Study on Modified Natural Gas Engine Considering NO_x Emission

摘要

Existing natural gas engines are modified from gasoline or diesel engine. But there are different combustion and emission mechanism for natural gas from gasoline and diesel. The NO_x emission of modified natural gas engine is higher remarkably than gasoline and diesel. There was also a conflict between NO_x emission and engine power of modified natural gas engine. This paper discusses influence factors of NO_x emission, including compression ratio, excess air coefficient, spark advanced timing, valve overlap angle, turbocharge, EGR rate and exhaust treatment. NO_x emission characteristics of existing modified engine were studied. NO_x emission and engine power of natural gas engine modified from gasoline and diesel engine were compared. Then some suggestion are brought out for descreasing NO_x emission of modified engine and designing low NO_x emission natural gas engine.