• Title/Summary/Keyword: Auto-ignition Characteristics

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TRANSIENT FLAMELET MODELING FOR COMBUSTION PROCESSES OF HSDI DIESEL ENGINES

  • Kim, H.J.;Kang, S.M.;Kim, Y.M.;Lee, J.H.;Lee, J.K.
    • International Journal of Automotive Technology
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    • v.7 no.2
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    • pp.129-137
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    • 2006
  • The representative interactive flamelet(RIF) concept has been applied to numerically simulate the combustion processes and pollutant formation in the HSDI diesel engine. In order to account for the spatial inhomogeneity of the scalar dissipation rate, the eulerian particle flamelet model using the multiple flamelets has been employed. The vaporization effects on turbulence-chemistry interaction are included in the present RIF procedure. the results of numerical modeling using the rif concept are compared with experimental data and with numerical results of the widely-used ad-hoc combustion model. Numerical results indicate that the rif approach including the vaporization effect on turbulent spray combustion process successfully predicts the ignition delay characteristics as well as the pollutant formation in the HSDI diesel engines.

The Evaluation of Hazard by Measurement of Combustible Characteristics of n-Tetradecane (노말테트라데칸의 연소특성치 측정에 의한 위험성 평가)

  • Ha, Dong-Myeong
    • Journal of the Korean Society of Safety
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    • v.27 no.5
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    • pp.70-76
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    • 2012
  • For the safe handling of n-tetradecane, the lower flash points and the upper flash point, fire point, AITs (auto-ignition temperatures) by ignition delay time were experimented. Also lower and upper explosion limits by using measured the lower and upper flash points for n-tetradecane were calculated. The lower flash points of n-tetradecane by using closed-cup tester were measured $104^{\circ}C$ and $112^{\circ}C$. The lower flash points and fire point of n-tetradecane by using open cup tester were measured $113^{\circ}C$ and $115^{\circ}C$, respectively. This study measured relationship between the AITs and the ignition delay times by using ASTM E659 apparatus for n-tetradecane. The experimental AIT of n-tridecane was $207^{\circ}C$. The calculated lower and upper explosion limit by using measured lower $104^{\circ}C$ and upper flash point $140^{\circ}C$ for n-tetradecane were 0.63 Vol.% and 3.18 Vol%.

Start of Combustion Detection Method for Gasoline Homogeneous Charge Compression Ignition Engine (가솔린 균일 예혼합 압축착화 엔진의 착화시점 검출)

  • Choe, Doo-Won;Lee, Min-Kwang;SunWoo, Myoung-Ho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.4
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    • pp.151-158
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    • 2008
  • Gasoline Homogeneous Charge Compression Ignition (HCCI) combustion is a new combustion concept. Unlike the conventional internal combustion engine, the premixed fuel mixture with high residual gas rate is auto-ignited and burned without flame propagation. There are several operating factors which affect HCCI combustion such as start of combustion (SOC), residual gas fraction, engine rpm, etc. Among these factors SOC is a critical factor in the combustion because it affects exhaust gas emissions, engine power, fuel economy and combustion characteristics. Therefore SOC of gasoline HCCI should be controlled precisely, and SOC detection should be preceded SOC control. This paper presents a control oriented SOC detection method using 50 percent normalized difference pressure. Normalized difference pressure is defined as the normalized value of difference pressure and difference pressure is difference between the in-cylinder firing pressure and the motoring pressure. These methods were verified through the HCCI combustion experiments. The SOC detection method using difference pressure provides a fast and precise SOC detection.

