• 한국연소학회지
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• 제18권4호
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• pp.1-11
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• 2013

The oxy-fuel combustion is $CO_2$ capture technology that uses mixture of pure $O_2$ and recirculated exhaust as oxidizer. Currently some Oxy-fuel power plants demonstration project is underway in worldwide. Meanwhile research project for converting 125 MWe Young-Dong power plant to 100 MWe oxy-fuel power plants is progress. In this paper, 1 D process analytical approach was applied for conducting process design and operating parameters sensitivity analysis for oxy-fuel combustion of Young-Dong power plant. As a result, appropriate gas recirculation rates was 74.3% that in order to maintain normal rating superheater, reheater steam temperature and boiler heat transfer patterns. And boiler efficiency 85.0%, CPU inlet $CO_2$ mole concentration 71.34% was predicted for retrofitted boiler. The oxygen concentration in the secondary recycle gas is predicted as 27.1%. Meanwhile the oxygen concentration 22.4% and moisture concentration 5.3% predicted for primary recycle gas. As the primary and secondary gas recirculation increases, then heat absorption of the reheater is tends to increases whereas superheater side is decreased, and also the efficiency is tends to decrease, according to results of sensitivity analysis for operating parameters. In addition, the ambient air ingression have a tendency to lead to decline of efficiency for boiler as well as decline of $CO_2$ purity of CPU inlet.

• 한국분무공학회지
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• 제8권1호
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• pp.9-15
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• 2003

The liquid phase LPG injection (LPLI) system is considered as one of the next generation fuel supply systems for LPG, vehicles, since it can accomplish the higher power, higher efficiency, and lower emission characteristics than the existing mixer type fuel supply system. However, during the injection of liquid LPG fuel into the inlet duct of an engine, a large quantity of heat is extracted due to evaporation of fuel. A problem is that the moisture in the air freezes around the outlet of a nozzle, which is called icing Phenomenon. It may cause damage to the outlet nozzle of an injector. The frozen ice deposit detached from the nozzle also may cause a considerable damage to the inlet valve or valve seat. In this work, the experimental investigation of the icing phenomenon was carried out. The results showed that the icing phenomenon and process were mainly affected by humidity of inlet air instead of the air temperature in the inlet duct. Also, it was observed that the icing occurs first in the inlet of a nozzle, and grows considerably at the upper part of the nozzle inlet and the opposite side of the nozzle entrance. An LPG fuel, mainly consisting of butane, has lower latent heat of vaporization than that of propane, which is an advantage in controlling the icing phenomenon.

• Environmental Engineering Research
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• 제24권4호
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• pp.529-542
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• 2019

Nowadays, drying methods for municipal solid waste quality improvement have been adopted in the developed and developing countries to valorize wastes for a renewable energy source, reduce dependency on fossil fuel and keep safer disposal at landfills. Among them, biodrying, biostabilization, thermal drying and solar drying are the most common. Drying of municipal solid waste could offer several environmental and economic benefits. Therefore, this review highlighted the drying methods for municipal solid waste quality improvement around the world and compared them based on the reduction of moisture, weight and volume of municipal solid wastes against drying temperature and time by using statistical analysis. It was observed that the drying temperature of different drying methods accounted for 115 ± 40℃ for thermal drying, 59 ± 37℃ for solar drying, 55 ± 15℃ for biodrying and 58 ± 11℃ for biostabilization. Among the drying methods, thermal drying provided the shortest drying time. The moisture reduction, weight reduction, volume reduction and heating value increase of municipal solid waste could vary with drying temperature and time. Finally, the benefits and drawbacks of different drying methods were specified, and recommendations were made for the future efficient drying.

• 한국연소학회지
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• 제7권3호
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• pp.23-31
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• 2002

Processes in an iron ore sintering bed can characterized as a relatively uniform progress of fuel, cokes combustion and complicated physical change of solid particles. The sintering bed was modelled as an unsteady one-dimensional progress of the fuel layer, containing two phases: solid and gas. Coke added to the raw mix, of which the amount is about 3.5% of the total weight, was assumed to form a single particle with other components. Numerical simulations of the condition in the iron ore sintering bed were performed for various parameters: moisture contents, cokes contents and air suction rates, along with the various particle diameters of the solid for sensitivity analysis. Calculation results showed that the influence of these parameters on the bed condition should be carefully evaluated, in order to achieve self-sustaining combustion without high temperature section. The model should be extended to consider the bed structural change and multiple solid phase, which could treat the inerts and fuel particles separately.

