• 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.

• Journal of the Korean Society of Visualization
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• v.20 no.2
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• pp.38-44
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• 2022

Due to increasingly strict emission regulations for carbon-based fuels in the shipping industry, there is a significant motivation to investigate the alternative fuel. Ammonia is one of the attractive alternative fuels as a carbon-free fuel. Since ammonia has different properties such as high vapor pressure and low boiling point compared to conventional fuels, further research into ammonia spray behavior is important. In this work, the spray characteristics of ammonia and other fluids (ethanol, n-decane) were compared by using numerical simulation. The results show that the spray characteristics of ammonia differs from those of the others due to the occurrence of flash boiling. The narrow-dispersed spray with accelerated velocity at the center have been observed for ammonia. It is also found that droplets of ammonia achieve smaller diameter with more uniform distribution, leading to better atomization behavior compared to the others.