Abstract: Hydrogen energy development is an important part of CO₂ emission reduction strategy. At present, hydrogen energy is mainly applied in the form of converting chemical energy into electrical energy through fuel cells. In contrast, hydrogen internal combustion engine (HICE) directly converts hydrogen energy into mechanical energy, which is then used in many fields such as transportation, machine operation and power generation, providing a different way of utilizing hydrogen energy, which plays an important role in promoting the development of hydrogen energy. The biggest difference between HICE and traditional internal combustion engine is that hydrogen replaces the traditional fossil fuel. The combustion characteristics of hydrogen have a great impact on the performance of internal combustion engine, and put forward new requirements for the structure of internal combustion engine. So far, there is little work to understand HICE from the hydrogen combustion characteristics. Therefore, the author attempts to understand the performance of HICE from the perspective of hydrogen combustion characteristics, and especially analyzes and discusses the thermal efficiency, output power, NO_x emission, abnormal combustion and other performance of HICE. These results show that compared with traditional internal combustion engines and fuel cells, HICE has excellent comprehensive performance in energy conservation and emission reduction, power output and cost. It is another effective conversion method from hydrogen energy to electric energy. The development of hydrogen internal combustion engines can also promote the large-scale application of hydrogen energy. The performance of conversion is affected by hydrogen combustion characteristics. The control of hydrogen combustion characteristics is important to improve the performance of HICE.

Key words: hydrogen internal combustion engine, hydrogen combustion characteristics, thermal efficiency, NO_x emission, , abnormal combustion