• 에너지공학
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• 제19권2호
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• pp.136-142
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• 2010

국내에 수입되어 사용되고 있는 발전용 석탄 2종에 대하여 기초적인 열중량분석기를 이용한 열특성 분석실험과 대용량 시험연소로를 이용한 연소시험을 수행하였다. 실험결과 고수분탄이 비록 착화 온도가 낮고 및 연소 구간이 짧아 초기 연소특성은 좋지만 비교탄에 비해 연소완료가 빨리 종결되지 못해 결과적으로는 연소 효율이 좋지 않았으며, 고수분탄의 활성화에너지는 고수분탄이 79 kJ/mol로서 비교탄의 53 kJ/mol에 비해 높은 특성을 보였다. 또한 시험연소로 시험과정에서 고수분탄의 화염 내 검은 색의 석탄분사체(Coal Jet) 형태가 비교탄에 비해 비교적 뚜렷이 관찰되어 연소속도가 다소 떨어지는 상호 연관성이 잘 설명되었고 연소후 미연분 발생량에서도 고수분탄이 다소 높게 나타났다. 그러나 고수분탄의 경우 낮은 유황분 함량으로 인해 연소 시 황산화물 배출량이 적어 고유황 함량의 석탄과의 혼합연소 시 유용하게 활용 될 수 있을 것으로 예상되었으며, 또한 회성분 분석결과 $Na_2O$와 $K_2O$ 등의 알카리비금속화합물 함량이 기존의 역청탄에 비해 매우 적고 회분자체의 함량도 매우 낮아 회분의 융착 정도가 높지 않게 나타났다.

• KEPCO Journal on Electric Power and Energy
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• 제2권2호
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• pp.279-284
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• 2016

Assessing the handling properties of coal becomes a major issue for the operation of a fuel supply system in power plants, due to the increased types of coal imported into Korea. In this study, the cohesion strengths of 13 bituminous and sub-bituminous coals from different countries were tested by measuring the amount of force that leads to a failure of consolidated particles. The particle size was in the range of 0.1-2.8 mm, which represents the coarse particles before pulverization. While the cohesion strength was proportional to the compression force in the tested range, the effects of the surface moisture content and the weight fraction of fines were crucial for cohesive coals. At fixed conditions of surface moisture and particle size, large variations were found in the cohesion propensity between coals. For coals of 0.1-0.5 mm with the moisture added close to the critical value, cohesive coals had the density over $900kg/m^3$ after consolidation. The cohesion propensity was not correlated with the basic properties of coals with sufficient statistical significance.

• Journal of Biosystems Engineering
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• 제36권5호
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• pp.303-313
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• 2011

This study was conducted to investigate the effects of axle weight distribution and inflation pressure of tire on the fuel economy of tractors as well as operational range of tractor engine in terms of engine speed and power when a 4WD tractor of 38.2 kW rated power at 2500 rpm is used for plowing and flooded-field rotavating in paddy fields. (1) Plowing operation required an average engine power of 9.6~13.5 kW which equals 25~35% of rated PTO power. Engine speed ranged from 1,320.4 to 1,737.4 rpm, work velocity from 3.4 to 4.8 km/h, and fuel consumption from 3.2 to 4.2 L/h, respectively. (2) Flooded-field rotavating required an average engine power of 11.5~18.5 kW which equals 30~48.4% of rated PTO power. Out of this 6.2~12.2 kW was used for PTO power. Engine speed ranged from 1,557 to 2,067 rpm, work velocity from 2.5~5.4 km/h and fuel consumption from 3.2~5.5 L/h, respectively. (3) Axle weight distribution, inflation pressure of tire and moisture content of soil did not affect significantly the specific volumetric fuel consumption but affected significantly the fuel consumption per unit area of operation. Fuel savings amounted to 65% in plowing operation and 20% in flooded-field rotavating when the axle weight distribution and inflation pressure of tire were optimally adjusted. (4) Optimal adjustment of axle weight distribution and inflation pressure of tire are expected to save fuel consumption by 10~65% per unit area of operation in plowing and 10~20% in flooded-field rotavating.

