• 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.

• Korean Chemical Engineering Research
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• 제55권6호
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• pp.846-853
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• 2017

순환유동층 모사장치와 $30kW_{th}$급 파일럿 연소기를 활용하여 슬러지 순산소 유동층 연소특성을 살펴보았다. 순환유동층 모사실험에서 최소유동화속도($U_{mf}$)는 0.120 m/s로 계산되었고, 고속유동화를 위한 공탑속도는 2.5 m/s 이상으로 결정되었다. 파일럿 연소실험에서는 일반공기 및 21~40% 순산소 연소실험이 수행되었다. 배출가스 온도의 경우 21~25% 순산소 연소가 일반공기 및 30% 이상의 순산소 연소보다 상대적으로 높았다. 또한, 배출가스 중 $CO_2$ 배출농도가 21~25% 순산소 연소 범위에서 80% 이상으로 나타났다. 이를 고려한 전반적인 연소특성을 살펴 보았을 때 25% 순산소 연소가 본 슬러지 연료 연소에 대한 장시간 운전에 있어 보다 적합한 것으로 사료된다.

• 한국자동차공학회논문집
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• 제25권3호
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• pp.326-335
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• 2017

It is known that diesel engines have the disadvantage of high emission levels of NOx and PM. Therefore, many combustion strategies have been developed to reduce these harmful NOx and PM emissions in a diesel engine. Among these strategies, HCCI(Homogeneous Charge Compression Ignition) and PCCI(Premixed Charge Compression Ignition) are the most popular as these can reduce NOx and PM simultaneously. However, when a single fuel like diesel is applied, it is difficult to control the combustion phase and this can lead to power reduction. In this study, premixed gasoline and pilot diesel were used to overcome the problems of controllability of the combustion phase and harmful emissions. We injected gasoline directly into the combustion chamber and the gasoline/air mixture was ignited with a pilot diesel fuel near the top dead center. The results showed that the combustion and emission characteristics of dual-fuel combustion were comparable to those of conventional diesel combustion. When we applied the dual-fuel PCCI combustion concept, more than 90 % of NOx and PM emission was reduced simultaneously without significant degradation of efficiency compared to conventional diesel combustion.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.207-214
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• 2004

Extra heavy vacuum residue oil has advantage as the fuel of a power plant in reducing the cost of power generation. Numerical study is conducted by the KIVA code to understand combustion, heat transfer and flow field characteristics in the test reactor. The combustion model of pulverized coal particles is adopted as the combustion process of extra heavy oil is similar to that of coal. As an initial phase of investigation parametric study is performed with respect to SMD and spray angle of injected spray droplets.

• 수산해양기술연구
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• 제55권4호
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• pp.411-418
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• 2019

In this study, to investigate the effect of physical and chemical properties of butanol on the engine performance and combustion characteristics, the coefficient of variations of IMEP (indicated mean effective pressure) and fuel conversion efficiency were obtained by measuring the combustion pressure and the fuel consumption quantity according to the engine load and the mixing ratio of diesel oil and butanol. In addition, the combustion pressure was analyzed to obtain the pressure increasing rate and heat release rate, and then the combustion temperature was calculated using a single zone combustion model. The experimental and analysis results of butanol blending oil were compared with the those of diesel oil under the similar operation conditions to determine the performance of the engine and combustion characteristics. As a result, the combustion stabilities of D.O. and butanol blending oil were good in this experimental range, and the indicated fuel conversion efficiency of butanol blending oil was slightly higher at low load but that of D.O. was higher above medium load. The premixed combustion period of D.O. was almost constant regardless of the load. As the load was lower and the butanol blending ratio was higher, the premixed combustion period of butanol blending oil was longer and the premixed combustion period was almost constant at high load regardless of butanol blending ratio. The average heat release rate was higher with increasing loads; especially as butanol blending ratio was increased at high load, the average heat release rate of butanol blending oil was higher than that of D.O. In addition, the calculated maximum. combustion temperature of butanol blending oil was higher than that of D.O. at all loads.

