以满足国六排放标准的重型天然气发动机为研究对象，在昆明地区按照GB 17691规定的WHTC循环测试工况，研究了天然气发动机排气温度、过量空气系数以及排气组分等对NH₃和N₂O排放的影响。研究发现，NH₃和N₂O主要在过量空气系数较小的时候生成。NH₃在发动机排气温度109~326 ℃下大量生成，而N₂O是在排气温度小于350 ℃时生成，特别是在发动机冷起动阶段。NH₃和N₂O的生成受天然气发动机排气成分影响较大，在合适的排气温度下，随着尾气中CO，THC和NO含量的上升，NH₃和N₂O的排放量上升；当尾气中SO₂排放升高时，N₂O排放量上升，NH₃的排放量下降。在WHTC循环测试中，NH₃和N₂O在WHTC循环测试开始后的60 s开始大量生成，其排放量在市区工况下波动较大，在市郊及高速工况下迅速减少。

A heavy-duty natural gas engine meeting China Ⅵ emission standard was taken as the research object. According to the test conditions of WHTC cycle in GB 17691, the effects of exhaust temperature, excess air coefficient and exhaust components on NH₃ and N₂O emissions were investigated at Kunming area. The results show that NH₃ and N₂O mainly generate when the excess air coefficient is small. NH₃ genertes in large quantities at the engine exhaust temperature from 109 ℃ to 326 ℃, while N₂O generates especially at the temperature less than 350 ℃, especially in the cold start stage. The generation of NH₃ and N₂O is greatly affected by the exhaust components of natural gas engine. Under the appropriate exhaust temperature, NH₃ and N₂O emissions increase with the increase of CO, THC and NO emissions. N₂O emission increases and NH₃ emission decreases when SO₂ emission increases. In the WHTC cycle test, NH₃ and N₂O generate in large quantities after 60 s of the start of WHTC cycle test, the generation amount fluctuates greatly in the urban condition and quickly decreases in the suburban condition.