• 해양환경안전학회지
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• 제22권5호
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• pp.554-563
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• 2016

선박엔진은 잔사유를 에너지원으로 활용하여 운항할 수 있으며, 이를 활용한 선박에서 환경 규제와 경제성을 모두 만족시키는 다양한 방안들이 모색되고 있다. 그 중에 한 방안으로 연료 첨가제를 활용하는 기술이 있을 수 있다. 분산제와 연소촉진제는 잔사유 활용 시 엔진의 연소특성 촉진에 기여할 것이라는 기대를 받고 있다. 따라서, 본 연구에서는 연소성 분석 장비(FIA/FCA)와 열 중량 분석 장비(TGA)를 활용하여 잔사유 연료첨가제가 혼합된 잔사유의 연소성을 분석하였다. 연소성 분석 장비(FIA/FCA)의 결과로는 연소에 의한 일의 총량을 분석하도록 분석법이 개발되었으며, 이 때문에 본 연구를 통하여 동일 장비를 활용하면서도 연소 효율을 간단하게 평가할 수 있는 방안을 제시하였다. 연소성 분석 결과인 ROHR 곡선으로부터, 단순한 삼각함수를 활용하여 연소특성을 예측할 수 있는 방안을 제시하였으며, 이 기법을 활용하여 기존의 압력 곡선과 유사한 결론을 도출할 수 있었다. 열 중량 분석(TGA)의 경우 연료유의 증발 특성에 민감하게 반응함을 확인하였고, 첨가제가 연료유 증발에 효과적으로 작용함을 확인하였다.

• 한국재료학회지
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• 제12권10호
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• pp.784-790
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• 2002

For mass product of nanocrystalline ZnO ultrafine powders, self-sustaining combustion process(SCP) and ultrasonic spray combustion method(USCM) were applied at the same time. Ultrasonic spray gun was attached on top of the vertical type furnace. The droplet was sprayed into reaction zone of the furnace to form SCP which produces spherical shape with soft agglomerate crystalline ZnO particles. To characterize formed particles, fuel and oxidizing agent for SCP were used glycine and zinc nitrate or zinc hydroxide. Respectively, with changing combustion temperature and mixture ratio of oxidizing agent and fuel, the best ultrasonic spray conditions were obtained. To observe ultrasonic spray effect, two types of powder synthesis processes were compared. One was directly sprayed into furnace from the precursor solution (Type A), the other directly was heated on the hot plate without using spray gun (Type B). Powder obtained by type A was porous sponge shape with heavy agglomeration, but powder obtained using type B was finer primary particle size, spherical shape with weak agglomeration and bigger value of specific surface area. 9/ This can be due to much lower reaction temperature of type B at ignition time than type A. Synthesized nanocrystalline ZnO powders at the best ultrasonic spray conditions have primary particle size in range 20~30nm and specific surface area is about 20m$^2$/g.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.201-206
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• 2005

In order to realistically represent the complex turbulence-chemistry interaction at the partially premixed turbulent lifted flames encountered in the gas turbine combustors, the combined conserved-scalar/level-set flamelet approach has been adopted. The parallel unstructured-grid finite-volume method has been developed to maintain the geometric flexibility and computational efficiency for the solution of the physically and geometrically complex flows. Special emphasis is given to the swirl effects on the combustion characteristics of the lean-premixed gas turbine combustor. Numerical results suggest that the present approach is capable of realistically simulating the combustion characteristics for the lean-premixed gas turbine engines and the lifted turbulent jet flame with a vitiated coflow.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.251-254
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• 2006

마이크로 추력기는 마이크로/나노 위성체의 구현을 위한 핵심 기술이며 다양한 다이크로 추력기 중 마이크로 고체 추진제 추력기는 각광받고 있는 추력기중 하나이다. 마이크로 고체 추진제 추력기는 노즐, 점화기, 추진제실 그리고 추진제로 구성되어 있다. 본 논문에서는 다양한 마이크로 고체 추진제 추력기들을 조사하고, 1mNs의 임펄스를 구현할 수 있는 추력기 모델을 제시하고 연소실의 설계 및 제작 방법에 대한 결과를 보고하겠다.

• 한국자동차공학회논문집
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• 제22권4호
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• pp.121-130
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• 2014

This paper is the second investigation on the effects of intake flow control methods on the part load performance in a spark ignition engine. In the previous work, two control methods, port throttling and masking, were compared with respect to lean misfire limit, fuel consumption and emissions. In this work, the effects of these two methods on EGR characteristics were studied and simultaneously the differences between EGR and lean combustion as a dilution method were investigated. The results show that EGR limit is expanded up to 23% and 3 ~ 5% improvement in the fuel consumption are achieved around 8 ~ 13% rates by the flow controls comparing with 10% limit and 1.5% reduction around 3% rate of non-control case. The masking method is more effective on the limit expansion than throttling as like as lean misfire limit; however there is no substantial difference in fuel consumptions improvement regardless the control methods except high load condition. Also it is observed that there exist critical EGR rates around which the combustion performance and NOx formation change remarkably and these rates generally coincide with optimum rates for the fuel consumption. In addition, dilution with fresh air is much more advantageous than that of the exhaust gas from the view point of dilution limit and fuel consumption, while utilization of the exhaust gas is more effective on NOx reduction in spite of considerably small dilution compared with the use of fresh air. Finally, the improvement of fuel consumption by massive EGR is highly dependent on the EGR limit at which the engine runs stably, therefore the stratified combustion technique might be a best solution for this purpose.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.369-374
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• 2011

