• 한국구조물진단유지관리공학회 논문집
• /
• 제28권2호
• /
• pp.9-16
• /
• 2024

본 논문에서는 부피단위의 화재곡선을 단위면적당 화재곡선으로 구하여 화재곡선 식을 FDS 표면열방출율법에 대입할 수 있도록 하고자 하였다. 화재곡선을 총 연소특성시간을 고려하여 무차원으로 표현하였으며, 성장구간비 𝛽_i, 유지구간비 𝛽_s , 감쇄구간비 𝛽_d를 고려하여 화재강도에 대한 적절한 비율을 나타내도록 개선하였다. 또한, 질량증가에 따라 변화하는 연소 특성시간 보정함수 𝛾(m/m₀)를 도출하였으며, 질량비가 증가함에 따라 성장시간 값을 제어하기 위해 성장구간비 𝛽_i를 보정하는 함수 α_i(m/m₀)를 도출하였다. 이에 따라 기존 데이터를 활용하여 연소물의 기준질량을 선정하고, 질량 증가에 따른 화재곡선을 예측할 수 있는 식을 확립하였다.

• 오토저널
• /
• 제5권4호
• /
• pp.41-46
• /
• 1983

The influence of inlet air humidity on the flame velocity and combustion of the spark ignition engine were described experimentally by means of the flame velocity measuring apparatus using ion-current. The flame velocity are greatly influenced air fuel ratio and engine speed, and linealy decrease according to the increasing of inlet air humidity. The flame travell curve is very similar to the rate of mass burned and combustion progressive is estimated mostly by only the rate of mass burned curve. The decreasing of the mean flame velocity is about 0.4m/s for increasing of 0.001 specific humidity and we think the reason is mainly decreasing of thermal conductivity.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 춘계학술대회논문집
• /
• pp.324-327
• /
• 2008

Two stage startup of high thrust liquid rocket engine can reduce the abrupt impulse to the vehicle and engine by changing oxidizer flow rate to the combustion chamber. Also it ensures stable ignition of combustion chamber against hard start and to prevent pump stall by the sudden supply of large mass flow rate. However high discharge pressure of oxidizer pump or temperature rise in gas generator may be a problem in applying the preliminary stage. To solve this problem, we analyzed the effect of the slope of oxidizer pump's head curve and the oxidizer mass flow rate to combustion chamber during preliminary stage using the rocket engine startup analysis code. A moderate slope(${\circleddash}{\sim}$-3) of head curve and 80% mass flow rate during preliminary stage can reduce the oxidizer pump discharge pressure by 15 to 20% comparing with the condition of ${\circleddash}$=-4.37 head curve and 70% mass flow rate. Also it can maintain the turbine inlet temperature rise within 50K from the nominal value.

• 한국연소학회지
• /
• 제22권2호
• /
• pp.42-49
• /
• 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.

• 한국자동차공학회논문집
• /
• 제10권5호
• /
• pp.58-64
• /
• 2002

A diesel engine has various merits such as high thermal-efficiency, superior fuel consumption and durability. Therefore the number of diesel engine in the world is increasing. As the seriousness of environmental pollution increases in the world, the method to reduce the noxious materials of CO2, NOx and P.M. is very important subject to correspond to exhaust gas regulations. A new concept, so called premixed charge compression ignition(PCCI), is focused among the various corresponding manners. In this study, we investigated the combustion characteristics of PCCI engine using a mixed fuels with that of commercial diesel engine. Finally we grasped a emission characteristics of PCCI engine. From this experiment, it could be found that NOx reduction is caused by the lower maximum temperature and soot reduction is caused by rapid combustion under diffusion combustion part. Also, it was found that 1st-combustion(cool flame) and 2nd-combustion(hot flame) is appeared in heat release curve, exhaust gas temperature is diminished and combustion variation is increased according to increasing of gasoline ratio.

• 한국자동차공학회논문집
• /
• 제11권2호
• /
• pp.96-103
• /
• 2003

In this paper, the heat loss to the constant volume vessel wall was investigated using instantaneous heat flux sensor, schlieren visualization, pressure rise curve. And the heat loss characteristics of plasma jet ignition were compared with conventional spark ignition. In case of plasma jet ignition, the flame kernel moves toward the center of combustion vessel in the initial period of combustion, and the flame surface spread out to the vessel wall. However, in case of conventional spark ignition, the flame surface contact with combustion vessel wall in the initial period of combustion. As a result, heat loss in the combustion duration for conventional spark ignition increase faster than that of plasma jet ignition. And the combustion enhancement rate of plasma jet ignition is higher than that of conventional spark ignition, and it was found that the heat loss rate is inversely proportional to the combustion enhancement rate.

