• 한국수소및신에너지학회논문집
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• 제26권2호
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• pp.164-169
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• 2015

Recent research has focused on alternative fuel to improve engine performance and to comply with emission regulation. Finding an alternative fuel and reducing environment pollution are the main goals for future internal combustion engines. The purpose of this study is to obtain low-emission and high-efficiency by hydrogen enriched CNG fuel in SI engine and is to clarify the effects of hydrogen enrichment in CNG fuelled engine on exhaust emission and performance. An experimental study was carried out to obtain fundamental data for performance and emission characteristics of hydrogen enrichment in SI engine. The experiment was conducted at 2500 rpm, bmep 2 bar, 4 bar conditions while CNG fuel was mixed with 10, 20 and 30% hydrogen blends. From the experimental results, combustion duration was shortened due to rapid flame propagation velocity of hydrogen and these were attributed to the burning velocity increasing exponentially with increasing hydrogen blending ratio. Hydrogen has much wider flammable limit than methane, gasoline and the minimum ignition energy is about an order of magnitude lower than for other combustion. By adding hydrogen, $CO_2$ and HC were reduced. However, $NO_X$ was increased dut to high rate of heat release for hydrogen substitutions.

• 한국수소및신에너지학회논문집
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• 제26권1호
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• pp.15-20
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• 2015

During the liquefaction of hydrogen, the ortho hydrogen is converted into the para form with heat release that evaporates the liquefied hydrogen into the gaseous one backwards. The ortho-para conversion catalysts are usually used during liquefaction to avoid such boil-off. In order to compare and analyze the performance of the ortho-para hydrogen conversion catalysts, in-situ FT-IR device was designed and manufactured to measure the para hydrogen conversion rate in real-time. $LaFeO_3$ and $La_{0.7}Sr_{0.3}Cu_{0.3}Fe_{0.7}O_3$ perovskite catalysts were prepared by the citrate sol-gel method and their spin conversion characteristics from ortho to para hydrogen were investigated by in-situ FTIR spectroscopy at 17K. It was found that the spin conversion was affected by surface area, particle size, and crystallite size of the catalysts. Thus, the $La_{0.7}Sr_{0.3}Cu_{0.3}Fe_{0.7}O_3$ perovskite catalyst that had higher surface area, higher crystallite size, and smaller particle size than $LaFeO_3$ showed the better spin conversion property of 32.3% at 17K in 120min interaction with the perovskite catalysts.

• Journal of Advanced Marine Engineering and Technology
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• 제38권9호
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• pp.1081-1086
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• 2014

본 연구는 4실린더 커먼레일 디젤기관에서 식물성 바이오 연료인 카롤라유(Canola oil)와 디젤연료를 혼합하여 사용하였을 때 바이오디젤 혼합율과 엔진 회전수 변화에 따른 연소 및 배기 배출물 특성을 조사하기 위하여 실험을 수행하였다. 실험 결과에 의하면 엔진 회전수 1,000, 1,500, 2,000(rpm)에서 연소 압력은 바이오디젤 혼합율이 증가할수록 감소하고, 2500rpm에서는 바이오디젤 혼합율이 증가할수록 증가 하였으며, 열 발생율은 바이오디젤 혼합율이 증가 할수록 모두 증가하였다. 연료 소비율은 바이오디젤 혼합율이 증가할수록 엔진 회전수가 상승할수록 증가하였다. CO 배출물은 엔진 회전수가 상승할수록, 바이오디젤 혼합율이 증가할수록 감소하였다. $CO_2$, NOx, 배출물은 엔진 회전수가 상승할수록 바이오디젤 혼합율이 증가할수록 증가하였다.

• 한국화재소방학회논문지
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• 제30권6호
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• pp.37-42
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• 2016

본 연구는 화재전파해석 모델을 이용하여 화재 위험성 평가에 적용되는 설계화재 구성의 적용가능성을 파악하고자 한다. 화재전파해석을 위해 열중량분석과 시편연소실험이 수행되었으며 실험에서 얻어진 물성을 FDS 열해리 모델에 적용하여 격자크기에 따른 화재해석을 수행하였다. 해석 결과 전체적인 화재성장특성은 실화재 실험결과와 큰 차이를 보였으나 초기 피크 발열량과 전체 방출 열에너지는 약 30% 이내에서 유사한 예측결과를 보였다. 본 연구의 해석모델은 화재성장율이나 최대발열량 도달시간 등과 같은 화재성장특성을 예측하는데 한계를 보였다. 그러나 지속적인 모델의 개선 및 재료 물성의 상세연구를 통해 설계화재시나리오 구성에 있어서 화재모델의 적용성이 있음을 보여준다.

