• International Journal of Naval Architecture and Ocean Engineering
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• 제5권4호
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• pp.559-568
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• 2013

Increased worldwide concerns about fossil fuel costs and effects on the environment lead many governments and scientific societies to consider the hydrogen as the fuel of the future. Many researches have been made to assess the suitability of using the hydrogen gas as fuel for internal combustion engines and gas turbines; this suitability was assessed from several viewpoints including the combustion characteristics, the fuel production and storage and also the thermodynamic cycle changes with the application of hydrogen instead of ordinary fossil fuels. This paper introduces the basic environmental differences happening when changing the fuel of a marine gas turbine from marine diesel fuel to gaseous hydrogen for the same power output. Environmentally, the hydrogen is the best when the $CO_2$ emissions are considered, zero carbon dioxide emissions can be theoretically attained. But when the $NO_x$ emissions are considered, the hydrogen is not the best based on the unit heat input. The hydrogen produces 270% more $NO_x$ than the diesel case without any control measures. This is primarily due to the increased air flow rate bringing more nitrogen into the combustion chamber and the increased combustion temperature (10% more than the diesel case). Efficient and of course expensive $NO_x$ control measures are a must to control these emissions levels.

• 한국자동차공학회논문집
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• 제14권6호
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• pp.73-81
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• 2006

A commercial diesel engine was converted into a dedicated natural gas engine to reduce the exhaust emissions in a retrofit of a diesel-fueled vehicle. The cylinder head and piston were remodeled into engine parts suited for a spark ignition engine using natural gas. The remodeling of the combustion chamber changed the compression ratio from 21.5 to 10.5. A multi-point port injection(MPI) system for a dedicated natural gas engine was also adopted to increase the engine power and torque through improved volumetric efficiency, to allow a rapid engine response to changes in throttle position, and to control the precise equivalence ratio during cold-start and engine warm-up. The performance and exhaust emissions of the retrofitted natural gas engine after remodeling a diesel engine are investigated. The emissions of the retrofitted natural gas engine were low enough to satisfy the limits for a transitional low emission vehicle(TLEV) in Korea. We concluded that a diesel engine can be effectively converted into a dedicated natural gas engine without any deterioration in engine performance or exhaust emissions.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2011년도 전기공동학술대회 논문집
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• pp.3-6
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• 2011

The utilization of gas as ship fuel requires a new set of regulations by IMO and society of classification. Maritime Safety Committee(MSC) and the subcommittee Bulk-Liquids and Gases(BLG) in IMO developed "Interim Guidelines on Safety for Natural Gas-fueled Engine Installation in Ships(Res.MSC.285(86))" for the use of natural gas in internal combustion engine. According to the requirement of Res.MSC.285(86) for natural gas-fueled engine installations in ships, several parts of ships should follow safety criteria in terms of Fuel bunkering, Gas safe Machinery spaces, Gas Fuel Storage and etc. In this thesis, details of the IGF code shall be described and development of the IGF code in IMO shall be illustrated.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.1-6
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• 2003

Natural gas is one of the promising alternative fuels because of the abundant deposits and the cleanness of emission gas. CNG has a lot of merits except lower burning speed has a slow disadvantage. One way to overcome the disadvantage is to raise a turbulence intensity. We give various intake for changing turbulence intensity in the cylinder by three kinds of swirl control valve with a way to raise a turbulence intensity. In the present study, a $1.8\ell$ conventional gasoline engine is modified to use a CNG as a fuel instead of gasoline. We try to virify combustion and emission characteristics in each engine parameters. Parameters of experimentation are equivalence ratio, spark timing and intake flow change. The results of this study are as swirl flows. In the case of adding swirl flow, burning speed and torque are increased. But NOx and THC concentration are increased a little respectively.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2181-2185
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• 2008

Fuel processing systems which convert HC fuel into $H_2$ rich gas (such as stream reforming, partial oxidation, auto-thermal reforming) need high temperature environment($600-1000^{\circ}C$). Generally, anode-off gas or mixture of anode-off gas and LNG is used as input gas of fuel reformer. In order to make efficient and low emission burner system for fuel reformer, it is necessary to elucidate the combustion and emission characteristic of fuel reformer burner. The purpose of this study is to develop a porous premixed flat ceramic burner that can be used for 1-5kW fuel cell reformer. Ceramic burner experiments using natural gas, hydrogen gas, anode off gas were carried out respectively to investigate the flame characteristics by heating capacity and equivalence ratio. Results show that the stable flat flames can be established for natural gas, hydrogen gas, anode off gas and mixture of natural & anode off gas as reformer fuel. For all of fuels, their burning velocities become smaller as the equivalence ratio goes to the lean mixture ratio, and a lift-off occurs at lean limit. Flame length in hydrogen and anode off gas became longer with increasing the heat capacity.