• Korean Chemical Engineering Research
• /
• 제48권1호
• /
• pp.58-67
• /
• 2010

본 연구에서는 국내 상용 순환유동층 보일러에서 연료로 사용하고 있는 저급 국내무연탄과 혼소용 연료로 이용할 예정인 목재펠릿의 각각의 연소 특성을 조사하기 위해 열중량 분석기(TGA)를 이용하여 비등온 실험(5, 10, 20, $30^{\circ}C/min$) 및 등온 조건으로 촤 연소 실험을 수행하였다. 목재펠릿의 경우는 승온 속도에 따라 차이가 있으나, 국내무연탄에 비해 낮은 온도인 $200{\sim}620^{\circ}C$ 사이에서 연소되었으며, 최대 반응속도를 나타내는 온도 또한 국내무연탄의 그것에 비해 매우 낮음을 알 수 있었다. 비등온 실험 결과를 Friedman 방법으로 해석한 결과, 무게감량이 가장 큰 2차 구간에서의 목재펠릿 및 국내무연탄의 활성화에너지는 44.12, 21.45 kcal/mol이었으며, 반응차수 및 빈도인자는 각각 5.153, 0.7453 및 $4.01{\times}10^{16}$, $1.39{\times}10^6(s^{-1})$임을 확인할 수 있었다. 또한 등온 조건으로 촤 연소 실험 결과, 화학반응 율속단계에서의 목재펠릿 및 국내무연탄의 활성화에너지는 각각 27.5, 51.2 kcal/mol이었으며, 빈도인자는 각각 $2.55{\times}10^{12}$, $1.49{\times}10^{10}(s^{-1})$임을 확인할 수 있었다. 국내무연탄에 비해 목재펠릿이 낮은 온도에서 연소 반응이 시작이 되고 반응차수 및 빈도인자가 높아 반응속도를 빠를 것으로 판단되어 혼소 시 연소 제어가 잘 이루어질 경우, 연소로 내의 연소 분위기가 향상될 것으로 예상된다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집B
• /
• pp.842-846
• /
• 2001

Our company produces boilers for industrial usages or power plants. The aim of this study is to investigate the flame structure, heat transfer to evaporator tube wall and NOx emission in the furnaces. Also we are to derive correct FEGT(Furnace Exit Gas Temperature) characteristic curve. When we design furnace and superheater, economizer etc. FEGT characteristic curve is very important factor for optimum design. We calculated turbulent reacting flow, heat transfer and NOx emission in furnace by using numerical modeling with the help of commercial code. Three dimensional steady state calculation is done. k-e turbulence model and equilibrium chemistry combustion model with $\beta-probability$ density function is used. To calculate radiation heat transfer discrete ordinates model is used. And we measured FEGT at several operating plants. Measurement is done by R-type thermocouple. Radiation shield is attached to the thermocouple to prevent radiation effect. Measured and calculated results show good agreement. And we could understand the flame structure and NOx formation positions in each furnaces.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제48권6호
• /
• pp.294-300
• /
• 1999

There is a growing interest in hybrid electric vehicles due to environmental concerns. Recent efforts are directed toward developing an improved main component systems for the hybrid electric vehicle applications. Soon after the introduction of electric starter for internal combustion engine early this century, despite being energy efficient and nonpolluting, electric vehicle lost the battle completly to internal combustion engine due to its limited range and inferior performance. Hybrid Electric vehicles offer the most promising solutions to reduce the emission of vehicles. This paper describes a method for cost reduction estimation of parallel hybrid electric vehicle. We used a cost reduction structure that consisted of five major subsystems (three-type and two-type motor) for parallel hybrid electric vehicle. Especially, we estimated the potential for cost reductions in parallel hybrid electric vehicle as a function of time using the learning curve. Also, we estimated the potentials of cost by depreciation.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
• /
• pp.666-669
• /
• 2002

The differences of the effects of mechanical substance pre-activation in the mills with divers force effect schemes on the self-propagating high temperature synthesis (SHS) of the $SiO_2$ + 37.5% Al system were investigated. The power saturation of activated material state are estimated referring on the variations of dilatometry curve paths. The effects of activation time on the temperature of sample self-ignited in the furnace, combustion temperature and completeness of the quartz reaction with aluminium were determined. The enhancing effects of organic modifiers of quartz particle surfaces on the further SHS synthesis development were shown.