• 한국화재소방학회논문지
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• 제30권3호
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• pp.23-30
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• 2016

현재, 국내 랙크식 창고의 소화설비들은 연면적 및 층수만을 고려하는 평면적인 입장에서의 사양설계로 이루어지고 있다. 하지만 수직적인 구조를 갖는 랙크식 창고는 평면적인 소화설비뿐만 아니라 입면적인 측면도 함께 고려되어져야 하며, 상황에 따른 적절한 성능설계를 지향하기 위해서는 랙크 내 적재되는 물품의 화재하중 산정이 우선시되어야 한다. 이에 본 연구에서는 국내 현장조사 결과와 국외 적재물품 위험도등급 등을 함께 고려하여 구성된 표준 파렛트단위 적재물품(파렛트 +박스단위 적재물품 +비닐포장재)의 화재특성을 분석하였다. 그 결과로 화재하중 산정을 위한 열방출율 및 화재감지기 등의 소화설비를 위한 환경조건인 연기발생률을 도출하였다.

• 한국분무공학회지
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• 제25권1호
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• pp.21-26
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• 2020

The objective of this work is to numerically reveal the effect of equivalence ratio change on the simultaneous reduction of NO_X and soot emissions from the simulated-EGR compression ignition engine containing CO₂. An experiment was conducted by using a single-cylinder common-rail injection system engine, an intake control system, and exhaust emissions analyzers. The numerical analysis results were validated under the same experimental conditions. To investigate the effect of equivalence ratio by simulated-EGR containing CO₂, the O₂, N₂, and CO₂ mole fraction were changed in the initial air conditions to the cylinder. The results were analyzed in terms of peak cylinder pressure, indicated mean effective pressure, indicated specific nitrogen oxide, and indicated specific soot. It was revealed that ignition delay characteristics and heat release rate (ROHR) characteristics were not significantly different according to the equivalence ratio. However, as the equivalence ratio increased from 0.68 to 0.83, the maximum combustion pressure and IMEP decreased by about 6.5% and 9.4%, respectively. In the case of ISFC, as is well known, the trend is opposite of IMEP. In the case of ISNO, as the equivalence ratio increased, less NO was generated, and as the equivalence ratio increased by 0.05, the ISSoot value of about 10% increased.

• 한국화재소방학회논문지
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• 제33권4호
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• pp.83-88
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• 2019

본 연구에서는 가솔린 풀화재 시 호흡량과 호흡주기 변화에 따라서 인체에 흡입되는 연소가스 농도에 관한 기초 연구를 수행하였다. 이를 위해서 ISO 9705 룸코너 시험기의 1/4 크기인 구획공간을 제작하였으며, 호흡유량 (2, 6, 10) LPM 에 대해서 연소가스를 지속적으로 흡입하는 경우(Infinity)와 호흡주기가 2 s와 5 s인 각각의 경우 일산화탄소와 산소 농도를 측정하였다. 그 결과 구획 공간에서 가솔린 풀화재의 이론 발열량이 5.34 kW인 연소조건에서 산소와 이산화탄소의 경우 모두 호흡주기에 비해서 호흡량이 증가함에 따른 농도 편차가 더욱 높은 것을 확인하였다. 또한, 호흡 주기가 증가함에 따라서 산소 농도의 경우 최소값의 변화가 평균값에 비해서 더욱 크게 나타난 반면 일산화탄소 농도의 경우 평균값의 변화가 최대값에 비해서 더욱 크게 나타났다. 이러한 결과는 화재 시 피난자의 호흡 특성에 따라서 실제 흡입되는 유해가스의 농도를 고려하여야 보다 정확한 피난 특성을 예측할 수 있는 것으로 사료된다.

• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.227-235
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• 2012

Finding an alternative fuel and reducing environmental pollution are the main goals for future internal combustion engines. The purpose of this study is to obtain low-emission and high-efficiency by hydrogen enriched LPG fuel in constant volume chamber. An experimental study was carried out to obtain fundamental data for the combustion and emission characteristics of pre-mixed hydrogen and LPG in a constant volume chamber (CVC) with various fractions of hydrogen-LPG blends. To maintain equal heating value of fuel blend, the amount of LPG was decreased as hydrogen was gradually added. Exhaust emissions were measured using a HORIBA exhaust gas analyzer for various fractions of hydrogen-LPG blends. The results showed that the rapid combustion duration was shortened, and the rate of heat release elevated as the hydrogen fraction in the fuel blend was increased. Moreover, the maximum rate of pressure rise also increased. These phenomena were attributed to the burning velocity which increased exponentially with the increased hydrogen fraction in the $H_2$-LPG fuel blend. Exhaust HC and $CO_2$ concentrations decreased, while NOX emission increased with an increase in the hydrogen fraction in the fuel blend. Our results could facilitate the application of hydrogen and LPG as a fuel in the current fossil hydrocarbon-based economy and the strict emission regulations in internal combustion engines.

• 대한기계학회논문집B
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• 제22권9호
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• pp.1317-1324
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• 1998

In general, DI gasoline engine has the advantages of higher power output, higher thermal efficiency, higher EGR tolerance and lower emissions due to the operation characteristics of increased volumetric efficiency, compression ratio and ultra-lean combustion scheme. In order to apply the concept of stratified charge into direct injection gasoline engine, some kinds of methodologies have been adapted in various papers. In this study, a reflector was adapted around the injector nozzle to apply the concept of stratified charge combustion which leads the air-fuel mixture to be rich near spark plug. Therefore, the mixture near the spark plug is locally rich to ignite while the lean mixture is wholly introduced into the combustion chamber. The characteristics of combustion is analyzed with the variations of fuel injection pressure and load in a stratified -charge direct injection single cylinder gasoline engine. The obtained results are summarized as follows ; 1. The MBT spark timing approached to TDC with the increase of load on account of the increase of evaporation energy, but has little relation with fuel injection pressure. 2. The stratification effects are apparent with the increase of injection pressure. It is considered by the development of secondary diffusive combustion and the increase of heat release of same region, but proceed rapidly than diesel engine. Especially, in the case of high pressure injection (l70bar) and high load (3.0kgf m), the diffusive combustion parts are developed excessively and results in the decrease of peak pressure than in the case of middle load. 3. The index of engine stability, COVimep value, is drastically decreased with the increase of load. 4. To get better performance of DI gasoline engine development, staged optimizaion must be needed such as injection pressure, reflector, intake swirl, injection timing, chamber shape, ignition system and so on. In this study, the I50bar injection pressure is appeared as the optimum.

• 대한기계학회논문집B
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• 제25권2호
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• pp.225-234
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• 2001

This paper represents the vector fields, three dimensional mean velocities, the turbulent intensities, the turbulent kinetic energy, and the Reynolds shear stresses in the X-Y plane of gas swirl burner with a cone type baffle plate measured by using X-probe from hot-wire anemometer system. This experiment is carried out at flow rates 350 and 450ℓ/min respectively, which are equivalent to the combustion air flow rate necessary for heat release 15,000 kcal/hr in gas furnace, in the test section of subsonic wind tunnel. The vector plot shows that the maximum axial mean velocity component exists in the narrow slits situated radially on the edge of gas swirl burner, for that reason, there is some entrainment phenomena of ambient air in the outer region of burner. Moreover, mean velocities in the initial region are largely distributed near the outer region of burner at Y/R≒0.97, but they diffuse and develop into the center flow region of burner according to the increase of axial distance. The turbulent intensities and the turbulent kinetic energy due to large inclination of mean velocity and swirl effect show that the maximum value in the initial region of burner is formed in the narrow slits situated radially on the edge of gas swirl burner and large values are mainly formed in the entire region of burner after X/R=2.4358, hence, the combustion reaction is anticipated to occur actively near this region. And the Reynolds shear stresses are also largely distributed from slite to vanes of gas swirl burner in the intial region, but their values largely disappear after X/R=3.2052.