경질 폴리우레탄폼의 착화성 및 열방출특성 연구

공영건,이두형 한국화재소방학회 2003 한국화재소방학회논문지 Vol.17 No.4

본 연구에서는 Setchkin 착화성시험장치와 산소소비원리를 이용한 콘칼로리미터를 사용하여 난연처리되지 않은 경질우레탄폼의 착화특성 및 열방출특성 및 플래쉬오버 가능성에 대하여 연구하였다. 연구결과 경질폴리우레탄폼의 유도발화온도(FIT)는 <TEX>$383^{\circ}C$</TEX>∼<TEX>$390^{\circ}C$</TEX>, 자연발화온도(SIT)는 <TEX>$493^{\circ}C$</TEX>∼<TEX>$495^{\circ}C$</TEX>로 나타났으며 자연발화온도가 유도발화온도에 비해 약 <TEX>$100^{\circ}C$</TEX> 높게 나타났다. 콘칼로리미터실험에서는 착화시간은 heat flux의 크기가 증가할수록 빨라졌으며 동일한 heat flux 크기에서는 밀도가 작을수록 착화시간은 짧게 나타났다. 열방출율은 <TEX>$50 ㎾\m^2$</TEX>에서 가장 크게 나타났으며, 최대열방출율의 경우 heat flux의 크기와 밀도가 커질수록 증가하는 경향을 보였다. 착화시간과 열방출율의 관점에서 경질폴리우레탄폼의 화재성능은 가해진 heat flux의 크기와 밀도에 큰 영향을 받는 것으로 나타났으며, Petrella의 제안방법에 의해 플래쉬오버 가능성을 분류한 결과 플래쉬오버 가능성이 큰 것으로 분류되었다. In this study; the ignition and heat release rate characteristics of rigid polyurethane foam were investigated in accordance with setchkin ignition tester and cone calorimeter which is using oxygen consumption principle. In the ignition temperature study; flash-ignition temperature was <TEX>$383^{\circ}C$</TEX>-<TEX>$390^{\circ}C$</TEX>, self-ignition temperature was<TEX>$ 493^{\circ}C$</TEX>∼495<TEX>$^{\circ}C$</TEX>. The self-ignition temperature of rigid polyurethane foam was about <TEX>$100^{\circ}C$</TEX> higher than the flash-ignition temperature. In the cone calorimeter study, the time to ignition of rigid polyurethane foam was faster as the external heat flux increase. In the same heat flux level, the time to ignition was faster as the density of rigid polyurethane foam decrease. Also the heat release rate was the largest value at the heat flux of /<TEX>$50 ㎾\m^2$</TEX> and had a tendency of increase as the heat flux level and density increase. In the standpoint of time to ignition and heat release rate, the fire performance of rigid polyurethane foam was influenced by the applied heat flux level and density and the flashover propensity classified by Petrella's proposal was high.

윤활 오일의 자연발화온도 측정에 관한 연구

김철진(Chul Jin Kim),손채훈(Chae Hoon Sohn) 한국연소학회 2011 KOSCOSYMPOSIUM논문집 Vol.- No.42

Auto-ignition temperature of flammable liquid oil is studied experimentally. The adopted oil is an unknown mixture with multi-components and known to have flash point temperature of 170 ℃ and auto-ignition temperature from a standard test method(ASTME-659-78) is measured 365 ℃. But there are a few problems with the measurement method of auto-ignition temperature. Therefore, a new ignition-test method is adopted in this work. Thereby, auto-ignition temperatures are measured 265 ℃ atatmospheric pressure and 220 ℃ at high pressure. It is especially useful for measurement of auto-ignition temperature for high pressure conditions.

Direct numerical simulations of ignition of a lean <i>n</i>-heptane/air mixture with temperature and composition inhomogeneities relevant to HCCI and SCCI combustion

Luong, Minh Bau,Yu, Gwang Hyeon,Lu, Tianfeng,Chung, Suk Ho,Yoo, Chun Sang Elsevier 2015 Combustion and Flame Vol.162 No.12

