| Abstract:In order to meet the new NH3 emission limits of China VI Emission Standards, a “slightly-rich air-fuel ratio and Ammonia Slip CatalystASC (ASC)” control strategy is developed and applied in this paper, which is based on NH3 emission generation mechanism and a large amount of engineering test data. Besides, a matching development test is carried out on a certain natural gas engine, which is proved to meet the requirements of the China VI Emission Standards. The test results show that: 1) NH3 emissions are derived from the catalytic converter, not from the original emissions of natural gas engines. 2) ASC using 0.177×10-3g/cm35g/ft3 precious metal content can achieve 72.2% conversion efficiency. By increasing the content of precious metals, the conversion efficiency has no great changes. 3) After post-processing of ASC with 0.177×10-3g/cm35g/ft3 precious metal content, NH3 emission reaches the lowest level with Air-fuel ratio being 0.996, which is lower than the standards. |