• 한국수소및신에너지학회논문집
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• 제31권3호
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• pp.314-321
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• 2020

In this work, a preliminary design of an inlet guide vane and runner for developing a 2.5 kW hydraulic turbine was conducted by using computational fluid dynamic analysis. Three-dimensional Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model were used to analyze the fluid flow in the hydraulic turbine. The hexahedral grid system was used to construct computational domain, and the grid dependency test was performed to obtain the optimal grid system. Velocity triangle diagram considering the flow angles of the inlet guide vane and runner was analyzed to obtain a basic geometry of the inlet guide vane and runner. Through modification of the preliminary design, the hydraulic performances of the turbine have improved under overall drop conditions. Especially, the efficiency and power of the turbine increased by 0.95% and 1.45%, respectively, compared to those of the reference model.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2002년도 춘계 학술발표회 논문집
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• pp.179-183
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• 2002

가압유동층은 복합발전이 가능하며, 총괄열효율이 높을 뿐만 아니라 가압에 의한 장치의 소형화 및 탈황효율의 증대 그리고 배가스 중의 NOx 농도를 줄일 수 있기 때문에 공해 배출 물질의 감소 등 상압유동층 연소에 비하여 많은 장점들을 가지고 있어 선진 국가들에서도 이미 상당한 진전을 보이고 있으며, 중국이나 일본에서도 차세대 연소기술로 이에 대한 연구가 활발히 진행되고 있다.(중략)

• 한국수소및신에너지학회논문집
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• 제29권6호
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• pp.559-569
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• 2018

Catalytic supports made of carbon have many advantages, such as high coking resistance, tailorable pore and surface structures, and ease of recycling of waste catalysts. Moreover, they do not require pre-reduction. In this study, ash-free coal (AFC) was obtained by the thermal extraction of carbonaceous components from raw coal and its performance as a carbon catalytic support was compared with that of well-known activated carbon (AC). Nickel was dispersed on the carbon supports and the resulting catalysts were applied to the steam reforming of toluene (SRT), a model compound of biomass tar. Interestingly, nickel catalysts dispersed on AFC, which has a very small surface area (${\sim}0.13m^2/g$), showed higher activity than those dispersed on AC, which has a large surface area ($1,173A/cm^2$). X-ray diffraction (XRD) analysis showed that the particle size of nickel deposited on AFC was smaller than that deposited on AC, with the average values on AFC ${\approx}11nm$ and on AC ${\approx}23nm$. This proved that heteroatomic functional groups in AFC, such as carboxyls, can provide ion-exchange or adsorption sites for the nano-scale dispersion of nickel. In addition, the pore structure, surface morphology, chemical composition, and chemical state of the prepared catalysts were analyzed using Brunauer-Emmett-Taylor (BET) analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, and temperature-programmed reduction (TPR).

• Korean Chemical Engineering Research
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• 제53권2호
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• pp.231-235
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• 2015

저등급석탄을 건조하고 무결합제로 성형하는 경우에 대한 조건별 특성 연구를 수행하였다. 인도네시아 산 두 종류의 저등급석탄을 전기오븐에서 건조시킨 후 성형에 사용하였으며, 석탄의 수분별, 입도별, 성형압력별, 보관일수별로 압축강도를 측정하여 성형특성을 비교하였다. 석탄의 수분별로는 10~15 wt%에서 가장 높은 강도를 나타내었으며, 석탄의 종류에 따라 가장 높은 강도를 갖는 수분 함량의 차이가 있었다. 석탄의 입도는 적을수록 높은 강도를 나타내며 입도가 증가할수록 수렴하는 경향을 나타내었다. 성형압력이 높아질수록 성형 강도가 높게 나타났으나, 약 300 kN 이상에서는 크게 차이를 보이지 않았다. 보관일수별로는 약 일주일 동안 강도가 급격히 감소한 후 수렴하는 경향을 보였다. 이상의 결과는 저등급석탄의 산지에서 고품위화시킨 석탄을 국내 반입하는 경우에 대한 성형석탄 제조 및 관리의 지침으로 활용될 수 있다.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2003년도 연료전지심포지움 2003논문집
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• pp.151-154
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• 2003

The lap-top with a integrated fuel cell system presented here proves that these solutions have a great potential. Though, there are things that have to be improved before they are introduced to the marked. In this system, heat and water management as well as dead end operation are critical issues which must be directly addressed in further research. Both modified stack design and other new cooling techniques are possible ways to continue the work.