DME and Diesel HCCI Combustion Characteristics (DME와 Diesel의 HCCI 연소특성 비교)

  • Lee, Joo-Kwang;Kook, Sang-Hoon;Park, Cheol-Woong;Bae, Choong-Sik
    • 한국연소학회:학술대회논문집
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    • 2003.12a
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    • pp.231-236
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    • 2003
  • HCCI(Homogeneous Charge Compression Ignition) combustion is an advanced combustion process explained as a homogeneously premixed charge of a fuel where air is admitted into the cylinder and compression ignited. It has possibility to reduce NOx by spontaneous auto-ignition at multiple points that allows very lean combustion resulting in low combustion temperatures. Particulate matters (PM) could be also reduced by the homogeneous combustion and no fuel-rich zones. Injection timing is extremely advanced to achieve homogeneous charge where a diesel fuel could not be vaporized sufficiently due to low pressure and low temperature condition. Also the over-penetration could be a severe problem. The small injection angle and multi-hole injectors were applied to solve these problems. Dimethyl ether (DME) as an altenative fuel was also applied to relive the bad vaporization problem associated with early injection of diesel fuel. Neat DME has a very high cetane rating and high vapor pressure. Contained oxygen reduces soot during the combustion. Experimental result shows DME can be easily operated in an HCCI engine. PM shows almost zero value and NOx is reduced more than 90% compared to direct-injection diesel engine operating mode but problem of early ignition needs more investigation.

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The Measurement and Investigation of Fire and Explosion Characteristics of Cyclohexanone (사이클로헥사논의 화재 및 폭발 특성치의 측정 및 고찰)

  • Ha, Dong-Myeong
    • Fire Science and Engineering
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    • v.25 no.4
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    • pp.28-34
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    • 2011
  • For the safe handling of cyclohexanone, the explosion limits at $25^{\circ}C$ were investigated. The lower flash points and AITs (auto-ignition temperatures) by ignition time delay for cyclohexanone were experimented. By using the literatures data, the lower and upper explosion limits of cyclohexanone recommended 1.1 Vol.% ($100^{\circ}C$) and 9.4 Vol.%, respectively. The lower flash points of cyclohexanone were experimented $42{\sim}43^{\circ}C$ by using closed-cup tester and $49{\sim}51^{\circ}C$ by using open cup tester. This study measured relationship between the AITs and the ignition delay times by using ASTM E659-78 apparatus for cyclohexanone and the experimental AIT of cyclohexanone was $415^{\circ}C$.

Effect of Nitrogen and Carbon Dioxide on DME Homogeneous Charge Compression Ignition Engine (DME 예혼합 압축착화 엔진에서 질소와 이산화탄소의 영향)

  • Jang, Jin-Young;Bae, Choong-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.5
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    • pp.171-178
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    • 2008
  • The combustion and exhaust emission characteristics were investigated in an DME fueled HCCI engine. Carbon dioxide, nitrogen and mixed gas, which was composed of carbon dioxide and nitrogen, were used as control parameters of combustion and exhaust emission. As the oxygen concentration in induction air, which was occurred by carbon dioxide, nitrogen and mixed gas, was reduced, the start of auto-ignition was retarded and the burn duration was extended due to obstruction of combustion and reduction of combustion temperature. Due to these fact, indicated mean effective pressure was increased and indicated combustion efficiency was decreased by carbon dioxide, nitrogen and mixed gas. In case of exhaust emission, hydrocarbon and carbon monoxide was increased by reduction of oxygen concentration in induction air. Especially, partial burning was appeared at lower than about 18% of oxygen concentration by supplying carbon dioxide. However it was overcome by intake air heating.

Application of Water Mist System for a Power Transformer Room -Cooling Characteristics (Part 2) (변압기실 화재에 대한 미분무수 소화시스템의 적용 -냉각특성을 중심으로(Part 2))

  • Choi Byung-Il;Han Yong-Shik;Kim Myung-Bae
    • Fire Science and Engineering
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    • v.19 no.4 s.60
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    • pp.37-41
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    • 2005
  • The present study describes the cooling performance of two kinds of water mist systems used in fire extinguishment. The cooling is necessary for the prevention of an auto re-ignition of the power transformer. A heat source for such the re-ignition is the accumulated thermal energy in the dielectric oil from the transformer core. Because of the weight of the real core, reduced-scale experiments are carried out. A similarity analysis Is also performed to determine the discharge time of the water mist systems from the experimental results. The discharge time to prevent the re-ignition in the real-scale transformer is estimated about 12 hour from the similarity analysis of the reduced-scale experiments.

