• Proceedings of the KSME Conference
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• 2000.04b
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• pp.447-452
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• 2000

The low-emission and high-performance diesel combustion is an important issue in the combustion research community. In order to understand the detailed diesel flame field involving the complex Physical Processes, It Is quite desirable to study diesel spray dynamics, auto-ignition and spray flame propagation. Dynamics of fuel spray is a crucial element for air-fuel mixture formation flame stabilization and pollutant formation. In the present study, the diesel RCM (Rapid Compression Machine) and the Electric Control injection system have been designed and developed to investigate the effects of injection Pressure, injection timing, and intake air temperature on spray dynamics and diesel combustion processes. In terms of the macroscopic spray combustion characteristics it is observed that the fuel jet atomization and the droplet breakup processes become much faster by increasing the injection pressure and the spray angle. With increasing the cylinder pressure there is a tendency that the shape of spray pattern in the downstream region tends to be spherical due to the increase of air density and the corresponding drag force. Effects of intake temperature and injection pressure on auto-ignition is experimently analysed and discussed in detail.

• Journal of the Korean Institute of Gas
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• v.20 no.2
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• pp.16-22
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• 2016

Auto ignition characteristic is an important factor for handling combustible substance and fire prevention. This research studied about auto ignition characteristic and activation energy of Ethylene Glycol (EG) and Diethylene Glycol (DEG) by using ASTM D2155 type ignition temperature measuring apparatus. As the auto ignition temperatures, it was possible to get $434^{\circ}C$ for EG within sample amount range of $75{\sim}160{\mu}l$ and $387^{\circ}C$ for DEG within sample amount range of $130{\sim}150{\mu}l$. Also, it was possible to get $579^{\circ}C$ and $569^{\circ}C$ as instantaneous ignition temperatures with sample amount of $140{\mu}l$ for EG and DEG respectively. By using least square method from Semenov equation on measured ignition temperature and ignition delay time from this study, it was possible to calculate activation energy of EG as 25.41 Kcal/mol and DEG as 14.07 Kcal/mol. Therefore, it was possible to claim that DEG has more risk of auto ignition since the auto ignition temperature, instantaneous ignition temperature and activation energy of DEG is lower than EG.

• Journal of ILASS-Korea
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• v.5 no.4
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• pp.66-71
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• 2000

The present study is mainly motivated to investigate the vaporization, auto-ignition and combustion processes in the high-pressure engine conditions. The high-pressure vaporization model is developed to realistically simulate the spray dynamics and vaporization characteristics in high-pressure and high-temperature environment. The interaction between chemistry and turbulence is treated by employing the Representative Interactive Flamelet (RIF) Model. The detailed chemistry of 114 elementary steps and 44 chemical species is adopted for the n-heptane/air reaction. In order to account for the spatial inhomogeneity of the scalar dissipation rate, the multiple RIFs are introduced. Numerical results indicate that the RIF approach together with the high-pressure vaporization model successfully predicts the ignition delay time and location as well as the essential features of a spray ignition and combustion processes.

• Journal of the Korean Society of Combustion
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• v.12 no.3
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• pp.33-39
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• 2007

The present study is mainly motivated to investigate the vaporization, auto-ignition and combustion processes in high-pressure engine conditions. In order to realistically simulate the dimethyl ether (DME) spray dynamics and vaporization characteristics in high-pressure and high-temperature environment, the high-pressure vaporization model is utilized. The interaction between chemistry and turbulence is treated by employing the Representative Interaction Flamelet (RIF) model. The detailed chemistry of 336 elementary steps and 78 chemical species is used for the DME/air reaction. Numerical results indicate that the RIF approach, together with the high-pressure vaporization model, successfully predicts the essential feature of ignition and spray combustion processes.

• Journal of ILASS-Korea
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• v.10 no.4
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• pp.16-25
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• 2005

The present study is mainly motivated to investigate the vaporization, auto-ignition and combustion processes in high-pressure engine conditions. In order to realistically simulate the dimethyl ether (DME) spray dynamics and vaporization characteristics in high-pressure and high-temperature environment, the high-pressure vaporization model is utilized. The interaction between chemistry and turbulence is treated by employing the Representative Interaction Flamelet(RIF) model. The detailed chemistry of 336 elementary steps and 78 chemical species is used for the DME/air reaction. Numerical results indicate that the RIF approach, together with the high-pressure vaporization model, successfully predicts the essential feature of ignition and spray combustion processes.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.5
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• pp.48-56
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• 2009

The auto-ignition tests of hybrid rockets with the concentrated hydrogen peroxide as an oxidizer were presented. Auto-ignition was successfully demonstrated by injecting decomposed gases from $H_2O_2$ into paraffin or polyethylene fuels. In addition, restart and instant ignition were realized with this rocket. For stable combustion, a higher $L^*$ value was required for the paraffin combustion compared with PE. On the other hand, much faster response time was demonstrated in case of a paraffin, which was 13 and 30 ms at ignition delay and rise time respectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.499-502
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• 2009

The auto-ignition tests of hybrid rockets with the concentrated hydrogen peroxide as an oxidizer were presented. Auto-ignition, restartability, and instant ignition were successfully demonstrated by injecting decomposed gases from $H_2O_2$ into paraffin or polyethylene fuels. In addition, much faster response time was demonstrated in case of a paraffin, which was 13 and 30 ms at ignition delay and rise time respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.11
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• pp.749-757
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• 2017

To cope with the development of alternative fuels and international environmental regulations, this study provides a numerical analysis of the effects of composition and temperature changes of n-decane and ethanol on auto-ignition characteristics. CHEMKIN-PRO is used as the analysis program and the LLNL model is used as the reaction model. The numerical results show that the ignition delay time increases as the mole fraction of ethanol increases for temperatures below 1000 K, where low temperature reactions occur. Because of the high octane number of ethanol, the high percentage of ethanol delays the increase in the concentration of OH radicals that cause ignition. The oxygen concentration in the mixture is changed to apply the exhaust gas recirculation and a numerical analysis is then performed. As the oxygen concentration decreases, the total ignition delay time increases because the nitrogen gas acts as a thermal load in the combustion chamber.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.143-149
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• 2008

The present study is mainly motivated to investigate the vaporization, auto-ignition and spray combustion processes in DI diesel engine using DME and n-heptane. In order to realistically simulate the dimethyl ether (DME) spray dynamics and vaporization characteristics in high-pressure and high-temperature environment, the high-pressure vaporization model has been utilized. The interaction between chemistry and turbulence is treated by employing the Representative Interaction Flamelet (RIF) model. The detailed chemistry of 336 elementary steps and 78 chemical species is used for the DME/air reaction. Based on numerical results, the detailed discussion has been made for the distinctly different combustion characteristics of DME diesel engine in term of vaporization, ignition delay, pollutant formation, and heat release rate.

• Journal of Power System Engineering
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• v.13 no.2
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• pp.5-10
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• 2009

In recently, studies concerned to the diesel engine uses a natural gas as a fuel oil whose infra has been built already was approached to PCCI or HCCI with keeping a high thermal efficiency and reducing NOx and PM have been researching actively in normally single cylinder. An ignition source is required to bum the natural gas by a spark plug in gasoline engines, due to a higher auto-ignition temperature of natural gas. Then gas oil and DME were introduced as the ignition source. In this study as basic data for practical use of natural gas PCCI and HCCI engines, combustion characteristics and emission characteristics on 4-cylinders natural gas PCCI and HCCI engines with gas oil and DME as ignition sources were analyzed and the engine load range that is main object for practical use of PCCI and HCCI engines was made clearly by empirical experiment.