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Emir Yilmaz,Mitsuhisa Ichiyanagi,Takashi Suzuki 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.5
Improving thermal efficiency of internal combustion engines has been a priority in the automotive industry. It is necessary to model the heat transfer phenomenon at the intake system and precisely predict intake air’s mass flow rate into the engine cylinder. In the previous studies, the heat transfer at the intake system was modeled as quasi-steady state phenomenon, based on Colburn analogy. Authors developed two empirical equations with the introduction of Graetz and Strouhal numbers. In the present study, further improvements were done by the addition of pressure ratio between the intake manifold and atmospheric pressure, along with Reynolds number in order to characterize the backflow gas effect on intake air temperature. Compared with the experimental results, maximum and average errors of intake air temperature estimations inside the manifold found to be 2.9 % and 0.9 %, respectively.
Bin Guo,Mitsuhisa Ichiyanagi,Takuma Ohashi,Qinyue Zheng,Takashi Suzuki 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7
Ammonia has received significant attention as a fuel due to its carbon-free molecular structure. However, burning ammonia is challenging because of its low laminar burning velocity. To promote the combustion velocity, the authors propose a constant volume combustion chamber with a sub-chamber. This study investigated the effects of the mixing time and equivalence ratio of the ammonia/oxygen/argon mixture on combustion. The mean velocity of the ejection from the sub-chamber can be calculated by evaluating the combustion pressure, mass fraction burned, and volume fraction burned. It was clarified that with the sub-chamber structure, the ejection from the sub-chamber improved the compression and turbulence of unburned gas in the main chamber and increased the mean flame velocity of ammonia combustion. The appropriate glow plug temperature could improve the ignitability of the fuel mixture, leading to increased combustion efficiency, maximum combustion pressure, and reduced combustion time.