• 공업화학
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• 제34권3호
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• pp.291-298
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• 2023

본 연구는 가축분뇨를 가스화 하여 연료 가스를 생산하는 공정의 경제성과 탄소배출 관점에서의 지속가능성을 평가하였다. 본 연구에서 고려한 가스화 공정은 가스화 시설, 연료가스 정제 시설 및 생산 가스를 수요처를 수송하기 위한 파이프 라인의 설치까지 전체 시설을 고려하여 해당 기술의 현실적인 타당성을 평가하였다. 해당 연구는 실험 결과를 반영하는 ASPEN PLUS 시뮬레이션을 토대로 도출되었다. 경제성 및 CO₂ 전 주기 평가 결과, 축분 가스화를 통해 얻어진 연로가스는 발열량은 낮지만, 높은 수소 함량으로 천연가스와 가격적으로 경쟁력이 있다는 결과를 확인하였다. 특히, 탄소 배출 측면에서 높은 수소 함량으로 연료를 연소하였을 때 발열량당 배출되는 이산화탄소의 양이 천연가스에 비해 낮아 탄소 배출량 감축에 기여할 수 있다는 점을 확인하였다. 또한 다양한 시나리오 분석을 통해 외부 요인 및 정책적 요인에 따른 경제성을 확인하였고, 재무 재표 분석을 통해 해당 기술을 실질적인 사업화 가능성을 평가하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.374-380
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• 2015

본 연구에서는 연료전지 캐소드 가스 확산층에서의 물의 영향이 연료전지 성능에 미치는 영향을 검토하기 위하여 연료전지 스택의 부하 변동에 따른 가스 확산층에서의 2상 현상의 구현이 가능한 동적 모델을 개발하였다. 개발된 모델에 대하여 2상의 영향에 의한 연료전지 부하변동에 따른 연료전지 스택 성능, 가스 확산층 내부에서의 물 증기와 산소의 농도분포, 가스 확산층의 두께 및 다공성이 연료전지 스택 전압에 미치는 영향에 대하여 검토하였다. 그 결과 본 연구의 범위 내에서 연료전지 스택 전압은 부하에 관계없이 2상 모델이 1상 모델보다 낮아짐을 알 수 있다. 촉매층 부근 가스 확산층에서의 산소 농도는 가장 낮고 물 증기의 농도는 가장 높음을 알 수 있었다. 또한, GDL의 두께가 두꺼울수록 GDL의 다공성이 작을수록 연료전지 스택 전압이 낮아짐을 알 수 있었다.

• 한국수소및신에너지학회논문집
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• 제31권4호
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• pp.380-386
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• 2020

This paper represents an analysis of the economic impact of firing natural gas/diesel and natural gas/by-product oil mixtures in diesel engine power plants. The objects of analysis is a power plant with electricity generation capacity (300 kW). Using performance data of original diesel engines, the fuel consumption characteristics of the duel fuel engines were simulated. Then, economic assessment was carried out using the performance data and the net present value method. A special focus was given to the evaluation of fuel cost saving when firing natural gas/diesel and natural gas/by-product oil mixtures instead of the pure diesel firing case. Analyses were performed by assuming fuel price changes in the market as well as by using current prices. The analysis results showed that co-firing of natural gas/diesel and natural gas/by-product oil would provide considerable fuel cost saving, leading to meaningful economic benefits.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1999년도 추계 학술발표회 논문집
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• pp.23-29
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• 1999

Experimental studies are conducted to investigate the flame stability and the thermal/fuel NOx formation characteristics of the low calorific value (LCV) coal derived gas fuel. Synthetic LCV fuel gas is produced by mixing carbon monoxide, hydrogen, nitrogen and ammonia on the basis that the thermal input of the syngas fuel into a burner is identical to that of natural gas. The syngas mixture is fed to and burnt with air on flat flame burner. With the variation of the equivalence ratio for specific syngas fuel, flame behaviors are observed to identify the flame instability due to blow-off or flashback and to define stable combustion range. Measurements of NOx content in combustion gas are made for comparing thermal and fuel NOx from the LCV syngas combustion with those of the natural gas one. In addition, the nitrogen dilution of the LCV syngas is preliminarily attempted as a NOx reduction technique, and its effects on thermal and fuel NOx production are discussed.

• 한국위험물학회지
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• 제6권2호
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• pp.77-86
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• 2018

Interest in renewable energy is increasing for eco-friendly use of energy, and fuel cells are being used in various ways such as houses and buildings as power generation methods that have low emissions such as $NO_X$ and $CO_2$. As the supply of fuel cells expands, more and more boilers are installed in the existing buildings, but safety management is not being performed properly. Therefore, in this study, a prior study was conducted on the status of fuel cell-boiler complex installation and related criteria, and the risk factors were analyzed according to the installation environment and structure. Based on these standards, the safety performance of the fuel cell-boiler combined installation is assessed by conducting a demonstration using the starting product of the simulated operation to derive the installation criteria (proposal) for the fuel cell-boiler combined installation. The installation criteria (proposal) include the construction and connection method of the piping according to the fuel cell-boiler complex installation.

