• 방재기술
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• 통권19호
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• pp.22-28
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• 1995

The rate of heat release is probably the single most important measure of fire hazard. Several tech-niques were developed for the measurement of rate of heat release, but were not suitable for fire test-ing purpose. Recently the application of oxygen consumption principle made it possible to development of well-characterized heat release rate measurement apparatus, the furniture calorimeter for large-scale fire tests and the cone calorimeter for bench-scale fire tests. The cone calorimeter can be used to determine the ignitability as well as heat release rate and smoke development, mass loss rate, combustion gas production etc. from burning materials. Thus, test method using cone calorimeter, an internationally recognized and accepted for the evalua-tion of fire properties, is a very promising tool for combustion study on various kind of materials and products.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.76-84
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• 2010

The aim of this study is to analyze the effect of the ethanol blending in diesel-ethanol blended fuels on the spray and combustion characteristics in a common-rail four-cylinder diesel engine. For the analysis of the spray characteristics, the spray images were obtained using a high speed camera with metal-halide lamps. From these spray images, the macroscopic spray characteristics such as the spray tip penetration and spray cone angle were investigated. Also, the combustion characteristics including the combustion pressure and the rate of heat release were studied with the analysis of the exhaust emissions in diesel-ethanol blended fuel driven diesel engine. It can be confirmed from the experiment on spray characteristics of diesel-ethanol blended fuels that the increased ethanol blending ratio induced the decrease of the spray tip penetration after the end of the injection. The spray cone angle slightly increased by the blending of ethanol fuel. In the experiment on atomization characteristics, the ethanol blending caused the improvement of the diesel atomization performance. On the other hand, at the same engine load condition, the increase of the ethanol blending ratio lead to lengthen the ignition delays, and to decrease the peak combustion pressure and the rate of heat release. Totally, the combustion and emission characteristics of ULSD and DE10 showed similar characteristics. However, in the case of DE20, CO and HC rapidly increased, and $NO_x$ decreased. It can be believed that 20% ethanol disturbed the combustion of diesel-ethanol blended fuel due to the low cetane number and evaporation.

• 한국전산유체공학회지
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• 제18권3호
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• pp.1-7
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• 2013

A pure oxygen combustion technology is crucial in Carbon Capture and Storage (CCS) technology especially in capturing of $CO_2$, where CCS will reduce 9 $GtCO_2$ by 2050, which is 19% of the total $CO_2$ reduction amount. To make pure oxygen combustion feasible, a regenerative system is required to enhance the efficiency of pure oxygen combustion system. However, an existing air combustion technology is not directly applicable due to the absence of nitrogen that occupies the 78% of air. This study, therefore, investigates the heat and fluid flow in a regenerative system for pure oxygen combustion by using commercial CFD software, FLUENT. Our regenerative system is composed of aluminium packed spheres. The effect of the amount of packed spheres in regenerator and the effect of presence or absence of a bypass of exhaust gas are investigated. The more thermal mass in regenerator makes the steady-state time longer and temperature variation between heating and regenerating cycle smaller. In the case of absence of bypass, the regenerator saturates because of enthalpy imbalance between exhaust gas and oxygen. We find that 40% of exhaust gas is to be bypassed to prevent the saturation of regenerator.

• 한국산학기술학회논문지
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• 제18권4호
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• pp.711-717
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• 2017

디젤엔진은 저온 상태의 냉시동 조건에서 디젤 미립화 특성 악화로 인한 시동성 및 유해배출가스 생성의 문제를 안고 있다. 본 연구에서는 냉시동 시의 연소개선을 위한 방안으로 다단분사 전략 적용 시의 연소 특성을 파악하고자 하였다. 본 연구에서는 냉시동성 개선을 위해 방안으로 다단분사 적용 시의 연소 특성을 파악하고자 하였다. 정적 연소 챔버 내에 설치한 압력센서를 이용하여 취득한 연소압 및 열방출율, 직접 화염 가시화기법을 적용한 화염강도를 이용하여 연소현상을 분석하고자 하였다. 시험 결과 단일 분사 대비하여 다단 분사 적용 시, 주분사에 의한 최대 연소압력 및 열방출 상승률이 증가하며, 주분사에 의한 화염 감지 기간이 단축됨을 확인하였다. 파일럿 분사량 변경을 통해 분사량 증대 시 파일럿 연소에 의한 열방출 향상에 기인한 주분사에 의한 연소가 개선됨을 확인하였다. 또한 분사압력 증대 시 연료 미립화 개선으로 인한 연소개선을 화염 강도 증대를 통해 확인할 수 있었다. 다만 분사량 및 분사압 증대는 벽면적심현상으로 인한 HC, CO의 배출 수준 악화를 초래할 수 있으므로, 실제 엔진 개발 시 이에 대한 정밀한 선정이 필요할 것으로 판단된다.

