• 한국세라믹학회지
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• 제53권3호
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• pp.354-361
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• 2016

The purpose of this study was to prepare lightweight foamed concrete by mixing coal fly ash of circulating fluidized bed combustion(CFBC) with cement, and to develop uses for recycling by analyzing carbonation behavior resulting from a change in conditions for pressurized carbonation. For concrete, CFBC coal fly ash was mixed with Portland cement to the water-binder ratio of 0.5, and aging was applied at room temperature after 3 days of curing at $20^{\circ}C$, RH 60%. For carbonation, temperature was fixed at $60^{\circ}C$ and time at 1 h in the use of autoclave. Pressures were controlled to be $5kgf/cm^2$ and the supercritical condition of $80kgf/cm^2$, and gas compositions were employed as $CO_2$ 100% and $CO_2$ 15%+N2 85%. In the characteristics of produced lightweight concrete, the characteristics of lightweight foamed concrete resulting from carbonation reaction were affirmed through rate of weight change, carbonation depth test, air permeability, and processing analysis for the day 28 specimen. Based on these results, it is concluded that the present approach could provide a viable method for mass production of eco-friendly lightweight foamed concrete from CFBC coal fly ash stabilized by carbonation.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.33-36
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• 2014

Gasification of biomass produces syngas containing CO, $H_2$ and/or $CH_4$, which can then be converted into energy or value-added fuels. One of key issues for efficient gasification is to minimize tar concentration in the syngas for use in a final conversion device such as gas engine. This study investigated the decomposition of primary tar by catalytic cracking using char as catalyst, of which the feature can be integrated into a fixed bed gasifier design. The pyrolysis vapor containing tar from pyrolysis of wood at $500^{\circ}C$ was passed through a reactor filled with or without char at $800^{\circ}C$ for a residence time of 1, 3 or 5 sec. Then, the condensable vapor (water and tar) and gases were analyzed for the yields and elemental composition. Four types of char particles with different microscopic surface area and pore size distribution: wood, paddy straw, palm kernel shell and activated carbon. The results were analyzed for the mass and carbon yields of tar and the composition of product gases to conclude the effects of char types and residence time.

• 한국수소및신에너지학회논문집
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• 제28권4호
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• pp.384-391
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• 2017

Effects of operating variables on solid circulation rate were measured and discussed using two-interconnected circulating fluidized bed system at ambient temperature and pressure. OCN 706-1100 particles were used as oxygen carrier. The measured solid circulation rates increased as the lower loop seal gas flow rates and the solid height in the fuel reactor increased. Suitable operating conditions to avoid choking of the air reactor were confirmed. Continuous long-term operations of steady-state solid circulation were also demonstrated at two different conditions based on the operating window.

• 에너지공학
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• 제11권3호
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• pp.224-229
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• 2002

본 연구에서는 순환유동층 보일러의 운전 중 비유동화 및 완전 베드 봉쇄를 유발할 수 있는, 분산판 위에서 발생되는 클링커에 대하여 그 발생원인을 순수 열 및 유동 측면에서 고찰해 보고자 하였다. 클링커는 그 화학성분 측면에서 실리콘, 철, 칼슘 등의 원소로 구성되어 있다. 비유동화 현상에 대하여 폭넓은 연구가 진행되어 왔으나, 현재까지 그 원인규명이 명확하게 이루어지고 있지는 못하는 현실이다. 본 연구에서는 FLUENT를 사용한 CFD 계산을 통하여 분산판의 노즐 형태와 노즐 배열을 달리하면서(노즐타입 1, 노즐타입 2)유동특성을 파악하여 클링커 발생 원인을 유추하였으며, 열 및 유동 측면에서 클링커 발생을 최소화할 수 있는 노즐 형태 및 배열을 제안(노즐타입 3)하였다.