• 한국기계가공학회지
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• 제19권11호
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• pp.1-7
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• 2020

Recently, hydrogen has gained considerable attention as an eco-friendly fuel, which helps in reducing carbon dioxide content. Specifically, there is a growing interest in vehicles powered by a hydrogen fuel cell, which is spotlighted as an environmental-friendly alternative. A hydrogen transport system, fuel cell system, fuel supply system, power management system, and hydrogen storage system are key parts of a hydrogen fuel cell truck. In this study, a hydrogen storage system is built and analyzed. The expansion length of the storage vessel at maximum operating pressure (87.5 MPa) was calculated with ABAQUS, and then the optimized system was designed and built. The leak and bubble tests were performed on the built storage system. The leakage of the system was measured to be under 5 cc/hr. Hence, it can be used as a research test for the safety evaluation of leading systems of hydrogen fuel-powered commercial vehicles.

• 동력기계공학회지
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• 제13권6호
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• pp.13-21
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• 2009

This basic study is required to examine spray or jet behavior depending on fuel phase. In this study, analyses of diesel fuel(n-Tridecane, $C_{13}H_{28}$) spray and natural gas fuel(Methane, $CH_4$) jet under high temperature and pressure are performed by a general-purpose program, ANSYS CFX release 11.0, and the results of these are compared with experimental results of diesel fuel spray using the exciplex fluorescence method. The simulation results of diesel spray is analyzed by using the combination of Large-Eddy Simulation(LES) and Lagrangian Particle Tracking(LPT) and of a natural gas jet is analyzed by using Multi-Component Model(MCM). There are two study variables considered, that is, ambient pressure and injection pressure. In a macroscopic analysis, the higher ambient pressure is, the shorter spray or jet tip penetration is at each time after start of injection. And the higher injection pressure is, the longer spray or jet tip penetration is at each time after start of injection. When liquid fuel is injected, droplets of the fuel need some time to evaporate. However, when natural gas fuel is injected, the fuel does not need time to evaporate. Gas fuel consists of minute particles. Therefore, the gas fuel is mixed with the ambient gas more quickly at the initial time of injection than the liquid fuel is done. The experimental results also validate the usefulness of this analysis.

• Journal of Advanced Marine Engineering and Technology
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• 제40권5호
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• pp.447-452
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• 2016

The use of gas as fuel, particularly liquefied natural gas (LNG), has increased in recent years owing to its lower sulfur and particulate emissions compared to fuel oil or marine diesel oil. LNG is a low temperature, volatile fuel with very low flash point. The major challenges of using LNG are related to fuel bunkering, storing, and handling during ship operation. The main components of an LNG fuel system are the bunkering equipment, fuel tanks, vaporizers/heaters, pressure build-up units (PBUs), and gas controlling units. Low-pressure dual-fuel (DF) engines are predominant in small LNG-powered vessels and have been operating in many small- and medium-sized ferries or LNG-fueled generators.(Tamura, K., 2010; Esoy, V., 2011[1][2]) Small ships sailing at coast or offshore rarely have continuous operation at constant engine load in contrast to large ships sailing in the ocean. This is because ship operators need to change the engine load frequently due to various obstacles and narrow channels. Therefore, controlling the overall system performance of a gas supply system during transient operations and decision of bunkering time under a very poor infrastructure condition is crucial. In this study, we analyzed the fuel consumption, the system stability, and the dynamic characteristics in supplying fuel gas for operating conditions with frequent engine load changes using a commercial analysis program. For the model ship, we selected the 'Econuri', Asia's first LNG-powered vessel, which is now in operation at Incheon Port of South Korea.

• Journal of Advanced Marine Engineering and Technology
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• 제32권7호
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• pp.1013-1018
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• 2008

For a sequential port fuel injection natural gas engine, its combustion and emission characteristics at low loads are crucial to meet light duty vehicle emission regulations. Fuel injection timing is an important parameter related to the mixture formation in the cylinder. Its effect on the combustion and emission characteristics of a natural gas engine were investigated at 0.2 MPa brake mean effective pressure (BMEP)/2000 rpm and 0.26 MPa BMEP/1500 rpm. The results show that early fuel injection timing is beneficial to the reduction of the coefficient of variation (COV) of indicated mean effective pressure (IMEP) under lean burn conditions and to extending the lean burn limits at the given loads. When relative air/fuel ratio is over 1.3, fuel injection timing has a relatively large effect on engine.out emissions. The levels of NOx emissions are more sensitive to the fuel injection timing at 0.26 MPa BMEP/1500 rpm. An early fuel injection timing under lean burn conditions can be used to control engine out NOx emissions.

• Journal of Advanced Marine Engineering and Technology
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• 제39권2호
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• pp.195-200
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• 2015

It is envisaged that the effect of increasingly stricter air emissions legislation implemented through IMO Annex VI and other local air quality controls, together with favorable financial conditions for the use of natural gas instead of liquid fuel oil as a bunker fuel, will see an increasing number of DF engine and single gas fuel engine applications to LNG carriers and other vessel types. As part of provision for the current international movements in the shipping industry to reduce GHG emission in air, new design concepts using natural gas as an alternative fuel source for propulsion of large commercial vessels, have been developed by shipyards and research institutes. In this study, an explosion analysis for a gas supply machinery room of LNG-fuelled container ship is presented. The gas fuel concept is employed for the high pressure ME-GI where a leakage in the natural gas double supply pipe to the engines is the subject of the present analysis. The consequences of a leak are simulated with computational fluid dynamics (CFD) tools to predict typical leak scenarios, gas cloud sizes and possible explosion pressures. In addition, capacity of the structure which is subject to explosion loads has been assessed.