• Journal of Advanced Marine Engineering and Technology
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• v.35 no.1
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• pp.53-59
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• 2011

The using of diesel engine will be increased in the world for fuel economy. But diesel engine emits harmful emissions such as much NOx, smoke etc. In this study, experiments were performed to investigate the spray characteristics of diesel spray in a common-rail system according to fuel temperature, injection pressure, injection period and fuel viscosity etc. using a high speed video camera. Diesel oil has different spray patten due to injection pressure and injection period in a common-rail system. A Filter pressure was influenced by fuel temperature which was turned to fuel viscosity related to a fluid flowing. The effect of the bio-diesel fuel mixing ratio on the spray and atomization characteristics was also investigated at various experimental conditions. It shows that the droplet atomization characteristics of bio-diesel fuel showed deteriorated results as the mixing ratio of biodiesel increased because of the high viscosity.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.29-38
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• 2010

The experimental study on paraffin wax/LDPE blended fuel for hybrid rocket was performed. Various combustion characteristics of blended fuel were compared with pure paraffin, HTPB, HDPE and SP-1a fuel in order to evaluate the performance of blended fuel. The regression rate of lab-scale and large-scale motor using pure paraffin fuel was increased by 10.2 and 9.8 factor when respectively compared to that of HDPE. The regression rate factor of blended fuel was 3.4 in which the regression rate of blended fuel was higher than that of HTPB and HDPE, but lower than that of pure paraffin, SP-1a fuel. The values of characteristic velocity and specific impulse of blended fuel was higher than those of pure paraffin, HTPB and HDPE, and almost the same as SP-1a fuel. As these results, it was confirmed that blended fuel can be an effective solid fuel for hybrid rocket.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2336-2338
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• 2000

고효율, 무공해의 신발전 기술인 연료전지 발전은 발전 용량 및 스택구성에 따라 차이가 있으나 기본적으로 저전압, 대전류 특성과 부하에 따라 발전 전압이 크게 변동하는 특성을 갖는 직류전원으로써 이를 상용으로 이용하기 위해서는 연료전지 발전 전력을 안정된 전력으로 변환하여 주는 장치가 필요하며, 이러한 전력 변환장치가 연료전지 발전의 최종 출력 전원의 질을 결정한다. 연료전지 전력변환장치는 전압조절기능, 승압 기능을 가져야 하고, 연료전지 본체와 부하를 안정하게 운전하기 위해 전력변환장치 뿐만 아니라 부하와 연료전지 본체의 운전상태 감지 기능, 각종 장치의 보호와 제어기능을 가져야 한다. 본 논문의 목적은 자동차용 연료전지 출력 전력변환장치의 종합제어장치의 설계를 위해 연료전지 스택시뮬레이터를 개발하는 것이다. 연료전지 스택 시뮬레이터는 연료전지 발전 특성과 일치하는 전력을 출력해 주는 직류전원 공급장치로써 이를 이용하여 연료전지 출력 전력변환장치의 종합제어장치를 충분한 예비실험과 수정, 보완함으로써 연료전지용 전력변환 시스템의 성능개선, 안정성 향상 등을 가질 수 있다.

• Journal of the KSME
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• v.55 no.7
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• pp.32-36
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• 2015

최근 화석 연료의 과다 사용에 따른 에너지 자원 고갈 및 환경오염에 대한 우려가 증가함에 따라 비화석연료 기반의 재생가능하고 지속가능하며, 환경친화성이 높은 에너지에 대한 관심이 급증하고 있다. 농산폐기물, 폐목재, 에너지작물, 도시고형폐기물, 미세조류, 거대조류 등 육상 및 해상에서 발생하는 바이오매스는 재생가능한 에너지원으로서 화석원료와는 달리 사용 후 발생하는 이산화탄소를 다시 흡수하는 탄소중립(carbon-nutral)의 특성을 갖고 있어 전세계적으로 많은 주목을 받고 있다. 바이오연료 중 당질계원료를 이용하는 바이오에탄올 및 식물성유지를 이용하는 바이오디젤은 현재 상업적인 생산이 이루어지고 있으나, 이들 1세대 바이오연료는 식량자원과의 경쟁이라는 원천적인 한계를 가지고 있고, 분자구조식에 산소를 포함하고 있기 때문에 기존 화석원료에서 출발하는 가솔린, 항공유 및 디젤과 비교하였을 때 에너지 함량이 낮은 단점이 있다. 따라서 기존 1세대 바이오연료에서 탈피하여, 식량자원과 경쟁이 없으며, 또한 분자구조식에 산소를 적게 포함하거나 아예 포함하지 않는 바이오연료("drop-in" 바이오연료) 생산에 많은 관심이 집중되고 있다. 이 글에서는 최근 그린공정으로 대표되는 초임계 유체를 이용한 "drop-in" 바이오연료를 제조하기 위한 바이오매스 액화의 기술동향을 소개하고자 한다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.201-203
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• 2007