• KEPCO Journal on Electric Power and Energy
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• 제5권3호
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• pp.189-195
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• 2019

논문에서는 상용급 가스터빈을 대상으로 해서 셰일가스를 연료로 공급할 때 유동 및 연소특성을 3-D 수치해석적 방법으로 구하였다. 이 때, Standard k-e 난류모델, 2단 메탄산화반응, Finite rate/Eddy dissipation 반응모델, DTRM 복사모델이 사용되었고, 기준조건(도시가스, PR 0.07)에서 출구 측에서 형성되는 온도는 이전 문헌 값과 비슷한 값을 보였다. 위 모델을 바탕으로 해서 연료조건으로 기존의 도시가스 외에 세 가지 셰일가스 조건(도시가스 대비 열량기준 80%, 90%, 105%)을 선정하였고, 각 연료조건에 대하여 세 가지 연료분사조건(PR=0.7, 0.9, 0.11)에 대한 해석을 수행하였다. 해석결과, 모든 셰일가스 연료공급 조건에 대하여 도시가스 대비 온도 혹은 NOx 측면에서 연소안정화를 만족하였다. 또한 모든 조건에 대해서 PR이 증가할수록 출구측 평균온도는 일정했지만 NOx량은 증가하였다. 이는 파일럿비가 증가할수록 상대적으로 확산연소가 증가했기 때문이다.

• 한국자동차공학회논문집
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• 제15권1호
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• pp.193-200
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• 2007

Natural gas is one of the most promising alternatives to gasoline and diesel fuels because of its lower harmful emissions, including $CO_2$, and high thermal efficiency. In particular, natural gas is seen as an alternative fuel for heavy-duty Diesel Engines because of the lower resulting emissions of PM, $CO_2$ and $NO_x$. Almost all CNG vehicles use the PFI-type Engine. However, PFI-type CNG Engines have a lower brake horse power, because of reduced volumetric efficiency and lower burning speed. This is a result of gaseous charge and the time losses increase as compared with the DI-type. This study was conducted to investigate the effect of injection conditions (early injection mode, late injection mode) on the combustion phenomena and performances in the or CNG Engine. A DI Diesel Engine with the same specifications used in a previous study was modified to a DI CNG Engine, and injection pressure was constantly kept at 60bar by a two-stage pressure-reducing type regulator. In this study, excess air ratios were varied from 1.0 to the lean limit, at the load conditions 50% throttle open rate and 1700rpm. The combustion characteristics of the or CNG Engine - such as in-cylinder pressure, indicated thermal efficiency, cycle-by-cycle variation, combustion duration and emissions - were investigated. Through this method, it was possible to verify that the combustion duration, the lean limit and the emissions were improved by control of injection timing and the stratified mixture conditions. And combustion duration is affected by not only excess air ratio, injection timing and position of piston but gas flow condition.

• 한국연소학회지
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• 제15권3호
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• pp.40-47
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• 2010

Calorific value of mixed gas, like liquefied natural gas (LNG), is strongly depends on its compositions which are affected by the mining place and producing time. The variation in calorific value have an direct influence on the combustion characteristics and performances of boiler, burner, vehicle, power plants etc. Thus, developing experimental method to measure exact calorific value is becoming an issue in the related industrial fields. Flame calorimeter is developed to get calorific value at the dynamic equilibrium state using electric substitution method. Refrigerant-11 carries heat from combustor and/or heater to the Peltier elements which pumped it out to the cooling water. It is found out that error in the measured calorific value of methane is 2.86% compared with the theoretical one. Developed design technique and the experimental data will be applied to design the national standard gas calorific value measuring apparatus.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.149-155
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• 2002

A promising new approach to achieve low pollutants emission and improvement of flame stabilities is tested experimentally using a hybrid cyclone jet combustor employing both premixed and diffusion combustion mode, Three kind of nozzles are used for LNG(Liquified Natural Gas) as a fuel. The combustor is operated by two method, One is ATI(Air Tangential Injection) mode, generated swirl flow by air as general swirl combustor, and the other is PTI(Premixed gas Tangential Injection) mode, The PTI mode consists of diffusion flame of axial direction and premixed cyclone flame of tangential direction in order to stabilized the diffusion flame. The results showed that the stable region of the PTI mode is more larger than the ATI mode. In addition, the reduction of NOx emission in PTI mode, as compared with that for the ATI mode is at least 50% in stable region. Also, even using the low calorific fuel as $CO_2$-blended gas, the cyclone jet combustor has high performance of flame stability.

• 한국가스학회:학술대회논문집
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• 한국가스학회 1998년도 추계학술발표회 논문집
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• pp.281-286
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• 1998