• 한국자동차공학회논문집
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• 제22권4호
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• pp.1-9
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• 2014

The vast stores of biomass available in the worldwide have the potential to displace significant amounts of petroleum fuels. Fast pyrolysis of biomass is one of several paths by which we can convert biomass to higher value products. The wood pyrolysis oil (WPO) has been regarded as an alternative fuel for petroleum fuels to be used in diesel engine. However, the use of WPO in a diesel engine requires modifications due to low energy density, high water contents, high acidity, high viscosity, and low cetane number of the WPO. One possible method by which the shortcomings may be circumvented is to co-fire WPO with other petroleum fuels. WPO has poor miscibility with light petroleum fuel oils; the most suitable candidates fuels for direct fuel mixing are methanol or ethanol. Early mixing with methanol or ethanol has the added benefit of significantly improving the storage and handling properties of the WPO. For separate injection co-firing, a WPO-ethanol blended fuel can be fired through diesel pilot injection in a dual-injection dieel engine. In this study, the performance and emission characteristics of a dual-injection diesel engine fuelled with diesel (pilot injection) and WPO-ethanol blend (main injection) were experimentally investigated. Results showed that although stable engine operation was possible with separate injection co-firing, the fuel conversion efficiency was slightly decreased due to high water contents of WPO compare to diesel combustion.

• 한국자동차공학회논문집
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• 제8권2호
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• pp.57-63
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• 2000

This paper deals with a study on combustion and emission characteristics of a direct injection diesel engine dual fueled with natural gas. Dual fuelling systems tend to emit high unburned fuel especially at low load, resulting in a decreased thermal efficiency. This is because natural gas-air mixtures are too lean for flame to propagate under low load conditions. Suction air quantity and injection timing controls are very useful to improve emissions and thermal efficiency at low load.

• 대한기계학회논문집B
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• 제41권1호
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• pp.53-62
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• 2017

이중냉각 환형핵연료 집합체를 위한 비틀림 혼합날개 지지격자의 강제대류열전달 성능을 실험적으로 평가하였다. 비틀림 혼합날개 지지격자는 부수로 간 혼합뿐 아니라 부수로 내 혼합을 동시에 증대시킬 수 있도록 설계되었다. 실험을 위한 이중냉각 환형핵연료 모의 집합체로, 봉 중심 간 거리와 봉 외경의 비가 1.08인 봉 간격이 좁은 $4{\times}4$ 정사각 배열의 봉다발을 준비하였다. 실험은 봉다발 유동의 축방향 평균속도가 1.5 m/s, 열유속은 $26kW/m^2$인 조건에서 수행하였다. 원주방향 온도 분포의 경우, 지지격자 상류에서는 부수로 중심 벽면에서, 하류에서는 비틀림 혼합날개 끝이 향하는 벽면에서 온도가 가장 낮게 나타났다. 축방향 온도 분포의 경우, 지지격자 하류 근처에서 온도가 급격하게 감소하는 것으로 측정되었고, 비틀림 혼합날개에 의해 누셀트 수는 최대 56 % 증대되는 것으로 나타났다. 본 실험결과를 토대로 봉 간격이 좁은 이중냉각 환형핵연료 집합체에서 비틀림 혼합날개 지지격자에 의해 강제대류열 전달 성능이 효과적으로 증대될 수 있음을 확인하였다.

• 한국분무공학회지
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• 제24권4호
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• pp.194-202
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• 2019

A mixture preparation strategy was proposed and evaluated in a diesel-natural gas dual-fuel engine to reduce hydrocarbon (HC) and carbon monoxide (CO) emissions under low load conditions. An experimental investigation was conducted in a single-cylinder compression-ignition engine. Natural gas was supplied with air during the intake stroke, and diesel was injected directly into the combustion chamber during the compression stroke. First, effects of diesel start of energizing (SOE) and natural gas substitution ratio on the combustion and exhaust gas emissions were analyzed. Based on the results, the mixture preparation strategy was established. A low natural gas substitution ratio and a high exhaust gas recirculation (EGR) rate were effective in reducing the HC and CO emissions.

• 방사성폐기물학회지
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• 제14권1호
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• pp.35-44
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• 2016

Leading national R&D project to design a PWR spent nuclear fuel interim dry storage system that has been under development since mid-2009, which consists of a dual purpose metal cask and concrete storage cask. To ensure the safe operation of dry storage systems in foreign countries, major confinement monitoring techniques currently consist of pressure and temperature measurement. In the case of a dual purpose metal cask, a pressure sensor is installed in the interspace of bolted double lid(primary and secondary lid) in order to measure pressure. A concrete storage cask is a canister based system made of double/redundant welded lid to ensure confinement integrity. For this reason, confinement monitoring method is real time temperature measurement by thermocouple placed in the air flow(air intake and exit) of the concrete structure(over pack and module). The use of various monitoring technologies and operating experiences for the interim dry storage system over the last decades in foreign countries were analyzed. On the basis of the analysis above, development of the confinement monitoring technology that can be used optimally in our system will be available in the near future.