Measurement of Combustible Characteristics of EC(Ethylene Carbonate) for Battery Electrolyte Organic Solvent (배터리 전해질 유기용매인 EC(Ethylene Carbonate)의 연소특성치 측정)

  • Yu-Ri Jang;Yu-Seon Jang;Jae-Jun Choi;Dong-Myeong Ha
    • Journal of the Korean Institute of Gas
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    • v.27 no.4
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    • pp.50-55
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    • 2023
  • Lithium-ion secondary batteries are currently in high demand and supply. The purpose of this study is to secure the safety of the process by studying the combustion characteristics of EC(Ethylene Carbonate), Which is mainly used as an electrolyte organic solvent for lithium ion batteries. The flash points of the EC by using Setaflash and Pensky-Martens closed-cup testers were experimented at 141 ℃ and 143 ℃, respectively. The flash points of the EC by Tag and Cleveland open cup testers were experimented at 152 ℃ and 156 ℃, respectively. The AIT(Auto Ignition Temperature) of the EC was experimented at 420 ℃. The LEL(Lower Explosive Limit) calculated by using lower flash point of Setaflash was calculated at 3.6 Vol.%.

A Study on the Spontaneous Ignition Characteristics of Wood Pellets related to Change in Flow Rate (공기유량의 변화에 대한 우드펠릿의 자연발화 특성에 관한 연구)

  • Kim, Hyeong-Seok;Choi, Yu-Jung;Choi, Jae-Wook
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.4
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    • pp.590-596
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    • 2019
  • Uses of fossil fuels like coal and oil increases with industrial development, and problems like abnormal climate come up as greenhouse gas increases. Accordingly, studies are actively conducted on eco-friendly renewable energy as a replacement for the main resources, and especially, wood pellets with high thermal efficiency are in the limelight as an alternative fuel in thermal power stations and gas boilers. However, despite a constant increase in their usage, few studies are conducted on their risks like fire and spontaneous combustion. Thus, this study found the auto-ignition temperature and critical ignition temperature of wood pellets with a change in flow rate in a thermostatic bath, using a sample vessel with 20 cm in length, 20 cm in height and 14 cm in thickness to predict their ignition characteristics. Consequently, at the flow rate of 0 NL/min, as the core temperature of the sample increased to higher than the ambient temperature, they ignited at $153^{\circ}C$, when the critical ignition temperature was $152.5^{\circ}C$. At the flow rates of 0.5 NL/min and 1.0 NL/min, it was $149.5^{\circ}C$, and at the flow rate of 1.5 NL/min, it was $147.5^{\circ}C$. Consequently, at the same storage, the more the flow rate, the lower the critical ignition temperature became.

Effect of Fuel Nozzle Configuration on the Reduction of NOx Emission in Medium-speed Marine Diesel Engine (연료분사 노즐 형상이 선박용 중형 디젤 엔진의 NOx에 미치는 영향 연구)

  • Yoon, Wook-Hyeon;Kim, Byong-Seok;Ryu, Sung-Hyup;Kim, Ki-Doo;Ha, Ji-Soo
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2005.11a
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    • pp.13-14
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    • 2005
  • Multi-dimensional combustion analysis and experiment has been carried out to investigate the effects of the injector nozzle hole diameter and number on the NOx formation and fuel consumption in HYUNDAI HiMSEN engine. The behavior of spray and combustion phenomena in diesel engine was examined by FIRE code. Wave breakup and Zeldovich models were adopted to describe the atomization characteristics and NOx formation. Wallfilm model suggested by Mundo, et al. and auto-ignition model suggested by Theobald and Cheng were adopted to investigate the spray-wall interaction characteristics and ignition delay. The information of spray angle and spray tip penetration length was extracted from fuel spray visualization experiment and the fuel injection rate profile was extracted from fuel injection system experiment as an input and verification data for the combustion analysis. Next, the nine different nozzle configurations were simulated to evaluate the effect of injector hole diameter and number on the NOx formation and fuel consumption.

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