Studies on Injection and Mixture Characteristics of High Pressure H₂ and O₂ under Ar atmosphere = Studies on Injection and Mixture Characteristics of High Pressure H₂ and O₂ under Ar atmosphere

다국어 초록 (Multilingual Abstract)

Facing with the hydrogen energy era in future, the development of high-efficiency and zero-emissions of power system is a worldwide problem and challenge. As a potential way to achieve high-efficiency and zero-emissions, the main idea of argon cycled engine concept is to use hydrogen as fuel and pure oxygen as oxidant in the combustion cycle of traditional internal combustion engine, and use Ar (with the specific heat ratio of up to 1.67) as intake charge instead of N₂. Argon cycled engine can substantially increase the theoretical thermal efficiency of traditional combustion engine and meanwhile avoid NOx emissions problem.
Since N₂ is replaced with Ar, the in-cylinder ambient density increases, which makes the in-cylinder mixture process of the direct injected gas an outstanding problem. In this paper, studies on penetration length, cone angle, entrainment rate, under-expanded region and other characteristics of H₂ and O₂ injection into the Ar environment were conducted based on experimental method.
Based on the high background pressure constant volume chamber and the high-speed camera system, the shape of gas jets under different conditions was studied by shadowing method. Maximum injection pressure is 10MPa. Maximum environment pressure is 1.2MPa.The experimental results show that increase of the injection pressure or the decrease of the environmental pressure leads to significant increases of the gas penetration length. Jet penetration length of O₂ is slightly lower than H₂ by 0-6%. The cone angle of the gas jet increases slightly with the increase of the injection pressure and the ambient pressure. Under all the experimental pressure boundary conditions, the H₂ jet cone angles are between 32 ° and 38 ° and the cone angles of the O₂ jet are between 22 ° and 28 °; The entrainment rate of the gas jet increases with increment of the injection pressure, the ambient pressure and the injection duration. Jet entrainment rate of O₂ is 2.43 to 2.98 times higher than H₂ jet.