• 대한기계학회논문집B
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• 제40권9호
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• pp.577-587
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• 2016

순산소 마일드 연소는 공기를 사용하는 연소에 비하여 열효율 및 연소안정성이 높고 배기가스 배출량이 낮아 유망한 연소기술 중 하나로 알려져 있지만 마일드 화염의 형성에는 아직까지 많은 어려움이 있는 실정이다. 본 논문에서는 순산소 마일드 형성을 위하여 연소기 형상 및 운전조건 변화가 순산소 마일드 연소에 미치는 영향을 3차원 수치해석을 적용하여 분석하였다. 수치해석 결과 마일드 연소화염의 특징인 고온영역과 평균온도를 감소시키는 데 있어서 산화제유속 증가가 보다 효과적임을 확인하였다. 또한 외부 예열이 없는 조건에서도 최적화된 산소-연료 공급조건에서 순산소 마일드 연소화염의 형성 가능성을 확인하였고 안정적인 순산소 마일드 연소는 당량비 0.90, 연료유속 10 m/s, 산소유속 200 m/s, 노즐간 거리 33.5 mm 조건에서 보다 안정적으로 형성됨을 확인할 수 있었다.

• 한국추진공학회지
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• 제16권4호
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• pp.87-92
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• 2012

우주발사체 추진기관은 일반적으로 산화제와 연료를 연소실로 공급하여 추진력을 얻게 된다. 개발중에 있는 한국형 발사체(KSLV-II) 2단 엔진의 경우 산화제로는 액체산소(Liquid Oxygen)를 사용하고 연료로는 JET-A1이 사용될 예정이다. 터보펌프 공급방식인 2단 엔진의 주요 구성은 연소기와 터보펌프, 엔진공급시스템 등으로 구성되어 있다. 액체 추진 엔진 개발을 위해서는 서브시스템인 연소기 개발이 선행되어야 하고 설계 및 제작된 연소기의 성능 검증은 연소기 연소시험설비(CCTF)에서 수행된다. 우주센터에 구축 예정인 연소기 연소시험설비에 대한 상세설계가 수행되었으며, 본 설계 결과를 기준으로 AMESim을 사용하여 연료공급시스템에 대한 모델링을 수행하여 연료 공급특성을 해석하였다.

• 한국자동차공학회논문집
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• 제17권5호
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• pp.61-66
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• 2009

An experimental investigation was conducted to analyze the effects of biodiesel-ethanol and biodiesel-diesel blended fuels on the characteristics of combustion and exhaust emissions, and size distributions of particulate matter in a single cylinder diesel engine. The three types of test fuel were biodiesel and two blended fuels which were added ethanol and diesel by 20 % volume based fraction into biodiesel, respectively. In this study, the injection rate, combustion pressure, exhaust emissions and size distributions of particulate matter were measured under various injection timings and injection pressures. The experimental results show that biodiesel-ethanol blended fuel has lengthened ignition delay and low combustion pressure in comparison with those of biodiesel and biodiesel-diesel blended fuel even if all fuels indicated similar trends of injection rate under equal injection pressures. In addition, the ethanol blended fuel significantly reduced nitrogen oxidies (NOx) and soot emissions. And then the size distribution of particulate matters shows that blended fuels restrain the formation of particles which were beyond the range of 150nm comparison with biodiesel fuel.

• 대한기계학회논문집B
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• 제33권12호
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• pp.968-976
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• 2009

As the global warming becomes a serious environmental problem, studies of reducing $CO_2$ emission in power generation area are in progress all over the world. One of the carbon capture and storage(CCS) technologies is known as oxy-fuel combustion power generation system. In the oxy-fuel combustion system, the exhaust gas is mainly composed of $CO_2$ and $H_2O$. Thus, high-purity $CO_2$ can be obtained after a proper $H_2O$ removal process. In this paper, an oxy-fuel combustion cycle that recovers the waste heat of a high-temperature fuel cell is analyzed thermodynamically. Variations of characteristics of $CO_2$ and $H_2O$ mixture which is extracted from the condenser and power consumption required to obtain highly-pure $CO_2$ gas were examined according to the variation of the condensing pressure. The influence of the number of compression stages on the power consumption of the $CO_2$ capture process was analyzed, and the overall system performance was also investigated.

• 대한기계학회논문집
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• 제19권11호
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• pp.3054-3062
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• 1995

Recently, the improvement of fuel economy and the reduction of exhaust smoke and NOx have been successfully achieved by supplying diesel engines with emulsified diesel oil with water particles. In the present paper, the difference between the combustion of injected emulsified fuel and that of diesel oil spray is clarified by means of taking high-speed and color photographs of the flames in the engine cylinder. As the results, the two kinds of fuels show different combustion behavior each other in the growth of initial flame and in the termination of combustion process in the cylinder. Then, suitable combustion chamber design for the use of emulsified fuel is discussed on the basis of experimental data for various distribution of spray in different kinds of piston cavities. Some methods of clearing troubles caused by emulsified fuel injection are also discussed on the basis of performance tests with a remodeling test engine.