小型天然ガスデュアルフュエル機関の燃焼改善に関する研究

Abstract

This study aims at improving exhaust emissions and thermal efficiencies in a natural-gas engine with diesel-fuel pilot injection. Performances and exhaust emissions were measured for various pilot injection conditions under a supercharged condition using a single cylinder small-bore test engine. Two-stage pilot injection was examined varying first/second pilot injection timings and quantities. The results show that two-stage injection offers lower NOx and HC emissions, while the available range of equivalence ratio is restricted. Advanced second injection lowers NOx emission, while it increases HC emission for a fixed BMEP. The smaller amount of second injection is preferable for lower NOx; however, the available range of equivalence ratio is narrower.