직접 분사식 수소 엔진의 연료 분사 각도와 당량비에 따른 연소 특성에 관한 수치적 연구

Abstract

Hydrocarbon-based fuels currently dominate the global energy system. Hydrocarbon-based fuel are very easy to transport, store, and use, but have a fatal disadvantage of emitting a large amount of harmful exhaust gases including greenhouse gases. As environment issues emerge, national and corporate efforts are being made to achieve carbon net zero. Many researches have been conducted to increase the thermal efficiency and performance of internal combustion engines using existing hydrocarbon fuels and to reduced their emissions. However, in order to ultimately achieve carbon neutrality, it is essential to fundamentally decarbonize fuels rather than simply reducing the reliance on internal combustion engines. Therefore, it is necessary to stop using hydrocarbon-based fuels and pursue the selective evolution of the internal combustion engine into a clean engine through the use of hydrogen, a carbon-free fuel. In this study, a 2.0 L class research engine was designed, and research was conducted through numerical methods. Simple performance, emissions, and combustion characteristics of the research engine were analyzed through 1D simulation. Based on the 1D numerical analysis result, 3D CFD analysis was performed. The behavior of the hydrogen spray in the cylinder was visually analyzed through 3D CFD analysis. The spray pattern and behavior were analyzed by changing the spray angle considering various equivalence ratio. A 45-degree spray angle results in the largest turbulent kinetic energy in the cylinder for all equivalence ratio conditions; however, misfires occur in the lean condition. Although hydrogen has a wide flammability range, poor mixture formation under lean conditions can result in misfires. A 60-degree spray angle results in the highest combustion temperatures and pressures for all equivalence ratio conditions and, correspondingly, the highest emissions of nitrogen oxides.