• 한국정밀공학회지
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• 제28권7호
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• pp.805-813
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• 2011

The dynamic stress of the diesel engine block is analyzed by using flexible-body dynamic analysis. Multiple loadings including the pressure load due to gas combustion, thermal load, and dynamic load are considered. Thermal load is assumed constant, however, pressure load and dynamic load are treated as time dependent. The present work is focused on the dynamic stress analysis, especially on finding critical points of the engine block. The analysis model includes four parts - engine block, generator, bed, and mounts. On the other hand, crank shaft, pistons, and main bearings are excluded from the model. However, their dynamic effects are applied by dynamic forces, obtained in the separate analysis. Dynamic stress is found by using flexible body dynamic analysis, and compared to the measured data.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.504-508
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• 2009

To obtain high power, diesel engines continuously increase combustion pressure and mean effective pressure each cylinder, and the excitation sources and noisy sources are increased, too. Moreover, to reduce the costs, shipyards make hull structures weaker than before. As above reasons, it is more difficult to control the vibration phenomenon nowadays. In this study, it was investigated why diesel generator sets reached the vibration allowable limits during the FAT and heavy vibration phenomenon of diesel generator sets using ODS test during onboard tests. Also, it is found out the stiffness of deck and common bed using the test result of their structural impedance. To find out the vibratory characteristics of diesel generator sets, MODAL tests were carried out. From the sensitivity analysis after above tests, it was selected points to be reinforced and studied troubleshooting to solve heavy vibration phenomenon of diesel generator sets.

• 한국추진공학회지
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• 제15권1호
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• pp.69-75
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• 2011

한국형발사체 엔진에 사용될 예정인 75톤급 연소기 채널냉각형 기술검증시제에 대한 연소시험을 수행하였다. 설비 공급 능력과 구조물 강도 제한으로 정상 유량의 50% 수준에서 시험이 수행되었다. 75톤급 채널냉각 연소기의 저압연소시험을 통해 점화구간과 연소구간에서의 작동성과 안정성이 확인되었다. 더불어 75톤 연소기의 성능요구조건을 만족시킬 수 있을 것으로 추정할 수 있었다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1998년도 제17회 KOSCI SYMPOSIUM 논문집
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• pp.31-36
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• 1998

An experimental study has been performed to characterize fundamental aspects of VOCs removal using non-thermal palsma technique. The removed VOCs in the present study are toluene ($C_6H_5CH_3$), ethene ($C_2H_4$), propene ($C_3H_6$) which are typical air pollutants generated from industry and automobile engines. The non-thermal plasma used in the present experiments has been produced in a wire-cylinder reactor with pulsed corona or a packed-bed reactor filled with ceramic bead. These differently generated non-thermal plasma have been visualized with an intensified CCD. The images of non-thermal plasma have been used for optimal design of a corona reactor used in the present study. The experimental results show that the removal efficiencies of VOCs with non-thermal plasma are dependant on the reactivity of VOCs with OH, O, and $O_3$. The results also show that the removal efficiencies of VOCs decrease significantly when VOCs are treated with NO that is also oxidized in the presence of OH, O, and $O_3$.

• 대한기계학회논문집B
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• 제32권8호
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• pp.636-644
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• 2008

The objective of this paper is to investigate characteristics of an autothermal reformer at various operating conditions. Numerical method has been used, and simulation model has been developed for the analysis. Pseudo-homogeneous model is incorporated because the reactor is filled with catalysts of a packed-bed type. Dominant chemical reactions are Full Combustion reaction, Steam Reforming(SR) reaction, Water-Gas Shift(WGS) reaction, and Direct Steam Reforming(DSR) reaction. Simulation results are compared with experimental results for code validation. Operating parameters of the autothermal reformer are inlet temperature, Oxygen to Carbon Ratio(OCR), Steam to Carbon Ratio(SCR), and Gas Hourly Space Velocity(GHSV). Temperature at the reactor center, fuel conversion, species at the reformer outlet, and reforming efficiency are shown as simulation results. SR reaction rate is improved by increased inlet temperature. Reforming efficiency and fuel conversion reached the maximum at 0.7 of OCR. SR reaction and WGS reaction are activated as SCR increases. When GHSV is increased, reforming efficiency increases but pressure drop from the increased GHSV may decrease the system efficiency.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.71-74
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• 2010

한국형발사체 엔진에 사용될 것으로 예상되는 75톤급 연소기의 기술검증시제를 이용하여 2회 연소시험을 수행하였다. 설비 공급 능력과 구조물 강도 제한으로 정상 유량의 50% 수준에서 시험이 수행되었다. 채널냉각 연소기를 이용한 저압연소시험을 통해 점화구간과 연소구간에서의 신뢰도와 안정성이 확인되었다. 더불어 75톤 연소기가 성능요구조건을 만족시킬 수 있을 것으로 추정할 수 있었다.