<P><B>Abstract</B></P> <P>The effects of temperature and composition stratifications on the ignition of a lean <I>n</I>-heptane/air mixture at three initial mean temperatures under elevated pressure are investigated using direct numerical simulations (DNSs) with a 58-species reduced mechanism. Two-dimensional DNSs are performed by varying several key parameters: initial mean temperature, <I>T</I> <SUB>0</SUB>, and the variance of temperature and equivalence ratio (<I>T</I>′ and <I>ϕ</I>′) with different T − ϕ correlations. It is found that for cases with <I>ϕ</I>′ only, the overall combustion occurs more quickly and the mean heat release rate (HRR) increases more slowly with increasing <I>ϕ</I>′ regardless of <I>T</I> <SUB>0</SUB>. For cases with <I>T</I>′ only, however, the overall combustion is retarded/advanced in time with increasing <I>T</I>′ for low/high <I>T</I> <SUB>0</SUB> relative to the negative-temperature coefficient (NTC) regime resulting from a longer/shorter overall ignition delay of the mixture. For cases with uncorrelated T − ϕ fields, the mean HRR is more distributed over time compared to the corresponding cases with <I>T</I>′ or <I>ϕ</I>′ only. For negatively-correlated cases, however, the temporal evolution of the overall combustion exhibits quite non-monotonic behavior with increasing <I>T</I>′ and <I>ϕ</I>′ depending on <I>T</I> <SUB>0</SUB>. All of these characteristics are found to be primarily related to the 0-D ignition delays of initial mixtures, the relative timescales between 0-D ignition delay and turbulence, and the dominance of the deflagration mode during the ignition. These results suggest that an appropriate combination of <I>T</I>′ and <I>ϕ</I>′ together with a well-prepared T − ϕ distribution can alleviate an excessive pressure-rise rate (PRR) and control ignition-timing in homogeneous charge compression-ignition (HCCI) combustion. In addition, critical species and reactions for the ignition of <I>n</I>-heptane/air mixture through the whole ignition process are estimated by comparing the temporal evolution of the mean mass fractions of important species with the overall reaction pathways of <I>n</I>-heptane oxidation mechanism. The chemical explosive mode analysis (CEMA) verifies the important species and reactions for the ignition at different locations and times by evaluating the explosive index (EI) of species and the participation index (PI) of reactions.</P>

열선에 의한 파이프라인내의 수소/공기 혼합기의 착화온도

김동준 한국화재소방학회 2014 한국화재소방학회논문지 Vol.28 No.4

In order to improve safety for hydrogen network infrastructure, the ignition temperature by hot wire was investigatedfor different hydrogen compositions in pipelines. The result shows that minimum temperature for ignition decreased withdecreasing hydrogen composition. The minimum temperature was confirmed at a hydrogen composition of approximately10 vol.%. The one of the reasons is supposed that buoyancy force should generate the convection of gas mixture. It was also found that humidity had a little effect on ignition temperature, flame temperature. 본 연구에서는 수소 네트워크 설비의 안전성 확보를 위한 기초연구로 파이프라인 내부에서의 수소/공기혼합기의 착화온도를 조사하였다. 착화원으로는 순간적으로 고온이 된 후 일정한 온도를 유지하는 열선을 사용하였다. 수소농도와 열선의 온도를 변화시키며 실험한 결과, 수소농도의 감소에 따라 최저착화온도도 감소하는 경향이 확인되었다. 착화를 위한 열선의 최저온도는 수소 농도 10 vol.%에서 가장 낮음이 확인되었다. 이러한 경향은 열선주변의 부력에 의한 영향이라 생각된다. 또한, 혼합기의 습도는 착화온도, 화염온도에 큰 영향을 미치는 않는 것이 확인되었다.

소나무와 떡갈나무의 주요 부위별 착화특성에 관한 연구

박영주(Park, Young-Ju),이시영(Lee, Si-Young),신영주(Sin, Young-Ju),김수영(Kim, Su-Young),김영탁(Kim, Young-Tak),이해평(Lee, Hae-Pyeong) 한국화재소방학회 2008 한국화재소방학회 학술대회 논문집 Vol.2008 No.춘계

