• 한국자동차공학회논문집
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• 제15권4호
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• pp.146-153
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• 2007

The detailed chemistry with reaction mechanism of GRI 2.11, which consists of 49 species and 279 elementary reactions, have been numerically conducted to investigate the flame structure and NO emission characteristics in a non-premixed counterflow flame of blended fuel of $H_2/CO_2/Ar$. The combination of $H_2,\;CO_2$, and Ar as fuel is selected to clearly display the contribution of hydrocarbon products to flame structure and NO emission characteristics due to the breakdown of $CO_2$. Radiative heat loss term is involved to correctly describe the flame dynamics especially at low strain rates. All mechanisms including thermal, $NO_2,\;N_2O$, and Fenimore are also taken into account to separately evaluate the effects of $CO_2$ addition on NO emission characteristics. The increase of added $CO_2$ quantity causes flame temperature to fall since at high strain rates diluent effect is prevailing and at low strain rates the breakdown of $CO_2$ produces relatively populous hydrocarbon products and thus the existence of hydrocarbon products inhibits chain branching. It is also found that the ratio of the contribution by Fenimore mechanism to that by thermal mechanism in the total mole production rate becomes much larger with increase in the $CO_2$ quantity and strain rate, even though the absolute quantity of NO production is deceased. Consequently, as strain rate and $CO_2$ quantity increase, NO production by Fenimore mechanism is remarkably augmented.

• 콘크리트학회논문집
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• 제28권6호
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• pp.647-653
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• 2016

본 연구에서는 FA (Fly Ash)를 20%치환한 배합에 대하여 TDFA (Tire Derived Fuel Ash)를 3.0~12.0%까지 중량 치환하면서 내구성 평가를 수행하였다. TDFA는 열병합발전소에서 열효율을 높이기 위해 폐타이어를 혼소시킨 뒤 발생한 산업부산물로서 국내에서 콘크리트에 적용한 연구는 없는 상태이다. 이를 위해 물-결합재를 50%, FA를 20% 치환한 Control 콘크리트를 제조하였으며, TDFA를 치환하면서 압축강도, 촉진 탄산화 시험, 촉진염해 시험, 공극구조평가를 수행하였다. 압축강도, 탄산화, 공극구조에서는 12%까지 TDFA를 FA와 치환해도 동등이상의 성능을 확보하였다. 특히 염해에 대해서는 TDFA의 치환률의 증가에 따라 뚜렷한 염화물 확산계수의 감소를 나타내어 최종적으로 75.3~70.9%까지 염화물 확산계수가 감소하였다. TDFA를 혼입한 콘크리트 배합시, 워커빌리티의 확보가 가능하다면 TDFA를 혼입한 콘크리트는 내구성 개선에 효과적일 것으로 판단된다.

• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.274-284
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• 2012

Recently, gasification technology for coal blended with biomass has been an issue. Especially, An advantages of coal blended with biomass are 1) obtaining high cold gas efficiency, 2) obtaining syn-gas of high-high heating value (HHV), and 3) controlling occurrence of $CO_2$. In this study, the efficiency and characteristic of 300 MW Shell type gasifier were predicted using CFD simulation. The CFD simulation was performed for biomass coal blending ratios of 0~0.2, 0.5, 1 and $O_2$/fuel ratios of 0.5~0.84. Kinetic parameters (A, $E_a$) obtained by $CO_2$ gasification experiment were used as inputs for the simulation. In results of CFD simulation, residence times of particle in 300MW Shell type gasifer presented as 7.39 sec ~ 13.65 sec. Temperature of exit increased with $O_2$/fuel ratio as 1400 K ~ 2800 K, while there is not an effects of biomass coal blending ratios. Considering both aspects of temperature for causing wall slagging and high cold gas efficiency, the optimal $O_2$/fuel ratio and blending ratio were found to be 0.585 and 0.05, respectively.

• 한국분무공학회지
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• 제25권3호
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• pp.111-118
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• 2020

This paper describes the effect of DME, biodiesel blended fuels on the macroscopic spray characteristics in a high pressure diesel injection system using Background Oriented Schlieren (BOS) method. The BOS method for visualization of impingement evaporation sprays to analyze macroscopic spray properties and evolutionary processes. In this work, the blending ratio of DME in the blended fuel are 0, 50, 100% by weight ratio. In order to investigate the macroscopic impinged spray characteristics under the various injection parameters and blending ratio. In this work, a mini-sac type single-hole nozzle injector with nozzle hole was length 0.7 mm and diameter of 0.3 mm was used. According to the result, the spray area of the collision wall increased as the DME mixing ratio increased, and the evolutionary pattern showed a stepwise increase due to the collision effect of the wall. Also, results of impinged spray area were increased according to increasing injection pressure.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.41-44
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• 2014

This study focused on the effect of the biomass blended ratio on air-staged pulverized coal furnace. The hybrid NOx reduction technology between fuel blending and air staging has been applied in an air-staged pulverized coal fired furnace. The results indicated that co-firing biomass with coal could reduce NOx emissions in an air-staged combustion. In addition, carbon burnout and flame temperature increased under the air-staged condition. A dominant synergistic effect on NOx reduction and carbon burnout was observed when biomass co-firing with coal was applied in air staged combustion.