• 대한환경공학회지
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• 제36권7호
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• pp.476-482
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• 2014

본 연구는 에멀젼 연료의 특성과 배출가스에 관하여 연구하였다. 엔진 배출가스 측정은 엔진 dinamometer로 실시하였다. 유화연료는 연소실내에서 미세폭발을 일으켜 연료를 잘게 쪼개어 주어 smoke를 감소시킨다. 그리고 물이 연소실내의 기화열을 빼앗아 연소실 내부의 온도를 낮추어 NOx 생성을 억제하는 효과를 갖는다. ND-13모드의 각 모드별 배출가스온도가 MDO에 비해 유화연료를 사용했을 때 낮게 나온 것으로 뒷받침 될 수 있었다. 유화연료의 함수율이 증가함에 따라 NOx와 smoke의 배출량은 줄어들었으며, 출력도 함수율 증가에 따라 유화연료 자체의 발열량 감소로 인하여 줄어든 것으로 판단된다. ND-13모드에서 MDO 유화연료를 시험결과 함수율 17% 유화연료의 NOx 감소량은 약 24%, smoke의 총감소량은 약 73%, $SO_2$ 감소량은 약 11%, 그리고 약 13%의 출력손실을 확인하였다.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.693-701
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• 2016

Steam gasification of low rank coals is possible at relatively low temperature and low pressure, and thus shows higher efficiency compared to high rank coals. In this study, the gasification reactivity of four different Indonesian low rank coals (Samhwa, Eco, Roto, Kideco-L) was evaluated in $T=700-800^{\circ}C$. The low rank coals containing $53.8{\pm}3.4$ wt% volatile matter in proximate analysis and $71.6{\pm}1.2$ wt% carbon in ultimate analysis showed comparable gasification reactivity. In addition, $K_2CO_3$ catalyst rapidly accelerated the reaction rate at $700^{\circ}C$, and all of the coals were converted over 90% within 1 hour. The XRD analysis showed no significant difference in carbonization between the coals, and the FT-IR spectrum showed similar functional groups except for differences due to moisture and minerals. TGA results in pyrolysis ($N_2$) and $CO_2$ gasification atmosphere showed very similar behavior up to $800^{\circ}C$ regardless of the coal species, which is consistent with the steam gasification results. This confirms that the indirect evaluation of the reactivity can be made by the above instrumental analyses.

• 한국농공학회논문집
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• 제64권2호
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• pp.57-69
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• 2022

This study analyzes the fuel conditions and environmental effects of converting heating in rural villages that rely on fossil fuels into wood fuel. In particular, we tried to derive the most important considerations when using wooden chips as fuel in aging agricultural villages where various variables such as weather, facility characteristics, fuel quality, and maintenance capabilities work. Above all, an experiment was conducted by comparing it with oak trees to determine whether Italian poplar, a representative attribute water created to supply fuel wood in Korea, is suitable for heating fuel. Through experiments, 1) Even though the supply of poplar wood chips during 10 hours of operation was 60.74 kg less than that of hardwood chips, the production of hot water was 140 kWh higher. 2) The higher the exhaust gas temperature, the proportional (increase) oxygen concentration and inversely (decrease) PM and CO emissions. 3) Poplar has twice as much ash content as hardwood and three times more fine dust has been detected, but it meets all the standards for wood quality at the Korea Forest Science Institute. 4) Under the condition that there is a difference in water content (7.7%), hardwood cost 1.13 times more wood chips per 1 MWh than poplar, and even if the water content is corrected equally, hardwood cost 1.05 times more per 1 MWh than poplar. 5) In conclusion, it was proved that the fuel possibility, economic possibility, and environmental possibility of poplar wood chips are sufficient.