FTIR analyzer and SPC were used to measure exhaust gas (NOx, SOx etc.) and PM (particulate matter), respectively. The results showed that the emissions of THC and CO produced from engine were increased with the increase of sulfur content in fuel oils at E2 and E3 cycle modes. The kinetic viscosity of the fuel increased as the sulfur content of the fuel increased, thereby the specific fuel oil consumption (SFC) of the engine improved. This result is considered to be due to improved combustion conditions due to increased average diameters of sprayed particles and due to increased kinetic viscosity under constant fuel injection pressure in this study. In the case of NOx emission, this study showed no significant change in amount of sulfur content.