• 한국연소학회지
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• 제22권2호
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• pp.42-49
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• 2017

A premixed combustion has many advantages including low NOx and CO emission, high thermal efficiency and a small volume of combustor. This study focused on combustion characteristics in a premixed combustion burner using the nickel based metal foam. The results show that the blue flame is found to be very stable at heating load 6,300-25,200 kcal/h by implementing the proper nickel based metal foam and baffle plate. The premixed flame mode is changed into green flame, red flame, blue flame and lift off flame with decreasing equivalence ratio. NOx emission was measured 80 ppm(0% oxygen base) from 0.710 to 0.810 of equivalence ratio and CO emission is 90 ppm(0% oxygen base) under the same equivalence ratio. It is also found that the stable blue flame region in flame stability curve becomes wider with increasing the heat load.

• 대한기계학회논문집B
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• 제32권7호
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• pp.513-517
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• 2008

A parametric study was made to understand the fundamentals of combustion of CNG fuel in a constant volume chamber in the respect of swirl effect, and the numbers of spark ignition. Optical devices were applied for the visualization of the physics of combustion, and combustion pressures and exhaust emission were measured at several equivalence ratios by controlling speeds of a swirling motor. When the speed of a swirling motor was raised the combustion conditions were improved. The corresponding maximum combustion pressure and heat release rate were increased and the speed of flame propagation was getting faster. This research may contribute to improve the performance of CNG engine and reduce emissions in future.

• 한국연소학회지
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• 제14권1호
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• pp.19-24
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• 2009

A novel low NOx oil burner of 0.7 MW (for a 1 ton steam/hr industrial boiler) was designed and tested to investigate the combustion characteristics through in-flame measurement and flue gas analysis. Flame shape was observed by CCD camera and $CH^*/{C_2}^*$ radical distribution in the flame were observed, along with measurement of flue gas composition such as NOx and CO, for various heat inputs, excess airs and pressure of the fuel spary nozzles. The flame showed the two-zone structure: fuel-rich and fuel-lean zone, which was very favorable for the low-NOx combustion, and the NOx emission for haevy oil combustion was significantly reduced to < 150 ppm at 4 % $O_2$, compared with the NOx level of a conventional heavy oil burner.

• 한국연소학회지
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• 제23권1호
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• pp.13-20
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• 2018

Transverse acoustic mode in annular combustion chambers affects air-fuel mixing characteristics in the nozzle and can result in heat release fluctuations in the combustor. In addition, the acoustic mode coupling between the nozzle and the combustion chamber is one of the key parameters determining combustion instability phenomenon in the annular combustor. In this study, acoustic coupling between the nozzle and annular combustor was numerically analyzed using 3D-based in house FEM code. As a result, it was found that the acoustic mode inside the combustion chamber at anti-node locations of the transverse mode was strongly influenced by the nozzle inlet boundary conditions.

• 한국연소학회지
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• 제23권1호
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• pp.28-35
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• 2018

Entropy waves(or hot spots) in a gas turbine combustor are generated by irregular heat release from flames, then can be coupled with acoustic waves when they are accelerated at the exit of the combustor. This coupling mechanism between the entropy and the acoustic waves is generally known to be one of the triggers for combustion instability, which is commonly called "indirect" combustion noise. This paper reviews the fundamental theories on generation, propagation, and coupling with acoustic field of entropy waves and recent research results on the indirect combustion noise for gas turbine combustors.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.171-174
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• 2012

Thermophotovoltaics is the direct energy conversion technology from thermal to electric (voltaic) energy via photon radiation, without any thermodynamic cycle. It is, in general, accomplished by immersing solid body in high temperature heat source (e.g. combustion field), in order to achieve high intensity irradiation, and by receiving the radiation thereof on photovoltaic cells. In this paper, advantages of combustion in porous inert medium in applying to the thermophotovoltaics are discussed in a view of its excess enthalpy features. In addition, the similarities of flame behaviors in porous inert medium to both in single and multi-channels are described.