• 한국자동차공학회논문집
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• 제2권3호
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• pp.85-93
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• 1994

The engine performance and combustion characteristics of diesel oil and fish oil blended with diesel oils were investigated at various blending rate of fish oil in a diesel engine. The maximum pressure showed no significant difference among test fuels at low load, but it was higher as the blending rate of fish oil increases at high load. Increasing the blending rate of fish oil, the rate of heat release and burned fraction were higher than those of diesel oil. The ignition delay became longer than that of diesel oil as the blending rate of fish oil increases, and its differences were larger at different loads. The combustion duration and density of smoke were shorter and lower as the blending rate of fish oil increases. The rate of fuel consumption showed no significant difference between diesel oil and fish blended with diesel oils.

• Journal of Biosystems Engineering
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• 제33권2호
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• pp.124-129
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• 2008

In this study, fuel qualities including kinematic viscosity and pour point in the various temperature, calorific value and combustion characteristics of two biodiesels based on the soybean and waste oil blended with light oil were investigated and discussed in order to figure out to confirm fuel compatibility taking the place of light oil in the hot air heater or boiler. As biodiesel content ratio increased calorific value of biodiesel decreased, and the difference was 13% between 100%-biodiesel and light oil. In general, pour points of the biodiesels were higher than light oil, and as biodiesel content ratio increased pour point increased. About 15 cSt was the pour point of biodiesels and light oil, which occurred at 3 to $4^{\circ}C$ in the biodiesels and $-25^{\circ}C$ in the light oil. Flame dimensions of biodiesels and light oil were almost same at the same combustion condition in the burner of the hot air heater. CO concentrations in the exhaustion gas were far lower than those of the light oil. Though pour point of biodiesel is a little inferior to light oil, still biodiesel can be an alternative fuel substituting for light oil in combustion system without much modifying the current oil combustion mechanism.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.179-182
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• 2014

A comparative DNS study of the ignition characteristics of dual-fueled reactivity controlled compression ignition (RCCI) and stratification charge compression ignition (SCCI) is investigated using a 116-species reduced primary reference fuel (PRF) mechanism. In the RCCI combustion, two PRF fuels (n-heptane and iso-octane) with opposite autoignition characteristics are separatedly supplied and in-cylinder blended such that spatial variations in fuel reactivity, fuel concentration and temperature are achieved. In the SCCI combustion, however, just a single fuel (PRF50) is used such that only fuel concentration and temperature inhomoginieties are obtained. Because three factors, rather than only two as in SCCI combustion, govern the overall RCCI combustion, combustion timing and combustion duration or heat release rate of RCCI combustion are flexibly and effectively controlled. It is found that the overall RCCI combustion occurs much earlier and its combustion duration is longer compared to SCC combustionI. Moreover, the negative temperature coefficient (NTC) has a positive effect on enhancing RCCI combustion by inducing a shorter combustion timing and a longer combustion duration as a result of the occurrence of a predominant low-speed deflagration-combustion mode.

• 한국자동차공학회논문집
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• 제19권4호
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• pp.32-37
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• 2011

Biodiesel fuel is already remarkable alternative fuel in many countries. So, many studies are performed on the environmental or economic effects as well as the characteristics of diesel engine fueled biodiesel in combustion and emission. In this study, an CRDI diesel engine used to commercial vehicle was fueled with diesel fuel and 20% biodiesel blended fuel (BDF 20%) with city mode in excess of 300 hours. Engine dynamometer testing was completed at regularly scheduled intervals to monitor the engine performance and exhaust emissions. The engine performance and exhaust emissions were sampled at 1 hour interval for analysis. To check the engine parts (valve and injector), the engine was inspected after test. It was concluded that there were no unusual deteriorations of the engine, or any unusual changes in engine power and exhaust emissions in spite of operation of 300 hours with BDF 20%.

• 오토저널
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• 제11권1호
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• pp.31-43
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• 1989

제2보 (2)에서는 식물유를 연료로 사용할 경우 문제점인 시동성, 내구성 및 카본생성을 억제하기 위하여 물리적인 방법으로 해결책을 모색하였다. 그러나, 본 연구는 기관자체는 전혀 변형시키지 않고, 점도저감을 위하여 화학적인 방법 즉, 식물유를 알콜과 반응시켜 에스테르변 환을 하여 해결하려는 방법으로, 에스테르화한 연료를 사용하였을 때의 기관성능 및 카본 퇴적 문제를 비교, 시험한 것이다. 또, 기름이 식물유와 같이 지방산으로 이루어져 있다면, 어느 기름도 에스테르 변환이 가능하기 때문에, 생선기름인 정어리기름의 에스테르연료도 사용하여 그 이용 가능성을 확실히 하였다. 또한, 각종 연료의 연소성에 관하여 보다 상세한 검토를 하기 위하여, 이들의 연소율 파형을 2개의 Wiebe의 연소함수의 조합으로 표현함과 동시에 연소율 파형을 구성하는 각 변수를 해석함으로써, 기관성능치와 연소성과의 정량적인 관계에 대해서도 조사한 것이다.