• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.3
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• pp.75-80
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• 2012

Gasification is a therm-chemical conversion process to convert various solid fuels into gaseous fuels under limited supply of oxygen in high temperature environment. Considering current availability of biomass resources in this country, the gasification is more attractive than any other technologies in that the process can accept various combustible solid fuels including plastic wastes. Mixed fuels of biomass and polyethylene pellets were used in gasification experiments in this study in order to assess their potential for synthesis gas production. The results showed that higher reaction temperatures were observed in mixed fuel compared to woodchip experiments. In addition, carbon monoxide, hydrogen, and methane concentrations were increased in the synthesis gas. Heating values of the synthesis gas were also higher than those from woodchip gasification. There are hundred thousand tons of agricultural plastic wastes generated in Korea every year. Co-gasification of biomass and agricultural plastic waste would provide affordable gaseous fuels in rural society.

• Journal of Mechanical Science and Technology
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• v.19 no.10
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• pp.1939-1949
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• 2005

Many studies have been conducted to increase regression rate of solid fuel in hybrid rocket. One of them resorts to swirl flow since it can extend the residence time of oxidizer in the fuel grain. Also, metal wires may lead to increase the regression rate of solid fuel as shown in solid propellants. In this study, a series of experiments was designed to investigate the enhancement of regression rate of solid fuel by embedded metal wires and by fuel port grain. And fuel port was designed with a helical configuration to attempt to induce swirl flow. PMMA with gaseous oxygen is the solid fuel used for investigation. Test results showed that embedded metal wires turned out to be ineffective method because only $3-4\%$ increases in regression rate were observed. However, fuel port grain configuration yields higher burning performance of up to $50\%$ increase in regression rate. Also pitch number as well as total impulse was found to be a design variable.

• Journal of Soil and Groundwater Environment
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• v.10 no.6
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• pp.63-67
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• 2005

Laboratory scale experiments were carried out to delineate the effects of liquid phases, such as soil water and light nonaqeous phase liquid (LNAPL) on the transport of gaseous ozone in unsaturated soil. Soil water enhanced the transport of ozone due to water film effect, which prevents direct reaction between soil particles and gaseous ozone, and increased water content reduced the breakthrough time of ozone because of increased average linear velocity and decreased air-water interface area. Diesel fuel as LNAPL also played a similar role with water film, so the breakthrough time of ozone in diesel-contaminated soil was significantly reduced compared with uncontaminated soil. Ozone breakthrough time was retarded with increased diesel concentration, however, because of high reactivity of diesel fuel with ozone. In unsaturated soil containing two liquids of soil water and LNAPL, the transport of ozone was mainly influenced by nonwetting fluid, diesel fuel in this study.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.3
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• pp.357-362
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• 2011

Complete mixture preparation of reactants prior to catalytic reforming is an enormously important step for successful operation of a fuel reformer. Incomplete mixing between fuel and reforming agents such as air and steam can cause temperature overshoot and deposit formation which can lead the failure of operation. For that purpose it is required to apply computational models describing coupled kinetics and transport phenomena in the mixing region, which are computationally expensive. Therefore, it is advantageous to analyze the gas-phase reaction kinetics prior to application of the coupled model. This study suggests one of the important design constraints, the required residence time in the mixing chamber to avoid substantial gas-phase reactions which can lead serious deposit formation on the downstream catalyst. The reactivity of various gaseous and liquid fuels were compared, then liquid fuels are far more reactive than gaseous fuels. n-Octane was used as a surrogate among the various hydrocarbons, which is one of the traditional liquid fuel surrogates. The conversion was slighted effected by reactants composition described by O/C and S/C. Finally, threshold residence times in the mixing region of a hydrocarbon reformer were studied and the mixing chamber is required to be designed to make complete mixture of reactants by tens of milliseconds at the temperature lower than $400^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.56 no.2
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• pp.160-166
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• 2019

In this study, we investigated the long-term stability of Nd₂NiO₄ solid oxide fuel cell (SOFC) cathodes to evaluate their chromium poisoning tolerance. Symmetrical cells consisting of Nd2NiO4 electrodes and a yttria-stabilized zirconia electrolyte were fabricated and the cell potential and polarization resistance were measured at 850 ℃ in the presence of gaseous chromium species for 800 h. Up to 500 h of operation, the cell potential remained constant at 500 mA/㎠. However, it increased slightly over the operation duration of 550-800 h. No appreciable increase was observed in the polarization resistance of the Nd₂NiO₄ cathode during the entire operation of 800 h. Physicochemical examinations revealed that the gaseous chromium species did not form chromium-related contamination not only in the Nd₂NiO₄ cathode but also at the cathode/electrolyte interface. The results demonstrated that Nd₂NiO₄ is resistant to chromium poisoning, and hence is a potential alternative to standard perovskite cathodes.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.3-12
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• 1991

