直喷氢内燃机实现 NO_x 近零排放的试验研究

The nitrogen oxides (NO_x) emission level of a direct injection hydrogen engine is relatively high due to the uneven mixture distribution in the cylinder and high combustion temperature. The effect of excessive air coefficient, speed, ignition angle, and hydrogen injection pressure on NO_x emission was investigated to explore the control method of reducing NO_x emission with a 2.0 L naturally aspirated direct-injection hydrogen engine. Without post-treatment, the working boundary of the maximum power with near-zero-emission (NO_x ≤ 20×10^-6) was achieved by the coupling of multiple parameters. The results show that NO_x emissions can be significantly reduced by lean-burning and delaying the ignition angle with making a sacrifice to a small extend in a small amount of thermal efficiency and combustion stability. The maximum power in the near-zero emission working area is 21.5 kW and the maximum thermal efficiency is 39%, and near zero emission can be achieved at all working points in this area.