• 한국자동차공학회논문집
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• 제18권4호
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• pp.132-139
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• 2010

This paper describes an investigation of the performance and emission characteristics of a commercial cylinder direct injection diesel engine operating on natural gas with pilot diesel ignition. Engine tests for variations in the pilot injection timing were performed at an engine speed of 1500 rpm. This study showed that the performance of the dual-fuel diesel engine increased as the engine load increased and as the pilot diesel injection timing angle advanced. The peaks of cylinder pressure, pressure rise rate, and heat release rate all increased while the fuel ignition timing advanced with the pilot injection timing. The engine operation was stable, and the least smoke was produced at a pilot injection timing of $12^{\circ}$ before top dead center. NOx emissions were only exhausted under high-load conditions, and they increased as the pilot injection timing angle advanced.

• 한국자동차공학회논문집
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• 제16권6호
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• pp.65-73
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• 2008

The purpose of this study is development of universal engine model for integrated Hybrid Electric Vehicle (HEV) simulator and a optimization of engine model. The engine model of this study is based on the MATLAB Simulink for universal and include engine fuel economy technologies for HEV. Various engine fuel economy technologies for HEV is estimated by commercial engine 1-D simulation program - WAVE. And, the 1-D simulation model of base version is compared with engine experiment result. The analyzed engine technologies with 1-D simulation are Dual-CVVT, Atkinson-Cycle and Cylinder-Deactivation System. There are improvement of fuel economy and power performance with Dual-CVVT model at part load and full load, pumping loss reduction with Cylinder-Deactivation System at idle and regeneration. Each estimated technologies are analyzed by 1-D simulation on all operation region for base data to converse simulink. The simulink based engine model maintains a signal with ECU for determination of engine operation point.

• 한국가스학회지
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• 제14권1호
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• pp.15-20
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• 2010

최근 들어 유럽 및 미국을 중심으로 각광받고 있는 가스화 열병합 설비는 석탄이나 바이오매스, 폐기물로부터 지역의 전기 및 냉난방 에너지를 공급하는 중소형 규모의 에너지 시스템으로서 시장적 측면이나 기술적 측면에서 그 활용 가능성이 매우 밝은 것으로 예견되고 있다. 가스화로부터 얻어지는 합성가스는 일반적으로 가스엔진, 스털링 엔진, 마이크로 가스터빈 및 중소형 가스터빈 등이 원동기 연료로 사용될 수 있다. 그러나 가스화를 통한 합성가스는 일반적으로 LPG, CNG와 같은 고발열량 가스연료에 비해 발열량이 낮고, 반응성 및 화염속도도 매우 큰 차이를 보인다. 본 연구는 저발열량의 합성가스연료를 이용한 고효율 전소엔진 개발의 전 단계로서 60kW급 디젤혼소엔진을 개발하였다. 저발열량의 합성가스를 모사하기 위해 CNG에 질소를 희석한 연료를 사용하였으며, 디젤 연료 분사를 제어하기 위한 인젝터 드라이버 및 ECU를 적용하였다.

• 한국분무공학회지
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• 제21권2호
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• pp.95-103
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• 2016

The effect of pilot injection quantity on the combustion and emissions characteristics of a compression ignition engine with a biodiesel-compressed natural gas (CNG) dual fuel combustion (DFC) system is studied in this work. Biodiesel is used as a pilot injection fuel to ignite the main fuel, CNG of DFC. The pilot injection quantity is controlled to investigate the characteristics of combustion and exhaust emissions in a single cylinder diesel engine. The injection pressure and injection timing of pilot fuel are maintained at approximately 120 MPa and BTDC 17 crank angle, respectively. Results show that the indicated mean effective pressure (IMEP) of biodiesel-CNG DFC mode is similar to that of diesel-CNG DFC mode at all load conditions. Combustion stability of biodiesel-CNG DFC mode decreased with increase of engine load, but no notable trend of cycle-to-cycle variations with increase of pilot injection quantity is discovered. The combustion of biodiesel-CNG begins at a retarded crank angle compared to that of diesel-CNG at low load, but it is advanced at high loads. Smoke and NOx of biodiesel-CNG are simultaneously increased with the increase of pilot fuel quantity. Compared to the diesel-CNG DFC, however, smoke and NOx emissions are slightly reduced over all operating conditions. Biodiesel-CNG DFC yields higher $CO_2$ emissions compared to diesel-CNG DFC over all engine conditions. CO and HC emissions for biodiesel-CNG DFC is decreased with the increase of pilot injection quantity.

• 한국정보통신학회논문지
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• 제21권3호
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• pp.613-619
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• 2017

본 논문에서는 PMS(Power Management System) HILS(Hardware In the Loop Simulaition) 가상 제어기 환경 구축을 위하여 디젤과 LNG를 연료로 사용가능한 DF(Dual Fuel) Generator를 MATLAB/SIMULINK 기반으로 모델링을 수행하고 시뮬레이션 결과 모니터링이 가능한 인터페이스를 구현하였다. DF Generator의 주요 구성은 기계적 동력을 공급하는 DF 엔진과 기계적 동력을 받아 전력을 생산 및 공급을 하는 동기발전기가 있다. DF 엔진의 서브모델은 throttle body, intake manifold, torque generation 그리고 mass of LNG and diesel quantity 가 있다. 또한, 단일 용량을 초과하는 전체 부하를 공유하기 위하여 병렬 연결된 DF Generator 와 governor 모델을 이용하여 부하 분담 시스템을 구현하였다. 시뮬레이션 결과와 가상 부하에 따른 예상 결과의 비교를 통해 DF Generator 모델의 신뢰성을 검증하였다.