본 연구에서는 영동지역의 임상별 대표 수종인 소나무와 떡갈나무를 대상으로 주요 부위별 함수율 측정 및 건조속도와 가연성과의 관계, KRS-RG-9000의 발화온도 시험기를 사용하여 착화특성을 고찰하였다. 강우 후의 함수율은 대체로 생엽과 가지부위가 <TEX>$52{\sim}70%$</TEX> 정도로 높았으며 상온에서 144 시간 경과 시 <TEX>$17{\sim}33%$</TEX>정도로 건조되었으며 낙엽은 함수율이 10% 정도 건조되었다. 착화특성은 부위별로 많은 차이가 있었으며 착화 위험성 순서로는 낙엽>생엽>수피>가지 순서로 나타나 수피와 가지 부위가 발화온도가 높게 나타남에 따라 저온에서 착화가 지연되는 시간이 낙엽과 생엽보다 길게 나타남을 알 수 있었다. In this study, we have carried out test to examine the ignition characteristics, such as a relation of moisture content and combustibility, and ignition temperature using KRS-RG-9000 tester, of significant part of above trees which are representative species of Young Dong Province of Korea. After rainfall, the percentage of moisture content of living leaves and branches was between 52 and 70%. But it was just between 17 and 33% after 144 hours drying at normal temperature. For dead leaves, it was 10% lower than of first. There was a significant difference on ignition characteristics. The hazard of ignition is highest on dead leaves. The ignition temperature of barks and branches is higher so a retard time is long than of living and dead leaves at normal temperature.

저온연소조건에서 n-heptane/alcohol 혼합연료의 냉염과 열염에 대한 착화지연 관찰

송재혁(Jaehyeok Song),강기중(Kijoong Kang),류승협(Seunghyup Ryu),최경민(Gyungmin Choi),김덕줄(Duckjool Kim) 한국연소학회 2013 한국연소학회지 Vol.18 No.4

The ignition delay time is an important factor to understand the combustion characteristics of internal combustion engine. In this study, ignition delay times of cool and thermal flame were observed separately in homogeneous charge compression ignition(HCCI) engine. This study presents numerical investigation of ignition delay time of n-heptane and alcohol(ethanol and n-butanol) binary fuel. The O₂ concentration in the mixture was set 9-10% to simulate high exhaust gas recirculation(EGR) rate condition. The numerical study on the ignition delay time was performed using CHEMKIN codes with various blending ratios and EGR rates. The results revealed that the ignition delay time increased with increasing the alcohol fraction in the mixture due to a decrease of oxidation of n-heptane at the low temperature. From the numerical analysis, ethanol needed more radical and higher temperature than n-butanol for oxidation. In addition, thermal ignition delay time is sharply increasing with decreasing O₂ fraction, but cool flame ignition delay time changes negligibly for both binary fuels. Also, in high temperature regime, the ignition delay time showed similar tendency with both blends regardless of blending ratio and EGR rate.

저온연소조건에서 n-heptane/alcohol 혼합연료의 냉염과 열염에 대한 착화지연 관찰

송재혁(Jaehyeok Song),강기중(Kijoong Kang),심태영(Taeyoung Shim),류승협(Seunghyup Ryu),최경민(Gyungmin Choi),김덕줄(Duckjool Kim) 한국연소학회 2013 KOSCOSYMPOSIUM논문집 Vol.2013 No.12

The ignition delay time is an important factor to understand the combustion characteristics of internal combustion engine. In this study, ignition delay times of cool and thermal flame were observed separately in homogeneous charge compression ignition(HCCI) engine. This study presents numerical investigation of ignition delay time of n-heptane and alcohol(ethanol and n-butanol) binary fuel. The O₂ concentration in the mixture was set 9-10% to simulate high exhaust gas recirculation(EGR) rate condition. The numerical study on the ignition delay time was performed using CHEMKIN codes with various blending ratios and EGR rates. The results revealed that the ignition delay time increased with increasing the alcohol fraction in the mixture due to a decrease of oxidation of n-heptane at the low temperature. In addition, thermal ignition delay time is sharply increasing with decreasing O₂ fraction, but cool flame ignition delay time changes negligibly for both binary fuels. Also, in high temperature regime, the ignition delay time showed similar tendency with both blends regardless of blending ratio and EGR rate.

Combustion improvement and emission reduction through control of ethanol ratio and intake air temperature in reactivity controlled compression ignition combustion engine

Jo, Seongin,Park, Suhan,Kim, Hyung Jun,Lee, Jong-Tae Elsevier 2019 APPLIED ENERGY Vol.250 No.-