Fuel cells are electrochemical devices that convert the chemical reaction energy directly into the electrical energy. In a typical fuel cell, gaseous fuel is fed continuously to the anode(negative electrode) compartment and the oxidant(i.e, oxygen from air) is fed continuously to the cathode(positive electrode) compartment; the electrochemical reactions take place at the electrodes to produce an electric current. Many of the operational characteristics of fuel cell systems are superior to those of conventional power generation system because of good efficiency, environmental protection, safty, modularity etc. From those reasons, the fuel cells are considered to be the solution to the future problem of energy conversion. The objective of this paper is to introduce the technical status of fuel cell technologies and our national project for the development of the phosporic acid fuel cell.

• Journal of the Korean Society of Safety
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• v.23 no.6
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• pp.95-99
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• 2008

Halon was known as a cause of the ozone layer destruction. In 1987, it was designated as one of the ozone-layer-destroying materials in the Montreal Protocol. Therefore substitutes of Halon agent has been developed including inert gas extinguish system, which is one of the most widely used fire extinguishing system. This study intended to increase the efficiency of inert gas extinguishing agent by using inert gas additives. As IG-541 shows high extinguishing power, the experiment was performed to measure the effects of gaseous additives to it. Cup-burner fire extinguishing apparatus was used with n-Heptane fuel. Among many of pure inert gaseous agents, Helium showed the most excellent extinguishing power. When Helium was added to IG-541, fire extinguishing power was increased and the concentration of oxygen in chimney also risen. By adding Helium to IG-541, the effectiveness of inert gas fire extinguishing system is able to be increased.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.5
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• pp.469-474
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• 2010

Gasoline engines have proven their utility in light, medium and heavy duty vehicles. Concern about long term availability of petroleum and the environment norms by the increased vehicular emission have mandated the search for safe fuel. CNG is an environmentally clean alternative to the existing spark ignition engines with the advantages of minimum change. A higher octane number and a higher self ignition temperature make it an attractive gaseous fuel. The thermal efficiency is better than gasoline for the same engine. The reduced carbon mono oxide, carbon di-oxide, hydrocarbon emissions is a favorable outcome along with a slight increase in $NO_x$ emission when compared with gasoline fuel to a dual fuel mode in the existing spark ignition engines. The result from the experiment shows that CNG could be a potential substitute fuel that maintains performance and emissions characteristics in gasoline engines.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.51-66
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• 1997

A heat transfer model of the intake valve in a spark ignition engine is presented, which is calibrated with a number of the valve temperature profiles measured during engine warm-up for the gaseous fuel(propane). The valve is divided into four identical elements for which the assumption of lumped thermal mass is applied. The calibration is made so that the difference between the measued and simulated valve temperatures becomes minimal. Then the model is applied to the cases of the liquid fuel(indolene) to estimate the amount of the liquid fuel vaporized from the intake valve by assuming that fuel evaporation accounts for the deficit of the heat balance budget. The results of the model show quantitative contribution of each heat transfer source to the heat balance. The behavior of the calculated mass fraction of the fuel vaporized from the intake valve explains how the liquid fuel evaporate during engine warm-up. The mass fraction at warmed-up condition is closely related with the fraction directly targeted on the valve back by the fuel spray geometry.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.112-122
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• 1995

As an alternative fuel producing less exhaust emissions, natural gas is of interest for use both in SI and CI engines. The potential of natural gas fuelled dual-fuel engine is considered high enough. However, much effort has to be made so that gaseous fuel is used efficiently with simultaneous minimum use of pilot oil. Hence, a simplified three-dimensional model, using a finite volume method in cylindrical coordinates, has been developed to facilitate an understanding of the dual-fuel combustion phenomena and to predict the complex interactions between the pilot distillate and natural gas. The computer model was calibrated by comparing it with the experimental results obtained from diesel engine like combustion bomb tests. In the pre-mixed natural gas combustion, the fuel burning was highly reliant on the injection condition and subsequent burning nature of the pilot distillate.