유도탄의 저온 사출 시스템 구현에 있어서 요구된 이탈모타 개발 중 나타난 복기 추진제의 연소불안정, 특히 chuffing 현상을 해결하기 위해 시도되었던 여러 가지 기술적 접근방법과 이들의 시험 결과를 수록하였다. 본 이탈모타에서는 일반적으로 점화 에너지와 관련이 깊은 것으로 알려진 chuffing 현상이 점화 에너지의 공급량이나 공급 방법 등에 의해는 억제 효과가 나타나지 않았고, 추진제에 damping 물질인 ZrC를 2% 첨가함으로써 억제되었다. 이로써 복기 추진제의 연소불안정을 해결할 수 있는 새로운 경험을 얻게 되었다.

• Advances in Automotive Engineering
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• 제1권1호
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• pp.105-121
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• 2018

The hybrid electric powertrain is a robust solution that allows for major improvements in both fuel economy and emission reduction. In the present study, a through-the-road hybrid vehicle model with an electric motor driving the rear axle and an Internal Combustion Engine (ICE) driving the front axle has been constructed. We then present a systematic method for the determination of a real time applicable optimal Energy Management Strategy (EMS) for a hybrid road vehicle. More precisely, we compare the performance of rule-based EMS strategies to an optimization-based strategy, namely ECMS (Equivalent Consumption Minimization Strategy). The comparison is conducted in parallel with a parameterization of the size of the internal combustion engine and the implementation of a Continuously Variable Transmission (CVT) that allows following the line of best fuel economy. For the FTP-75 driving cycle, the constrained engine On-off control algorithm is shown to offer a 28% improvement potential of fuel consumption compared to the conventional internal combustion engine while the ECMS strategy achieves an improved potential of nearly 33%.

• Corrosion Science and Technology
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• 제14권2호
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• pp.54-58
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• 2015

A heavy oil of low quality has been mainly used in the diesel engine of the merchant ship as the oil price has been significantly jumped for several years. Thus, a combustion chamber of the engine has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas of the combustion chamber has been getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of the engine parts such as exhaust valve, piston crown and cylinder head surrounded with combustion chamber are more serious compared to the other parts of the engine. Therefore, an optimum repair welding for these engine parts is very important to prolong their lifetime in a economical point of view. In this study, 1.25Cr-0.5Mo filler metal was welded with SMAW method in the forged steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected and base metal zones were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% $H_2SO_4$ solution. The weld metal and base metal zones exhibited the highest and lowest values of hardness respectively. And, the corrosion resistance of the heat affected and weld metal zones was also increased than that of the base metal zone. Furthermore, it appeared that the corrosive products with red color and local corrosion like as a pitting corrosion were more frequently observed on the surface of the base metal zone compared to the heat affected and weld metal zones. Consequently, it is suggested that the mechanical and corrosion characteristics of the piston crown can be predominantly improved by repair welding method using the 1.25Cr-0.5Mo electrode.

• Korean Chemical Engineering Research
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• 제57권4호
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• pp.492-500
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• 2019

본 연구에서는 $9.2MW_e$의 상용규모 순환유동층 보일러에서 화학첨가제 사용에 따른 미세입자 저감에 대한 영향을 확인하였다. 또한 화력 발전소에서 화석연료의 연소 중 발생하는 미세입자를 포집하기 위하여 간단하고 효과적인 포집설비를 개발하였다. 연소 배가스 중 PM 10이하의 입자를 감소시키기 위하여 화학첨가제를 사용하였으며, 사용한 화학첨가제는 borax solution을 사용하였다. 포집된 미세입자 중 PM 10이하의 입자 거동을 확인하기 위하여 입도분석기와 SEM 분석을 통해 확인하였다. Borax solution은 배가스중에 용융된 미네랄을 흡수하여 미세입자를 성장시키는 경향이 있는 것을 알 수 있었다. 결과적으로 borax solution을 사용함으로써 $10{\mu}m$ 이하의 미세입자가 감소되었음을 확인할 수 있었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.285-288
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• 2008

본 연구는 연료(수소)층과 산화제(공기)층의 사이에 불활성기체(질소)또는 연료(수소)를 평행분사하는 수치해석을 다루고 있다. 수치해석을 위해서 완전 보존되는 비정상 2차 시간정확도법과 2차 TVD방법이 유한 체적법과 사용되었다. 결과는 3가지 종류로 구성되어있다. 첫째는 연료와 산화제의 단일 혼합층이고, 둘째는 연료와 산화제의 사이에 불활성기체를 분사하는 방식이며, 세 번째는 연료와 산화제의 사이에 연료를 분사하는 방식이다. 전체 유동층의 수직두께는 4cm이며 삽입된 중간층의 두께는 1,2,4mm의 세가지 경우에 대하여 계산하였다.