<P><B>Abstract</B></P> <P>The reactivity controlled compression ignition (RCCI) combustion has the potential to simultaneously reduce the NO<SUB>X</SUB> and PM emissions and maintain combustion performance even when injection timing is advanced. Because intake air temperature is an important factor affecting the reactivity of fuels, it is necessary to study optimized fuel supply ratios according to the intake air temperature. Therefore, the purpose of this study was to analyze combustion and exhaust characteristics in relation to the fuel supply ratio, injection timing, and intake air temperature. In this study, ethanol was injected into an intake port; increasing the ethanol supplied ratio increased the ignition delay. Thus, the net indicated mean effective pressure (IMEP<SUB>net</SUB>), compared with conventional diesel combustion, increased from 4.14 to 4.90 bar for the advanced injection timing (BTDC 27°). In addition, because the combustion period was lengthened and combustion temperature lowered, the NO<SUB>X</SUB> emission decreased (19.1 → 2.7 g/kWh); however, the THC (1.1 → 2.5 g/kWh) and CO (5.2 → 10.1 g/kWh) emissions increased. Moreover, burning an homogeneous mixture of ethanol decreased the particulate matter emission from 74 to 45 μg/m<SUP>3</SUP>. However, under high intake air temperature conditions, the effect of ethanol ratio on ignition delay was small. Therefore, the injection timing at which the maximum IMEP<SUB>net</SUB> occurred was retarded. In addition, as the intake air temperature increased, the THC and CO emissions decreased and that of NO<SUB>X</SUB> increased.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Diesel/ethanol RCCI combustion simultaneously reduces NOx and PM. </LI> <LI> The IMEP<SUB>net</SUB> increases as the ethanol supplied ratio increases for early injection. </LI> <LI> RCCI combustion increases the thermal efficiency with reduction in the heat transfer and exhaust losses. </LI> <LI> The increase in the intake air temperature retards the optimal injection timing. </LI> <LI> The higher the intake air temperature, the higher the increase in the diesel supply ratio. </LI> </UL> </P>

석탄점화온도의 직접적인 측정에 의한 촤산화 반응율에 대한 실험적 연구

권종서(Jong Seo Kwon),김량균(Ryang Gyoon Kim),송주헌(Ju Hun Song),장영준(Young June Chang),전충환(Chung Hwan Jeon) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5

본 연구의 목적은 한국화력발전소에서 사용되는 석탄의 촤 산화반응율을 연구하는 것이다. 석탄촤 산화반응율은 입자의 점화온도에 근거한 Semenov 의 열착화이론을 활용하여 도출하였다. 이에 필요한 석탄촤 입자의 점화온도는 가열 및 측정이 가능한 열전대를 통해 직접적인 방법으로 측정하였다. 아역 청탄인 WIRA 와 역청탄인 YAKUTUGOL 의 석탄화 점화온도는 입자 직경의 변화에 따라 측정을 했으며, 입자의 직경이 커질수록 석탄화 점화온도는 상승하였다. 입자 직경에 따른 석탄촤 점화온도의 결과를 통해 활성화 에너지 및 빈도인자를 도출하였다. 본 연구를 통해 도출한 석탄촤 산화반응율 값을 기존의 연구 데이터와 비교한 결과 유사함을 확인할 수 있었다. The experiment was designed to study the char oxidation kinetics of pulverized coals commonly utilized in Korean power plants. The kinetics has been estimated using the Semenov’s thermal spontaneous ignition theory adapted to coal char particle ignition temperature. The ignition temperature of coal char particle is obtained by a direct measurement of the particle temperature with photo detector as well as by means of a solid thermocouple which is used as both a heating and a measuring element. The ignition temperatures for subbituminous coal WIRA and bituminous coal YAKUTUGOL have been measured for 4 sizes in the range of 0.4 - 1 ㎜. The ignition temperature of the particle increases with the increasing diameter. The results were used to calculate the activation energy and the pre-exponential factor. As a result, the kinetics is an agreement with ones reported from other investigations.

석탄점화온도의 직접적인 측정에 의한 아역청탄 촤산화 반응율에 대한 실험적 연구

권종서(Jong Seo Kwon),김량균(Ryang Gyoon Kim),송주헌(Ju Hun Song),장영준(Young June Chang),전충환(Chung Hwan Jeon) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5

The experiment was designed to study the coal char oxidation kinetics. The kinetics has been estimated using the Semenov's thermal spontaneous ignition theory adapted to coal char particle ignition temperature. The ignition temperature of coal char particle is obtained by a method of direct measurement of the particle temperature. The ignition temperature is detected by means of a thermocouple which is used as both a heating and a measuring element. The ignition temperatures for bituminous coal YAKUTUGOL have been measured at 4 particle sizes in the range of 0.4 - 1 ㎜. The ignition temperature of the particle increases with the raising of the diameter. The results were used to calculate the activation energy and the pre-exponential factor. As a result, the kinetics are in agreement with coal char kinetics from other investigations.