본 논문에서는, 연료전지 시스템의 기계적 주변장치 (MBOP)와 전기적 주변장치 (EBOP)의 최적 설계를 위해서 PEMFC 스택을 전기화학반응을 기초로 모델링한다. 모델링을 위해 기본적인 PEMFC의 구조와 동작 원리를 설명한다. 연료전지의 이론적 최고 전압인 평형전위를 깁스 자유에너지와 네른스트 방정식으로 유도한다. 전류밀도에 따른 전압 손실인 활성화, 저항, 농도 분극현상을 표현하기 위해서 수식을 유도한다. 수소가 이온화되지 못하고 산소극으로 넘어가서 발생되는 연료손실 및 내부전류와 지속적인 정역반응인 교환전류도 모델링된다. 평형전압에서 각 분극을 뺀 실제 운전 전압을 시뮬레이션하고, 유량과 압력에 따른 출력 특성을 시뮬레이션 한다. 부하변동 시 출력특성을 시뮬레이터와 실험결과로 비교한다.

• Journal of the Korean Institute of Gas
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• v.11 no.4
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• pp.29-34
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• 2007

In recent years, the need for more fuel-efficient and lower-emission vehicles has driven the technical development of alternative fuels such as LPG(Liquefied Petroleum Gas) which is able to meet the limits of better emission levels without many modifications to current engine design. LPG has a hish vapor pressure and lower viscosity and surface tension than diesel and gasoline fuels. These different fuel characteristics make it difficult to directly apply the conventional gasoline or diesel fuel pump. In this study, experiments are performed to get performance and efficiency of the fuel pump under different condition of the temperature, rotating speeds, and composition of fuel. The characteristics of fuel pump were affected by cavitation occurred from the variation of temperature and composition.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.460-466
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• 2017

The common petroleum can make precipitation such as a wax in a polar region due to severely cold weather condition, which can cause problems to fuel supply system. The petroleum product used in the polar region has thus been manufactured and sold suitable for the cold environment. However it is difficult to supply such petroleum products on time since these were mainly supplied abroad. In this article, the original fuel properties were first analyzed in order to find alternative fuel products for polar region. Jet fuel which is excellent cold characteristics was chosen and the fuel properties was tested by adding a constant concentration of lubricant additives to the jet fuel. As a result, the lubricant additive R621 showed the best lubricity, and adding 1000 mg/L of R621 content to the jet fuel was sufficient to enhance the lubricity. We envision that the jet fuel added 1000 mg/L of R621A can be suitable for alternative special antarctic blend diesel (SAB) in an severe polar environment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.7
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• pp.593-600
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• 2015

In this study, a combined hybrid rocket system is newly introduced which has characteristics of both gas generators and afterburner type hybrid rockets. In particular, a combined gas generator utilizing solid fuel and liquid/gas oxidizer was designed as a primary combustor of the system. Combustion tests were carried out with various equivalence ratio affected by parameters such as fuel length, oxidizer flow rate, fuel port diameter and fuel type. In general, fuel-rich gas generator produces low combustion gas temperature to meet the temperature requirement and the target temperature was transiently set less than 1600 K. Since it was found that controlling parameters showed limited effects on the change of equivalence ratio, mixture of $O_2$ and $N_2$ as an oxidizer was additionally introduced. As a result, a combined gas generator successfully produced combustion gas temperature of less than 1600 K Future studies will carry out more combustion tests to attain fuel-rich combustion gas temperature less than 1200 K, which was a temperature requirement of a gas generator system in the previous studies.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.2
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• pp.42-51
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• 2014

An experiment was conducted to study fuel injection characteristics of high boiling point test fuels (HBPTF), which are newly developed with higher boiling points than conventional aviation fuels, for various injection pressures when the fuel was heated to the temperature higher than their boiling points. The injection characteristics with elevating fuel temperature were quantified by the flow coefficient (${\alpha}$) and the cavitation number ($K_c$), and it was found that the trends between ${\alpha}$ and $K_c$ for various fuels were very similar with each other. In addition, compared with a conventional fuel, HBPTFs not only have higher fuel temperatures at which the effect of fuel boiling on the injection initiates, but also are less affected by the fuel boiling inside the injectors at temperatures over the boiling point.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.2
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• pp.250-258
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• 2010

A numerical analysis of reactive flow in a liftoff flame is accomplished to elucidate the characteristics of flame propagation velocity and volume integral of reaction rate with the variation of nozzle diameter and fuel injection flow rate in a liftoff flame consisted with fuel rich region, fuel lean region and diffusion flame region. The increase of fuel injection velocity enhances flame propagation velocity for the selected three nozzle diameter(d=0.25, 0.30, 0.35mm), but its effect on the flame propagation velocity is not much greater than 4.3%. The increase of fuel flow rate is directly and linearly related with the volume reaction rate and so the volume reaction rate, not the flame propagation velocity, might be considered to accommodate the variation of fuel flow rate in a liftoff flame.