• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1140-1151
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• 2023

Fully Ceramic Microencapsulated (FCM) fuel is emerging advanced fuel material for the future nuclear reactors. The fuel pellet in the FCM fuel is composed of matrix and a large number of TRistructural-ISOtopic (TRISO) fuel particles which are randomly dispersed in the SiC matrix. The minimum layer thickness in a TRISO fuel particle is on the order of 10^-5 m, and the length of the FCM pellet is on the order of 10^-2 m. Hence, the heat transfer in the FCM pellet is a multi-scale phenomenon. In this study, three multi-scale heat conduction models including the Multi-region Layered (ML) model, Multi-region Non-layered (MN) model and Homogeneous model for FCM pellet were constructed. In the ML model, the random distributed TRISO fuel particles and coating layers are completely built. While the TRISO fuel particles with coating layers are homogenized in the MN model and the whole fuel pellet is taken as the homogenous material in the Homogeneous model. Taking the results by the ML model as the benchmark, the abilities of the MN model and Homogenous model to predict the maximum and average temperature were discussed. It was found that the MN model and the Homogenous model greatly underestimate the temperature of TRISO fuel particles. The reason is mainly that the conventional equivalent thermal conductivity (ETC) models do not take the internal heat source into account and are not suitable for the TRISO fuel particle. Then the improved ETCs considering internal heat source were derived. With the improved ETCs, the MN model is able to capture the peak temperature as well as the average temperature at a wide range of the linear powers (165 W/cm~ 415 W/cm) and the packing fractions (20%-50%). With the improved ETCs, the Homogenous model is better to predict the average temperature at different linear powers and packing fractions, and able to predict the peak temperature at high packing fractions (45%-50%).

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.145-148
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• 2008

Fuel flexibility of CFBC boiler was examined. Combustion characteristics of low grade coal, coal sludge, coal RDF mixture and RDF were compared. The operation result of a commercial 130TPH CFBC co-generation boiler burning a low grade Chinese coal were analysed. Burning characteristics of coal/RDF mixture and coal and industrial sludge mixture were studied in a 0.1MWth scale CFBC test rig. Also RDF fuel were tested in a 8TPH CFBC test facility. Though fuel characteristics were different, the combustion modes were all very stable. The temperature were maintained in between $800-950^{\circ}C$.

• 한국기계연구소 소보
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• v.4 no.1
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• pp.89-97
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• 1981

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.162-175
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• 1995

Exhaust emissions in diesel engine are affected by fuel properties, but the reason for this is not clear. Especially, the recent strong interest in using low-grade fuel such as used vegetable oil as alternative diesel fuel demands extensive investigation in order to clarify the exhaust emissions. The purpose of this study is to evaluate the feasibility of a used vegetable oil as an alternative fuel in a diesel engine in terms of exhaust emissions. The emission concentration of used vegetable oil such as formaldehyde and acrolein is two times than that of diesel fuel. However, since that of alcohol is ten times than that of used vegetable oil and that concentration is very low, it is not a problem for human health.

• Journal of the Korean Society of Combustion
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• v.12 no.4
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• pp.47-56
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• 2007

Utilization of sewage sludge for industrial fuel should be considered in appropriate calory with low emission of environmental pollutants and the amount of sewage sludge for continuously long-time operation. For the low grade fuel(<4,000kcal/kg), one of proper processes is that coal and oil are added into sewage sludge to remove impurities and increase calory(>7,000kcal/kg) and the amount of fuel having sewage sludge. Recently, 2-step agglomeration has been attempted by secondarily agglomerate sewage sludge onto the primary nuclei formed by agglomeration of coal and oil. Furthermore, sawdust and waste oil can substitute about 1/3 each for coal and mineral oil consumed in this process, which will lead to securing alternative energy resources from environmental pollutants as well as cost reduction.

• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.1-6
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• 2012

Recently the government declared an all-out war on bogus fuel in order to crack down on tax evasion and ensure fuel safety. The move came after four people were killed in explosion at the two gas station. Illegally processed gasoline is the only one of low grade fuels. The problems are induced by relatively high vapor pressure of bogus fuel.

• Journal of the Korean Ceramic Society
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• v.42 no.12 s.283
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• pp.777-786
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• 2005

The Solid Oxide Fuel Cell (SOFC) is an electrochemical device to convert chemical energy of a fuel into electricity at temperatures from about 600 to $1000^{\circ}C$. The SOFC offers certain advantages over lower temperature fuel cells, notably its ability to use CO as a fuel rather than being poisoned by it, and high grade exhaust heat for combined heat and power, or combined cycle gas turbine applications. This paper reviews the operating principle, materials for different cell and stack components, cell designs, and applications of SOFCs. Among all designs of Solid Oxide Fuel Cells (SOFCs), the most progress has been achieved with the tubular design. However, the electrical resistance of tubular SOFCs is high, and specific power output $(W/cm^2)$ and volumetric power density $(W/cm^3)$ low. Planar SOFCs, in contrast, are capable of achieving very high power densities.

• Tribology and Lubricants
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• v.28 no.4
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• pp.178-183
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• 2012

The fuel system of a vehicle is a very important compotent, as it provides the firing resources to the combustion chamber of the engine. However, improper operation of the system can generate bad condition or start-off during engine revolution. This study analyzed several examples of failure that had originated in the field. In the first example, the driver operated a vehicle containing both gasoline and LPG in the fuel tank, but the gasoline fuel remained unused for a few months. Therefore the fuel pump was clogged because of gasoline congelation. The second example, dealt with fuel leakage that occurred from the slightly torn O-ring connecting the fuel lines. The third example, pertained to engine damage and power-down owing to the usage of proor-quality fuel and ingredient. Therefore, it is necessary to take adequate measures to prevent the failure of the fuel system of vehicle.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.11
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• pp.1046-1053
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• 2010

The objective of this study was to investigate the pyrolytic reaction characteristics of a mixed fuel of municipal solid wastes and low-grade anthracite. The reaction variables are pyrolysis condition of mixing ratio, reaction temperature, temperature increase rate. As a result, the optimum mixing ratio was 20 wt.% low-grade anthracite in MSW, which maintains for the low heating value over 3,500 kcal/kg on pyrolysis. The most high reaction velocity constant was shown at $700^{\circ}C$. Also, under the all experimental condition, the reaction velocity constant increased linearly as temperature rate increase, but pyrolysis has to be considered electric power cost and yield of char at lower temperature rate.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.44-51
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• 2003

By blending of various low boiling point oxygenated agents to lower grade fuels, significant improvements were simultaneously obtained in smoke, CO, PM, SOF and BSEC. Especially, our trends were remarkably obtained by retarding injection timing, by decreasing boiling point and increasing blending contents of additives in case of oxygenated agents rather than non-oxygenated agents. Also, it was revealed that when 20vo1.% DMM added to high viscosity fuels and injection timing was retarded, NOx-smoke trade off relationship was much better than that of ordinary diesel fuel. Thus, lower grade fuels with high viscosity could be expected to be used efficiently and cleanly in diesel operation by blending low boiling point oxygenates.