• Korean Chemical Engineering Research
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• 제54권2호
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• pp.234-238
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• 2016

본 연구에서는 용매추출 공정 중 최종 건조 과정에서 회수방식을 달리하여 무회분석탄을 제조한 후 물리적 특성과 화학적 구조를 비교하였다. 무회분석탄 제조에는 아역청탄 등급의 Kideco coal과 극성용매인 N-methyl-2-pyrrolidone(NMP)를 사용하였으며, 회수방식으로는 감압건조, 희석침전, 분무건조 방식을 사용하였다. 제조된 무회분석탄의 물성변화를 확인하기 위해 공업분석, 원소분석, 발열량분석을 실시하였고, 화학적 구조를 알아보고자 FT-IR, NMR 분석을 하였다. 공업분석을 통해 무회분석탄의 회분함량이 원탄에 비해 줄어든 것을 확인하였다. FT-IR 분석 결과 감압건조로 회수한 샘플은 추출용매의 피크가 나타나는 반면 희석침전방식으로 제조한 무회분석탄에는 추출용매 피크가 사라지는 것을 확인하였다. 희석침전방식을 사용할 경우 다른 회수방식에 비해 저온공정이 가능하였고, 추출용매로부터 무회분석탄을 보다 확실하게 분리할 수 있었다.

• 청정기술
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• 제22권4호
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• pp.299-307
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• 2016

These days, coal is one of the most important energy resources used for transportation, industry, and electricity. There are two types of coal: high-rank and low-rank. Low-rank coal has a low calorific value and contains large amounts of useless moisture. The quality of low-rank coal can be increased by simple drying technology and it needs to be stabilized by hydrocarbons (e.g. palm acid oil, PAO) to prevent spontaneous combustion and moisture re-adsorption. Spontaneous combustion becomes a major problem during coal mining, storage, and transportation. It can involve the loss of life, property, and economic value; reduce the quality of the coal; and increase greenhouse gas emissions. Besides spontaneous combustion, moisture re-adsorption also leads to a decrease in quality of the coal due to its lower heating value. In this work, PAO was used for additive to stabilize the upgraded coal. The objectives of the experiments were to determine the stabilization characteristic of coal by analyzing the behavior of upgraded coal by drying and PAO addition regarding crossing-point temperature of coal, the moisture behavior of briquette coal, and thermal decomposition behavior of coal.

• 한국수소및신에너지학회논문집
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• 제28권6호
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• pp.721-728
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• 2017

In this work, an one-dimensional analysis on spontaneous combustion in a coal stockpile was conducted using a commercial software $gPROMS^{(R)}$ based on assumption suggested by Arioy and Akgun. According to them, it is assumed that there is temperature difference between the surface of coal particle and the gas surrounded around the particle, and it is also assumed that the velocity of the gas is constant and thus oxygen is fed to the stockpile with same velocity. The higher temperature zone is formed to the surface of the coal stockpile at the initial phase and it became deepen as time is taken. Finally it was found that the temperature difference between coal particle and the gas was calculated as $57^{\circ}C$ and spontaneous combustion have not been occurred during 6 months since coal was piled in the stock.

• 한국수소및신에너지학회논문집
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• 제20권6호
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• pp.519-525
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• 2009

The catalytic steam reforming of woody biomass tar and soot to convert a synthetic gas containing hydrogen was investigated by using a bench-scale biomass gasification system. One commercial nickel-based catalyst, Katalco 46-6Q, and two different kinds of natural minerals, dolomite and olivine, were tested as a reforming catalyst at various reforming temperatures. The reaction characteristics of woody biomass tar were also investigated by TGA at a variety of heating rates. With all three catalysts conversion efficiency of tar and soot increased at increasing temperature. The reforming of tar and soot in the synthetic gas induce the increase of combustible gases such as $H_2$, CO and $CH_4$ in the product gas. The nickel-based catalyst showed a higher tar and soot conversion efficiency than mineral catalysts under the same temperature conditions.

• 청정기술
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• 제19권4호
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• pp.469-475
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• 2013

본 연구에서는 팜 잔사유를 이용하여 고품위화된 저등급 석탄의 건조 안정화 특성을 알아보았다. 인도네시아 저등급 석탄인 에코탄을 사용하였고, 팜지방산증류물(palm fatty acid distillate, PFAD)을 혼합시킨 후 $107^{\circ}C$ 질소분위기에서 건조하였으며 그 후에 안정화 특성을 평가하였다. 교차점온도(crossing-point temperature, CPT) 측정을 통해 자연발화 경향을 확인하였으며, 저온산화 실험을 통해 $CO_2$, CO 가스 배출량은 건조석탄보다 고품위 석탄이 감소하는 것을 확인하였다. 수분 재흡착 실험을 통해 고품위 석탄이 대기방치와 항온항습 분위기에서 수분 재흡착이 줄어드는 것을 확인하였다. 고품위화된 석탄은 PFAD의 표면코팅을 통해 안정화 되며, 함량이 증가할수록 안정화도가 높아졌다.